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Commit b48b2a5c authored by Juha Jeronen's avatar Juha Jeronen Committed by Jean-Baptiste Kempf
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IVTC trivial fixes 2 

Signed-off-by: default avatarJean-Baptiste Kempf <jb@videolan.org>
parent f7c77e92
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modules/video_filter/deinterlace.c
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...@@ -2446,573 +2446,572 @@ static int RenderPhosphor( filter_t *p_filter, ...@@ -2446,573 +2446,572 @@ static int RenderPhosphor( filter_t *p_filter,
* @see CalculateInterlaceScore() * @see CalculateInterlaceScore()
* @see EstimateNumBlocksWithMotion() * @see EstimateNumBlocksWithMotion()
* *
* Overall explanation: * Overall explanation:
* *
* This filter attempts to do in realtime what Transcode's * This filter attempts to do in realtime what Transcode's
* ivtc->decimate->32detect chain does offline. Additionally, it removes * ivtc->decimate->32detect chain does offline. Additionally, it removes
* soft telecine. It is an original design, based on some ideas from * soft telecine. It is an original design, based on some ideas from
* Transcode, some from TVTime, and some original. * Transcode, some from TVTime, and some original.
* *
* If the input material is pure NTSC telecined film, inverse telecine * If the input material is pure NTSC telecined film, inverse telecine
* (also known as "film mode") will (ideally) exactly recover the original * will (ideally) exactly recover the original progressive film frames.
* (progressive film frames. The output will run at 4/5 of the original * The output will run at 4/5 of the original framerate with no loss of
* (framerate with no loss of information. Interlacing artifacts are removed, * information. Interlacing artifacts are removed, and motion becomes
* and motion becomes as smooth as it was on the original film. * as smooth as it was on the original film. For soft-telecined material,
* For soft-telecined material, on the other hand, the progressive frames * on the other hand, the progressive frames alredy exist, so only the
* alredy exist, so only the timings are changed such that the output * timings are changed such that the output becomes smooth 24fps (or would,
* becomes smooth 24fps (or would, if the output device had an infinite * if the output device had an infinite framerate).
* framerate). *
* * Put in simple terms, this filter is targeted for NTSC movies and
* Put in simple terms, this filter is targeted for NTSC movies and * especially anime. Virtually all 1990s and early 2000s anime is
* especially anime. Virtually all 1990s and early 2000s anime is * hard-telecined. Because the source material is like that,
* hard-telecined. Because the source material is like that, * IVTC is needed for also virtually all official R1 (US) anime DVDs.
* IVTC is needed for also virtually all official R1 (US) anime DVDs. *
* * Note that some anime from the turn of the century (e.g. Silent Mobius
* Note that some anime from the turn of the century (e.g. Silent Mobius * and Sol Bianca) is a hybrid of telecined film and true interlaced
* and Sol Bianca) is a hybrid of telecined film and true interlaced * computer-generated effects and camera pans. In this case, applying IVTC
* computer-generated effects and camera pans. In this case, applying IVTC * will effectively attempt to reconstruct the frames based on the film
* will effectively attempt to reconstruct the frames based on the film * component, but even if this is successful, the framerate reduction will
* component, but even if this is successful, the framerate reduction will * cause the computer-generated effects to stutter. This is mathematically
* cause the computer-generated effects to stutter. This is mathematically * unavoidable. Instead of IVTC, a framerate doubling deinterlacer is
* unavoidable. Instead of IVTC, a framerate doubling deinterlacer is * recommended for such material. Try "Phosphor", "Bob", or "Linear".
* recommended for such material. Try "Phosphor", "Bob", or "Linear". *
* * Fortunately, 30fps true progressive anime is on the rise (e.g. ARIA,
* Fortunately, 30fps true progressive anime is on the rise (e.g. ARIA, * Black Lagoon, Galaxy Angel, Ghost in the Shell: Solid State Society,
* Black Lagoon, Galaxy Angel, Ghost in the Shell: Solid State Society, * Mai Otome, Last Exile, and Rocket Girls). This type requires no
* Mai Otome, Last Exile, and Rocket Girls). This type requires no * deinterlacer at all.
* deinterlacer at all. *
* * Another recent trend is using 24fps computer-generated effects and
* Another recent trend is using 24fps computer-generated effects and * telecining them along with the cels (e.g. Kiddy Grade, Str.A.In. and
* telecining them along with the cels (e.g. Kiddy Grade, Str.A.In. and * The Third: The Girl with the Blue Eye). For this group, IVTC is the
* The Third: The Girl with the Blue Eye). For this group, IVTC is the * correct way to deinterlace, and works properly.
* correct way to deinterlace, and works properly. *
* * Soft telecined anime, while rare, also exists. Stellvia of the Universe
* Soft telecined anime, while rare, also exists. Stellvia of the Universe * and Angel Links are examples of this. Stellvia constantly alternates
* and Angel Links are examples of this. Stellvia constantly alternates * between soft and hard telecine - pure CGI sequences are soft-telecined,
* between soft and hard telecine - pure CGI sequences are soft-telecined, * while sequences incorporating cel animation are hard-telecined.
* while sequences incorporating cel animation are hard-telecined. * This makes it very hard for the cadence detector to lock on,
* This makes it very hard for the cadence detector to lock on, * and indeed Stellvia gives some trouble for the filter.
* and indeed Stellvia gives some trouble for the filter. *
* * To finish the list of different material types, Azumanga Daioh deserves
* To finish the list of different material types, Azumanga Daioh deserves * a special mention. The OP and ED sequences are both 30fps progressive,
* a special mention. The OP and ED sequences are both 30fps progressive, * while the episodes themselves are hard-telecined. This filter should
* while the episodes themselves are hard-telecined. This filter should * mostly work correctly with such material, too. (The beginning of the OP
* mostly work correctly with such material, too. (The beginning of the OP * shows some artifacts, but otherwise both the OP and ED are indeed
* shows some artifacts, but otherwise both the OP and ED are indeed * rendered progressive. The technical reason is that the filter has been
* rendered progressive. The technical reason is that the filter has been * designed to aggressively reconstruct film frames, which helps in many
* designed to aggressively reconstruct film frames, which helps in many * cases with hard-telecined material. In very rare cases, this approach may
* cases with hard-telecined material. In very rare cases, this approach may * go wrong, regardless of whether the input is telecined or progressive.)
* go wrong, regardless of whether the input is telecined or progressive.) *
* * Finally, note also that IVTC is the only correct way to deinterlace NTSC
* Finally, note also that IVTC is the only correct way to deinterlace NTSC * telecined material. Simply applying an interpolating deinterlacing filter
* telecined material. Simply applying an interpolating deinterlacing filter * (with no framerate doubling) is harmful for two reasons. First, even if
* (with no framerate doubling) is harmful for two reasons. First, even if * the filter does not damage already progressive frames, it will lose half
* (the filter does not damage already progressive frames, it will lose half * of the available vertical resolution of those frames that are judged
* (of the available vertical resolution of those frames that are judged * interlaced. Some algorithms combining data from multiple frames may be
* interlaced. Some algorithms combining data from multiple frames may be * able to counter this to an extent, effectively performing something akin
* able to counter this to an extent, effectively performing something akin * to the frame reconstruction part of IVTC. A more serious problem is that
* to the frame reconstruction part of IVTC. A more serious problem is that * any motion will stutter, because (even in the ideal case) one out of
* any motion will stutter, because (even in the ideal case) one out of * every four film frames will be shown twice, while the other three will
* every four film frames will be shown twice, while the other three will * be shown only once. Duplicate removal and framerate reduction - which are
* be shown only once. Duplicate removal and framerate reduction - which are * part of IVTC - are also needed to properly play back telecined material
* part of IVTC - are also needed to properly play back telecined material * on progressive displays at a non-doubled framerate.
* on progressive displays at a non-doubled framerate. *
* * So, try this filter on your NTSC anime DVDs. It just might help.
* So, try this filter on your NTSC anime DVDs. It just might help. *
* *
* * Technical details:
* Technical details: *
* *
* * First, NTSC hard telecine in a nutshell:
* First, NTSC hard telecine in a nutshell: *
* * Film is commonly captured at 24 fps. The framerate must be raised from
* Film is commonly captured at 24 fps. The framerate must be raised from * 24 fps to 59.94 fields per second, This starts by pretending that the
* 24 fps to 59.94 fields per second, This starts by pretending that the * original framerate is 23.976 fps. When authoring, the audio can be
* original framerate is 23.976 fps. When authoring, the audio can be * slowed down by 0.1% to match. Now 59.94 = 5/4 * (2*23.976), which gives
* slowed down by 0.1% to match. Now 59.94 = 5/4 * (2*23.976), which gives * a nice ratio made out of small integers.
* a nice ratio made out of small integers. *
* * Thus, each group of four film frames must become five frames in the NTSC
* Thus, each group of four film frames must become five frames in the NTSC * video stream. One cannot simply repeat one frame of every four, because
* video stream. One cannot simply repeat one frame of every four, because * this would result in jerky motion. To slightly soften the jerkiness,
* this would result in jerky motion. To slightly soften the jerkiness, * the extra frame is split into two extra fields, inserted at different
* the extra frame is split into two extra fields, inserted at different * times. The content of the extra fields is (in classical telecine)
* times. The content of the extra fields is (in classical telecine) * duplicated as-is from existing fields.
* duplicated as-is from existing fields. *
* * The field duplication technique is called "3:2 pulldown". The pattern
* The field duplication technique is called "3:2 pulldown". The pattern * is called the cadence. The output from 3:2 pulldown looks like this
* is called the cadence. The output from 3:2 pulldown looks like this * (if the telecine is TFF, top field first):
* (if the telecine is TFF, top field first): *
* * a b c d e Telecined frame (actual frames stored on DVD)
* a b c d e Telecined frame (actual frames stored on DVD) * T1 T1 T2 T3 T4 *T*op field content
* T1 T1 T2 T3 T4 *T*op field content * B1 B2 B3 B3 B4 *B*ottom field content
* B1 B2 B3 B3 B4 *B*ottom field content *
* * Numbers 1-4 denote the original film frames. E.g. T1 = top field of
* Numbers 1-4 denote the original film frames. E.g. T1 = top field of * original film frame 1. The field Tb, and one of either Bc or Bd, are
* original film frame 1. The field Tb, and one of either Bc or Bd, are * the extra fields inserted in the telecine. With exact duplication, it
* the extra fields inserted in the telecine. With exact duplication, it * of course doesn't matter whether Bc or Bd is the extra field, but
* of course doesn't matter whether Bc or Bd is the extra field, but * with "full field blended" material (see below) this will affect how to
* with "full field blended" material (see below) this will affect how to * correctly wxtract film frame 3.
* correctly wxtract film frame 3. *
* * See the following web pages for illustrations and discussion:
* See the following web pages for illustrations and discussion: * http://neuron2.net/LVG/telecining1.html
* http://neuron2.net/LVG/telecining1.html * http://arbor.ee.ntu.edu.tw/~jackeikuo/dvd2avi/ivtc/
* http://arbor.ee.ntu.edu.tw/~jackeikuo/dvd2avi/ivtc/ *
* * Note that film frame 2 has been stored "half and half" into two telecined
* Note that film frame 2 has been stored "half and half" into two telecined * frames (b and c). Note also that telecine produces a sequence of
* frames (b and c). Note also that telecine produces a sequence of * 3 progressive frames (d, e and a) followed by 2 interlaced frames
* 3 progressive frames (d, e and a) followed by 2 interlaced frames * (b and c).
* (b and c). *
* * The output may also look like this (BFF telecine, bottom field first):
* The output may also look like this (BFF telecine, bottom field first): *
* * a' b' c' d' e'
* a' b' c' d' e' * T1 T2 T3 T3 T4
* T1 T2 T3 T3 T4 * B1 B1 B2 B3 B4
* B1 B1 B2 B3 B4 *
* * Now field Bb', and one of either Tc' or Td', are the extra fields.
* Now field Bb', and one of either Tc' or Td', are the extra fields. * Again, film frame 2 is stored "half and half" (into b' and c').
* Again, film frame 2 is stored "half and half" (into b' and c'). *
* * Whether the pattern is like abcde or a'b'c'd'e', depends on the telecine
* Whether the pattern is like abcde or a'b'c'd'e', depends on the telecine * field dominance (TFF or BFF). This must match the video field dominance,
* field dominance (TFF or BFF). This must match the video field dominance, * but is conceptually different. Importantly, there is no temporal
* but is conceptually different. Importantly, there is no temporal * difference between those fields that came from the same film frame.
* difference between those fields that came from the same film frame. * Also, see the section on soft telecine below.
* Also, see the section on soft telecine below. *
* * In a hard telecine, the TFD and VFD must match for field renderers
* In a hard telecine, the TFD and VFD must match for field renderers * (e.g. traditional DVD player + CRT TV) to work correctly; this should be
* (e.g. traditional DVD player + CRT TV) to work correctly; this should be * fairly obvious by considering the above telecine patterns and how a
* fairly obvious by considering the above telecine patterns and how a * field renderer displays the material (one field at a time, dominant
* field renderer displays the material (one field at a time, dominant * field first).
* field first). *
* * The VFD may, *correctly*, flip mid-stream, if soft field repeats
* Note that the VFD may, *correctly*, flip mid-stream, if soft field repeats * (repeat_pict) have been used. They are commonly used in soft telecine
* (repeat_pict) have been used. They are commonly used in soft telecine * (see below), but also occasional lone field repeats exist in some streams,
* (see below), but also occasional lone field repeats exist in some streams, * e.g., Sol Bianca.
* e.g., Sol Bianca. *
* * See e.g.
* See e.g. * http://www.cambridgeimaging.co.uk/downloads/Telecine%20field%20dominance.pdf
* http://www.cambridgeimaging.co.uk/downloads/Telecine%20field%20dominance.pdf * for discussion. The document discusses mostly PAL, but includes some notes
* for discussion. The document discusses mostly PAL, but includes some notes * on NTSC, too.
* on NTSC, too. *
* * The reason for the words "classical telecine" above, when field
* The reason for the words "classical telecine" above, when field * duplication was first mentioned, is that there exists a
* duplication was first mentioned, is that there exists a * "full field blended" version, where the added fields are not exact
* "full field blended" version, where the added fields are not exact * duplicates, but are blends of the original film frames. This is rare
* "duplicates, but are blends of the original film frames. This is rare * in NTSC, but some material like this reportedly exists. See
* in NTSC, but some material like this reportedly exists. See * http://www.animemusicvideos.org/guides/avtech/videogetb2a.html
* http://www.animemusicvideos.org/guides/avtech/videogetb2a.html * In these cases, the additional fields are a (probably 50%) blend of the
* In these cases, the additional fields are a (probably 50%) blend of the * frames between which they have been inserted. Which one of the two
* frames between which they have been inserted. Which one of the two * possibilites is the extra field then becomes important.
* possibilites is the extra field then becomes important. * This filter does NOT support "full field blended" material.
* This filter does NOT support "full field blended" material. *
* * To summarize, the 3:2 pulldown sequence produces a group of ten fields
* To summarize, the 3:2 pulldown sequence produces a group of ten fields * out of every four film frames. Only eight of these fields are unique.
* out of every four film frames. Only eight of these fields are unique. * To remove the telecine, the duplicate fields must be removed, and the
* To remove the telecine, the duplicate fields must be removed, and the * original progressive frames restored. Additionally, the presentation
* original progressive frames restored. Additionally, the presentation * timestamps (PTS) must be adjusted, and one frame out of five (containing
* timestamps (PTS) must be adjusted, and one frame out of five (containing * no new information) dropped. The duration of each frame in the output
* no new information) dropped. The duration of each frame in the output * becomes 5/4 of that in the input, i.e. 25% longer.
* becomes 5/4 of that in the input, i.e. 25% longer. *
* * Theoretically, this whole mess could be avoided by soft telecining, if the
* Theoretically, this whole mess could be avoided by soft telecining, if the * original material is pure 24fps progressive. By using the stream flags
* original material is pure 24fps progressive. By using the stream flags * correctly, the original progressive frames can be stored on the DVD.
* correctly, the original progressive frames can be stored on the DVD. * In such cases, the DVD player will apply "soft" 3:2 pulldown. See the
* In such cases, the DVD player will apply "soft" 3:2 pulldown. See the * following section.
* following section. *
* * Also, the mess with cadence detection for hard telecine (see below) could
* Also, the mess with cadence detection for hard telecine (see below) could * be avoided by using the progressive frame flag and a five-frame future
* be avoided by using the progressive frame flag and a five-frame future * buffer, but no one ever sets the flag correctly for hard-telecined
* buffer, but no one ever sets the flag correctly for hard-telecined * streams. All frames are marked as interlaced, regardless of their cadence
* streams. All frames are marked as interlaced, regardless of their cadence * position. This is evil, but sort-of-understandable, given that video
* position. This is evil, but sort-of-understandable, given that video * editors often come with "progressive" and "interlaced" editing modes,
* editors often come with "progressive" and "interlaced" editing modes, * but no separate "telecined" mode that could correctly handle this
* but no separate "telecined" mode that could correctly handle this * information.
* information. *
* * In practice, most material with its origins in Asia (including virtually
* In practice, most material with its origins in Asia (including virtually * all official US (R1) anime DVDs) is hard-telecined. Combined with the
* all official US (R1) anime DVDs) is hard-telecined. Combined with the * turn-of-the-century practice of rendering true interlaced effects
* turn-of-the-century practice of rendering true interlaced effects * on top of the hard-telecined stream, we have what can only be described
* on top of the hard-telecined stream, we have what can only be described * as a monstrosity. Fortunately, recent material is much more consistent,
* as a monstrosity. Fortunately, recent material is much more consistent, * even though still almost always hard-telecined.
* even though still almost always hard-telecined. *
* * Finally, note that telecined video is often edited directly in interlaced
* Finally, note that telecined video is often edited directly in interlaced * form, disregarding safe cut positions as pertains to the telecine sequence
* form, disregarding safe cut positions as pertains to the telecine sequence * (there are only two: between "d" and "e", or between "e" and the
* (there are only two: between "d" and "e", or between "e" and the * next "a"). Thus, the telecine sequence will in practice jump erratically
* (next "a"). Thus, the telecine sequence will in practice jump erratically * at cuts [**]. An aggressive detection strategy is needed to cope with
* at cuts [**]. An aggressive detection strategy is needed to cope with * this.
* this. *
* * [**] http://users.softlab.ece.ntua.gr/~ttsiod/ivtc.html
* [**] http://users.softlab.ece.ntua.gr/~ttsiod/ivtc.html *
* *
* * Note about chroma formats: 4:2:0 is very common at least on anime DVDs.
* Note about chroma formats: 4:2:0 is very common at least on anime DVDs. * In the interlaced frames in a hard telecine, the chroma alternates
* In the interlaced frames in a hard telecine, the chroma alternates * every chroma line, even if the chroma format is 4:2:0! This means that
* every chroma line, even if the chroma format is 4:2:0! This means that * if the interlaced picture is viewed as-is, the luma alternates every line,
* if the interlaced picture is viewed as-is, the luma alternates every line, * while the chroma alternates only every two lines of the picture.
* while the chroma alternates only every two lines of the picture. *
* * That is, an interlaced frame in a 4:2:0 telecine looks like this
* That is, an interlaced frame from a 4:2:0 telecine looks like this * (numbers indicate which film frame the data comes from):
* (numbers indicate which frame the data comes from): *
* * luma stored 4:2:0 chroma displayed chroma
* luma stored 4:2:0 chroma displayed chroma * 1111 1111 1111
* 1111 1111 1111 * 2222 1111
* 2222 1111 * 1111 2222 2222
* 1111 2222 2222 * 2222 2222
* 2222 2222 * ... ... ...
* ... ... ... *
* * The deinterlace filter sees the stored 4:2:0 chroma. The "displayed chroma"
* The deinterlace filter sees the stored 4:2:0 chroma. * is only generated later in the filter chain (probably when YUV is converted
* The "displayed chroma" is only generated later in the filter chain * to the display format, if the display does not accept YUV 4:2:0 directly).
* (probably when YUV is converted to the display format, if the display *
* does not accept YUV 4:2:0 directly). *
* * Next, how NTSC soft telecine works:
* *
* Next, how NTSC soft telecine works: * a b c d Frame index (actual frames stored on DVD)
* * T1 T2 T3 T4 *T*op field content
* a b c d Frame index (actual frames stored on DVD) * B1 B2 B3 B4 *B*ottom field content
* T1 T2 T3 T4 *T*op field content *
* B1 B2 B3 B4 *B*ottom field content * Here the progressive frames are stored as-is. The catch is in the stream
* * flags. For hard telecine, which was explained above, we have
* Here the progressive frames are stored as-is. The catch is in the stream * VFD = constant and nb_fields = 2, just like in a true progressive or
* flags. For hard telecine, which was explained above, we have * true interlaced stream. Soft telecine, on the other hand, looks like this:
* VFD = constant and nb_fields = 2, just like in a true progressive or *
* true interlaced stream. Soft telecine, on the other hand, looks like this: * a b c d
* * 3 2 3 2 nb_fields
* a b c d * T B B T *Video* field dominance (for TFF telecine)
* 3 2 3 2 nb_fields * B T T B *Video* field dominance (for BFF telecine)
* T B B T *Video* field dominance (for TFF telecine) *
* B T T B *Video* field dominance (for BFF telecine) * Now the video field dominance flipflops every two frames!
* *
* Now the video field dominance flipflops every two frames! * Note that nb_fields = 3 means the frame duration will be 1.5x that of a
* * normal frame. Often, soft-telecined frames are correctly flagged as
* Note that nb_fields = 3 means the frame duration will be 1.5x that of a * progressive.
* normal frame. Often, soft-telecined frames are correctly flagged as *
* progressive. * Here the telecining is expected to be done by the player, utilizing the
* * soft field repeat (repeat_pict) feature. This is indeed what a field
* Here the telecining is expected to be done by the player, utilizing the * renderer (traditional interlaced equipment, or a framerate doubler)
* soft field repeat (repeat_pict) feature. This is indeed what a field * should do with such a stream.
* renderer (traditional interlaced equipment, or a framerate doubler) *
* should do with such a stream. * In the IVTC filter, our job is to even out the frame durations, but
* * disregard video field dominance and just pass the progressive pictures
* In the IVTC filter, our job is to even out the frame durations, but * through as-is.
* disregard video field dominance and just pass the progressive pictures *
* through as-is. * Fortunately, for soft telecine to work at all, the stream flags must be
* * set correctly. Thus this type can be detected reliably by reading
* Fortunately, for soft telecine to work at all, the stream flags must be * nb_fields from three consecutive frames:
* set correctly. Thus this type can be detected reliably by reading *
* nb_fields from three consecutive frames: * Let P = previous, C = current, N = next. If the frame to be rendered is C,
* * there are only three relevant nb_fields flag patterns for the three-frame
* Let P = previous, C = current, N = next. If the frame to be rendered is C, * stencil concerning soft telecine:
* there are only three relevant nb_fields flag patterns for the three-frame *
* stencil concerning soft telecine: * P C N What is happening:
* * 2 3 2 Entering soft telecine at frame C, or running inside it already.
* P C N What is happening: * 3 2 3 Running inside soft telecine.
* 2 3 2 Entering soft telecine at frame C, or running inside it already. * 3 2 2 Exiting soft telecine at frame C. C is the last frame that should
* 3 2 3 Running inside soft telecine. * be handled as soft-telecined. (If we do timing adjustments to the
* 3 2 2 Exiting soft telecine at frame C. C is the last frame that should * "3"s only, we can already exit soft telecine mode when we see
* be handled as soft-telecined. (If we do timing adjustments to the * this pattern.)
* "3"s only, we can already exit soft telecine mode when we see *
* this pattern.) * Note that the same stream may alternate between soft and hard telecine,
* * but these cannot occur at the same time. The start and end of the
* Note that the same stream may alternate between soft and hard telecine, * soft-telecined parts can be read off the stream flags, and the rest of
* but these cannot occur at the same time. The start and end of the * the stream can be handed to the hard IVTC part of the filter for analysis.
* soft-telecined parts can be read off the stream flags, and the rest of *
* the stream can be handed to the hard IVTC part of the filter for analysis. * Finally, note also that a stream may also request a lone field repeat
* * (a sudden "3" surrounded by "2"s). Fortunately, these can be handled as
* Finally, note also that a stream may also request a lone field repeat * a two-frame soft telecine, as they match the first and third
* (a sudden "3" surrounded by "2"s). Fortunately, these can be handled as * flag patterns above.
* (a two-frame soft telecine, as they match the first and third *
* flag patterns above. * Combinations with several "3"s in a row are not valid for soft or hard
* * telecine, so if they occur, the frames can be passed through as-is.
* Combinations with several "3"s in a row are not valid for soft or hard *
* telecine, so if they occur, the frames can be passed through as-is. *
* * Cadence detection for hard telecine:
* *
* Cadence detection for hard telecine: * Consider viewing the TFF and BFF hard telecine sequences through a
* * three-frame stencil. Again, let P = previous, C = current, N = next.
* Consider viewing the TFF and BFF hard telecine sequences through a * A brief analysis leads to the following cadence tables.
* three-frame stencil. Again, let P = previous, C = current, N = next. *
* A brief analysis leads to the following cadence tables. * PCN = stencil position (Previous Current Next),
* * Dups. = duplicate fields,
* PCN = stencil position (Previous Current Next), * Best field pairs... = combinations of fields which correctly reproduce
* Dups. = duplicate fields, * the original progressive frames,
* Best field pairs... = combinations of fields which correctly reproduce * * = see timestamp considerations below for why
* the original progressive frames, * this particular arrangement.
* * = see timestamp considerations below for why *
* this particular arrangement. * For TFF:
* *
* For TFF: * PCN Dups. Best field pairs for progressive (correct, theoretical)
* * abc TP = TC TPBP = frame 1, TCBP = frame 1, TNBC = frame 2
* PCN Dups. Best field pairs for progressive (correct, theoretical) * bcd BC = BN TCBP = frame 2, TNBC = frame 3, TNBN = frame 3
* abc TP = TC TPBP = frame 1, TCBP = frame 1, TNBC = frame 2 * cde BP = BC TCBP = frame 3, TCBC = frame 3, TNBN = frame 4
* bcd BC = BN TCBP = frame 2, TNBC = frame 3, TNBN = frame 3 * dea none TPBP = frame 3, TCBC = frame 4, TNBN = frame 1
* cde BP = BC TCBP = frame 3, TCBC = frame 3, TNBN = frame 4 * eab TC = TN TPBP = frame 4, TCBC = frame 1, TNBC = frame 1
* dea none TPBP = frame 3, TCBC = frame 4, TNBN = frame 1 *
* eab TC = TN TPBP = frame 4, TCBC = frame 1, TNBC = frame 1 * (table cont'd)
* * PCN Progressive output*
* (table cont'd) * abc frame 2 = TNBC (compose TN+BC)
* PCN Progressive output* * bcd frame 3 = TNBN (copy N)
* abc frame 2 = TNBC (compose TN+BC) * cde frame 4 = TNBN (copy N)
* bcd frame 3 = TNBN (copy N) * dea (drop)
* cde frame 4 = TNBN (copy N) * eab frame 1 = TCBC (copy C), or TNBC (compose TN+BC)
* dea (drop) *
* eab frame 1 = TCBC (copy C), or TNBC (compose TN+BC) * On the rows "dea" and "eab", frame 1 refers to a frame from the next
* * group of 4. "Compose TN+BC" means to construct a frame using the
* On the rows "dea" and "eab", frame 1 refers to a frame from the next * top field of N, and the bottom field of C. See ComposeFrame().
* group of 4. "Compose TN+BC" means to construct a frame using the *
* top field of N, and the bottom field of C. See ComposeFrame(). * For BFF, swap all B and T, and rearrange the symbol pairs to again
* * read "TxBx". We have:
* For BFF, swap all B and T, and rearrange the symbol pairs to again *
* read "TxBx". We have: * PCN Dups. Best field pairs for progressive (correct, theoretical)
* * abc BP = BC TPBP = frame 1, TPBC = frame 1, TCBN = frame 2
* PCN Dups. Best field pairs for progressive (correct, theoretical) * bcd TC = TN TPBC = frame 2, TCBN = frame 3, TNBN = frame 3
* abc BP = BC TPBP = frame 1, TPBC = frame 1, TCBN = frame 2 * cde TP = TC TPBC = frame 3, TCBC = frame 3, TNBN = frame 4
* bcd TC = TN TPBC = frame 2, TCBN = frame 3, TNBN = frame 3 * dea none TPBP = frame 3, TCBC = frame 4, TNBN = frame 1
* cde TP = TC TPBC = frame 3, TCBC = frame 3, TNBN = frame 4 * eab BC = BN TPBP = frame 4, TCBC = frame 1, TCBN = frame 1
* dea none TPBP = frame 3, TCBC = frame 4, TNBN = frame 1 *
* eab BC = BN TPBP = frame 4, TCBC = frame 1, TCBN = frame 1 * (table cont'd)
* * PCN Progressive output*
* (table cont'd) * abc frame 2 = TCBN (compose TC+BN)
* PCN Progressive output* * bcd frame 3 = TNBN (copy N)
* abc frame 2 = TCBN (compose TC+BN) * cde frame 4 = TNBN (copy N)
* bcd frame 3 = TNBN (copy N) * dea (drop)
* cde frame 4 = TNBN (copy N) * eab frame 1 = TCBC (copy C), or TCBN (compose TC+BN)
* dea (drop) *
* eab frame 1 = TCBC (copy C), or TCBN (compose TC+BN) * From these cadence tables we can extract two strategies for
* * cadence detection. We use both.
* From these cadence tables we can extract two strategies for *
* cadence detection. We use both. * Strategy 1: duplicated fields ("vektor").
* *
* Strategy 1: duplicated fields. * Consider that each stencil position has a unique duplicate field
* * condition. In one unique position, "dea", there is no match; in all
* Consider that each stencil position has a unique duplicate field * other positions, exactly one. By conservatively filtering the
* condition. In one unique position, "dea", there is no match; in all * possibilities based on detected hard field repeats (identical fields
* other positions, exactly one. By conservatively filtering the * in successive input frames), it is possible to gradually lock on
* possibilities based on detected hard field repeats (identical fields * to the cadence. This kind of strategy is used by the classic IVTC filter
* in successive input frames), it is possible to gradually lock on * in TVTime/Xine by Billy Biggs (Vektor), hence the name.
* to the cadence. This kind of strategy is used by Vektor's classic *
* IVTC filter from TVTime (although there are some implementation * "Conservative" here means that we do not rule anything out, but start at
* differences when compared to ours). * each stencil position by suggesting the position "dea", and then only add
* * to the list of possibilities based on field repeats that are detected at
* "Conservative" here means that we do not rule anything out, but start at * the present stencil position. This estimate is then filtered by ANDing
* each stencil position by suggesting the position "dea", and then only add * against a shifted (time-advanced) version of the estimate from the
* to the list of possibilities based on field repeats that are detected at * previous stencil position. Once the detected position becomes unique,
* the present stencil position. This estimate is then filtered by ANDing * the filter locks on. If the new detection is inconsistent with the
* against a shifted (time-advanced) version of the estimate from the * previous one, the detector resets itself and starts from scratch.
* previous stencil position. Once the detected position becomes unique, *
* the filter locks on. If the new detection is inconsistent with the * The strategy is very reliable, as it only requires running (fuzzy)
* previous one, the detector resets itself and starts from scratch. * duplicate field detection against the input. It is very good at staying
* * locked on once it acquires the cadence, and it does so correctly very
* The strategy is very reliable, as it only requires running (fuzzy) * often. These are indeed characteristics that can be observed in the
* duplicate field detection against the input. It is very good at staying * behaviour of the TVTime/Xine filter.
* locked on once it acquires the cadence, and it does so correctly very *
* often. These are indeed characteristics that can be observed in the * Note especially that 8fps/12fps animation, common in anime, will cause
* behaviour of Vektor's classic filter. * spurious hard-repeated fields. The conservative nature of the method
* * makes it very good at dealing with this - any spurious repeats will only
* Note especially that 8fps/12fps animation, common in anime, will cause * slow down the lock-on, not completely confuse it. It should also be good
* spurious hard-repeated fields. The conservative nature of the method * at detecting the presence of a telecine, as neither true interlaced nor
* makes it very good at dealing with this - any spurious repeats will only * true progressive material should contain any hard field repeats.
* slow down the lock-on, not completely confuse it. It should also be good * (This, however, has not been tested yet.)
* at detecting the presence of a telecine, as neither true interlaced nor *
* true progressive material should contain any hard field repeats. * The disadvantages are that at times the method may lock on slowly,
* (This, however, has not been tested yet.) * because the detection must be filtered against the history until
* * a unique solution is found. Resets, if they happen, will also
* The disadvantages are that at times the method may lock on slowly, * slow down the lock-on.
* because the detection must be filtered against the history until *
* a unique solution is found. Resets, if they happen, will also * The hard duplicate detection required by this strategy can be made
* slow down the lock-on. * data-adaptive in several ways. TVTime uses a running average of motion
* * scores for its history buffer. We utilize a different, original approach.
* The hard duplicate detection required by this strategy can be made * It is rare, if not nonexistent, that only one field changes between
* data-adaptive in several ways. TVTime uses a running average of motion * two valid frames. Thus, if one field changes "much more" than the other
* scores for its history buffer. We utilize a different, original approach. * in fieldwise motion detection, the less changed one is probably a
* It is rare, if not nonexistent, that only one field changes between * duplicate. Importantly, this works with telecined input, too - the field
* two valid frames. Thus, if one field changes "much more" than the other * that changes "much" may be part of another film frame, while the "less"
* in fieldwise motion detection, the less changed one is probably a * changed one is actually a duplicate from the previous film frame.
* duplicate. Importantly, this works with telecined input, too - the field * If both fields change "about as much", then no hard field repeat
* that changes "much" may be part of another film frame, while the "less" * is detected.
* changed one is actually a duplicate from the previous film frame. *
* If both fields change "about as much", then no hard field repeat *
* is detected. * Strategy 2: progressive/interlaced field combinations ("scores").
* *
* * We can also form a second strategy, which is not as reliable in practice,
* Strategy 2: progressive/interlaced field combinations. * but which locks on faster when it does. This is original to this filter.
* *
* We can also form a second strategy, which is not as reliable in practice, * Consider all possible field pairs from two successive frames: TCBC, TCBN,
* but which locks on faster. This is original to this filter. * TNBC, TNBN. After one frame, these become TPBP, TPBC, TCBP, TCBC.
* * These eight pairs (seven unique, disregarding the duplicate TCBC)
* Consider all possible field pairs from two successive frames: TCBC, TCBN, * are the exhaustive list of possible field pairs from two successive
* TNBC, TNBN. After one frame, these become TPBP, TPBC, TCBP, TCBC. * frames in the three-frame PCN stencil.
* These eight pairs (seven unique, disregarding the duplicate TCBC) *
* are the exhaustive list of possible field pairs from two successive * The above tables list triplets of field pair combinations for each cadence
* frames in the three-frame PCN stencil. * position, which should produce progressive frames. All the given triplets
* * are unique in each table alone, although the one at "dea" is
* The field pairs can be used for cadence position detection. The above * indistinguishable from the case of pure progressive material. It is also
* tables list triplets of field pair combinations for each cadence position, * the only one which is not unique across both tables.
* which should produce progressive frames. All the given triplets are unique *
* in each table alone, although the one at "dea" is indistinguishable from * Thus, all sequences of two neighboring triplets are unique across both
* the case of pure progressive material. It is also the only one which is * tables. (For "neighboring", each table is considered to wrap around from
* not unique across both tables. * "eab" back to "abc", i.e. from the last row back to the first row.)
* * Furthermore, each sequence of three neighboring triplets is redundantly
* Thus, all sequences of two neighboring triplets are unique across both * unique (i.e. is unique, and reduces the chance of false positives).
* tables. (For "neighboring", each table is considered to wrap around from * (In practice, though, we already know which table to consider, from the fact
* "eab" back to "abc", i.e. from the last row back to the first row.) * that TFD and VFD must match. Checking only the relevant table makes the
* Furthermore, each sequence of three neighboring triplets is redundantly * strategy slightly more robust.)
* unique (i.e. is unique, and reduces the chance of false positives). *
* * The important idea is: *all other* field pair combinations should produce
* The important idea is: *all other* field pair combinations should produce * frames that look interlaced. This includes those combinations present in
* frames that look interlaced. This includes those combinations present in * the "wrong" (i.e. not current position) rows of the table (insofar as
* the "wrong" (i.e. not current position) rows of the table (insofar as * those combinations are not also present in the "correct" row; by the
* those combinations are not also present in the "correct" row; by the * uniqueness property, *every* "wrong" row will always contain at least one
* uniqueness property, *every* "wrong" row will always contain at least one * combination that differs from those in the "correct" row).
* combination that differs from those in the "correct" row). *
* * We generate the artificial frames TCBC, TCBN, TNBC and TNBN (virtually;
* As for how we use these observations, we generate the artificial frames * no data is actually moved). Two of these are just the frames C and N,
* TCBC, TCBN, TNBC and TNBN (virtually; no data is actually moved). * which already exist; the two others correspond to composing the given
* Two of these are just the frames C and N, which already exist; the two * field pairs. We then compute the interlace score for each of these frames.
* others correspond to composing the given field pairs. We then compute * The interlace scores of what are now TPBP, TPBC and TCBP, also needed,
* the interlace score for each of these frames. The interlace scores * were computed by this same mechanism during the previous input frame.
* of what are now TPBP, TPBC and TCBP, also needed, were computed by * These can be slided in history and reused.
* this same mechanism during the previous input frame. These can be slided *
* in history and reused. * We then check, using the computed interlace scores, and taking into
* * account the video field dominance information, which field combination
* We then check, using the computed interlace scores, and taking into * triplet given in the appropriate table produces the smallest sum of
* account the video field dominance information (to only check valid * interlace scores. Unless we are at PCN = "dea" (which could also be pure
* combinations), which field combination triplet given in the tables * progressive!), this immediately gives us the most likely current cadence
* produces the smallest sum of interlace scores. Unless we are at * position. Combined with a two-step history, the sequence of three most
* PCN = "dea" (which could also be pure progressive!), this immediately * likely positions found this way always allows us to make a more or less
* gives us the most likely current cadence position. Combined with a * reliable detection. (That is, when a reliable detection is possible; if the
* two-step history, the sequence of three most likely positions found this * video has no motion at all, every detection will report the position "dea".
* way always allows us to make a more or less reliable detection. (That is, * In anime, still shots are common. Thus we must augment this with a
* when a reliable detection is possible; note that if the video has no * full-frame motion detection that switches the detector off if no motion
* motion at all, every detection will report the position "dea". In anime, * was detected.)
* still shots are common. Thus we must augment this with a full-frame motion *
* detection that switches the detector off if no motion was detected.) * The detection seems to need four full-frame interlace analyses per frame.
* * Actually, three are enough, because the previous N is the new C, so we can
* The detection seems to need four full-frame interlace analyses per frame. * slide the already computed result. Also during initialization, we only
* Actually, three are enough, because the previous N is the new C, so we can * need to compute TNBN on the first frame; this has become TPBP when the
* slide the already computed result. Also during initialization, we only * third frame is reached. Similarly, we compute TNBN, TNBC and TCBN during
* need to compute TNBN on the first frame; this has become TPBP when the * the second frame (just before the filter starts), and these get slided
* third frame is reached. Similarly, we compute TNBN, TNBC and TCBN during * into TCBC, TCBP and TPBC when the third frame is reached. At that point,
* the second frame (just before the filter starts), and these get slided * initialization is complete.
* into TCBC, TCBP and TPBC when the third frame is reached. At that point, *
* initialization is complete. * Because we only compare interlace scores against each other, no threshold
* * is needed in the cadence detector. Thus it, trivially, adapts to the
* Because we only compare interlace scores against each other, no threshold * material automatically.
* is needed in the cadence detector. Thus it, trivially, adapts to the *
* material automatically. * The weakness of this approach is that any comb metric detects incorrectly
* * every now and then. Especially slow vertical camera pans often get treated
* The weakness of this approach is that any comb metric detects incorrectly * wrong, because the messed-up field combination looks less interlaced
* every now and then. Especially slow vertical camera pans often get treated * according to the comb metric (especially in anime) than the correct one
* wrong, because the messed-up field combination looks less interlaced * (which contains, correctly, one-pixel thick cartoon outlines, parts of
* according to the comb metric (especially in anime) than the correct one * which often perfectly horizontal).
* (which contains, correctly, one-pixel thick cartoon outlines, parts of *
* which often perfectly horizontal). * The advantage is that this strategy catches horizontal camera pans
* * immediately and reliably, while the other strategy may still be trying
* The advantage is that this strategy catches horizontal camera pans * to lock on.
* immediately and reliably, while the other strategy may still be trying *
* to lock on. *
* * Frame reconstruction:
* *
* Frame reconstruction: * We utilize a hybrid approach. If a valid cadence is locked on, we use the
* * operation table to decide what to do. This handles those cases correctly,
* We utilize a hybrid approach. If a valid cadence is locked on, we use the * which would be difficult for the interlace detector alone (e.g. vertical
* operation table to decide what to do. This handles those cases correctly, * camera pans). Note that the operations that must be performed for IVTC
* which would be difficult for the interlace detector alone (e.g. vertical * include timestamp mangling and frame dropping, which can only be done
* camera pans). Note that the operations that must be performed for IVTC * reliably on a valid cadence.
* include timestamp mangling and frame dropping, which can only be done *
* reliably on a valid cadence. * When the cadence fails (we detect this from a sudden upward jump in the
* * interlace scores of the constructed frames), we reset the "vektor"
* When the cadence fails (we detect this from a sudden upward jump in the * detector strategy and fall back to an emergency frame composer, where we
* interlace scores of the constructed frames), we reset the "TVTime" * use ideas from Transcode's IVTC.
* detector strategy and fall back to an emergency frame composer, where we *
* use ideas from Transcode's IVTC. * In this emergency mode, we simply output the least interlaced frame out of
* * the combinations TNBN, TNBC and TCBN (where only one of the last two is
* In the emergency mode, we simply output the least interlaced frame out of * tested, based on the stream TFF/BFF information). In this mode, we do not
* the combinations TNBN, TNBC and TCBN (where only one of the last two is * touch the timestamps, and just pass all five frames from each group right
* tested, based on the stream TFF/BFF information). In this mode, we do not * through. This introduces some stutter, but in practice it is often not
* touch the timestamps, and just pass all five frames from each group right * noticeable. This is because the kind of material that is likely to trip up
* through. This introduces some stutter, but in practice it is often not * the cadence detector usually includes irregular 8fps/12fps motion. With
* noticeable. This is because the kind of material that is likely to trip up * true 24fps motion, the cadence quickly locks on, and stays locked on.
* the cadence detector usually includes irregular 8fps/12fps motion. With *
* true 24fps motion, the cadence quickly locks on, and stays locked on. * Once the cadence locks on again, we resume normal operation based on
* * the operation table.
* Once the cadence locks on again, we resume normal operation based on *
* the operation table. *
* * Timestamp mangling:
* *
* Timestamp mangling: * To make five into four we need to extend frame durations by 25%.
* * Consider the following diagram (times given in 90kHz ticks, rounded to
* To make five into four we need to extend frame durations by 25%. * integers; this is just for illustration, and for comparison with the
* Consider the following diagram (times given in 90kHz ticks, rounded to * "scratch paper" comments in pulldown.c of TVTime/Xine):
* integers; this is just for illustration): *
* * NTSC input (29.97 fps)
* NTSC input (29.97 fps) * a b c d e a (from next group) ...
* a b c d e a (from next group) ... * 0 3003 6006 9009 12012 15015
* 0 3003 6006 9009 12012 15015 * 0 3754 7508 11261 15015
* 0 3754 7508 11261 15015 * 1 2 3 4 1 (from next group) ...
* 1 2 3 4 1 (from next group) ... * Film output (23.976 fps)
* Film output (23.976 fps) *
* * Three of the film frames have length 3754, and one has 3753
* Three of the film frames have length 3754, and one has 3753 * (it is 1/90000 sec shorter). This rounding was chosen so that the lengths
* (it is 1/90000 sec shorter). This rounding was chosen so that the lengths * of the group of four sum to the original 15015.
* (of the group of four sum to the original 15015. *
* * From the diagram we get these deltas for presentation timestamp adjustment
* From the diagram we get these deltas for presentation timestamp adjustment * (in 90 kHz ticks, for illustration):
* (in 90 kHz ticks, for illustration): * (1-a) (2-b) (3-c) (4-d) (skip) (1-a) ...
* (1-a) (2-b) (3-c) (4-d) (skip) (1-a) ... * 0 +751 +1502 +2252 (skip) 0 ...
* 0 +751 +1502 +2252 (skip) 0 ... *
* * In fractions of (p_next->date - p_cur->date), regardless of actual
* In fractions of (p_next->date - p_cur->date), regardless of actual * time unit, the deltas are:
* time unit, the deltas are: * (1-a) (2-b) (3-c) (4-d) (skip) (1-a) ...
* (1-a) (2-b) (3-c) (4-d) (skip) (1-a) ... * 0 +0.25 +0.50 +0.75 (skip) 0 ...
* 0 +0.25 +0.50 +0.75 (skip) 0 ... *
* * This is what we actually use. In our implementation, the values are stored
* This is what we actually use. In our implementation, the values are stored * multiplied by 4, as integers.
* multiplied by 4, as integers. *
* * The "current" frame should be displayed at [original time + delta].
* The "current" frame should be displayed at [original time + delta]. * E.g., when "current" = b (i.e. PCN = abc), start displaying film frame 2
* E.g., when "current" = b (i.e. PCN = abc), start displaying film frame 2 * at time [original time of b + 751 ticks]. So, when we catch the cadence,
* at time [original time of b + 751 ticks]. So, when we catch the cadence, * we will start mangling the timestamps according to the cadence position
* we will start mangling the timestamps according to the cadence position * of the "current" frame, using the deltas given above. This will cause
* of the "current" frame, using the deltas given above. This will cause * a one-time jerk, most noticeable if the cadence happens to catch at
* a one-time jerk, most noticeable if the cadence happens to catch at * position "d". (Alternatively, upon lock-on, we could wait until we are
* position "d". (Alternatively, upon lock-on, we could wait until we are * at "a" before switching on IVTC, but this makes the maximal delay
* at "a" before switching on IVTC, but this makes the maximal delay * [max. detection + max. wait] = 3 + 4 = 7 input frames, which comes to
* [max. detection + max. wait] = 3 + 4 = 7 input frames, which comes to * 7/30 ~ 0.23 seconds instead of the 3/30 = 0.10 seconds from purely
* [7/30 ~ 0.23 seconds instead of the 3/30 = 0.10 seconds from purely * the detection. The one-time jerk is simpler to implement and gives the
* the detection. I prefer the one-time jerk, which also happens to be * faster lock-on.)
* simpler to implement.) *
* * It is clear that "e" is a safe choice for the dropped frame. This can be
* It is clear that "e" is a safe choice for the dropped frame. This can be * seen from the timings and the cadence tables. First, consider the timings.
* seen from the timings and the cadence tables. First, consider the timings. * If we have only one future frame, "e" is the only one whose PTS, comparing
* If we have only one future frame, "e" is the only one whose PTS, comparing * to the film frames, allows dropping it safely. To see this, consider which
* to the film frames, allows dropping it safely. To see this, consider which * film frame needs to be rendered as each new input frame arrives. Secondly,
* film frame needs to be rendered as each new input frame arrives. Secondly, * consider the cadence tables. It is ok to drop "e", because the same
* consider the cadence tables. It is ok to drop "e", because the same * film frame "1" is available also at the next PCN position "eab".
* film frame "1" is available also at the next PCN position "eab". * (As a side note, it is interesting that Vektor's filter drops "b".
* (As a side note, it is interesting that Vektor's filter drops "b". * See the TVTime sources.)
* See the TVTime sources.) *
* * When the filter falls out of film mode, the timestamps of the incoming
* When the filter falls out of film mode, the timestamps of the incoming * frames are left untouched. Thus, the output from this filter has a
* frames are left untouched. Thus, the output from this filter has a * variable framerate: 4/5 of the input framerate when IVTC is active
* variable framerate: 4/5 of the input framerate when IVTC is active * (whether hard or soft), and the same framerate as input when it is not
* (whether hard or soft), and the same framerate as input when it is not * (or when in emergency mode).
* (or when in emergency mode). *
* *
* * For other open-source IVTC codes, which may be a useful source for ideas,
* For other open-source IVTC codes, which may be a useful source for ideas, * see the following:
* see the following: *
* * The classic filter by Billy Biggs (Vektor). Written in 2001-2003 for
* The classic filter by Billy Biggs (Vektor). Written in 2001-2003 for * TVTime, and adapted into Xine later. In xine-lib 1.1.19, it is at
* TVTime, and adapted into Xine later. In xine-lib 1.1.19, it is at * src/post/deinterlace/pulldown.*. Also needed are tvtime.*, and speedy.*.
* src/post/deinterlace/pulldown.*. Also needed are tvtime.*, and speedy.*. *
* * Transcode's ivtc->decimate->32detect chain by Thanassis Tsiodras.
* Transcode's ivtc->decimate->32detect chain by Thanassis Tsiodras. * Written in 2002, added in Transcode 0.6.12. This probably has something
* Written in 2002, added in Transcode 0.6.12. This probably has something * to do with the same chain in MPlayer, considering that MPlayer acquired
* to do with the same chain in MPlayer, considering that MPlayer acquired * an IVTC filter around the same time. In Transcode 1.1.5, the IVTC part is
* an IVTC filter around the same time. In Transcode 1.1.5, the IVTC part is * at filter/filter_ivtc.c. Transcode 1.1.5 sources can be downloaded from
* at filter/filter_ivtc.c. Transcode 1.1.5 sources can be downloaded from * http://developer.berlios.de/project/showfiles.php?group_id=10094
* http://developer.berlios.de/project/showfiles.php?group_id=10094
*/ */
/** /**
......
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