@@ -47,7 +47,8 @@ The whole audio output can viewed as a pipeline transforming one audio format to
...
@@ -47,7 +47,8 @@ The whole audio output can viewed as a pipeline transforming one audio format to
<listitem><para><emphasis> i_physical_channels </emphasis> : Define the channels which are physically encoded in the buffer. This field is a bitmask of values defined in audio_output.h, for instance AOUT_CHAN_CENTER, AOUT_CHAN_LEFT, etc. Beware : the numeric value doesn't represent the number of coefficients per sample, see aout_FormatNbChannels() for that. The coefficients for each channel are always stored interleaved, because it is much easier for the mixer to deal with interleaved coefficients. Consequently, decoders which output planar data must implement an interleaving function. Coefficients must be output in the following order (WG-4 specification) : left, right, left surround, right surround, center, LFE.</para></listitem>
<listitem><para><emphasis> i_physical_channels </emphasis> : Define the channels which are physically encoded in the buffer. This field is a bitmask of values defined in audio_output.h, for instance AOUT_CHAN_CENTER, AOUT_CHAN_LEFT, etc. Beware : the numeric value doesn't represent the number of coefficients per sample, see aout_FormatNbChannels() for that. The coefficients for each channel are always stored interleaved, because it is much easier for the mixer to deal with interleaved coefficients. Consequently, decoders which output planar data must implement an interleaving function. Coefficients must be output in the following order (WG-4 specification) : left, right, left surround, right surround, center, LFE.</para></listitem>
<listitem><para><emphasis> i_original_channels </emphasis> : Define the channels from the original stream which have been used to constitute a buffer. For instance, imagine your output plug-ins only has mono output (AOUT_CHAN_CENTER), and your stream is stereo. You can either use both channels of the stream (i_original_channels == AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT), or select one of them. i_original_channels uses the same bitmask as i_physical_channels, and also features special bits AOUT_CHAN_DOLBYSTEREO, which indicates whether the input stream is downmixed to Dolby surround sound, and AOUT_CHAN_DUALMONO, which indicates that the stereo stream is actually constituted of two mono streams, and only one of them should be selected (for instance, two languages on one VCD).
<listitem><para><emphasis> i_original_channels </emphasis> : Define the channels from the original stream which have been used to constitute a buffer. For instance, imagine your output plug-ins only has mono output (AOUT_CHAN_CENTER), and your stream is stereo. You can either use both channels of the stream (i_original_channels == AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT), or select one of them. i_original_channels uses the same bitmask as i_physical_channels, and also features special bits AOUT_CHAN_DOLBYSTEREO, which indicates whether the input stream is downmixed to Dolby surround sound, and AOUT_CHAN_DUALMONO, which indicates that the stereo stream is actually constituted of two mono streams, and only one of them should be selected (for instance, two languages on one VCD).</para></listitem>
