Add Dirac encoding support to VLC using the Schroedinger library.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 1c2a95b85ef3e984fd963e7fff6c1c03693b9255)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

configure.ac

@@ -3060,7 +3060,7 @@ PKG_ENABLE_MODULES_VLC([DIRAC], [], [dirac >= 0.10.0], [dirac encoder], [auto])
 dnl
 dnl  schroedinger decoder plugin (for dirac format video)
 dnl
-PKG_ENABLE_MODULES_VLC([SCHROEDINGER], [], [schroedinger-1.0 >= 1.0.6], [dirac decoder using schroedinger], [auto])
+PKG_ENABLE_MODULES_VLC([SCHROEDINGER], [], [schroedinger-1.0 >= 1.0.10], [dirac decoder and encoder using schroedinger], [auto])
 
 dnl
 dnl  PNG decoder module

modules/codec/schroedinger.c

@@ -8,6 +8,7 @@
  *
  * Authors: Jonathan Rosser <jonathan.rosser@gmail.com>
  *          David Flynn <davidf at rd dot bbc.co.uk>
+ *          Anuradha Suraparaju <asuraparaju at gmail dot com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -31,6 +32,8 @@
 # include "config.h"
 #endif
 
+#include <assert.h>
+
 #include <vlc_common.h>
 #include <vlc_plugin.h>
 #include <vlc_codec.h>
@@ -43,6 +46,27 @@
  *****************************************************************************/
 static int        OpenDecoder  ( vlc_object_t * );
 static void       CloseDecoder ( vlc_object_t * );
+static int        OpenEncoder  ( vlc_object_t * );
+static void       CloseEncoder ( vlc_object_t * );
+
+#define ENC_CFG_PREFIX "sout-schro-"
+
+#define ENC_CHROMAFMT "chroma_fmt"
+#define ENC_CHROMAFMT_TEXT N_("Chroma format")
+#define ENC_CHROMAFMT_LONGTEXT N_("Picking chroma format will force a " \
+                                  "conversion of the video into that format")
+static const char *const enc_chromafmt_list[] =
+  { "420", "422", "444" };
+static const char *const enc_chromafmt_list_text[] =
+  { N_("4:2:0"), N_("4:2:2"), N_("4:4:4") };
+
+
+#define ENC_CODINGMODE "auto_coding_mode"
+#define ENC_CODINGMODE_TEXT N_("Automate picture coding mode")
+#define ENC_CODINGMODE_LONGTEXT N_("Use the input picture to determine how to" \
+                                   " code it - interlaced or progressive")
+
+static const char **ppsz_enc_options = NULL;
 
 vlc_module_begin ()
     set_category( CAT_INPUT )
@@ -51,6 +75,66 @@ vlc_module_begin ()
     set_capability( "decoder", 200 )
     set_callbacks( OpenDecoder, CloseDecoder )
     add_shortcut( "schroedinger" )
+
+    add_submodule()
+    set_description( N_("Dirac video encoder using libschroedinger") )
+    set_capability( "encoder", 105 )
+    set_callbacks( OpenEncoder, CloseEncoder )
+    add_shortcut( "schroedinger", "schro" )
+
+    int i_numopts =  schro_encoder_get_n_settings();
+    /* Allocate for schro encoder options + chroma format + coding mode
+       + null */
+    ppsz_enc_options = (const char **)malloc( sizeof( char * )*( i_numopts + 3 ) );
+    if( unlikely( ppsz_enc_options == NULL ) )
+        return VLC_ENOMEM;
+
+    for( int i = 0; i < i_numopts; ++i ) {
+        const SchroEncoderSetting *p_setting = schro_encoder_get_setting_info( i );
+        bool b_advanced = ( strlen( p_setting->name ) > 6 && !strncmp( p_setting->name, "magic_ ", 6 ) );
+        char *p_cfg_setting_name = malloc( strlen( ENC_CFG_PREFIX ) + strlen( p_setting->name ) + 1 );
+
+        if( unlikely( p_cfg_setting_name == NULL ) )
+            return VLC_ENOMEM;
+
+        strcpy( p_cfg_setting_name, ENC_CFG_PREFIX );
+        strcat( p_cfg_setting_name, p_setting->name );
+
+        ppsz_enc_options[i] = strdup( p_setting->name );
+        switch( p_setting->type ) {
+            case SCHRO_ENCODER_SETTING_TYPE_BOOLEAN:
+                add_bool( p_cfg_setting_name, p_setting->default_value, p_setting->name, p_setting->name, b_advanced );
+                break;
+            case SCHRO_ENCODER_SETTING_TYPE_INT:
+                add_integer( p_cfg_setting_name, p_setting->default_value, p_setting->name, p_setting->name, b_advanced );
+                change_integer_range( p_setting->min, p_setting->max );
+                break;
+            case SCHRO_ENCODER_SETTING_TYPE_DOUBLE:
+                add_float( p_cfg_setting_name, p_setting->default_value, p_setting->name, p_setting->name, b_advanced );
+                change_float_range( p_setting->min, p_setting->max );
+                break;
+            case SCHRO_ENCODER_SETTING_TYPE_ENUM:
+                add_string( p_cfg_setting_name, p_setting->enum_list[(int)p_setting->default_value], p_setting->name, p_setting->name, b_advanced );
+                vlc_config_set( p_config, VLC_CONFIG_LIST, (int)(p_setting->max-p_setting->min+1), p_setting->enum_list, p_setting->enum_list, 0 );
+                break;
+            default:
+                break;
+        }
+        free( p_cfg_setting_name );
+    }
+
+    ppsz_enc_options[i_numopts] = strdup( ENC_CHROMAFMT );
+    add_string( ENC_CFG_PREFIX ENC_CHROMAFMT, "420",
+                ENC_CHROMAFMT_TEXT, ENC_CHROMAFMT_LONGTEXT, false )
+    change_string_list( enc_chromafmt_list, enc_chromafmt_list_text, 0 );
+
+    ppsz_enc_options[i_numopts+1] = strdup( ENC_CODINGMODE );
+    add_bool( ENC_CFG_PREFIX ENC_CODINGMODE, true,
+                ENC_CODINGMODE_TEXT, ENC_CODINGMODE_LONGTEXT, false )
+
+    ppsz_enc_options[i_numopts+2] = NULL;
+
+
 vlc_module_end ()
 
 /*****************************************************************************
@@ -393,3 +477,663 @@ static picture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
     }
 }
 
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static block_t *Encode( encoder_t *p_enc, picture_t *p_pict );
+
+
+/*****************************************************************************
+ * picture_pts_t : store pts alongside picture number, not carried through
+ * encoder
+ *****************************************************************************/
+struct picture_pts_t
+{
+   bool b_empty;      /* entry is invalid */
+   uint32_t u_pnum;  /* dirac picture number */
+   mtime_t i_pts;    /* associated pts */
+};
+
+/*****************************************************************************
+ * encoder_sys_t : Schroedinger encoder descriptor
+ *****************************************************************************/
+#define SCHRO_PTS_TLB_SIZE 256
+struct encoder_sys_t
+{
+    /*
+     * Schro properties
+     */
+    SchroEncoder *p_schro;
+    SchroVideoFormat *p_format;
+    int started;
+    bool b_auto_field_coding;
+
+    uint32_t i_input_picnum;
+    block_fifo_t *p_dts_fifo;
+
+    block_t *p_chain;
+
+    struct picture_pts_t pts_tlb[SCHRO_PTS_TLB_SIZE];
+    mtime_t i_pts_offset;
+    mtime_t i_field_time;
+
+    bool b_eos_signalled;
+    bool b_eos_pulled;
+};
+
+static struct
+{
+    unsigned int i_height;
+    int i_approx_fps;
+    SchroVideoFormatEnum i_vf;
+} schro_format_guess[] = {
+    /* Important: Keep this list ordered in ascending picture height */
+    {1, 0, SCHRO_VIDEO_FORMAT_CUSTOM},
+    {120, 15, SCHRO_VIDEO_FORMAT_QSIF},
+    {144, 12, SCHRO_VIDEO_FORMAT_QCIF},
+    {240, 15, SCHRO_VIDEO_FORMAT_SIF},
+    {288, 12, SCHRO_VIDEO_FORMAT_CIF},
+    {480, 30, SCHRO_VIDEO_FORMAT_SD480I_60},
+    {480, 15, SCHRO_VIDEO_FORMAT_4SIF},
+    {576, 12, SCHRO_VIDEO_FORMAT_4CIF},
+    {576, 25, SCHRO_VIDEO_FORMAT_SD576I_50},
+    {720, 50, SCHRO_VIDEO_FORMAT_HD720P_50},
+    {720, 60, SCHRO_VIDEO_FORMAT_HD720P_60},
+    {1080, 24, SCHRO_VIDEO_FORMAT_DC2K_24},
+    {1080, 25, SCHRO_VIDEO_FORMAT_HD1080I_50},
+    {1080, 30, SCHRO_VIDEO_FORMAT_HD1080I_60},
+    {1080, 50, SCHRO_VIDEO_FORMAT_HD1080P_50},
+    {1080, 60, SCHRO_VIDEO_FORMAT_HD1080P_60},
+    {2160, 24, SCHRO_VIDEO_FORMAT_DC4K_24},
+    {0, 0, 0},
+};
+
+/*****************************************************************************
+ * ResetPTStlb: Purge all entries in @p_enc@'s PTS-tlb
+ *****************************************************************************/
+static void ResetPTStlb( encoder_t *p_enc )
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+    for( int i=0; i<SCHRO_PTS_TLB_SIZE; i++ )
+    {
+        p_sys->pts_tlb[i].b_empty = true;
+    }
+}
+
+
+/*****************************************************************************
+ * StorePicturePTS: Store the PTS value for a particular picture number
+ *****************************************************************************/
+static void StorePicturePTS( encoder_t *p_enc, uint32_t u_pnum, mtime_t i_pts )
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    for( int i=0; i<SCHRO_PTS_TLB_SIZE; i++ )
+    {
+        if( p_sys->pts_tlb[i].b_empty )
+        {
+            p_sys->pts_tlb[i].u_pnum = u_pnum;
+            p_sys->pts_tlb[i].i_pts = i_pts;
+            p_sys->pts_tlb[i].b_empty = false;
+
+            return;
+        }
+    }
+
+    msg_Err( p_enc, "Could not store PTS %"PRId64" for frame %u", i_pts, u_pnum );
+}
+
+/*****************************************************************************
+ * GetPicturePTS: Retrieve the PTS value for a particular picture number
+ *****************************************************************************/
+static mtime_t GetPicturePTS( encoder_t *p_enc, uint32_t u_pnum )
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    for( int i=0; i<SCHRO_PTS_TLB_SIZE; i++ )
+    {
+        if( !p_sys->pts_tlb[i].b_empty &&
+            p_sys->pts_tlb[i].u_pnum == u_pnum )
+        {
+             p_sys->pts_tlb[i].b_empty = true;
+             return p_sys->pts_tlb[i].i_pts;
+        }
+    }
+
+    msg_Err( p_enc, "Could not retrieve PTS for picture %u", u_pnum );
+    return 0;
+}
+
+static inline bool SchroSetEnum( const encoder_t *p_enc, const SchroEncoderSetting *p_setting, const char *psz_value ) {
+    encoder_sys_t *p_sys = p_enc->p_sys;
+    if( psz_value && p_setting && p_setting->type == SCHRO_ENCODER_SETTING_TYPE_ENUM ) {
+        int i_index = -1;
+        int i_list_size = p_setting->max - p_setting->min + 1;
+        for( int i = 0; i < i_list_size; ++i ) {
+            if( strcmp( p_setting->enum_list[i], psz_value ) )
+                continue;
+            i_index = p_setting->min + i;
+            schro_encoder_setting_set_double( p_sys->p_schro, p_setting->name, i_index );
+            return true;
+        }
+        if( i_index == -1 ) {
+            msg_Err( p_enc, "Invalid %s: %s", p_setting->name, psz_value );
+        }
+    }
+    return false;
+}
+
+static bool SetEncChromaFormat( encoder_t *p_enc, uint32_t i_codec )
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    switch( i_codec ) {
+    case VLC_CODEC_I420:
+        p_enc->fmt_in.i_codec = i_codec;
+        p_enc->fmt_in.video.i_bits_per_pixel = 12;
+        p_sys->p_format->chroma_format = SCHRO_CHROMA_420;
+           break;
+    case VLC_CODEC_I422:
+        p_enc->fmt_in.i_codec = i_codec;
+        p_enc->fmt_in.video.i_bits_per_pixel = 16;
+        p_sys->p_format->chroma_format = SCHRO_CHROMA_422;
+        break;
+    case VLC_CODEC_I444:
+        p_enc->fmt_in.i_codec = i_codec;
+        p_enc->fmt_in.video.i_bits_per_pixel = 24;
+        p_sys->p_format->chroma_format = SCHRO_CHROMA_444;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}
+
+
+/*****************************************************************************
+ * OpenEncoder: probe the encoder and return score
+ *****************************************************************************/
+static int OpenEncoder( vlc_object_t *p_this )
+{
+    encoder_t *p_enc = (encoder_t *)p_this;
+    encoder_sys_t *p_sys = p_enc->p_sys;
+    int i_tmp;
+    float f_tmp;
+    bool b_tmp;
+    char *psz_tmp;
+
+    if( p_enc->fmt_out.i_codec != VLC_CODEC_DIRAC &&
+        !p_enc->b_force )
+    {
+        return VLC_EGENERIC;
+    }
+
+    if( !p_enc->fmt_in.video.i_frame_rate || !p_enc->fmt_in.video.i_frame_rate_base ||
+        !p_enc->fmt_in.video.i_height || !p_enc->fmt_in.video.i_width )
+    {
+        msg_Err( p_enc, "Framerate and picture dimensions must be non-zero" );
+        return VLC_EGENERIC;
+    }
+
+    /* Allocate the memory needed to store the decoder's structure */
+    if( ( p_sys = calloc( 1, sizeof( *p_sys ) ) ) == NULL )
+        return VLC_ENOMEM;
+
+    p_enc->p_sys = p_sys;
+    p_enc->pf_encode_video = Encode;
+    p_enc->fmt_out.i_codec = VLC_CODEC_DIRAC;
+    p_enc->fmt_out.i_cat = VIDEO_ES;
+
+    if( ( p_sys->p_dts_fifo = block_FifoNew() ) == NULL )
+    {
+        CloseEncoder( p_this );
+        return VLC_ENOMEM;
+    }
+
+    ResetPTStlb( p_enc );
+
+    /* guess the video format based upon number of lines and picture height */
+    int i = 0;
+    SchroVideoFormatEnum guessed_video_fmt = SCHRO_VIDEO_FORMAT_CUSTOM;
+    /* Pick the dirac_video_format in this order of preference:
+     *  1. an exact match in frame height and an approximate fps match
+     *  2. the previous preset with a smaller number of lines.
+     */
+    do
+    {
+        if( schro_format_guess[i].i_height > p_enc->fmt_in.video.i_height )
+        {
+            guessed_video_fmt = schro_format_guess[i-1].i_vf;
+            break;
+        }
+        if( schro_format_guess[i].i_height != p_enc->fmt_in.video.i_height )
+            continue;
+        int src_fps = p_enc->fmt_in.video.i_frame_rate / p_enc->fmt_in.video.i_frame_rate_base;
+        int delta_fps = abs( schro_format_guess[i].i_approx_fps - src_fps );
+        if( delta_fps > 2 )
+            continue;
+
+        guessed_video_fmt = schro_format_guess[i].i_vf;
+        break;
+    } while( schro_format_guess[++i].i_height );
+
+    schro_init();
+    p_sys->p_schro = schro_encoder_new();
+    if( !p_sys->p_schro ) {
+        msg_Err( p_enc, "Failed to initialize libschroedinger encoder" );
+        return VLC_EGENERIC;
+    }
+    schro_encoder_set_packet_assembly( p_sys->p_schro, true );
+
+    if( !( p_sys->p_format = schro_encoder_get_video_format( p_sys->p_schro ) ) ) {
+        msg_Err( p_enc, "Failed to get Schroedigner video format" );
+        schro_encoder_free( p_sys->p_schro );
+        return VLC_EGENERIC;
+    }
+
+    /* initialise the video format parameters to the guessed format */
+    schro_video_format_set_std_video_format( p_sys->p_format, guessed_video_fmt );
+
+    /* constants set from the input video format */
+    p_sys->p_format->width                  = p_enc->fmt_in.video.i_width;
+    p_sys->p_format->height                 = p_enc->fmt_in.video.i_height;
+    p_sys->p_format->frame_rate_numerator   = p_enc->fmt_in.video.i_frame_rate;
+    p_sys->p_format->frame_rate_denominator = p_enc->fmt_in.video.i_frame_rate_base;
+    unsigned u_asr_num, u_asr_den;
+    vlc_ureduce( &u_asr_num, &u_asr_den,
+                 p_enc->fmt_in.video.i_sar_num,
+                 p_enc->fmt_in.video.i_sar_den, 0 );
+    p_sys->p_format->aspect_ratio_numerator   = u_asr_num;
+    p_sys->p_format->aspect_ratio_denominator = u_asr_den;
+
+    config_ChainParse( p_enc, ENC_CFG_PREFIX, ppsz_enc_options, p_enc->p_cfg );
+
+    int i_numopts =  schro_encoder_get_n_settings();
+
+    for( int i = 0; i < i_numopts; ++i ) {
+        const SchroEncoderSetting *p_setting = schro_encoder_get_setting_info( i );
+        char *p_cfg_setting_name = malloc( strlen( ENC_CFG_PREFIX ) + strlen( p_setting->name ) + 1 );
+        if( unlikely( p_cfg_setting_name == NULL ) )
+            return VLC_ENOMEM;
+
+        strcpy( p_cfg_setting_name, ENC_CFG_PREFIX );
+        strcat( p_cfg_setting_name, p_setting->name );
+
+        switch( p_setting->type ) {
+            case SCHRO_ENCODER_SETTING_TYPE_BOOLEAN:
+                schro_encoder_setting_set_double ( p_sys->p_schro, p_setting->name, var_GetBool( p_enc, p_cfg_setting_name ) );
+                break;
+            case SCHRO_ENCODER_SETTING_TYPE_INT:
+                i_tmp = var_GetInteger( p_enc, p_cfg_setting_name );
+                schro_encoder_setting_set_double( p_sys->p_schro, p_setting->name, i_tmp );
+                /* A kludge to set bitrate to the value in sout-transcode-vb */
+                if( !strcmp( p_setting->name, "bitrate" ) ) {
+                    if( i_tmp == p_setting->default_value )
+                        schro_encoder_setting_set_double( p_sys->p_schro, p_setting->name, p_enc->fmt_out.i_bitrate );
+                       p_enc->fmt_out.i_bitrate = schro_encoder_setting_get_double( p_sys->p_schro, p_setting->name );
+                }
+                break;
+            case SCHRO_ENCODER_SETTING_TYPE_DOUBLE:
+                f_tmp = var_GetFloat( p_enc, p_cfg_setting_name );
+                if( f_tmp >= 0.0 )
+                    schro_encoder_setting_set_double( p_sys->p_schro, p_setting->name, f_tmp );
+                break;
+            case SCHRO_ENCODER_SETTING_TYPE_ENUM:
+                psz_tmp = var_GetString( p_enc, p_cfg_setting_name );
+                if( !psz_tmp )
+                    goto error;
+                else if( *psz_tmp != '\0' ) {
+                    if( !SchroSetEnum( p_enc, p_setting, psz_tmp ) ) {
+                        free( psz_tmp );
+                        goto error;
+                    }
+                }
+                free( psz_tmp );
+                break;
+            default:
+                break;
+        }
+        free( p_cfg_setting_name );
+    }
+
+    psz_tmp = var_GetString( p_enc, ENC_CFG_PREFIX ENC_CHROMAFMT );
+    if( !psz_tmp )
+        goto error;
+    else {
+        uint32_t i_codec;
+        if( !strcmp( psz_tmp, "420" ) ) {
+            i_codec = VLC_CODEC_I420;
+        }
+        else if( !strcmp( psz_tmp, "422" ) ) {
+            i_codec = VLC_CODEC_I422;
+        }
+        else if( !strcmp( psz_tmp, "444" ) ) {
+            i_codec = VLC_CODEC_I444;
+        }
+        else {
+            msg_Err( p_enc, "Invalid chroma format: %s", psz_tmp );
+            free( psz_tmp );
+            goto error;
+        }
+        SetEncChromaFormat( p_enc, i_codec );
+    }
+    free( psz_tmp );
+
+
+    b_tmp = var_GetBool( p_enc, ENC_CFG_PREFIX ENC_CODINGMODE );
+    if( b_tmp == true )
+        p_sys->b_auto_field_coding = true;
+    else
+        p_sys->b_auto_field_coding = false;
+
+    p_sys->started = 0;
+
+    return VLC_SUCCESS;
+error:
+    CloseEncoder( p_this );
+    return VLC_EGENERIC;
+}
+
+
+struct enc_picture_free_t
+{
+   picture_t *p_pic;
+   encoder_t *p_enc;
+};
+
+/*****************************************************************************
+ * EncSchroFrameFree: schro_frame callback to release the associated picture_t
+ * When schro_encoder_reset() is called there will be pictures in the
+ * encoding pipeline that need to be released rather than displayed.
+ *****************************************************************************/
+static void EncSchroFrameFree( SchroFrame *frame, void *priv )
+{
+    struct enc_picture_free_t *p_free = priv;
+
+    if( !p_free )
+        return;
+
+    picture_Release( p_free->p_pic );
+    free( p_free );
+    (void)frame;
+}
+
+/*****************************************************************************
+ * CreateSchroFrameFromPic: wrap a picture_t in a SchroFrame
+ *****************************************************************************/
+static SchroFrame *CreateSchroFrameFromInputPic( encoder_t *p_enc,  picture_t *p_pic )
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+    SchroFrame *p_schroframe = schro_frame_new();
+    struct enc_picture_free_t *p_free;
+
+    if( !p_schroframe )
+        return NULL;
+
+    if( !p_pic )
+        return NULL;
+
+    p_schroframe->format = SCHRO_FRAME_FORMAT_U8_420;
+    if( p_sys->p_format->chroma_format == SCHRO_CHROMA_422 )
+    {
+        p_schroframe->format = SCHRO_FRAME_FORMAT_U8_422;
+    }
+    else if( p_sys->p_format->chroma_format == SCHRO_CHROMA_444 )
+    {
+        p_schroframe->format = SCHRO_FRAME_FORMAT_U8_444;
+    }
+
+    p_schroframe->width  = p_sys->p_format->width;
+    p_schroframe->height = p_sys->p_format->height;
+
+    p_free = malloc( sizeof( *p_free ) );
+    if( unlikely( p_free == NULL ) ) {
+        schro_frame_unref( p_schroframe );
+        return NULL;
+    }
+
+    p_free->p_pic = p_pic;
+    p_free->p_enc = p_enc;
+    schro_frame_set_free_callback( p_schroframe, EncSchroFrameFree, p_free );
+
+    for( int i=0; i<3; i++ )
+    {
+        p_schroframe->components[i].width  = p_pic->p[i].i_visible_pitch;
+        p_schroframe->components[i].stride = p_pic->p[i].i_pitch;
+        p_schroframe->components[i].height = p_pic->p[i].i_visible_lines;
+        p_schroframe->components[i].length =
+            p_pic->p[i].i_pitch * p_pic->p[i].i_lines;
+        p_schroframe->components[i].data   = p_pic->p[i].p_pixels;
+
+        if( i!=0 )
+        {
+            p_schroframe->components[i].v_shift =
+                SCHRO_FRAME_FORMAT_V_SHIFT( p_schroframe->format );
+            p_schroframe->components[i].h_shift =
+                SCHRO_FRAME_FORMAT_H_SHIFT( p_schroframe->format );
+        }
+    }
+
+    return p_schroframe;
+}
+
+/* Attempt to find dirac picture number in an encapsulation unit */
+static int ReadDiracPictureNumber( uint32_t *p_picnum, block_t *p_block )
+{
+    uint32_t u_pos = 4;
+    /* protect against falling off the edge */
+    while( u_pos + 13 < p_block->i_buffer )
+    {
+        /* find the picture startcode */
+        if( p_block->p_buffer[u_pos] & 0x08 )
+        {
+            *p_picnum = GetDWBE( p_block->p_buffer + u_pos + 9 );
+            return 1;
+        }
+        /* skip to the next dirac data unit */
+        uint32_t u_npo = GetDWBE( p_block->p_buffer + u_pos + 1 );
+        assert( u_npo <= UINT32_MAX - u_pos );
+        if( u_npo == 0 )
+            u_npo = 13;
+        u_pos += u_npo;
+    }
+    return 0;
+}
+
+
+static block_t *Encode( encoder_t *p_enc, picture_t *p_pic )
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+    block_t *p_block, *p_output_chain = NULL;
+    SchroFrame *p_frame;
+    bool b_go = true;
+
+    if( !p_pic ) {
+        if( !p_sys->started || p_sys->b_eos_pulled )
+            return NULL;
+
+        if( !p_sys->b_eos_signalled ) {
+            p_sys->b_eos_signalled = 1;
+            schro_encoder_end_of_stream( p_sys->p_schro );
+        }
+    } else {
+        /* we only know if the sequence is interlaced when the first
+         * picture arrives, so final setup is done here */
+        /* XXX todo, detect change of interlace */
+        p_sys->p_format->interlaced = !p_pic->b_progressive;
+        p_sys->p_format->top_field_first = p_pic->b_top_field_first;
+
+        if( p_sys->b_auto_field_coding )
+            schro_encoder_setting_set_double( p_sys->p_schro, "interlaced_coding", !p_pic->b_progressive );
+    }
+
+    if( !p_sys->started ) {
+        date_t date;
+
+        if( p_pic->format.i_chroma != p_enc->fmt_in.i_codec ) {
+            char chroma_in[5], chroma_out[5];
+            vlc_fourcc_to_char( p_pic->format.i_chroma, chroma_in );
+            chroma_in[4]  = '\0';
+            chroma_out[4] = '\0';
+            vlc_fourcc_to_char( p_enc->fmt_in.i_codec, chroma_out );
+            msg_Warn( p_enc, "Resetting chroma from %s to %s", chroma_out, chroma_in );
+            if( !SetEncChromaFormat( p_enc, p_pic->format.i_chroma ) ) {
+                msg_Err( p_enc, "Could not reset chroma format to %s", chroma_in );
+                return NULL;
+            }
+        }
+
+        date_Init( &date, p_enc->fmt_in.video.i_frame_rate, p_enc->fmt_in.video.i_frame_rate_base );
+        /* FIXME - Unlike dirac-research codec Schro doesn't have a function that returns the delay in pics yet.
+         *   Use a default of 1
+         */
+        date_Increment( &date, 1 );
+        p_sys->i_pts_offset = date_Get( &date );
+        if( schro_encoder_setting_get_double( p_sys->p_schro, "interlaced_coding" ) > 0.0 ) {
+            date_Set( &date, 0 );
+            date_Increment( &date, 1);
+            p_sys->i_field_time = date_Get( &date ) / 2;
+        }
+
+        schro_video_format_set_std_signal_range( p_sys->p_format, SCHRO_SIGNAL_RANGE_8BIT_VIDEO );
+        schro_encoder_set_video_format( p_sys->p_schro, p_sys->p_format );
+        schro_encoder_start( p_sys->p_schro );
+        p_sys->started = 1;
+    }
+
+    if( !p_sys->b_eos_signalled ) {
+        /* create a schro frame from the input pic and load */
+        /* Increase ref count by 1 so that the picture is not freed until
+           Schro finishes with it */
+        picture_Hold( p_pic );
+
+        p_frame = CreateSchroFrameFromInputPic( p_enc, p_pic );
+        if( !p_frame )
+            return NULL;
+        schro_encoder_push_frame( p_sys->p_schro, p_frame );
+
+
+        /* store pts in a lookaside buffer, so that the same pts may
+        * be used for the picture in coded order */
+        StorePicturePTS( p_enc, p_sys->i_input_picnum, p_pic->date );
+        p_sys->i_input_picnum++;
+
+        /* store dts in a queue, so that they appear in order in
+         * coded order */
+        p_block = block_New( p_enc, 1 );
+        if( !p_block )
+            return NULL;
+        p_block->i_dts = p_pic->date - p_sys->i_pts_offset;
+        block_FifoPut( p_sys->p_dts_fifo, p_block );
+        p_block = NULL;
+
+        /* for field coding mode, insert an extra value into both the
+         * pts lookaside buffer and dts queue, offset to correspond
+         * to a one field delay. */
+        if( schro_encoder_setting_get_double( p_sys->p_schro, "interlaced_coding" ) > 0.0 ) {
+            StorePicturePTS( p_enc, p_sys->i_input_picnum, p_pic->date + p_sys->i_field_time );
+            p_sys->i_input_picnum++;
+
+            p_block = block_New( p_enc, 1 );
+            if( !p_block )
+                return NULL;
+            p_block->i_dts = p_pic->date - p_sys->i_pts_offset + p_sys->i_field_time;
+            block_FifoPut( p_sys->p_dts_fifo, p_block );
+            p_block = NULL;
+        }
+    }
+
+    do
+    {
+        SchroStateEnum state;
+        state = schro_encoder_wait( p_sys->p_schro );
+        switch( state )
+        {
+        case SCHRO_STATE_NEED_FRAME:
+            b_go = false;
+            break;
+        case SCHRO_STATE_AGAIN:
+            break;
+        case SCHRO_STATE_END_OF_STREAM:
+            p_sys->b_eos_pulled = 1;
+            b_go = false;
+            break;
+        case SCHRO_STATE_HAVE_BUFFER:
+        {
+            SchroBuffer *p_enc_buf;
+            uint32_t u_pic_num;
+            int i_presentation_frame;
+            p_enc_buf = schro_encoder_pull( p_sys->p_schro, &i_presentation_frame );
+            p_block = block_New( p_enc, p_enc_buf->length );
+            if( !p_block )
+                return NULL;
+
+            memcpy( p_block->p_buffer, p_enc_buf->data, p_enc_buf->length );
+            schro_buffer_unref( p_enc_buf );
+
+            /* Presence of a Sequence header indicates a seek point */
+            if( 0 == p_block->p_buffer[4] )
+            {
+                p_block->i_flags |= BLOCK_FLAG_TYPE_I;
+
+                if( !p_enc->fmt_out.p_extra ) {
+                    const uint8_t eos[] = { 'B','B','C','D',0x10,0,0,0,13,0,0,0,0 };
+                    uint32_t len = GetDWBE( p_block->p_buffer + 5 );
+                    /* if it hasn't been done so far, stash a copy of the
+                     * sequence header for muxers such as ogg */
+                    /* The OggDirac spec advises that a Dirac EOS DataUnit
+                     * is appended to the sequence header to allow guard
+                     * against poor streaming servers */
+                    /* XXX, should this be done using the packetizer ? */
+                    p_enc->fmt_out.p_extra = malloc( len + sizeof( eos ) );
+                    if( !p_enc->fmt_out.p_extra )
+                        return NULL;
+                    memcpy( p_enc->fmt_out.p_extra, p_block->p_buffer, len );
+                    memcpy( (uint8_t*)p_enc->fmt_out.p_extra + len, eos, sizeof( eos ) );
+                    SetDWBE( (uint8_t*)p_enc->fmt_out.p_extra + len + 10, len );
+                    p_enc->fmt_out.i_extra = len + sizeof( eos );
+                }
+            }
+
+            if( ReadDiracPictureNumber( &u_pic_num, p_block ) ) {
+                block_t *p_dts_block = block_FifoGet( p_sys->p_dts_fifo );
+                p_block->i_dts = p_dts_block->i_dts;
+                   p_block->i_pts = GetPicturePTS( p_enc, u_pic_num );
+                block_Release( p_dts_block );
+                block_ChainAppend( &p_output_chain, p_block );
+            } else {
+                /* End of sequence */
+                block_ChainAppend( &p_output_chain, p_block );
+            }
+            break;
+        }
+        default:
+            break;
+        }
+    } while( b_go );
+
+    return p_output_chain;
+}
+
+/*****************************************************************************
+ * CloseEncoder: Schro encoder destruction
+ *****************************************************************************/
+static void CloseEncoder( vlc_object_t *p_this )
+{
+    encoder_t *p_enc = (encoder_t *)p_this;
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    /* Free the encoder resources */
+    if( p_sys->p_schro )
+        schro_encoder_free( p_sys->p_schro );
+
+    free( p_sys->p_format );
+
+    if( p_sys->p_dts_fifo )
+        block_FifoRelease( p_sys->p_dts_fifo );
+
+    block_ChainRelease( p_sys->p_chain );
+
+    free( p_sys );
+}