]> git.sesse.net Git - vlc/commitdiff
* include/vlc_block_helper.h: new block_FindStartcodeFromOffset() function.
authorGildas Bazin <gbazin@videolan.org>
Sat, 6 Dec 2003 23:25:23 +0000 (23:25 +0000)
committerGildas Bazin <gbazin@videolan.org>
Sat, 6 Dec 2003 23:25:23 +0000 (23:25 +0000)
* modules/packetizer/mpegvideo.c: rewrote the packetizer to use the block helper functions.

include/vlc_block_helper.h
modules/packetizer/mpegvideo.c

index bb155023be58eda299e89e169b2deffb352220d4..f22f7fcf4434184738502a443fa499568505064b 100644 (file)
@@ -2,7 +2,7 @@
  * vlc_block_helper.h: Helper functions for data blocks management.
  *****************************************************************************
  * Copyright (C) 2003 VideoLAN
- * $Id: vlc_block_helper.h,v 1.5 2003/11/16 21:07:30 gbazin Exp $
+ * $Id: vlc_block_helper.h,v 1.6 2003/12/06 23:25:23 gbazin Exp $
  *
  * Authors: Gildas Bazin <gbazin@netcourrier.com>
  *
@@ -436,4 +436,72 @@ static inline int block_PeekOffsetBytes( block_bytestream_t *p_bytestream,
     return VLC_SUCCESS;
 }
 
+static inline int block_FindStartcodeFromOffset(
+    block_bytestream_t *p_bytestream, int *pi_offset,
+    uint8_t *p_startcode, int i_startcode_length )
+{
+    block_t *p_block, *p_block_backup = 0;
+    int i_size, i_offset, i_offset_backup = 0;
+    int i_caller_offset_backup = 0, i_match;
+
+    /* Find the right place */
+    i_size = *pi_offset + p_bytestream->i_offset;
+    for( p_block = p_bytestream->p_block;
+         p_block != NULL; p_block = p_block->p_next )
+    {
+        i_size -= p_block->i_buffer;
+        if( i_size < 0 ) break;
+    }
+
+    if( i_size >= 0 )
+    {
+        /* Not enough data, bail out */
+        return VLC_EGENERIC;
+    }
+
+    /* Begin the search.
+     * We first look for an occurence of the 1st startcode byte and
+     * if found, we do a more thorough check. */
+    i_size = p_block->i_buffer + i_size;
+    *pi_offset -= i_size;
+    i_match = 0;
+    for( ; p_block != NULL; p_block = p_block->p_next )
+    {
+        for( i_offset = i_size; i_offset < p_block->i_buffer; i_offset++ )
+        {
+            if( p_block->p_buffer[i_offset] == p_startcode[i_match] )
+            {
+                if( !i_match )
+                {
+                    p_block_backup = p_block;
+                    i_offset_backup = i_offset;
+                    i_caller_offset_backup = *pi_offset;
+                }
+
+                if( i_match + 1 == i_startcode_length )
+                {
+                    /* We have it */
+                    *pi_offset += i_offset - i_match;
+                    return VLC_SUCCESS;
+                }
+
+                i_match++;
+            }
+            else if ( i_match )
+            {
+                /* False positive */
+                p_block = p_block_backup;
+                i_offset = i_offset_backup;
+                *pi_offset = i_caller_offset_backup;
+                i_match = 0;
+            }
+
+        }
+        i_size = 0;
+        *pi_offset += i_offset;
+    }
+
+    return VLC_EGENERIC;
+}
+
 #endif /* VLC_BLOCK_HELPER_H */
index ff3815a8ec9a150a068971e30358941e558b8e91..f612389773e6e664ae47bacdd855f9ab9f26f200 100644 (file)
@@ -1,11 +1,12 @@
 /*****************************************************************************
- * mpegvideo.c
+ * mpegvideo.c: parse and packetize an MPEG1/2 video stream
  *****************************************************************************
  * Copyright (C) 2001, 2002 VideoLAN
- * $Id: mpegvideo.c,v 1.23 2003/11/27 22:44:50 massiot Exp $
+ * $Id: mpegvideo.c,v 1.24 2003/12/06 23:25:23 gbazin Exp $
  *
  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
  *          Eric Petit <titer@videolan.org>
+ *          Gildas Bazin <gbazin@netcourrier.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
@@ -45,6 +46,8 @@
 #include <vlc/decoder.h>
 #include <vlc/input.h>
 
+#include "vlc_block_helper.h"
+
 /*****************************************************************************
  * Module descriptor
  *****************************************************************************/
@@ -57,43 +60,40 @@ vlc_module_begin();
     set_callbacks( Open, Close );
 vlc_module_end();
 
-
 /*****************************************************************************
  * Local prototypes
  *****************************************************************************/
 static block_t *Packetize( decoder_t *, block_t ** );
-
-static int mpgv_FindStartCode( uint8_t **pp_start, uint8_t *p_end );
+static block_t *ParseMPEGBlock( decoder_t *, block_t * );
 
 struct decoder_sys_t
 {
-    /* sequence header and extention */
+    /*
+     * Input properties
+     */
+    block_bytestream_t bytestream;
+    int i_state;
+    int i_offset;
+    uint8_t p_startcode[3];
+
+    /* Sequence header and extention */
     block_t *p_seq;
     block_t *p_ext;
 
-    /* current frame being building */
+    /* Current frame being built */
     block_t    *p_frame;
     vlc_bool_t b_frame_slice;
-    vlc_bool_t b_frame_corrupted;
-    vlc_bool_t b_gop;
-
-    /* pts of current picture */
     mtime_t i_pts;
     mtime_t i_dts;
 
-    /* gathering buffer */
-    int         i_buffer;
-    int         i_buffer_size;
-    uint8_t     *p_buffer;
-    uint8_t     *p_start, *p_old;
-
-    /* */
+    /* Sequence properties */
     int         i_frame_rate;
     int         i_frame_rate_base;
     vlc_bool_t  b_seq_progressive;
     vlc_bool_t  b_low_delay;
+    int         i_aspect_ratio_info;
 
-    /* */
+    /* Picture properties */
     int i_temporal_ref;
     int i_picture_type;
     int i_picture_structure;
@@ -101,14 +101,18 @@ struct decoder_sys_t
     int i_repeat_first_field;
     int i_progressive_frame;
 
-    /* */
-    int     i_seq_old;  /* How many picture from last seq */
-
-    /* */
-
     mtime_t i_interpolated_dts;
     mtime_t i_old_duration;
     mtime_t i_last_ref_pts;
+
+    /* Number of pictues since last sequence header */
+    int i_seq_old;
+
+};
+
+enum {
+    STATE_NOSYNC,
+    STATE_NEXT_SYNC
 };
 
 /*****************************************************************************
@@ -126,26 +130,25 @@ static int Open( vlc_object_t *p_this )
         return VLC_EGENERIC;
     }
 
-    es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC( 'm', 'p', 'g', 'v' ) );
+    es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC('m','p','g','v') );
     p_dec->pf_packetize = Packetize;
 
     p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
 
+    /* Misc init */
+    p_sys->i_state = STATE_NOSYNC;
+    p_sys->bytestream = block_BytestreamInit( p_dec );
+    p_sys->p_startcode[0] = 0;
+    p_sys->p_startcode[1] = 0;
+    p_sys->p_startcode[2] = 1;
+    p_sys->i_offset = 0;
+
     p_sys->p_seq = NULL;
     p_sys->p_ext = NULL;
     p_sys->p_frame = NULL;
     p_sys->b_frame_slice = VLC_FALSE;
-    p_sys->b_frame_corrupted = VLC_FALSE;
-    p_sys->b_gop = VLC_FALSE;
 
-    p_sys->i_buffer = 0;
-    p_sys->i_buffer_size = 10000;
-    p_sys->p_buffer = malloc( p_sys->i_buffer_size );
-    p_sys->p_start = p_sys->p_buffer;
-    p_sys->p_old = NULL;
-
-    p_sys->i_dts = 0;
-    p_sys->i_pts = 0;
+    p_sys->i_dts = p_sys->i_pts = 0;
 
     p_sys->i_frame_rate = 1;
     p_sys->i_frame_rate_base = 1;
@@ -175,6 +178,8 @@ static void Close( vlc_object_t *p_this )
     decoder_t     *p_dec = (decoder_t*)p_this;
     decoder_sys_t *p_sys = p_dec->p_sys;
 
+    block_BytestreamRelease( &p_sys->bytestream );
+
     if( p_sys->p_seq )
     {
         block_Release( p_sys->p_seq );
@@ -185,9 +190,9 @@ static void Close( vlc_object_t *p_this )
     }
     if( p_sys->p_frame )
     {
-        block_Release( p_sys->p_frame );
+        block_ChainRelease( p_sys->p_frame );
     }
-    free( p_sys->p_buffer );
+
     free( p_sys );
 }
 
@@ -197,323 +202,356 @@ static void Close( vlc_object_t *p_this )
 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 {
     decoder_sys_t *p_sys = p_dec->p_sys;
-    block_t       *p_chain_out = NULL;
-    block_t       *p_block;
+    block_t       *p_pic;
 
     if( pp_block == NULL || *pp_block == NULL )
     {
         return NULL;
     }
-    p_block = *pp_block;
-    *pp_block = NULL;
 
-    if( p_block->b_discontinuity )
+    if( (*pp_block)->b_discontinuity )
     {
-        p_sys->b_frame_corrupted = VLC_TRUE;
+        p_sys->i_state = STATE_NOSYNC;
+        if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
+        p_sys->p_frame = NULL;
+        p_sys->b_frame_slice = VLC_FALSE;
     }
 
-    /* Append data */
-    if( p_sys->i_buffer + p_block->i_buffer > p_sys->i_buffer_size )
-    {
-        uint8_t *p_buffer = p_sys->p_buffer;
-
-        p_sys->i_buffer_size += p_block->i_buffer + 1024;
-        p_sys->p_buffer = realloc( p_sys->p_buffer, p_sys->i_buffer_size );
+    block_BytestreamPush( &p_sys->bytestream, *pp_block );
 
-        if( p_sys->p_start )
-        {
-            p_sys->p_start = p_sys->p_start - p_buffer + p_sys->p_buffer;
-        }
-        if( p_sys->p_old )
+    while( 1 )
+    {
+        switch( p_sys->i_state )
         {
-            p_sys->p_old = p_sys->p_old - p_buffer + p_sys->p_buffer;
-        }
 
-    }
-    memcpy( &p_sys->p_buffer[p_sys->i_buffer], p_block->p_buffer,
-            p_block->i_buffer );
-    p_sys->i_buffer += p_block->i_buffer;
+        case STATE_NOSYNC:
+            if( block_FindStartcodeFromOffset( &p_sys->bytestream,
+                    &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
+            {
+                p_sys->i_state = STATE_NEXT_SYNC;
+            }
 
+            if( p_sys->i_offset )
+            {
+                block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
+                p_sys->i_offset = 0;
+                block_BytestreamFlush( &p_sys->bytestream );
+            }
 
-    if( p_sys->i_buffer > 10*1000000 )
-    {
-        msg_Err( p_dec, "mmh reseting context" );
-        p_sys->i_buffer = 0;
-    }
+            if( p_sys->i_state != STATE_NEXT_SYNC )
+            {
+                /* Need more data */
+                return NULL;
+            }
 
-    /* Split data in block */
-    for( ;; )
-    {
-        if( mpgv_FindStartCode( &p_sys->p_start, &p_sys->p_buffer[p_sys->i_buffer] ) )
-        {
-            block_Release( p_block );
+            p_sys->i_offset = 1; /* To find next startcode */
+
+        case STATE_NEXT_SYNC:
+            /* TODO: If p_block == NULL, flush the buffer without checking the
+             * next sync word */
 
-            if( p_sys->p_seq == NULL )
+            /* Find the next startcode */
+            if( block_FindStartcodeFromOffset( &p_sys->bytestream,
+                    &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
             {
-                block_ChainRelease( p_chain_out );
+                /* Need more data */
                 return NULL;
             }
-            return p_chain_out;
-        }
 
-        if( p_sys->p_old )
-        {
-            /* Extract the data */
-            int i_frag = p_sys->p_start - p_sys->p_old;
-            block_t *p_frag = block_New( p_dec, i_frag );
+            /* Get the new fragment and set the pts/dts */
+            p_pic = block_New( p_dec, p_sys->i_offset );
+            p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
+            p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
 
-            memcpy( p_frag->p_buffer, p_sys->p_old, i_frag );
-            if( i_frag < p_sys->i_buffer )
+            block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
+                            p_pic->i_buffer );
+
+            /* don't reuse the same timestamps several times */
+            if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
             {
-                memmove( p_sys->p_buffer, &p_sys->p_buffer[i_frag],
-                         p_sys->i_buffer - i_frag );
+                /* We have a picture start code */
+                p_sys->bytestream.p_block->i_pts = 0;
+                p_sys->bytestream.p_block->i_dts = 0;
             }
-            p_sys->i_buffer -= i_frag;
-            p_sys->p_start -= i_frag;
-            p_sys->p_old   -= i_frag;
 
-            if( p_sys->b_frame_slice && ( p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf ) )
-            {
-                /* We have a complete picture output it */
-                if( p_sys->p_seq == NULL )
-                {
-                    msg_Dbg( p_dec, "waiting sequence start" );
-                    block_ChainRelease( p_sys->p_frame );
-                }
-                else if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 && p_sys->i_interpolated_dts <= 0 )
-                {
-                    msg_Dbg( p_dec, "need a starting pts/dts" );
-                    block_ChainRelease( p_sys->p_frame );
-                }
-                else if( p_sys->b_frame_corrupted )
-                {
-                    msg_Warn( p_dec, "trashing a corrupted picture" );
-                    block_ChainRelease( p_sys->p_frame );
-                    p_sys->b_frame_corrupted = VLC_FALSE;
-                }
-                else
-                {
-                    block_t *p_pic = block_ChainGather( p_sys->p_frame );
-                    mtime_t i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base / p_sys->i_frame_rate);
-
-                    if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
-                    {
-                        i_duration /= 2;
-                    }
-
-                    if( p_sys->b_seq_progressive )
-                    {
-                        if( p_sys->i_top_field_first == 0 && p_sys->i_repeat_first_field == 1 )
-                        {
-                            i_duration *= 2;
-                        }
-                        else if( p_sys->i_top_field_first == 1 && p_sys->i_repeat_first_field == 1 )
-                        {
-                            i_duration *= 3;
-                        }
-                    }
-                    else
-                    {
-                        if( p_sys->i_picture_structure == 0x03 )
-                        {
-                            if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
-                            {
-                                i_duration += i_duration / 2;
-                            }
-                        }
-                    }
-
-                    if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
-                    {
-                        /* Trivial case (DTS == PTS) */
-                        /* Correct interpolated dts when we receive a new pts/dts */
-                        if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
-                        if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
-                    }
-                    else
-                    {
-                        /* Correct interpolated dts when we receive a new pts/dts */
-                        if( p_sys->i_last_ref_pts > 0 )
-                            p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
-                        if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
-
-                        p_sys->i_last_ref_pts = p_sys->i_pts;
-                    }
-
-                    p_pic->i_dts    = p_sys->i_interpolated_dts;
-                    /* Set PTS only if I frame or come from stream */
-                    if( p_sys->i_pts > 0 )
-                    {
-                        p_pic->i_pts    = p_sys->i_pts;
-                    }
-                    else if( p_sys->i_picture_type == 0x03 )
-                    {
-                        p_pic->i_pts = p_pic->i_dts;
-                    }
-                    else
-                    {
-                        p_pic->i_pts = -1;
-                    }
-
-                    if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
-                    {
-                        /* Trivial case (DTS == PTS) */
-                        p_sys->i_interpolated_dts += i_duration;
-                    }
-                    else
-                    {
-                        p_sys->i_interpolated_dts += p_sys->i_old_duration;
-                        p_sys->i_old_duration = i_duration;
-                    }
-
-                    p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
-
-                    //msg_Dbg( p_dec, "pic: type=%d dts=%lld pts-dts=%lld", p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
-
-                    block_ChainAppend( &p_chain_out, p_pic );
+            p_sys->i_offset = 0;
 
-                }
+            /* Get picture if any */
+            if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
+            {
+                p_sys->i_state = STATE_NOSYNC;
+                break;
+            }
 
-                /* reset context */
-                p_sys->p_frame = NULL;
-                p_sys->b_frame_slice = VLC_FALSE;
-                p_sys->b_gop = VLC_FALSE;
-                p_sys->i_pts = 0;
-                p_sys->i_dts = 0;
+            /* We've just started the stream, wait for the first PTS.
+             * We discard here so we can still get the sequence header. */
+            if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
+                p_sys->i_interpolated_dts <= 0 )
+            {
+                msg_Dbg( p_dec, "need a starting pts/dts" );
+                p_sys->i_state = STATE_NOSYNC;
+                block_Release( p_pic );
+                break;
             }
 
-            if( p_frag->p_buffer[3] == 0xb8 )
+            /* So p_block doesn't get re-added several times */
+            *pp_block = block_BytestreamPop( &p_sys->bytestream );
+
+            p_sys->i_state = STATE_NOSYNC;
+
+            return p_pic;
+        }
+    }
+}
+
+/*****************************************************************************
+ * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
+ *****************************************************************************/
+static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
+{
+    decoder_sys_t *p_sys = p_dec->p_sys;
+    block_t *p_pic = NULL;
+
+    /*
+     * Check if previous picture is finished
+     */
+    if( ( p_sys->b_frame_slice &&
+          (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
+          p_sys->p_seq == NULL )
+    {
+        /* We have a picture but without a sequence header we can't
+         * do anything */
+        msg_Dbg( p_dec, "waiting for sequence start" );
+        if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
+        p_sys->p_frame = NULL;
+        p_sys->b_frame_slice = VLC_FALSE;
+
+    }
+    else if( p_sys->b_frame_slice &&
+             (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
+    {
+        mtime_t i_duration;
+
+        p_pic = block_ChainGather( p_sys->p_frame );
+
+        i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
+                                p_sys->i_frame_rate );
+
+        if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
+        {
+            i_duration /= 2;
+        }
+
+        if( p_sys->b_seq_progressive )
+        {
+            if( p_sys->i_top_field_first == 0 &&
+                p_sys->i_repeat_first_field == 1 )
             {
-                if( p_sys->p_seq &&
-                    p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
-                {
-                    /* Usefull for mpeg1: repeat sequence header every second */
-                    block_ChainAppend( &p_sys->p_frame,
-                                       block_Duplicate( p_sys->p_seq ) );
-                    if( p_sys->p_ext )
-                    {
-                        block_ChainAppend( &p_sys->p_frame,
-                                           block_Duplicate( p_sys->p_ext ) );
-                    }
-
-                    p_sys->i_seq_old = 0;
-                }
-                p_sys->b_gop = VLC_TRUE;
+                i_duration *= 2;
             }
-            else if( p_frag->p_buffer[3] == 0xb3 )
+            else if( p_sys->i_top_field_first == 1 &&
+                     p_sys->i_repeat_first_field == 1 )
             {
-                static const int code_to_frame_rate[16][2] =
-                {
-                    { 1, 1 },   /* invalid */
-                    { 24000, 1001 }, { 24, 1 }, { 25, 1 },       { 30000, 1001 },
-                    { 30, 1 },       { 50, 1 }, { 60000, 1001 }, { 60, 1 },
-                    { 1, 1 },        { 1, 1 },  { 1, 1 },        { 1, 1 },  /* invalid */
-                    { 1, 1 },        { 1, 1 },  { 1, 1 }                    /* invalid */
-                };
-
-                /* sequence header */
-                if( p_sys->p_seq )
-                {
-                    block_Release( p_sys->p_seq );
-                }
-                if( p_sys->p_ext )
+                i_duration *= 3;
+            }
+        }
+        else
+        {
+            if( p_sys->i_picture_structure == 0x03 )
+            {
+                if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
                 {
-                    block_Release( p_sys->p_ext );
-                    p_sys->p_ext = NULL;
+                    i_duration += i_duration / 2;
                 }
-                p_sys->p_seq = block_Duplicate( p_frag );
-                p_sys->i_seq_old = 0;
+            }
+        }
 
-                p_dec->fmt_out.video.i_width = ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
-                p_dec->fmt_out.video.i_height= ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
+        if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
+        {
+            /* Trivial case (DTS == PTS) */
+            /* Correct interpolated dts when we receive a new pts/dts */
+            if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
+            if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
+        }
+        else
+        {
+            /* Correct interpolated dts when we receive a new pts/dts */
+            if( p_sys->i_last_ref_pts > 0 )
+                p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
+            if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
 
-                p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
-                p_sys->i_frame_rate_base = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
+            p_sys->i_last_ref_pts = p_sys->i_pts;
+        }
 
+        p_pic->i_dts = p_sys->i_interpolated_dts;
 
-                p_sys->b_seq_progressive = VLC_TRUE;
-                p_sys->b_low_delay = VLC_TRUE;
+        /* Set PTS only if we have a B frame or if it comes from the stream */
+        if( p_sys->i_pts > 0 )
+        {
+            p_pic->i_pts = p_sys->i_pts;
+        }
+        else if( p_sys->i_picture_type == 0x03 )
+        {
+            p_pic->i_pts = p_pic->i_dts;
+        }
+        else
+        {
+            p_pic->i_pts = 0;
+        }
+
+        if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
+        {
+            /* Trivial case (DTS == PTS) */
+            p_sys->i_interpolated_dts += i_duration;
+        }
+        else
+        {
+            p_sys->i_interpolated_dts += p_sys->i_old_duration;
+            p_sys->i_old_duration = i_duration;
+        }
+
+        p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
 
 #if 0
-                msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
-                         p_dec->fmt_out.video.i_width,
-                         p_dec->fmt_out.video.i_height,
-                         (float)p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
+        msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
+        p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
 #endif
-            }
-            else if( p_frag->p_buffer[3] == 0xb5 )
+
+        /* Reset context */
+        p_sys->p_frame = NULL;
+        p_sys->b_frame_slice = VLC_FALSE;
+    }
+
+    /*
+     * Check info of current fragment
+     */
+    if( p_frag->p_buffer[3] == 0xb8 )
+    {
+        /* Group start code */
+        if( p_sys->p_seq &&
+            p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
+        {
+            /* Usefull for mpeg1: repeat sequence header every second */
+            block_ChainAppend( &p_sys->p_frame,
+                               block_Duplicate( p_sys->p_seq ) );
+            if( p_sys->p_ext )
             {
-                int i_type = p_frag->p_buffer[4] >> 4;
-                /* extention start code */
-                if( i_type == 0x01 )
-                {
-                    /* sequence extention */
-                    if( p_sys->p_ext)
-                    {
-                        block_Release( p_sys->p_ext );
-                    }
-                    p_sys->p_ext = block_Duplicate( p_frag );
-
-                    if( p_frag->i_buffer >= 10 )
-                    {
-                        p_sys->b_seq_progressive = p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
-                        p_sys->b_low_delay = p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
-                    }
-                }
-                else if( i_type == 0x08 )
-                {
-                    /* picture extention */
-                    p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
-                    p_sys->i_top_field_first   = p_frag->p_buffer[7] >> 7;
-                    p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
-                    p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
-                }
+                block_ChainAppend( &p_sys->p_frame,
+                                   block_Duplicate( p_sys->p_ext ) );
             }
-            else if( p_frag->p_buffer[3] == 0x00 )
+
+            p_sys->i_seq_old = 0;
+        }
+    }
+    else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
+    {
+        /* Sequence header code */
+        static const int code_to_frame_rate[16][2] =
+        {
+            { 1, 1 },  /* invalid */
+            { 24000, 1001 }, { 24, 1 }, { 25, 1 },       { 30000, 1001 },
+            { 30, 1 },       { 50, 1 }, { 60000, 1001 }, { 60, 1 },
+            /* Unofficial 15fps from Xing*/
+            { 15, 1001 },
+            /* Unofficial economy rates from libmpeg3 */
+            { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
+            { 1, 1 },  { 1, 1 }  /* invalid */
+        };
+
+        if( p_sys->p_seq ) block_Release( p_sys->p_seq );
+        if( p_sys->p_ext ) block_Release( p_sys->p_ext );
+
+        p_sys->p_seq = block_Duplicate( p_frag );
+        p_sys->i_seq_old = 0;
+        p_sys->p_ext = NULL;
+
+        p_dec->fmt_out.video.i_width =
+            ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
+        p_dec->fmt_out.video.i_height =
+            ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
+        p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
+
+        /* TODO: MPEG1 aspect ratio */
+
+        p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
+        p_sys->i_frame_rate_base =
+            code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
+
+        p_sys->b_seq_progressive = VLC_TRUE;
+        p_sys->b_low_delay = VLC_TRUE;
+
+#if 0
+        msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
+                 p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
+                 p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
+#endif
+    }
+    else if( p_frag->p_buffer[3] == 0xb5 )
+    {
+        int i_type = p_frag->p_buffer[4] >> 4;
+
+        /* Extention start code */
+        if( i_type == 0x01 )
+        {
+            static const int mpeg2_aspect[16][2] =
             {
-                /* picture */
-                p_sys->i_seq_old++;
+                {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
+                {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
+                {0,1}, {0,1}
+            };
 
-                if( p_frag->i_buffer >= 6 )
-                {
-                    p_sys->i_temporal_ref = ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
-                    p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 )&0x03;
-                }
-                if( !p_sys->b_frame_slice )
-                {
-                    p_sys->i_dts = p_block->i_dts; p_block->i_dts = 0;
-                    p_sys->i_pts = p_block->i_pts; p_block->i_pts = 0;
-                }
-            }
-            else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
+            /* sequence extention */
+            if( p_sys->p_ext) block_Release( p_sys->p_ext );
+            p_sys->p_ext = block_Duplicate( p_frag );
+
+            if( p_frag->i_buffer >= 10 )
             {
-                /* Slice */
-                p_sys->b_frame_slice = VLC_TRUE;
+                p_sys->b_seq_progressive =
+                    p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
+                p_sys->b_low_delay =
+                    p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
             }
 
-            /* Append the block */
-            block_ChainAppend( &p_sys->p_frame, p_frag );
+#if 0
+            p_dec->fmt_out.video.i_aspect =
+                mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
+                VOUT_ASPECT_FACTOR /
+                mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
+#endif
+
+        }
+        else if( i_type == 0x08 )
+        {
+            /* picture extention */
+            p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
+            p_sys->i_top_field_first   = p_frag->p_buffer[7] >> 7;
+            p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
+            p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
         }
-        p_sys->p_old = p_sys->p_start;
-        p_sys->p_start += 4;
     }
-}
-
-static int mpgv_FindStartCode( uint8_t **pp_start, uint8_t *p_end )
-{
-    uint8_t *p = *pp_start;
-
-    for( p = *pp_start; p < p_end - 4; p++ )
+    else if( p_frag->p_buffer[3] == 0x00 )
     {
-        if( p[0] == 0 && p[1] == 0 && p[2] == 1 )
+        /* Picture start code */
+        p_sys->i_seq_old++;
+
+        if( p_frag->i_buffer >= 6 )
         {
-            *pp_start = p;
-            return VLC_SUCCESS;
+            p_sys->i_temporal_ref =
+                ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
+            p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
         }
-    }
 
-    *pp_start = p;
-    return VLC_EGENERIC;
-}
+        p_sys->i_dts = p_frag->i_dts;
+        p_sys->i_pts = p_frag->i_pts;
+    }
+    else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
+    {
+        /* Slice start code */
+        p_sys->b_frame_slice = VLC_TRUE;
+    }
 
+    /* Append the block */
+    block_ChainAppend( &p_sys->p_frame, p_frag );
 
+    return p_pic;
+}