mp4.c

/*****************************************************************************
 * mp4.c : MP4 file input module for vlc
 *****************************************************************************
 * Copyright (C) 2001-2004 VideoLAN
 * $Id: mp4.c,v 1.59 2004/02/07 13:26:24 fenrir Exp $
 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
 *
 * 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
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <stdlib.h>                                      /* malloc(), free() */

#include <vlc/vlc.h>
#include <vlc/input.h>
#include <vlc_playlist.h>
#include "iso_lang.h"

#include "libmp4.h"
#include "mp4.h"
#include "drms.h"

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
static int  Open ( vlc_object_t * );
static void Close( vlc_object_t * );

vlc_module_begin();
    set_description( _("MP4 stream demuxer") );
    set_capability( "demux", 242 );
    set_callbacks( Open, Close );
vlc_module_end();

/* TODO:
 *  - DEMUX_GET_META and meta parsing
 */

/*****************************************************************************
 * Local prototypes
 *****************************************************************************/
static int    Demux   ( input_thread_t * );
static int    DemuxRef( input_thread_t *p_input )
{
    return 0;
}
static int   Seek     ( input_thread_t *, mtime_t );
static int   Control  ( input_thread_t *, int, va_list );

/*****************************************************************************
 * Declaration of local function
 *****************************************************************************/
static void MP4_TrackCreate ( input_thread_t *, mp4_track_t *, MP4_Box_t  *);
static void MP4_TrackDestroy( input_thread_t *, mp4_track_t * );

static int  MP4_TrackSelect ( input_thread_t *, mp4_track_t *, mtime_t );
static void MP4_TrackUnselect(input_thread_t *, mp4_track_t * );

static int  MP4_TrackSeek   ( input_thread_t *, mp4_track_t *, mtime_t );

static uint64_t MP4_TrackGetPos    ( mp4_track_t * );
static int      MP4_TrackSampleSize( mp4_track_t * );
static int      MP4_TrackNextSample( input_thread_t *, mp4_track_t * );
static void     MP4_TrackSetELST( input_thread_t *, mp4_track_t *, int64_t );

/* Return time in s of a track */
static inline int64_t MP4_TrackGetPTS( input_thread_t *p_input, mp4_track_t *p_track )
{
    unsigned int i_sample;
    unsigned int i_index;
    int64_t i_dts;

    i_sample = p_track->i_sample - p_track->chunk[p_track->i_chunk].i_sample_first;
    i_dts = p_track->chunk[p_track->i_chunk].i_first_dts;
    i_index = 0;
    while( i_sample > 0 )
    {
        if( i_sample > p_track->chunk[p_track->i_chunk].p_sample_count_dts[i_index] )
        {
            i_dts += p_track->chunk[p_track->i_chunk].p_sample_count_dts[i_index] *
                        p_track->chunk[p_track->i_chunk].p_sample_delta_dts[i_index];
            i_sample -= p_track->chunk[p_track->i_chunk].p_sample_count_dts[i_index];
            i_index++;
        }
        else
        {
            i_dts += i_sample *
                        p_track->chunk[p_track->i_chunk].p_sample_delta_dts[i_index];
            i_sample = 0;
            break;
        }
    }

    /* now handle elst */
    if( p_track->p_elst )
    {
        demux_sys_t         *p_sys = p_input->p_demux_data;
        MP4_Box_data_elst_t *elst = p_track->p_elst->data.p_elst;

        /* convert to offset */
        if( ( elst->i_media_rate_integer[p_track->i_elst] > 0 ||
              elst->i_media_rate_fraction[p_track->i_elst] > 0 ) &&
            elst->i_media_time[p_track->i_elst] > 0 )
        {
            i_dts -= elst->i_media_time[p_track->i_elst];
        }

        /* add i_elst_time */
        i_dts += p_track->i_elst_time * p_track->i_timescale / p_sys->i_timescale;

        if( i_dts < 0 ) i_dts = 0;
    }

    return (int64_t)1000000 * i_dts / p_track->i_timescale;
}
static inline int64_t MP4_GetMoviePTS(demux_sys_t *p_sys )
{
    return (int64_t)1000000 * p_sys->i_time / p_sys->i_timescale;
}

#define FREE( p ) if( p ) { free( p ); (p) = NULL;}

/*****************************************************************************
 * Open: check file and initializes MP4 structures
 *****************************************************************************/
static int Open( vlc_object_t * p_this )
{
    input_thread_t  *p_input = (input_thread_t *)p_this;
    demux_sys_t     *p_sys;

    uint8_t         *p_peek;

    MP4_Box_t       *p_ftyp;
    MP4_Box_t       *p_rmra;
    MP4_Box_t       *p_mvhd;
    MP4_Box_t       *p_trak;

    unsigned int    i;
    vlc_bool_t      b_seekable;

    /* a little test to see if it could be a mp4 */
    if( stream_Peek( p_input->s, &p_peek, 8 ) < 8 )
    {
        msg_Warn( p_input, "MP4 plugin discarded (cannot peek)" );
        return VLC_EGENERIC;
    }
    switch( VLC_FOURCC( p_peek[4], p_peek[5], p_peek[6], p_peek[7] ) )
    {
        case FOURCC_ftyp:
        case FOURCC_moov:
        case FOURCC_foov:
        case FOURCC_moof:
        case FOURCC_mdat:
        case FOURCC_udta:
        case FOURCC_free:
        case FOURCC_skip:
        case FOURCC_wide:
        case VLC_FOURCC( 'p', 'n', 'o', 't' ):
            break;
         default:
            msg_Warn( p_input, "MP4 plugin discarded (not a valid file)" );
            return VLC_EGENERIC;
    }

    /* I need to seek */
    stream_Control( p_input->s, STREAM_CAN_SEEK, &b_seekable );
    if( !b_seekable )
    {
        msg_Warn( p_input, "MP4 plugin discarded (unseekable)" );
        return VLC_EGENERIC;
    }

    /*Set exported functions */
    p_input->pf_demux = Demux;
    p_input->pf_demux_control = Control;

    /* create our structure that will contains all data */
    p_input->p_demux_data = p_sys = malloc( sizeof( demux_sys_t ) );
    memset( p_sys, 0, sizeof( demux_sys_t ) );

    /* Now load all boxes ( except raw data ) */
    if( ( p_sys->p_root = MP4_BoxGetRoot( p_input ) ) == NULL )
    {
        msg_Warn( p_input, "MP4 plugin discarded (not a valid file)" );
        goto error;
    }

    MP4_BoxDumpStructure( p_input, p_sys->p_root );

    if( ( p_ftyp = MP4_BoxGet( p_sys->p_root, "/ftyp" ) ) )
    {
        switch( p_ftyp->data.p_ftyp->i_major_brand )
        {
            case( FOURCC_isom ):
                msg_Dbg( p_input,
                         "ISO Media file (isom) version %d.",
                         p_ftyp->data.p_ftyp->i_minor_version );
                break;
            default:
                msg_Dbg( p_input,
                         "unrecognized major file specification (%4.4s).",
                          (char*)&p_ftyp->data.p_ftyp->i_major_brand );
                break;
        }
    }
    else
    {
        msg_Dbg( p_input, "file type box missing (assuming ISO Media file)" );
    }

    /* the file need to have one moov box */
    if( MP4_BoxCount( p_sys->p_root, "/moov" ) <= 0 )
    {
        MP4_Box_t *p_foov = MP4_BoxGet( p_sys->p_root, "/foov" );

        if( !p_foov )
        {
            msg_Err( p_input, "MP4 plugin discarded (no moov box)" );
            goto error;
        }
        /* we have a free box as a moov, rename it */
        p_foov->i_type = FOURCC_moov;
    }

    if( ( p_rmra = MP4_BoxGet( p_sys->p_root,  "/moov/rmra" ) ) )
    {
        playlist_t *p_playlist;
        int        i_count = MP4_BoxCount( p_rmra, "rmda" );
        int        i;

        msg_Dbg( p_input, "detected playlist mov file (%d ref)", i_count );

        p_playlist =
            (playlist_t *)vlc_object_find( p_input,
                                           VLC_OBJECT_PLAYLIST,
                                           FIND_ANYWHERE );
        if( p_playlist )
        {
            //p_playlist->pp_items[p_playlist->i_index]->b_autodeletion = VLC_TRUE;
            for( i = 0; i < i_count; i++ )
            {
                MP4_Box_t *p_rdrf = MP4_BoxGet( p_rmra, "rmda[%d]/rdrf", i );
                char      *psz_ref;
                uint32_t  i_ref_type;

                if( !p_rdrf || !( psz_ref = p_rdrf->data.p_rdrf->psz_ref ) )
                {
                    continue;
                }
                i_ref_type = p_rdrf->data.p_rdrf->i_ref_type;

                msg_Dbg( p_input, "new ref=`%s' type=%4.4s",
                         psz_ref, (char*)&i_ref_type );

                if( i_ref_type == VLC_FOURCC( 'u', 'r', 'l', ' ' ) )
                {
                    if( strstr( psz_ref, "qt5gateQT" ) )
                    {
                        msg_Dbg( p_input, "ignoring pseudo ref =`%s'", psz_ref );
                        continue;
                    }
                    if( !strncmp( psz_ref, "http://", 7 ) ||
                        !strncmp( psz_ref, "rtsp://", 7 ) )
                    {
                        msg_Dbg( p_input, "adding ref = `%s'", psz_ref );
                        playlist_Add( p_playlist, psz_ref, psz_ref,
                                      PLAYLIST_APPEND, PLAYLIST_END );
                    }
                    else
                    {
                        /* msg dbg relative ? */
                        char *psz_absolute = alloca( strlen( p_input->psz_source ) + strlen( psz_ref ) + 1);
                        char *end = strrchr( p_input->psz_source, '/' );

                        if( end )
                        {
                            int i_len = end + 1 - p_input->psz_source;

                            strncpy( psz_absolute, p_input->psz_source, i_len);
                            psz_absolute[i_len] = '\0';
                        }
                        else
                        {
                            strcpy( psz_absolute, "" );
                        }
                        strcat( psz_absolute, psz_ref );
                        msg_Dbg( p_input, "adding ref = `%s'", psz_absolute );
                        playlist_Add( p_playlist, psz_absolute, psz_absolute,
                                      PLAYLIST_APPEND, PLAYLIST_END );
                    }
                }
                else
                {
                    msg_Err( p_input, "unknown ref type=%4.4s FIXME (send a bug report)",
                             (char*)&p_rdrf->data.p_rdrf->i_ref_type );
                }
            }
            vlc_object_release( p_playlist );
        }
        else
        {
            msg_Err( p_input, "can't find playlist" );
        }
    }

    if( !(p_mvhd = MP4_BoxGet( p_sys->p_root, "/moov/mvhd" ) ) )
    {
        if( !p_rmra )
        {
            msg_Err( p_input, "cannot find /moov/mvhd" );
            goto error;
        }
        else
        {
            msg_Warn( p_input, "cannot find /moov/mvhd (pure ref file)" );
            p_input->pf_demux = DemuxRef;
            return VLC_SUCCESS;
        }
    }
    else
    {
        p_sys->i_timescale = p_mvhd->data.p_mvhd->i_timescale;
        p_sys->i_duration = p_mvhd->data.p_mvhd->i_duration;
    }

    if( !( p_sys->i_tracks = MP4_BoxCount( p_sys->p_root, "/moov/trak" ) ) )
    {
        msg_Err( p_input, "cannot find any /moov/trak" );
        goto error;
    }
    msg_Dbg( p_input, "find %d track%c",
                        p_sys->i_tracks,
                        p_sys->i_tracks ? 's':' ' );

    /*  create one program */
    vlc_mutex_lock( &p_input->stream.stream_lock );
    if( input_InitStream( p_input, 0 ) == -1)
    {
        vlc_mutex_unlock( &p_input->stream.stream_lock );
        msg_Err( p_input, "cannot init stream" );
        goto error;
    }
    if( p_sys->i_duration/p_sys->i_timescale > 0 )
    {
        p_input->stream.i_mux_rate =
            p_input->stream.p_selected_area->i_size / 50 /
            ( p_sys->i_duration / p_sys->i_timescale );
    }
    else
    {
        p_input->stream.i_mux_rate = 0;
    }
    vlc_mutex_unlock( &p_input->stream.stream_lock );


    /* allocate memory */
    p_sys->track = calloc( p_sys->i_tracks, sizeof( mp4_track_t ) );
    memset( p_sys->track, 0, p_sys->i_tracks * sizeof( mp4_track_t ) );

    /* now process each track and extract all usefull informations */
    for( i = 0; i < p_sys->i_tracks; i++ )
    {
        p_trak = MP4_BoxGet( p_sys->p_root, "/moov/trak[%d]", i );
        MP4_TrackCreate( p_input, &p_sys->track[i], p_trak );

        if( p_sys->track[i].b_ok )
        {
            char *psz_cat;
            switch( p_sys->track[i].fmt.i_cat )
            {
                case( VIDEO_ES ):
                    psz_cat = "video";
                    break;
                case( AUDIO_ES ):
                    psz_cat = "audio";
                    break;
                default:
                    psz_cat = "unknown";
                    break;
            }

            msg_Dbg( p_input, "adding track[Id 0x%x] %s (%s) language %s",
                            p_sys->track[i].i_track_ID,
                            psz_cat,
                            p_sys->track[i].b_enable ? "enable":"disable",
                            p_sys->track[i].fmt.psz_language ? p_sys->track[i].fmt.psz_language : "undef" );
        }
        else
        {
            msg_Dbg( p_input, "ignoring track[Id 0x%x]", p_sys->track[i].i_track_ID );
        }

    }
    return VLC_SUCCESS;

error:
    if( p_sys->p_root )
    {
        MP4_BoxFree( p_input, p_sys->p_root );
    }
    free( p_sys );
    return VLC_EGENERIC;
}

/*****************************************************************************
 * Demux: read packet and send them to decoders
 *****************************************************************************
 * TODO check for newly selected track (ie audio upt to now )
 *****************************************************************************/
static int Demux( input_thread_t *p_input )
{
    demux_sys_t *p_sys = p_input->p_demux_data;
    unsigned int i_track;


    unsigned int i_track_selected;
    vlc_bool_t   b_play_audio;

    /* check for newly selected/unselected track */
    for( i_track = 0, i_track_selected = 0; i_track <  p_sys->i_tracks; i_track++ )
    {
        mp4_track_t *tk = &p_sys->track[i_track];

        if( tk->b_selected && tk->i_sample >= tk->i_sample_count )
        {
            msg_Warn( p_input, "track[0x%x] will be disabled", tk->i_track_ID );
            MP4_TrackUnselect( p_input, tk);
        }
        else if( tk->b_ok )
        {
            vlc_bool_t b;
            es_out_Control( p_input->p_es_out, ES_OUT_GET_ES_STATE, tk->p_es, &b );

            if( tk->b_selected && !b )
            {
                MP4_TrackUnselect( p_input, tk );
            }
            else if( !tk->b_selected && b)
            {
                MP4_TrackSelect( p_input, tk, MP4_GetMoviePTS( p_sys ) );
            }

            if( tk->b_selected )
            {
                i_track_selected++;
            }
        }
    }

    if( i_track_selected <= 0 )
    {
        msg_Warn( p_input, "no track selected, exiting..." );
        return 0;
    }

    /* first wait for the good time to read a packet */
    input_ClockManageRef( p_input,
                          p_input->stream.p_selected_program,
                          p_sys->i_pcr );

    /* update pcr XXX in mpeg scale so in 90000 unit/s */
    p_sys->i_pcr = MP4_GetMoviePTS( p_sys ) * 9 / 100;

    /* we will read 100ms for each stream so ...*/
    p_sys->i_time += __MAX( p_sys->i_timescale / 10 , 1 );

    /* Check if we need to send the audio data to decoder */
    b_play_audio = !p_input->stream.control.b_mute;

    for( i_track = 0; i_track < p_sys->i_tracks; i_track++ )
    {
        mp4_track_t *tk = &p_sys->track[i_track];

        if( !tk->b_ok || !tk->b_selected )
        {
            continue;
        }

        while( MP4_TrackGetPTS( p_input, tk ) < MP4_GetMoviePTS( p_sys ) )
        {
#if 0
            msg_Dbg( p_input, "tk=%lld mv=%lld",
                     MP4_TrackGetPTS( p_input, tk ),
                     MP4_GetMoviePTS( p_sys ) );
#endif

            if( MP4_TrackSampleSize( tk ) > 0 &&
                ( b_play_audio || tk->fmt.i_cat != AUDIO_ES ) )
            {
                block_t *p_block;

                /* go,go go ! */
                if( stream_Seek( p_input->s, MP4_TrackGetPos( tk ) ) )
                {
                    msg_Warn( p_input, "track[0x%x] will be disabled (eof?)", tk->i_track_ID );
                    MP4_TrackUnselect( p_input, tk );
                    break;
                }

                /* now read pes */
                if( ( p_block = stream_Block( p_input->s,
                                              MP4_TrackSampleSize( tk ) ) ) == NULL )
                {
                    msg_Warn( p_input, "track[0x%x] will be disabled (eof?)", tk->i_track_ID );
                    MP4_TrackUnselect( p_input, tk );
                    break;
                }

                if( tk->b_drms && tk->p_drms )
                {
                    drms_decrypt( tk->p_drms,
                                  (uint32_t*)p_block->p_buffer,
                                  p_block->i_buffer );
                }
                p_block->i_dts =
                    input_ClockGetTS( p_input,
                                      p_input->stream.p_selected_program,
                                      MP4_TrackGetPTS( p_input, tk ) * 9/100 );

                p_block->i_pts = tk->fmt.i_cat == VIDEO_ES ? 0 : p_block->i_dts;

                if( !tk->b_drms || ( tk->b_drms && tk->p_drms ) )
                {
                    es_out_Send( p_input->p_es_out, tk->p_es, p_block );
                }
            }

            /* Next sample */
            if( MP4_TrackNextSample( p_input, tk ) )
            {
                break;
            }
        }
    }

    return 1;
}
/*****************************************************************************
 * Seek: Got to i_date
 ******************************************************************************/
static int   Seek     ( input_thread_t *p_input, mtime_t i_date )
{
    demux_sys_t *p_sys = p_input->p_demux_data;
    unsigned int i_track;

    /* First update update global time */
    p_sys->i_time = i_date * p_sys->i_timescale / 1000000;
    p_sys->i_pcr  = i_date* 9 / 100;

    /* Now for each stream try to go to this time */
    for( i_track = 0; i_track < p_sys->i_tracks; i_track++ )
    {
        mp4_track_t *tk = &p_sys->track[i_track];

        if( tk->b_ok && tk->b_selected )
        {
            MP4_TrackSeek( p_input, tk, i_date );
        }
    }
    return( 1 );
}

/*****************************************************************************
 * Control:
 *****************************************************************************/
static int Control( input_thread_t *p_input, int i_query, va_list args )
{
    demux_sys_t *p_sys = p_input->p_demux_data;

    double f, *pf;
    int64_t i64, *pi64;

    switch( i_query )
    {
        case DEMUX_GET_POSITION:
            pf = (double*)va_arg( args, double * );
            if( p_sys->i_duration > 0 )
            {
                *pf = (double)p_sys->i_time / (double)p_sys->i_duration;
            }
            else
            {
                *pf = 0.0;
            }
            return VLC_SUCCESS;

        case DEMUX_SET_POSITION:
            f = (double)va_arg( args, double );
            if( p_sys->i_timescale > 0 )
            {
                i64 = (int64_t)( f * (double)1000000 *
                                 (double)p_sys->i_duration /
                                 (double)p_sys->i_timescale );
                return Seek( p_input, i64 );
            }
            else return VLC_SUCCESS;

        case DEMUX_GET_TIME:
            pi64 = (int64_t*)va_arg( args, int64_t * );
            if( p_sys->i_timescale > 0 )
            {
                *pi64 = (mtime_t)1000000 *
                        (mtime_t)p_sys->i_time /
                        (mtime_t)p_sys->i_timescale;
            }
            else *pi64 = 0;
            return VLC_SUCCESS;

        case DEMUX_SET_TIME:
            i64 = (int64_t)va_arg( args, int64_t );
            return Seek( p_input, i64 );

        case DEMUX_GET_LENGTH:
            pi64 = (int64_t*)va_arg( args, int64_t * );
            if( p_sys->i_timescale > 0 )
            {
                *pi64 = (mtime_t)1000000 *
                        (mtime_t)p_sys->i_duration /
                        (mtime_t)p_sys->i_timescale;
            }
            else *pi64 = 0;
            return VLC_SUCCESS;

        case DEMUX_GET_FPS:
            msg_Warn( p_input, "DEMUX_GET_FPS unimplemented !!" );
            return VLC_EGENERIC;

        case DEMUX_GET_META:
            return VLC_EGENERIC;

        default:
            msg_Err( p_input, "control query unimplemented !!!" );
            return demux_vaControlDefault( p_input, i_query, args );
    }
}

/*****************************************************************************
 * Close: frees unused data
 *****************************************************************************/
static void Close ( vlc_object_t * p_this )
{
    unsigned int i_track;
    input_thread_t *  p_input = (input_thread_t *)p_this;
    demux_sys_t *p_sys = p_input->p_demux_data;

    msg_Dbg( p_input, "freeing all memory" );

    MP4_BoxFree( p_input, p_sys->p_root );
    for( i_track = 0; i_track < p_sys->i_tracks; i_track++ )
    {
        MP4_TrackDestroy( p_input, &p_sys->track[i_track] );
    }
    FREE( p_sys->track );

    free( p_sys );
}



/****************************************************************************
 * Local functions, specific to vlc
 ****************************************************************************/

/* now create basic chunk data, the rest will be filled by MP4_CreateSamplesIndex */
static int TrackCreateChunksIndex( input_thread_t *p_input,
                                   mp4_track_t *p_demux_track )
{
    MP4_Box_t *p_co64; /* give offset for each chunk, same for stco and co64 */
    MP4_Box_t *p_stsc;

    unsigned int i_chunk;
    unsigned int i_index, i_last;

    if( ( !(p_co64 = MP4_BoxGet( p_demux_track->p_stbl, "stco" ) )&&
          !(p_co64 = MP4_BoxGet( p_demux_track->p_stbl, "co64" ) ) )||
        ( !(p_stsc = MP4_BoxGet( p_demux_track->p_stbl, "stsc" ) ) ))
    {
        return( VLC_EGENERIC );
    }

    p_demux_track->i_chunk_count = p_co64->data.p_co64->i_entry_count;
    if( !p_demux_track->i_chunk_count )
    {
        msg_Warn( p_input, "no chunk defined" );
        return( VLC_EGENERIC );
    }
    p_demux_track->chunk = calloc( p_demux_track->i_chunk_count,
                                   sizeof( mp4_chunk_t ) );

    /* first we read chunk offset */
    for( i_chunk = 0; i_chunk < p_demux_track->i_chunk_count; i_chunk++ )
    {
        p_demux_track->chunk[i_chunk].i_offset =
                p_co64->data.p_co64->i_chunk_offset[i_chunk];
    }

    /* now we read index for SampleEntry( soun vide mp4a mp4v ...)
        to be used for the sample XXX begin to 1
        We construct it begining at the end */
    i_last = p_demux_track->i_chunk_count; /* last chunk proceded */
    i_index = p_stsc->data.p_stsc->i_entry_count;
    if( !i_index )
    {
        msg_Warn( p_input, "cannot read chunk table or table empty" );
        return( VLC_EGENERIC );
    }

    while( i_index )
    {
        i_index--;
        for( i_chunk = p_stsc->data.p_stsc->i_first_chunk[i_index] - 1;
                i_chunk < i_last; i_chunk++ )
        {
            p_demux_track->chunk[i_chunk].i_sample_description_index =
                    p_stsc->data.p_stsc->i_sample_description_index[i_index];
            p_demux_track->chunk[i_chunk].i_sample_count =
                    p_stsc->data.p_stsc->i_samples_per_chunk[i_index];
        }
        i_last = p_stsc->data.p_stsc->i_first_chunk[i_index] - 1;
    }

    p_demux_track->chunk[0].i_sample_first = 0;
    for( i_chunk = 1; i_chunk < p_demux_track->i_chunk_count; i_chunk++ )
    {
        p_demux_track->chunk[i_chunk].i_sample_first =
            p_demux_track->chunk[i_chunk-1].i_sample_first +
                p_demux_track->chunk[i_chunk-1].i_sample_count;
    }

    msg_Dbg( p_input,
             "track[Id 0x%x] read %d chunk",
             p_demux_track->i_track_ID,
             p_demux_track->i_chunk_count );

    return( VLC_SUCCESS );
}
static int TrackCreateSamplesIndex( input_thread_t *p_input,
                                    mp4_track_t *p_demux_track )
{
    MP4_Box_t *p_stts; /* makes mapping between sample and decoding time,
                          ctts make same mapping but for composition time,
                          not yet used and probably not usefull */
    MP4_Box_t *p_stsz; /* gives sample size of each samples, there is also stz2
                          that uses a compressed form FIXME make them in libmp4
                          as a unique type */
    /* TODO use also stss and stsh table for seeking */
    /* FIXME use edit table */
    int64_t i_sample;
    int64_t i_chunk;

    int64_t i_index;
    int64_t i_index_sample_used;

    int64_t i_last_dts;

    p_stts = MP4_BoxGet( p_demux_track->p_stbl, "stts" );
    p_stsz = MP4_BoxGet( p_demux_track->p_stbl, "stsz" ); /* FIXME and stz2 */

    if( ( !p_stts )||( !p_stsz ) )
    {
        msg_Warn( p_input, "cannot read sample table" );
        return( VLC_EGENERIC );
    }

    p_demux_track->i_sample_count = p_stsz->data.p_stsz->i_sample_count;


    /* for sample size, there are 2 case */
    if( p_stsz->data.p_stsz->i_sample_size )
    {
        /* 1: all sample have the same size, so no need to construct a table */
        p_demux_track->i_sample_size = p_stsz->data.p_stsz->i_sample_size;
        p_demux_track->p_sample_size = NULL;
    }
    else
    {
        /* 2: each sample can have a different size */
        p_demux_track->i_sample_size = 0;
        p_demux_track->p_sample_size =
            calloc( p_demux_track->i_sample_count, sizeof( uint32_t ) );

        for( i_sample = 0; i_sample < p_demux_track->i_sample_count; i_sample++ )
        {
            p_demux_track->p_sample_size[i_sample] =
                    p_stsz->data.p_stsz->i_entry_size[i_sample];
        }
    }
    /* we have extract all information from stsz,
        now use stts */

    /* if we don't want to waste too much memory, we can't expand
       the box !, so each chunk will contain an "extract" of this table
       for fast research */

    i_last_dts = 0;
    i_index = 0; i_index_sample_used =0;

    /* create and init last data for each chunk */
    for(i_chunk = 0 ; i_chunk < p_demux_track->i_chunk_count; i_chunk++ )
    {

        int64_t i_entry, i_sample_count, i;
        /* save last dts */
        p_demux_track->chunk[i_chunk].i_first_dts = i_last_dts;
    /* count how many entries needed for this chunk
       for p_sample_delta_dts and p_sample_count_dts */

        i_sample_count = p_demux_track->chunk[i_chunk].i_sample_count;

        i_entry = 0;
        while( i_sample_count > 0 )
        {
            i_sample_count -= p_stts->data.p_stts->i_sample_count[i_index+i_entry];
            if( i_entry == 0 )
            {
                i_sample_count += i_index_sample_used; /* don't count already used sample
                                                   int this entry */
            }
            i_entry++;
        }

        /* allocate them */
        p_demux_track->chunk[i_chunk].p_sample_count_dts =
            calloc( i_entry, sizeof( uint32_t ) );
        p_demux_track->chunk[i_chunk].p_sample_delta_dts =
            calloc( i_entry, sizeof( uint32_t ) );

        /* now copy */
        i_sample_count = p_demux_track->chunk[i_chunk].i_sample_count;
        for( i = 0; i < i_entry; i++ )
        {
            int64_t i_used;
            int64_t i_rest;

            i_rest = p_stts->data.p_stts->i_sample_count[i_index] - i_index_sample_used;

            i_used = __MIN( i_rest, i_sample_count );

            i_index_sample_used += i_used;
            i_sample_count -= i_used;

            p_demux_track->chunk[i_chunk].p_sample_count_dts[i] = i_used;

            p_demux_track->chunk[i_chunk].p_sample_delta_dts[i] =
                        p_stts->data.p_stts->i_sample_delta[i_index];