mp4.c

/*****************************************************************************
 * mp4.c : MP4 file input module for vlc
 *****************************************************************************
 * Copyright (C) 2001-2004, 2010 VLC authors and VideoLAN
 *
 * 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 Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "mp4.h"

#include <vlc_plugin.h>

#include <vlc_demux.h>
#include <vlc_charset.h>                           /* EnsureUTF8 */
#include <vlc_meta.h>                              /* vlc_meta_t, vlc_meta_ */
#include <vlc_input.h>
#include <assert.h>

#include "id3genres.h"                             /* for ATOM_gnre */

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

vlc_module_begin ()
    set_category( CAT_INPUT )
    set_subcategory( SUBCAT_INPUT_DEMUX )
    set_description( N_("MP4 stream demuxer") )
    set_shortname( N_("MP4") )
    set_capability( "demux", 240 )
    set_callbacks( Open, Close )
vlc_module_end ()

/*****************************************************************************
 * Local prototypes
 *****************************************************************************/
static int   Demux   ( demux_t * );
static int   DemuxRef( demux_t *p_demux ){ (void)p_demux; return 0;}
static int   DemuxFrg( demux_t * );
static int   DemuxAsLeaf( demux_t * );
static int   Seek    ( demux_t *, mtime_t );
static int   Control ( demux_t *, int, va_list );

struct demux_sys_t
{
    MP4_Box_t    *p_root;      /* container for the whole file */

    mtime_t      i_pcr;

    uint64_t     i_overall_duration; /* Full duration, including all fragments */
    uint64_t     i_time;         /* time position of the presentation
                                  * in movie timescale */
    uint32_t     i_timescale;    /* movie time scale */
    uint64_t     i_duration;     /* movie duration */
    unsigned int i_tracks;       /* number of tracks */
    mp4_track_t  *track;         /* array of track */
    float        f_fps;          /* number of frame per seconds */

    bool         b_fragmented;   /* fMP4 */
    bool         b_seekable;
    bool         b_fastseekable;
    bool         b_smooth;       /* Is it Smooth Streaming? */

    bool            b_index_probed;
    bool            b_fragments_probed;
    mp4_fragment_t  moovfragment; /* moov */
    mp4_fragment_t *p_fragments;  /* known fragments (moof following moov) */

    struct
    {
        mp4_fragment_t *p_fragment;
        uint32_t        i_current_box_type;
        uint32_t        i_mdatbytesleft;
    } context;

    /* */
    MP4_Box_t    *p_tref_chap;

    /* */
    input_title_t *p_title;
};

#define BOXDATA(type) type->data.type

/*****************************************************************************
 * Declaration of local function
 *****************************************************************************/
static void MP4_TrackCreate ( demux_t *, mp4_track_t *, MP4_Box_t  *, bool b_force_enable );
static int MP4_frg_TrackCreate( demux_t *, mp4_track_t *, MP4_Box_t *);
static void MP4_TrackDestroy(  mp4_track_t * );

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

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

static uint64_t MP4_TrackGetPos    ( mp4_track_t * );
static uint32_t MP4_TrackGetReadSize( mp4_track_t *, uint32_t * );
static int      MP4_TrackNextSample( demux_t *, mp4_track_t *, uint32_t );
static void     MP4_TrackSetELST( demux_t *, mp4_track_t *, int64_t );

static void     MP4_UpdateSeekpoint( demux_t * );
static const char *MP4_ConvertMacCode( uint16_t );

static MP4_Box_t * MP4_GetTrexByTrackID( MP4_Box_t *p_moov, const uint32_t i_id );

static bool AddFragment( demux_t *p_demux, MP4_Box_t *p_moox );
static int  ProbeFragments( demux_t *p_demux, bool b_force );
static int  ProbeIndex( demux_t *p_demux );
static mp4_fragment_t *GetFragmentByPos( demux_t *p_demux, uint64_t i_pos, bool b_exact );
static mp4_fragment_t *GetFragmentByTime( demux_t *p_demux, const mtime_t i_time );

static int LeafIndexGetMoofPosByTime( demux_t *p_demux, const mtime_t i_target_time,
                                      uint64_t *pi_pos, mtime_t *pi_mooftime );
static mtime_t LeafGetFragmentTimeOffset( demux_t *p_demux, mp4_fragment_t * );
static int LeafGetTrackAndChunkByMOOVPos( demux_t *p_demux, uint64_t *pi_pos,
                                      mp4_track_t **pp_tk, unsigned int *pi_chunk );
static int LeafMapTrafTrunContextes( demux_t *p_demux, MP4_Box_t *p_moof );

/* Helpers */

static uint32_t stream_ReadU32( stream_t *s, void *p_read, uint32_t i_toread )
{
    uint32_t i_return = 0;
    if ( i_toread > INT32_MAX )
    {
        i_return = stream_Read( s, p_read, INT32_MAX );
        if ( i_return < INT32_MAX )
            return i_return;
        else
            i_toread -= INT32_MAX;
    }
    i_return += stream_Read( s, (uint8_t *)p_read + i_return, (int32_t) i_toread );
    return i_return;
}

static bool MP4_stream_Tell( stream_t *s, uint64_t *pi_pos )
{
    int64_t i_pos = stream_Tell( s );
    if ( i_pos < 0 )
        return false;
    else
    {
        *pi_pos = (uint64_t) i_pos;
        return true;
    }
}

static MP4_Box_t * MP4_GetTrexByTrackID( MP4_Box_t *p_moov, const uint32_t i_id )
{
    MP4_Box_t *p_trex = MP4_BoxGet( p_moov, "mvex/trex" );
    while( p_trex )
    {
        if ( p_trex->i_type == ATOM_trex && BOXDATA(p_trex)->i_track_ID == i_id )
                break;
        else
            p_trex = p_trex->p_next;
    }
    return p_trex;
}

static MP4_Box_t * MP4_GetTrakByTrackID( MP4_Box_t *p_moov, const uint32_t i_id )
{
    MP4_Box_t *p_trak = MP4_BoxGet( p_moov, "trak" );
    MP4_Box_t *p_tkhd;
    while( p_trak )
    {
        if( p_trak->i_type == ATOM_trak &&
            (p_tkhd = MP4_BoxGet( p_trak, "tkhd" )) &&
            BOXDATA(p_tkhd)->i_track_ID == i_id )
                break;
        else
            p_trak = p_trak->p_next;
    }
    return p_trak;
}

/* Return time in microsecond of a track */
static inline int64_t MP4_TrackGetDTS( demux_t *p_demux, mp4_track_t *p_track )
{
    demux_sys_t *p_sys = p_demux->p_sys;
    mp4_chunk_t chunk;
    if( p_sys->b_fragmented )
        chunk = *p_track->cchunk;
    else
        chunk = p_track->chunk[p_track->i_chunk];

    unsigned int i_index = 0;
    unsigned int i_sample = p_track->i_sample - chunk.i_sample_first;
    int64_t i_dts = chunk.i_first_dts;

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

    /* now handle elst */
    if( p_track->p_elst )
    {
        demux_sys_t         *p_sys = p_demux->p_sys;
        MP4_Box_data_elst_t *elst = p_track->BOXDATA(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 CLOCK_FREQ * i_dts / p_track->i_timescale;
}

static inline int64_t MP4_TrackGetPTSDelta( demux_t *p_demux, mp4_track_t *p_track )
{
    demux_sys_t *p_sys = p_demux->p_sys;
    mp4_chunk_t *ck;
    if( p_sys->b_fragmented )
        ck = p_track->cchunk;
    else
        ck = &p_track->chunk[p_track->i_chunk];

    unsigned int i_index = 0;
    unsigned int i_sample = p_track->i_sample - ck->i_sample_first;

    if( ck->p_sample_count_pts == NULL || ck->p_sample_offset_pts == NULL )
        return -1;

    for( i_index = 0;; i_index++ )
    {
        if( i_sample < ck->p_sample_count_pts[i_index] )
            return ck->p_sample_offset_pts[i_index] * CLOCK_FREQ /
                   (int64_t)p_track->i_timescale;

        i_sample -= ck->p_sample_count_pts[i_index];
    }
}

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

static void LoadChapter( demux_t  *p_demux );

static int LoadInitFrag( demux_t *p_demux )
{
    demux_sys_t *p_sys = p_demux->p_sys;

    if( p_sys->b_smooth ) /* Smooth Streaming */
    {
        if( ( p_sys->p_root = MP4_BoxGetSmooBox( p_demux->s ) ) == NULL )
        {
            goto LoadInitFragError;
        }
        else
        {
            MP4_Box_t *p_smoo = MP4_BoxGet( p_sys->p_root, "uuid" );
            if( !p_smoo || CmpUUID( &p_smoo->i_uuid, &SmooBoxUUID ) )
                goto LoadInitFragError;
            /* Get number of tracks */
            p_sys->i_tracks = 0;
            for( int i = 0; i < 3; i++ )
            {
                MP4_Box_t *p_stra = MP4_BoxGet( p_smoo, "uuid[%d]", i );
                if( p_stra && BOXDATA(p_stra)->i_track_ID )
                    p_sys->i_tracks++;
                /* Get timescale and duration of the video track; */
                if( p_sys->i_timescale == 0 )
                {
                    p_sys->i_timescale = BOXDATA(p_stra)->i_timescale;
                    p_sys->i_duration = BOXDATA(p_stra)->i_duration;
                    p_sys->i_overall_duration = BOXDATA(p_stra)->i_duration;
                    if( p_sys->i_timescale == 0 )
                    {
                        msg_Err( p_demux, "bad timescale" );
                        goto LoadInitFragError;
                    }
                }
            }
        }
    }
    else
    {
        /* Load all boxes ( except raw data ) */
        if( ( p_sys->p_root = MP4_BoxGetRoot( p_demux->s ) ) == NULL )
        {
            goto LoadInitFragError;
        }
    }
    return VLC_SUCCESS;

LoadInitFragError:
    msg_Warn( p_demux, "MP4 plugin discarded (not a valid initialization chunk)" );
    return VLC_EGENERIC;
}

static int InitTracks( demux_t *p_demux )
{
    demux_sys_t *p_sys = p_demux->p_sys;

    p_sys->track = calloc( p_sys->i_tracks, sizeof( mp4_track_t ) );
    if( p_sys->track == NULL )
        return VLC_EGENERIC;

    if( p_sys->b_fragmented )
    {
        mp4_track_t *p_track;
        for( uint16_t i = 0; i < p_sys->i_tracks; i++ )
        {
            p_track = &p_sys->track[i];
            p_track->cchunk = calloc( 1, sizeof( mp4_chunk_t ) );
            if( unlikely( !p_track->cchunk ) )
            {
                free( p_sys->track );
                return VLC_EGENERIC;
            }
        }
    }
    return VLC_SUCCESS;
}

static void CreateTracksFromSmooBox( demux_t *p_demux )
{
    demux_sys_t *p_sys = p_demux->p_sys;

    MP4_Box_t *p_smoo = MP4_BoxGet( p_sys->p_root, "uuid" );
    mp4_track_t *p_track;
    int j = 0;
    for( int i = 0; i < 3; i++ )
    {
        MP4_Box_t *p_stra = MP4_BoxGet( p_smoo, "uuid[%d]", i );
        if( !p_stra || BOXDATA(p_stra)->i_track_ID == 0 )
            continue;
        else
        {
            p_track = &p_sys->track[j]; j++;
            MP4_frg_TrackCreate( p_demux, p_track, p_stra );
            p_track->p_es = es_out_Add( p_demux->out, &p_track->fmt );
        }
    }
}

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

    const 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;
    bool      b_enabled_es;

    /* A little test to see if it could be a mp4 */
    if( stream_Peek( p_demux->s, &p_peek, 11 ) < 11 ) return VLC_EGENERIC;

    switch( VLC_FOURCC( p_peek[4], p_peek[5], p_peek[6], p_peek[7] ) )
    {
        case ATOM_moov:
        case ATOM_foov:
        case ATOM_moof:
        case ATOM_mdat:
        case ATOM_udta:
        case ATOM_free:
        case ATOM_skip:
        case ATOM_wide:
        case ATOM_uuid:
        case VLC_FOURCC( 'p', 'n', 'o', 't' ):
            break;
        case ATOM_ftyp:
            /* We don't yet support f4v, but avformat does. */
            if( p_peek[8] == 'f' && p_peek[9] == '4' && p_peek[10] == 'v' )
                return VLC_EGENERIC;
            break;
         default:
            return VLC_EGENERIC;
    }

    /* create our structure that will contains all data */
    p_sys = calloc( 1, sizeof( demux_sys_t ) );
    if ( !p_sys )
        return VLC_EGENERIC;

    /* I need to seek */
    stream_Control( p_demux->s, STREAM_CAN_SEEK, &p_sys->b_seekable );
    if( !p_sys->b_seekable )
    {
        msg_Warn( p_demux, "MP4 plugin discarded (not seekable)" );
        free( p_sys );
        return VLC_EGENERIC;
    }
    stream_Control( p_demux->s, STREAM_CAN_FASTSEEK, &p_sys->b_fastseekable );

    /*Set exported functions */
    p_demux->pf_demux = Demux;
    p_demux->pf_control = Control;

    p_demux->p_sys = p_sys;

    if( stream_Peek( p_demux->s, &p_peek, 24 ) < 24 ) return VLC_EGENERIC;
    if( !CmpUUID( (UUID_t *)(p_peek + 8), &SmooBoxUUID ) )
    {
        p_sys->b_smooth = true;
        p_sys->b_fragmented = true;
    }

    if( LoadInitFrag( p_demux ) != VLC_SUCCESS )
        goto error;

    if( MP4_BoxCount( p_sys->p_root, "/moov/mvex" ) > 0 )
    {
        if ( p_sys->b_seekable )
        {
            /* Probe remaining to check if there's really fragments
               or if that file is just ready to append fragments */
            ProbeFragments( p_demux, false );
            p_sys->b_fragmented = !!MP4_BoxCount( p_sys->p_root, "/moof" );
        }
        else
            p_sys->b_fragmented = true;

        if ( p_sys->b_fragmented && !p_sys->i_overall_duration )
            ProbeFragments( p_demux, true );
    }

    if ( !p_sys->moovfragment.p_moox )
        AddFragment( p_demux, MP4_BoxGet( p_sys->p_root, "/moov" ) );

    /* we always need a moov entry, but smooth has a workaround */
    if ( !p_sys->moovfragment.p_moox && !p_sys->b_smooth )
        goto error;

    if ( p_sys->b_smooth )
    {
        p_demux->pf_demux = DemuxFrg;
    }
    else if( p_sys->b_fragmented )
    {
        p_demux->pf_demux = DemuxAsLeaf;
    }

    if( p_sys->b_smooth )
    {
        if( InitTracks( p_demux ) != VLC_SUCCESS )
            goto error;
        CreateTracksFromSmooBox( p_demux );
        return VLC_SUCCESS;
    }

    MP4_BoxDumpStructure( p_demux->s, p_sys->p_root );

    if( ( p_ftyp = MP4_BoxGet( p_sys->p_root, "/ftyp" ) ) )
    {
        switch( BOXDATA(p_ftyp)->i_major_brand )
        {
            case( ATOM_isom ):
                msg_Dbg( p_demux,
                         "ISO Media file (isom) version %d.",
                         BOXDATA(p_ftyp)->i_minor_version );
                break;
            case( ATOM_3gp4 ):
            case( VLC_FOURCC( '3', 'g', 'p', '5' ) ):
            case( VLC_FOURCC( '3', 'g', 'p', '6' ) ):
            case( VLC_FOURCC( '3', 'g', 'p', '7' ) ):
                msg_Dbg( p_demux, "3GPP Media file Release: %c",
#ifdef WORDS_BIGENDIAN
                        BOXDATA(p_ftyp)->i_major_brand
#else
                        BOXDATA(p_ftyp)->i_major_brand >> 24
#endif
                        );
                break;
            case( VLC_FOURCC( 'q', 't', ' ', ' ') ):
                msg_Dbg( p_demux, "Apple QuickTime file" );
                break;
            case( VLC_FOURCC( 'i', 's', 'm', 'l') ):
                msg_Dbg( p_demux, "PIFF (= isml = fMP4) file" );
                break;
            default:
                msg_Dbg( p_demux,
                         "unrecognized major file specification (%4.4s).",
                          (char*)&BOXDATA(p_ftyp)->i_major_brand );
                break;
        }
    }
    else
    {
        msg_Dbg( p_demux, "file type box missing (assuming ISO Media file)" );
    }

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

        if( !p_foov )
        {
            msg_Err( p_demux, "MP4 plugin discarded (no moov,foov,moof box)" );
            goto error;
        }
        /* we have a free box as a moov, rename it */
        p_foov->i_type = ATOM_moov;
        p_sys->moovfragment.p_moox = p_foov;
    }

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

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

        input_thread_t *p_input = demux_GetParentInput( p_demux );
        input_item_t *p_current = input_GetItem( p_input );

        input_item_node_t *p_subitems = input_item_node_Create( p_current );

        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 = strdup( BOXDATA(p_rdrf)->psz_ref ) ) )
            {
                continue;
            }
            i_ref_type = BOXDATA(p_rdrf)->i_ref_type;

            msg_Dbg( p_demux, "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_demux, "ignoring pseudo ref =`%s'", psz_ref );
                    continue;
                }
                if( !strncmp( psz_ref, "http://", 7 ) ||
                    !strncmp( psz_ref, "rtsp://", 7 ) )
                {
                    ;
                }
                else
                {
                    char *psz_absolute;
                    char *psz_path = strdup( p_demux->psz_location );
                    char *end = strrchr( psz_path, '/' );
                    if( end ) end[1] = '\0';
                    else *psz_path = '\0';

                    if( asprintf( &psz_absolute, "%s://%s%s",
                                  p_demux->psz_access, psz_path, psz_ref ) < 0 )
                    {
                        free( psz_ref );
                        free( psz_path );
                        input_item_node_Delete( p_subitems );
                        vlc_object_release( p_input) ;
                        return VLC_ENOMEM;
                    }

                    free( psz_ref );
                    psz_ref = psz_absolute;
                    free( psz_path );
                }
                msg_Dbg( p_demux, "adding ref = `%s'", psz_ref );
                input_item_t *p_item = input_item_New( psz_ref, NULL );
                input_item_CopyOptions( p_current, p_item );
                input_item_node_AppendItem( p_subitems, p_item );
                vlc_gc_decref( p_item );
            }
            else
            {
                msg_Err( p_demux, "unknown ref type=%4.4s FIXME (send a bug report)",
                         (char*)&BOXDATA(p_rdrf)->i_ref_type );
            }
            free( psz_ref );
        }
        input_item_node_PostAndDelete( p_subitems );
        vlc_object_release( p_input );
    }

    if( !(p_mvhd = MP4_BoxGet( p_sys->p_root, "/moov/mvhd" ) ) )
    {
        if( !p_rmra )
        {
            msg_Err( p_demux, "cannot find /moov/mvhd" );
            goto error;
        }
        else
        {
            msg_Warn( p_demux, "cannot find /moov/mvhd (pure ref file)" );
            p_demux->pf_demux = DemuxRef;
            return VLC_SUCCESS;
        }
    }
    else
    {
        p_sys->i_timescale = BOXDATA(p_mvhd)->i_timescale;
        if( p_sys->i_timescale == 0 )
        {
            msg_Err( p_this, "bad timescale" );
            goto error;
        }
    }

    if ( p_sys->i_overall_duration == 0 )
    {
        /* Try in mehd if fragmented */
        MP4_Box_t *p_mehd = MP4_BoxGet( p_demux->p_sys->p_root, "moov/mvex/mehd");
        if ( p_mehd )
            p_sys->i_overall_duration = p_mehd->data.p_mehd->i_fragment_duration;
        else
            p_sys->i_overall_duration = p_sys->moovfragment.i_duration;
    }

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

    if( InitTracks( p_demux ) != VLC_SUCCESS )
        goto error;

    /* Search the first chap reference (like quicktime) and
     * check that at least 1 stream is enabled */
    p_sys->p_tref_chap = NULL;
    b_enabled_es = false;
    for( i = 0; i < p_sys->i_tracks; i++ )
    {
        MP4_Box_t *p_trak = MP4_BoxGet( p_sys->p_root, "/moov/trak[%d]", i );


        MP4_Box_t *p_tkhd = MP4_BoxGet( p_trak, "tkhd" );
        if( p_tkhd && (BOXDATA(p_tkhd)->i_flags&MP4_TRACK_ENABLED) )
            b_enabled_es = true;

        MP4_Box_t *p_chap = MP4_BoxGet( p_trak, "tref/chap", i );
        if( p_chap && p_chap->data.p_tref_generic->i_entry_count > 0 && !p_sys->p_tref_chap )
            p_sys->p_tref_chap = p_chap;
    }

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

        if( p_sys->track[i].b_ok && !p_sys->track[i].b_chapter )
        {
            const 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;
                case( SPU_ES ):
                    psz_cat = "subtitle";
                    break;

                default:
                    psz_cat = "unknown";
                    break;
            }

            msg_Dbg( p_demux, "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 if( p_sys->track[i].b_ok && p_sys->track[i].b_chapter )
        {
            msg_Dbg( p_demux, "using track[Id 0x%x] for chapter language %s",
                     p_sys->track[i].i_track_ID,
                     p_sys->track[i].fmt.psz_language ?
                     p_sys->track[i].fmt.psz_language : "undef" );
        }
        else
        {
            msg_Dbg( p_demux, "ignoring track[Id 0x%x]",
                     p_sys->track[i].i_track_ID );
        }
    }

    mp4_fragment_t *p_fragment = &p_sys->moovfragment;
    while ( p_fragment )
    {
        msg_Dbg( p_demux, "fragment offset %"PRId64", data %"PRIu64"<->%"PRIu64", duration %"PRId64,
                 p_fragment->p_moox->i_pos, p_fragment->i_chunk_range_min_offset,
                 p_fragment->i_chunk_range_max_offset, CLOCK_FREQ * p_fragment->i_duration / p_sys->i_timescale );
        p_fragment = p_fragment->p_next;
    }

    /* */
    LoadChapter( p_demux );

    return VLC_SUCCESS;

error:
    if( p_sys->p_root )
    {
        MP4_BoxFree( p_demux->s, 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( demux_t *p_demux )
{
    demux_sys_t *p_sys = p_demux->p_sys;
    unsigned int i_track;


    unsigned int i_track_selected;

    /* 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];
        bool b;

        if( !tk->b_ok || tk->b_chapter ||
            ( tk->b_selected && tk->i_sample >= tk->i_sample_count ) )
        {
            continue;
        }

        es_out_Control( p_demux->out, ES_OUT_GET_ES_STATE, tk->p_es, &b );

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

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

    if( i_track_selected <= 0 )
    {
        p_sys->i_time += __MAX( p_sys->i_timescale / 10 , 1 );
        if( p_sys->i_timescale > 0 )
        {
            int64_t i_length = CLOCK_FREQ *
                               (mtime_t)p_sys->moovfragment.i_duration /
                               (mtime_t)p_sys->i_timescale;
            if( MP4_GetMoviePTS( p_sys ) >= i_length )
                return 0;
            return 1;
        }

        msg_Warn( p_demux, "no track selected, exiting..." );
        return 0;
    }

    /* */
    MP4_UpdateSeekpoint( p_demux );

    /* first wait for the good time to read a packet */
    p_sys->i_pcr = MP4_GetMoviePTS( p_sys );

    bool b_data_sent = false;

    /* Find next track matching contiguous data */
    mp4_track_t *tk = NULL;
    uint64_t i_candidate_pos = UINT64_MAX;
    for( i_track = 0; i_track < p_sys->i_tracks; i_track++ )
    {
        mp4_track_t *tk_tmp = &p_sys->track[i_track];
        if( !tk_tmp->b_ok || tk_tmp->b_chapter || !tk_tmp->b_selected || tk_tmp->i_sample >= tk_tmp->i_sample_count )
            continue;

        uint64_t i_pos = MP4_TrackGetPos( tk_tmp );
        if ( i_pos <= i_candidate_pos )
        {
            i_candidate_pos = i_pos;
            tk = tk_tmp;
        }
    }

    if ( !tk )
    {
        msg_Dbg( p_demux, "Could not select track by data position" );
        goto end;
    }

#if 0
    msg_Dbg( p_demux, "tk(%i)=%"PRId64" mv=%"PRId64" pos=%"PRIu64, i_track,
             MP4_TrackGetDTS( p_demux, tk ),
             MP4_GetMoviePTS( p_sys ), i_candidate_pos );
#endif

    uint32_t i_nb_samples = 0;
    uint32_t i_samplessize = MP4_TrackGetReadSize( tk, &i_nb_samples );
    if( i_samplessize > 0 )
    {
        block_t *p_block;
        int64_t i_delta;
        uint64_t i_current_pos;

        /* go,go go ! */
        if ( !MP4_stream_Tell( p_demux->s, &i_current_pos ) )
            goto end;

        if( i_current_pos != i_candidate_pos )
        {
            if( stream_Seek( p_demux->s, i_candidate_pos ) )
            {
                msg_Warn( p_demux, "track[0x%x] will be disabled (eof?)",
                          tk->i_track_ID );
                MP4_TrackUnselect( p_demux, tk );
                goto end;
            }
        }

        /* now read pes */
        if( !(p_block = stream_Block( p_demux->s, i_samplessize )) )
        {
            msg_Warn( p_demux, "track[0x%x] will be disabled (eof?)",
                      tk->i_track_ID );
            MP4_TrackUnselect( p_demux, tk );
            goto end;
        }
        else if( tk->fmt.i_cat == SPU_ES )
        {
            if ( tk->fmt.i_codec != VLC_CODEC_TX3G &&
                 tk->fmt.i_codec != VLC_CODEC_SPU )
                p_block->i_buffer = 0;
        }

        /* dts */
        p_block->i_dts = VLC_TS_0 + MP4_TrackGetDTS( p_demux, tk );
        /* pts */
        i_delta = MP4_TrackGetPTSDelta( p_demux, tk );
        if( i_delta != -1 )
            p_block->i_pts = p_block->i_dts + i_delta;
        else if( tk->fmt.i_cat != VIDEO_ES )
            p_block->i_pts = p_block->i_dts;
        else
            p_block->i_pts = VLC_TS_INVALID;

        if ( !b_data_sent )
        {
            es_out_Control( p_demux->out, ES_OUT_SET_PCR, VLC_TS_0 + p_sys->i_pcr );
            b_data_sent = true;
        }
        es_out_Send( p_demux->out, tk->p_es, p_block );
    }

    /* Next sample */
    if ( i_nb_samples ) /* sample size could be 0, need to go fwd. see return */
        MP4_TrackNextSample( p_demux, tk, i_nb_samples );

end:
    if ( b_data_sent )
    {
        p_sys->i_pcr = INT64_MAX;
        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  ||
                 (tk->fmt.i_cat != AUDIO_ES && tk->fmt.i_cat != VIDEO_ES) )
                continue;
            p_sys->i_pcr = __MIN( MP4_TrackGetDTS( p_demux, tk ), p_sys->i_pcr );
            p_sys->i_time = p_sys->i_pcr * p_sys->i_timescale / CLOCK_FREQ;
        }
    }

    return b_data_sent || ( i_samplessize == 0 && i_nb_samples );
}