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

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include "mp4.h"

#include <vlc_demux.h>
#include <vlc_charset.h>                           /* EnsureUTF8 */
#include <vlc_input.h>
#include <vlc_aout.h>
#include <vlc_plugin.h>
#include <assert.h>
#include <limits.h>
#include "../codec/cc.h"

/*****************************************************************************
 * 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 */
    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_seekmode;

    bool            b_index_probed;
    bool            b_fragments_probed;

    mp4_fragments_t fragments;

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

    /* */
    MP4_Box_t    *p_tref_chap;

    /* */
    input_title_t *p_title;

    /* ASF in MP4 */
    asf_packet_sys_t asfpacketsys;
    uint64_t i_preroll;         /* foobar */
    int64_t  i_preroll_start;
};

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

static block_t * MP4_Block_Read( demux_t *, const mp4_track_t *, int );
static void MP4_Block_Send( demux_t *, mp4_track_t *, block_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 bool     MP4_TrackIsInterleaved( const mp4_track_t * );

static void     MP4_UpdateSeekpoint( demux_t * );

static MP4_Box_t * MP4_GetTrexByTrackID( MP4_Box_t *p_moov, const uint32_t i_id );
static void MP4_GetDefaultSizeAndDuration( demux_t *p_demux,
                                           const MP4_Box_data_tfhd_t *p_tfhd_data,
                                           uint32_t *pi_default_size,
                                           uint32_t *pi_default_duration );

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 int LeafIndexGetMoofPosByTime( demux_t *p_demux, const mtime_t i_target_time,
                                      uint64_t *pi_pos, mtime_t *pi_mooftime );
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 );

/* ASF Handlers */
static asf_track_info_t * MP4ASF_GetTrackInfo( asf_packet_sys_t *p_packetsys, uint8_t i_stream_number );
static void MP4ASF_Send(asf_packet_sys_t *p_packetsys, uint8_t i_stream_number, block_t **pp_frame);
static void MP4ASF_ResetFrames( demux_sys_t *p_sys );

/* RTP Hint track */
static block_t * MP4_RTPHint_Convert( demux_t *p_demux, block_t *p_block, vlc_fourcc_t i_codec );
static block_t * MP4_RTPHintToFrame( demux_t *p_demux, block_t *p_block, uint32_t packetcount );

/* Helpers */

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

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

static es_out_id_t * MP4_AddTrackES( es_out_t *out, mp4_track_t *p_track )
{
    es_out_id_t *p_es = es_out_Add( out, &p_track->fmt );
    /* Force SPU which isn't selected/defaulted */
    if( p_track->fmt.i_cat == SPU_ES && p_es && p_track->b_forced_spu )
        es_out_Control( out, ES_OUT_SET_ES_DEFAULT, p_es );

    return p_es;
}

/* 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;
    const mp4_chunk_t *p_chunk;
    if( p_sys->b_fragmented )
        p_chunk = p_track->cchunk;
    else
        p_chunk = &p_track->chunk[p_track->i_chunk];

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

    while( i_sample > 0 && i_index < p_chunk->i_entries_dts )
    {
        if( i_sample > p_chunk->p_sample_count_dts[i_index] )
        {
            i_dts += p_chunk->p_sample_count_dts[i_index] *
                p_chunk->p_sample_delta_dts[i_index];
            i_sample -= p_chunk->p_sample_count_dts[i_index];
            i_index++;
        }
        else
        {
            i_dts += i_sample * p_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 bool MP4_TrackGetPTSDelta( demux_t *p_demux, mp4_track_t *p_track,
                                         int64_t *pi_delta )
{
    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 false;

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

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

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;

    /* 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 AllocateTracks( demux_t *p_demux, unsigned i_tracks )
{
    demux_sys_t *p_sys = p_demux->p_sys;

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

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

static block_t * MP4_EIA608_Convert( block_t * p_block )
{
    /* Rebuild codec data from encap */
    size_t i_copied = 0;
    size_t i_remaining = __MIN(p_block->i_buffer, INT64_MAX / 3);
    uint32_t i_bytes = 0;
    block_t *p_newblock;

    /* always need at least 10 bytes (atom size+header+1pair)*/
    if ( i_remaining < 10 ||
         !(i_bytes = GetDWBE(p_block->p_buffer)) ||
         (i_bytes > i_remaining) ||
         memcmp("cdat", &p_block->p_buffer[4], 4) ||
         !(p_newblock = block_Alloc( i_remaining * 3 - 8 )) )
    {
        p_block->i_buffer = 0;
        return p_block;
    }

    uint8_t *p_write = p_newblock->p_buffer;
    uint8_t *p_read = &p_block->p_buffer[8];
    i_bytes -= 8;
    i_remaining -= 8;

    do
    {
        p_write[i_copied++] = CC_PKT_BYTE0(0); /* cc1 == field 0 */
        p_write[i_copied++] = p_read[0];
        p_write[i_copied++] = p_read[1];
        p_read += 2;
        i_bytes -= 2;
        i_remaining -= 2;
    } while( i_bytes >= 2 );

    /* cdt2 is optional */
    if ( i_remaining >= 10 &&
         (i_bytes = GetDWBE(p_read)) &&
         (i_bytes <= i_remaining) &&
         !memcmp("cdt2", &p_read[4], 4) )
    {
        p_read += 8;
        i_bytes -= 8;
        i_remaining -= 8;
        do
        {
            p_write[i_copied++] = CC_PKT_BYTE0(0); /* cc1 == field 0 */
            p_write[i_copied++] = p_read[0];
            p_write[i_copied++] = p_read[1];
            p_read += 2;
            i_bytes -= 2;
        } while( i_bytes >= 2 );
    }

    block_Release( p_block );
    p_newblock->i_buffer = i_copied;
    p_newblock->i_flags = BLOCK_FLAG_ORDERED_CAPTIONS;
    return p_newblock;
}

static block_t * MP4_Block_Read( demux_t *p_demux, const mp4_track_t *p_track, int i_size )
{
    block_t *p_block = vlc_stream_Block( p_demux->s, i_size );
    if ( !p_block )
        return NULL;

    /* might have some encap */
    if( p_track->fmt.i_cat == SPU_ES )
    {
        switch( p_track->fmt.i_codec )
        {
            case VLC_CODEC_TX3G:
            case VLC_CODEC_SPU:
            /* accept as-is */
            break;
            case VLC_CODEC_EIA608_1:
                p_block = MP4_EIA608_Convert( p_block );
            break;
        default:
            p_block->i_buffer = 0;
            break;
        }
    }
    else if( p_track->fmt.i_original_fourcc == ATOM_rrtp )
    {
        p_block = MP4_RTPHint_Convert( p_demux, p_block, p_track->fmt.i_codec );
    }

    return p_block;
}

static void MP4_Block_Send( demux_t *p_demux, mp4_track_t *p_track, block_t *p_block )
{
    if ( p_track->b_chans_reorder )
    {
        aout_ChannelReorder( p_block->p_buffer, p_block->i_buffer,
                             p_track->fmt.audio.i_channels,
                             p_track->rgi_chans_reordering,
                             p_track->fmt.i_codec );
    }

    p_block->i_flags |= p_track->i_block_flags;

    /* ASF packets in mov */
    if( p_track->p_asf )
    {
        /* Fake a new stream from MP4 block */
        stream_t *p_stream = p_demux->s;
        p_demux->s = vlc_stream_MemoryNew( p_demux, p_block->p_buffer, p_block->i_buffer, true );
        if ( p_demux->s )
        {
            p_track->i_dts_backup = p_block->i_dts;
            p_track->i_pts_backup = p_block->i_pts;
            /* And demux it as ASF packet */
            DemuxASFPacket( &p_demux->p_sys->asfpacketsys, p_block->i_buffer, p_block->i_buffer );
            vlc_stream_Delete(p_demux->s);
        }
        block_Release(p_block);
        p_demux->s = p_stream;
    }
    else
        es_out_Send( p_demux->out, p_track->p_es, p_block );
}

/*****************************************************************************
 * 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( vlc_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 */
    vlc_stream_Control( p_demux->s, STREAM_CAN_SEEK, &p_sys->b_seekable );
    vlc_stream_Control( p_demux->s, STREAM_CAN_FASTSEEK,
                        &p_sys->b_fastseekable );
    p_sys->b_seekmode = p_sys->b_fastseekable;

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

    p_sys->context.i_lastseqnumber = 1;

    MP4_Fragments_Init( &p_sys->fragments );

    p_demux->p_sys = p_sys;

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


    if( ( p_ftyp = MP4_BoxGet( p_sys->p_root, "/ftyp" ) ) )
    {
        switch( BOXDATA(p_ftyp)->i_major_brand )
        {
            case MAJOR_isom:
                msg_Dbg( p_demux,
                         "ISO Media (isom) version %d.",
                         BOXDATA(p_ftyp)->i_minor_version );
                break;
            case MAJOR_3gp4:
            case MAJOR_3gp5:
            case MAJOR_3gp6:
            case MAJOR_3gp7:
                msg_Dbg( p_demux, "3GPP Media Release: %4.4s",
                         (char *)&BOXDATA(p_ftyp)->i_major_brand );
                break;
            case MAJOR_qt__:
                msg_Dbg( p_demux, "Apple QuickTime media" );
                break;
            case MAJOR_isml:
                msg_Dbg( p_demux, "PIFF (= isml = fMP4) media" );
                break;
            case MAJOR_dash:
                msg_Dbg( p_demux, "DASH Stream" );
                break;
            default:
                msg_Dbg( p_demux,
                         "unrecognized major media specification (%4.4s).",
                          (char*)&BOXDATA(p_ftyp)->i_major_brand );
                break;
        }
        /* also lookup in compatibility list */
        for(uint32_t i=0; i<BOXDATA(p_ftyp)->i_compatible_brands_count; i++)
        {
            if (BOXDATA(p_ftyp)->i_compatible_brands[i] == MAJOR_dash)
            {
                msg_Dbg( p_demux, "DASH Stream" );
            }
            else if (BOXDATA(p_ftyp)->i_compatible_brands[i] == VLC_FOURCC('s', 'm', 'o', 'o') )
            {
                msg_Dbg( p_demux, "Handling VLC Smooth Stream" );
            }
        }
    }
    else
    {
        msg_Dbg( p_demux, "file type box missing (assuming ISO Media)" );
    }

    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" );

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

            MP4_Box_t *p_mdat = MP4_BoxGet( p_sys->p_root, "mdat" );
            if ( p_mdat )
            {
                vlc_stream_Seek( p_demux->s, p_mdat->i_pos );
                msg_Dbg( p_demux, "rewinding to mdat %"PRId64, p_mdat->i_pos );
            }
        }
        else
            p_sys->b_fragmented = true;
    }

    if ( !MP4_Fragment_Moov(&p_sys->fragments)->p_moox )
        AddFragment( p_demux, MP4_BoxGet( p_sys->p_root, "/moov" ) );

    if ( !MP4_Fragment_Moov(&p_sys->fragments)->p_moox )
        goto error;

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

    if( p_sys->b_fragmented )
    {
        p_demux->pf_demux = DemuxAsLeaf;
        msg_Dbg( p_demux, "Set experimental DemuxLeaf mode" );
    }

    if( !p_sys->b_seekable && p_demux->pf_demux == Demux )
    {
        msg_Warn( p_demux, "MP4 plugin discarded (not seekable)" );
        goto error;
    }

    /* the file need to have one moov box */
    MP4_Fragment_Moov(&p_sys->fragments)->p_moox = MP4_BoxGet( p_sys->p_root, "/moov", 0 );
    if( !MP4_Fragment_Moov(&p_sys->fragments)->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;
        MP4_Fragment_Moov(&p_sys->fragments)->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 = p_demux->p_input;
        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 || !BOXDATA(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 );
                        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_item, p_current );
                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 );
    }

    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;
        }
    }

    const unsigned i_tracks = MP4_BoxCount( p_sys->p_root, "/moov/trak" );
    if( i_tracks < 1 )
    {
        msg_Err( p_demux, "cannot find any /moov/trak" );
        goto error;
    }
    msg_Dbg( p_demux, "found %u track%c", i_tracks, i_tracks ? 's':' ' );

    if( AllocateTracks( p_demux, i_tracks ) != 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) && (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 &&
            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, true, !b_enabled_es );

        if( p_sys->track[i].b_ok && !p_sys->track[i].b_chapters_source )
        {
            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_chapters_source )
        {
            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 );
        }
    }

    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_mehd->data.p_mehd )
            p_sys->i_overall_duration = p_mehd->data.p_mehd->i_fragment_duration;
        else
        {
            for( i = 0; i < p_sys->i_tracks; i++ )
            {
                mtime_t i_duration = GetTrackTotalDuration( &p_sys->fragments, p_sys->track[i].i_track_ID );
                p_sys->i_overall_duration = __MAX( p_sys->i_overall_duration, (uint64_t)i_duration );
            }
        }
    }

#ifdef MP4_VERBOSE
    DumpFragments( VLC_OBJECT(p_demux), &p_sys->fragments, p_sys->i_timescale );
#endif

    if( !p_sys->b_fragmented && p_sys->i_tracks > 1 && p_sys->b_seekable && !p_sys->b_seekmode )
    {
        for( unsigned i = 0; i < p_sys->i_tracks; i++ )
        {
            mp4_track_t *tk = &p_sys->track[i];
            if( !MP4_TrackIsInterleaved( tk ) )
            {
                msg_Warn( p_demux, "that media doesn't look interleaved, will need to seek");
                p_sys->b_seekmode = true;
                break;
            }
        }
    }

    /* */
    LoadChapter( p_demux );