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[demuxers/Mp4] Support fragmented mp4 with default dts increment spec…
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…ified in trex box only, prefill time base for H.264 streams from SPS

It is assumed that only one trex box exists and the track id matches the video track.
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@eumagga0x2a
eumagga0x2a committed Mar 13, 2020
1 parent 8b8ec79 commit 3581d6a
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Showing 5 changed files with 77 additions and 5 deletions.
3 changes: 2 additions & 1 deletion avidemux_plugins/ADM_demuxers/Mp4/ADM_mp4.cpp
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Expand Up @@ -265,6 +265,7 @@ MP4Header::MP4Header(void)
_currentAudioTrack=0;
_reordered=0;
_videoScale=1;
_defaultDurationEx=0;
_videoFound=0;
delayRelativeToVideo=0;
_flavor=Mp4Regular;
Expand Down Expand Up @@ -333,7 +334,7 @@ uint8_t MP4Header::getExtraHeaderData(uint32_t *len, uint8_t **data)
//______________________________________
uint8_t MP4Header::open(const char *name)
{
printf("** opening 3gpp files **");
printf("** opening 3gpp files **\n");
_fd=ADM_fopen(name,"rb");
if(!_fd)
{
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2 changes: 2 additions & 0 deletions avidemux_plugins/ADM_demuxers/Mp4/ADM_mp4.h
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Expand Up @@ -186,6 +186,7 @@ class MP4Header :public vidHeader
uint64_t delayRelativeToVideo;
uint8_t lookupMainAtoms(void *tom);
void parseMvhd(void *tom);
uint8_t parseTrex(void *ztom);
uint8_t parseTrack(void *ztom);
uint8_t parseElst(void *tom,int64_t *delay,int64_t *skip);
bool parseMoof(adm_atom &son);
Expand All @@ -204,6 +205,7 @@ class MP4Header :public vidHeader
bool adjustElstDelay(void);
uint32_t _videoScale;
uint32_t _movieScale;
uint32_t _defaultDurationEx; // dts increment in ticks _videoScale
int64_t _movieDuration; // in ms
uint32_t _videoFound;
bool processAudio( MP4Track *track, uint32_t trackScale,
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73 changes: 69 additions & 4 deletions avidemux_plugins/ADM_demuxers/Mp4/ADM_mp4Analyzer.cpp
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Expand Up @@ -118,6 +118,12 @@ uint8_t MP4Header::lookupMainAtoms(void *ztom)
switch(id)
{
case ADM_MP4_MVHD: parseMvhd(&son);break;
case ADM_MP4_MVEX:
{
ADM_info("Found mvex at position %u of size %u\n",son.getStartPos(),son.getRemainingSize());
parseTrex(&son);
}
break;
case ADM_MP4_TRACK:
if(!parseTrack(&son))
{
Expand Down Expand Up @@ -199,8 +205,45 @@ void MP4Header::parseMvhd(void *ztom)
}

/**
\fn parseMvhd
\brief Parse mvhd header
\fn parseTrex
\brief Some iso5 files specify dts increment via trex box only. We ignore other trex data for now.
*/
uint8_t MP4Header::parseTrex(void *ztom)
{
if(_defaultDurationEx)
{
ADM_warning("Multiple trex boxes not handled!\n");
return 0;
}
adm_atom *tom=(adm_atom *)ztom;
ADMAtoms id;
uint32_t container;
uint32_t trackId=0;
while(!tom->isDone())
{
adm_atom son(tom);
if(!ADM_mp4SearchAtomName(son.getFCC(),&id,&container))
{
aprintf("[parseTrex] Unknown atom %s\n",fourCC::tostringBE(son.getFCC()));
son.skipAtom();
continue;
}
if(id!=ADM_MP4_TREX) continue;
ADM_info("Found trex, assuming it is for the video track, reading it.\n");
son.skipBytes(4); // version and flags
trackId=son.read32();
son.skipBytes(4); // stsd id
_defaultDurationEx=tom->read32();
ADM_info("Default duration from trex for track id %u: %u\n",trackId,_defaultDurationEx);
son.skipAtom();
return 1;
}
ADM_info("trex box not found.\n");
return 0;
}
/**
\fn parseTrack
\brief Parse track header
*/
uint8_t MP4Header::parseTrack(void *ztom)
{
Expand Down Expand Up @@ -922,7 +965,12 @@ uint8_t MP4Header::parseStbl(void *ztom,uint32_t trackType,uint32_t trackScale)
mixDump(VDEO.extraData+offset,len);
// Verify width and height, the values from the container may be wrong.
ADM_SPSInfo sps;
if(extractSPSInfo(VDEO.extraData,VDEO.extraDataSize,&sps) && sps.width && sps.height)
if(false==extractSPSInfo(VDEO.extraData,VDEO.extraDataSize,&sps))
{
ADM_warning("Could not decode H.264 extradata.\n");
break;
}
if(sps.width && sps.height)
{
if(lw && lw!=sps.width)
ADM_warning("Width mismatch, container says %u, codec %u, trusting codec\n",lw,sps.width);
Expand All @@ -931,7 +979,24 @@ uint8_t MP4Header::parseStbl(void *ztom,uint32_t trackType,uint32_t trackScale)
ADM_warning("Height mismatch, container says %u, codec %u, trusting codec\n",lh,sps.height);
_video_bih.biHeight=_mainaviheader.dwHeight=sps.height;
}else
ADM_warning("Could not decode H.264 extradata to verify video width and height.\n");
ADM_warning("Got invalid dimensions from SPS, cannot verify video width and height.\n");
// Prefill time base from fps1000 value we got from SPS, we handle only standard cases here.
switch(sps.fps1000)
{
case 23976:
_videostream.dwScale=1001;
_videostream.dwRate=24000;
break;
case 29970:
_videostream.dwScale=1001;
_videostream.dwRate=30000;
break;
case 24000: case 25000: case 30000: case 50000: case 60000:
_videostream.dwScale=1000;
_videostream.dwRate=sps.fps1000;
break;
default:break;
}
break;
} // while
son.skipAtom();
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2 changes: 2 additions & 0 deletions avidemux_plugins/ADM_demuxers/Mp4/ADM_mp4Fragments.cpp
View file
Expand Up @@ -121,6 +121,8 @@ bool MP4Header::parseTraf(adm_atom &tom,uint64_t moofStart)
TRAF_INFO(0x20,defaultFlags,32);

if(trafFlags&0x10000) {aprintf("Empty duration\n");info.emptyDuration=true;}
if(!info.emptyDuration && !info.defaultDuration && _defaultDurationEx)
info.defaultDuration=_defaultDurationEx; // from trex
if(trafFlags&0x20000)
{

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2 changes: 2 additions & 0 deletions avidemux_plugins/ADM_demuxers/Mp4/ADM_mp4Leaf.h
View file
Expand Up @@ -18,6 +18,7 @@
/* Container atom */
MKMP4LEAF('moov',MOOV,1),
MKMP4LEAF('moof',MOOF,1),
MKMP4LEAF('mvex',MVEX,1),
MKMP4LEAF('trak',TRACK,1),
MKMP4LEAF('mdia',MDIA,1),
MKMP4LEAF('minf',MINF,1),
Expand All @@ -31,6 +32,7 @@ MKMP4LEAF('trun',TRUN,0),
MKMP4LEAF('mfhd',MFHD,0),
MKMP4LEAF('mvhd',MVHD,0),
MKMP4LEAF('tkhd',TKHD,0),
MKMP4LEAF('trex',TREX,0),
MKMP4LEAF('mdhd',MDHD,0),
MKMP4LEAF('hdlr',HDLR,0),

Expand Down

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