Mp4InfoReaderpublic class Mp4InfoReader extends Object Read audio info from file.
The info is held in the mvdh and mdhd fields as shown below
|--- ftyp
|--- moov
|......|
|......|----- mvdh
|......|----- trak
|...............|----- mdia
|.......................|---- mdhd
|.......................|---- minf
|..............................|---- smhd
|..............................|---- stbl
|......................................|--- stsd
|.............................................|--- mp4a
|......|----- udta
|
|--- mdat
|
| Fields Summary |
|---|
| public static Logger | logger |
| Methods Summary |
|---|
| private boolean | isTrackAtomVideo(Mp4FtypBox ftyp, Mp4BoxHeader boxHeader, java.nio.ByteBuffer mvhdBuffer)
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MDIA.getFieldName());
if (boxHeader == null)
{
return false;
}
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MDHD.getFieldName());
if (boxHeader == null)
{
return false;
}
mvhdBuffer.position(mvhdBuffer.position() + boxHeader.getDataLength());
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MINF.getFieldName());
if (boxHeader == null)
{
return false;
}
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.VMHD.getFieldName());
if (boxHeader != null)
{
return true;
}
return false;
| | public org.jaudiotagger.audio.generic.GenericAudioHeader | read(java.io.RandomAccessFile raf)
Mp4AudioHeader info = new Mp4AudioHeader();
//File Identification
Mp4BoxHeader ftypHeader = Mp4BoxHeader.seekWithinLevel(raf, Mp4AtomIdentifier.FTYP.getFieldName());
if (ftypHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_CONTAINER.getMsg());
}
ByteBuffer ftypBuffer = ByteBuffer.allocate(ftypHeader.getLength() - Mp4BoxHeader.HEADER_LENGTH);
raf.getChannel().read(ftypBuffer);
ftypBuffer.rewind();
Mp4FtypBox ftyp = new Mp4FtypBox(ftypHeader, ftypBuffer);
ftyp.processData();
info.setBrand(ftyp.getMajorBrand());
//Get to the facts everything we are interested in is within the moov box, so just load data from file
//once so no more file I/O needed
Mp4BoxHeader moovHeader = Mp4BoxHeader.seekWithinLevel(raf, Mp4AtomIdentifier.MOOV.getFieldName());
if (moovHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
ByteBuffer moovBuffer = ByteBuffer.allocate(moovHeader.getLength() - Mp4BoxHeader.HEADER_LENGTH);
raf.getChannel().read(moovBuffer);
moovBuffer.rewind();
//Level 2-Searching for "mvhd" somewhere within "moov", we make a slice after finding header
//so all get() methods will be relative to mvdh positions
Mp4BoxHeader boxHeader = Mp4BoxHeader.seekWithinLevel(moovBuffer, Mp4AtomIdentifier.MVHD.getFieldName());
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
ByteBuffer mvhdBuffer = moovBuffer.slice();
Mp4MvhdBox mvhd = new Mp4MvhdBox(boxHeader, mvhdBuffer);
info.setLength(mvhd.getLength());
//Advance position, TODO should we put this in box code ?
mvhdBuffer.position(mvhdBuffer.position() + boxHeader.getDataLength());
//Level 2-Searching for "trak" within "moov"
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.TRAK.getFieldName());
int endOfFirstTrackInBuffer = mvhdBuffer.position() + boxHeader.getDataLength();
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
//Level 3-Searching for "mdia" within "trak"
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MDIA.getFieldName());
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
//Level 4-Searching for "mdhd" within "mdia"
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MDHD.getFieldName());
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
Mp4MdhdBox mdhd = new Mp4MdhdBox(boxHeader, mvhdBuffer.slice());
info.setSamplingRate(mdhd.getSampleRate());
//Level 4-Searching for "hdlr" within "mdia"
/*We dont currently need to process this because contains nothing we want
mvhdBuffer.position(mvhdBuffer.position() + boxHeader.getDataLength());
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4NotMetaFieldKey.HDLR.getFieldName());
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
Mp4HdlrBox hdlr = new Mp4HdlrBox(boxHeader, mvhdBuffer.slice());
hdlr.processData();
*/
//Level 4-Searching for "minf" within "mdia"
mvhdBuffer.position(mvhdBuffer.position() + boxHeader.getDataLength());
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MINF.getFieldName());
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
//Level 5-Searching for "smhd" within "minf"
//Only an audio track would have a smhd frame
int pos = mvhdBuffer.position();
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.SMHD.getFieldName());
if (boxHeader == null)
{
mvhdBuffer.position(pos);
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.VMHD.getFieldName());
//try easy check to confirm that it is video
if(boxHeader!=null)
{
throw new CannotReadVideoException(ErrorMessage.MP4_FILE_IS_VIDEO.getMsg());
}
else
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
}
mvhdBuffer.position(mvhdBuffer.position() + boxHeader.getDataLength());
//Level 5-Searching for "stbl within "minf"
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.STBL.getFieldName());
if (boxHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_AUDIO.getMsg());
}
//Level 6-Searching for "stsd within "stbl" and process it direct data, dont think these are mandatory so dont throw
//exception if unable to find
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.STSD.getFieldName());
if (boxHeader != null)
{
Mp4StsdBox stsd = new Mp4StsdBox(boxHeader, mvhdBuffer);
stsd.processData();
int positionAfterStsdHeaderAndData = mvhdBuffer.position();
///Level 7-Searching for "mp4a within "stsd"
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.MP4A.getFieldName());
if (boxHeader != null)
{
ByteBuffer mp4aBuffer = mvhdBuffer.slice();
Mp4Mp4aBox mp4a = new Mp4Mp4aBox(boxHeader, mp4aBuffer);
mp4a.processData();
//Level 8-Searching for "esds" within mp4a to get No Of Channels and bitrate
boxHeader = Mp4BoxHeader.seekWithinLevel(mp4aBuffer, Mp4AtomIdentifier.ESDS.getFieldName());
if (boxHeader != null)
{
Mp4EsdsBox esds = new Mp4EsdsBox(boxHeader, mp4aBuffer.slice());
//Set Bitrate in kbps
info.setBitrate(esds.getAvgBitrate() / 1000);
//Set Number of Channels
info.setChannelNumber(esds.getNumberOfChannels());
info.setKind(esds.getKind());
info.setProfile(esds.getAudioProfile());
info.setEncodingType(EncoderType.AAC.getDescription());
}
}
else
{
//Level 7 -Searching for drms within stsd instead (m4p files)
mvhdBuffer.position(positionAfterStsdHeaderAndData);
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.DRMS.getFieldName());
if (boxHeader != null)
{
Mp4DrmsBox drms = new Mp4DrmsBox(boxHeader, mvhdBuffer);
drms.processData();
//Level 8-Searching for "esds" within drms to get No Of Channels and bitrate
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.ESDS.getFieldName());
if (boxHeader != null)
{
Mp4EsdsBox esds = new Mp4EsdsBox(boxHeader, mvhdBuffer.slice());
//Set Bitrate in kbps
info.setBitrate(esds.getAvgBitrate() / 1000);
//Set Number of Channels
info.setChannelNumber(esds.getNumberOfChannels());
info.setKind(esds.getKind());
info.setProfile(esds.getAudioProfile());
info.setEncodingType(EncoderType.DRM_AAC.getDescription());
}
}
//Level 7-Searching for alac (Apple Lossless) instead
else
{
mvhdBuffer.position(positionAfterStsdHeaderAndData);
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.ALAC.getFieldName());
if (boxHeader != null)
{
//Process First Alac
Mp4AlacBox alac = new Mp4AlacBox(boxHeader, mvhdBuffer);
alac.processData();
//Level 8-Searching for 2nd "alac" within box that contains the info we really want
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.ALAC.getFieldName());
if (boxHeader != null)
{
alac = new Mp4AlacBox(boxHeader, mvhdBuffer);
alac.processData();
info.setEncodingType(EncoderType.APPLE_LOSSLESS.getDescription());
info.setChannelNumber(alac.getChannels());
info.setBitrate(alac.getBitRate()/1000);
}
}
}
}
}
//Set default channels if couldn't calculate it
if (info.getChannelNumber() == -1)
{
info.setChannelNumber(2);
}
//Set default bitrate if couldnt calculate it
if (info.getBitRateAsNumber() == -1)
{
info.setBitrate(128);
}
//This is the most likely option if cant find a match
if (info.getEncodingType().equals(""))
{
info.setEncodingType(EncoderType.AAC.getDescription());
}
logger.config(info.toString());
//Level 2-Searching for others "trak" within "moov", if we find any traks containing video
//then reject it if no track if not video then we allow it because many encoders seem to contain all sorts
//of stuff that you wouldn't expect in an audio track
mvhdBuffer.position(endOfFirstTrackInBuffer);
while(mvhdBuffer.hasRemaining())
{
boxHeader = Mp4BoxHeader.seekWithinLevel(mvhdBuffer, Mp4AtomIdentifier.TRAK.getFieldName());
if (boxHeader != null)
{
if(isTrackAtomVideo(ftyp,boxHeader,mvhdBuffer))
{
throw new CannotReadVideoException(ErrorMessage.MP4_FILE_IS_VIDEO.getMsg());
}
}
else
{
break;
}
}
//Build AtomTree to ensure it is valid, this means we can detect any problems early on
new Mp4AtomTree(raf,false);
return info;
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