MP4FindTrackId - Man Page
Find a track id
Syntax
#include <mp4.h>
MP4TrackId MP4FindTrackId(
MP4FileHandle hFile,
u_int16_t index,
const char* type = NULL,
u_int8_t subType = 0
)
Arguments
- hFile
Specifies the mp4 file to which the operation applies.
- index
Specifies which track is desired from matching tracks.
- type
Specifies the type of track to be matched. A NULL value implies any type of track. See MP4GetTrackType() for predefined values.
- subType
Specifies the subtype of the track to be matched. Subtypes are only defined for audio and video tracks, see MP4GetAudioTrackType() and MP4GetVideoTrackType() for predefined values. A zero value implies any subtype.
Return Values
Upon success, the track id of the specified track. Upon an error, MP4_INVALID_TRACK_ID.
Description
MP4FindTrackId gets the track id associated with the index'th track of the specified track type. For example, to get the track id of the first video track:
MP4FindTrackId(hFile, 0, MP4_VIDEO_TRACK_TYPE);
For audio and video tracks, a subtype can be specified to find a track of a particular encoding. For example, to get the track id of the first audio track encoded with MPEG-1 audio:
MP4FindTrackId(hFile, 0, MP4_AUDIO_TRACK_TYPE, MP4_MPEG1_AUDIO_TYPE);
Caveat: The track id's do not imply anything about the ordering of the track information within the mp4 file.