| .TH "MP4" "3" "Version 0.9" "Cisco Systems Inc." "MP4 File Format Library" |
| .SH "NAME" |
| .LP |
| \fBMP4FindTrackId\fR \- Find a track id |
| .SH "SYNTAX" |
| .LP |
| #include <mp4.h> |
| .LP |
| MP4TrackId \fBMP4FindTrackId\fR( |
| .br |
| MP4FileHandle \fIhFile\fP, |
| .br |
| u_int16_t \fIindex\fP, |
| .br |
| const char* \fItype\fP = NULL, |
| .br |
| u_int8_t \fIsubType\fP = 0 |
| .br |
| ) |
| .SH "ARGUMENTS" |
| .LP |
| .TP |
| \fIhFile\fP |
| Specifies the mp4 file to which the operation applies. |
| .TP |
| \fIindex\fP |
| Specifies which track is desired from matching tracks. |
| .TP |
| \fItype\fP |
| Specifies the type of track to be matched. A NULL value implies any type of track. See MP4GetTrackType() for predefined values. |
| .TP |
| \fIsubType\fP |
| 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. |
| .SH "RETURN VALUES" |
| .LP |
| Upon success, the track id of the specified track. Upon an error, MP4_INVALID_TRACK_ID. |
| |
| .SH "DESCRIPTION" |
| .LP |
| \fBMP4FindTrackId\fR 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: |
| .LP |
| MP4FindTrackId(hFile, 0, MP4_VIDEO_TRACK_TYPE); |
| .LP |
| 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: |
| .LP |
| MP4FindTrackId(hFile, 0, MP4_AUDIO_TRACK_TYPE, MP4_MPEG1_AUDIO_TYPE); |
| .LP |
| Caveat: The track id's do not imply anything about the ordering of the track information within the mp4 file. |
| .SH "SEE ALSO" |
| .LP |
| MP4(3) MP4FindTrackIndex(3) |
