mvTrackData(3dm)mvTrackData(3dm)NAME
mvTrackData: mvGetTrackNumDataIndex mvGetTrackDataInfo
mvGetTrackDataOffset mvGetTrackDataIndexAtTime - retrieve information
about track data
SYNOPSIS
#include <dmedia/moviefile.h>
int mvGetTrackNumDataIndex( MVid track );
DMstatus mvGetTrackDataIndexAtTime( MVid track,
MVtime time, MVtimescale timescale,
int *index, MVframe *frameOffset );
DMstatus mvGetTrackDataInfo( MVid track,
int index, size_t *returnSize, int *paramsId,
MVdatatype *dataType, MVframe *frames );
DMstatus mvGetTrackDataOffset( MVid track,
int index, off64_t *fileOffset );
DESCRIPTION
Each instance in time correspond to some chunk of data in the file,
unless it belongs to an empty segment. Functions in this page provide
information about these chunks of data referenced by a track.
mvGetNumDataIndex
This function returns the number of data chunks referenced by a track.
mvGetTrackDataIndexAtTime
track is the id of the track.
time is the time instance the user wishes to query.
timescale is the time scale for time.
index contains the returned index. If index==-1, then the time which you
are querying about contains an empty edit (which was created with
mvInsertTrackGapAtTime or mvInsertMovieGapAtTime). This is how one can
easily test for track gaps.
frameOffset contains the frame offset from the beginning of the chunk to
which the time instance corresponds. If the returned index is -1, this
value is meaningless.
mvGetTrackDataInfo
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mvTrackData(3dm)mvTrackData(3dm)
track is the id of the track.
index is the index of the data chunk the user wishes to query.
returnSize contains the size of the data chunk returned by the movie
library.
paramsId contains the index to the set of DMparams that describes this
data chunk. See also mvTrackDataParams(3dm).
dataType contains the datatype of the data chunk. Currently, only
MV_FRAMETYPE_MASK is supported, of which only MV_FRAMETYPE_DELTA and
MV_FRAMETYPE_KEY are supported.
frames contains the number of frames in the data chunk index.
mvGetTrackDataOffset
Takes an index and fills in the fileOffset with the offset in bytes of
the start of the chunk referenced by index.
track is the id of the track.
index is the index of the data chunk the user wishes to query.
fileOffset is the location where the data chunk resides on the storage
device.
SEE ALSOmvIntro(3dm), mvReadTrackData(3dm), mvInsertTrackData(3dm),
mvInsertTrackDataAtOffset(3dm), mvInsertFramesAtTime(3dm),
mvTrackDataParams(3dm).
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