a media specific offset for the buffer data.
For video frames, this is the frame number of this buffer.
For audio samples, this is the offset of the first sample in this buffer.
For file data or compressed data this is the byte offset of the first
byte in this buffer.
a media specific offset for the buffer data. For video frames, this is the frame number of this buffer. For audio samples, this is the offset of the first sample in this buffer. For file data or compressed data this is the byte offset of the first byte in this buffer.