On 05/03/15 11:18, Martin Storsjö wrote:
In a truncated fragmented mp4 file (or a fragmented mp4 file where
fragments are accessed non-sequentially), the tfdt atom gives the
absolute timestamp of the fragment.  Without this atom, all streams
are assumed to start at the same timestamp (dts=0, unless edit lists
are present). For a truncated stream (where earlier fragments are
skipped), not all streams start at the exact same timestamp (since
frames in different streams have different durations, and the timestamps
at the fragment boundary don't line up exactly in all of them). Therefore,
the tfdt atom is essential for getting correct AV sync in such streams,
otherwise it will be off by less than one frame length.



Ok, but might be useful to have some documentation about it.

lu

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