[Ffmpeg-devel] Timestamp troubles

[Michael Niedermayer]

Hi

On Tue, Feb 21, 2006 at 02:07:44PM -1000, Steve Lhomme wrote:
> Hi everyone,
> 
> We're currently adding some kind of frame browsing in DrDivX OSS, using 
> (Dr)FFMPEG as the decoding engine. So far so good.
> 
> But we also want to seek in the stream backward and forward. We use 
> av_seek_frame for that, with the video stream index we're looking for.
> 
> The problem is that the timestamps of packets seem to be inconsistent. 
> Here are 2 cases to explain the situation :
> 
> - goats.wmv:
> 
> * timestamps in the AVStream.index_entries ranges from 1 to 78 (78s)

fixed


> * the AVFormatContext.duration is 78.866.000 (probably in ?s)
> * AVStream.time_base is (1, 1.000)
> * AVCodecContext.time_base is (1, 1.000)
> 
> 
> So, it looks like the timestamp to give to av_seek_frame should be 
> between 1 and 78, that is the duration multiplied by both time bases. Or 
> it could just simply be the duration divided by AV_TIME_BASE (1.000.000).
> 
> 
> - chems1.vob
> 
> * timestamps in the AVStream.index_entries ranges from 3.484 to 1.601.884
> * the AVFormatContext.duration is 17.760.000 (probably in ?s)
> * AVStream.time_base is (1, 90.000)
> * AVCodecContext.time_base is (25.025, 1.001)
> 
> And in that case I have no idea how to translate a value in the 
> "duration" format to something that will match the value needed to look 
> in the index_entries.

duration * 90000 / AV_TIME_BASE


[...]
-- 
Michael