On date Tuesday 2011-07-19 17:02:45 -0700, Argo Vela encoded: > Thank you, Stefano! > > If I may follow-up... > > --- On Tue, 7/19/11, Stefano Sabatini <[email protected]> wrote: > > > > On date Tuesday 2011-07-19 16:02:35 -0700, Argo Vela encoded: > >> > >> As one component of analyzing a media stream, I'm > >> curious to know if it is possible to come up with > >> the duration of the media content in a packet such > >> as might be found in MPEG2-TS. As a concrete > >> example, given a muxed stream of AAC audio & H.264 > >> video, would it be possible to calculate a 2-tuple > >> <PTS,duration> for each packet in the stream? > >> > >> If so, then I would have two questions: > >> > >> (1) Are the libav libraries a good tool to use for > >> such a task? > > > > ffprobe -show_packets > > As a test, when I run ffprobe against a sample file, in > this case an FLV1, I receive the following caution: >
> [flv @ 0x974c100]Estimating duration from bitrate, this may be inaccurate Check estimate_timings* code in libavformat/utils.c, this means that the duration is not set in the *container*. > Is there any means of estimating the potential error in > this estimate? Ie, how inaccurate is "inaccurate"? :-) > Does this message apply to the audio, video, or both? Impossible to esteem the "inaccuracy" here. > Also, I noticed that while the audio packets all had what > appears to be a reasonable value for the packet duration, > the video packets all had durations of zero. It appears > that in this particular sample file the video packets each > contain a single video frame, however at 24fps, this should > still yield a duration of approximately 42ms per packet. Do > you have any idea why this might be happening? No, can you post a sample showing the problem? > For reference, ffprobe reports the following build info: > libavutil version: 50.15.1 > libavcodec version: 52.72.2 > libavformat version: 52.64.2 > built on Jul 19 2011 06:30:13, gcc: 4.5.2 > > Thank you for your time! _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
