Am 18.02.2016 um 00:27 schrieb Moritz Barsnick: > I had wondered myself: > http://lists.ffmpeg.org/pipermail/ffmpeg-user/2016-January/030178.html > (I'm using a "multipart/replace" stream, or whatever that crude MIME > invention is called.) > > So the input option "-use_wallclock_as_timestamps" should do the trick, > possibly in combination with "-re". > > I don't recall whether ffmpeg could grab the timestamps from the stream > - I believe not. I do know that my stream, coming from "motion", does > not provide a "Last-modified" header or the likes per frame.
"-use_wallclock_as_timestamps" can be very helpful, thanks! Seems not to be documented. I've tried it, and the timestamps are the number of seconds since 1/1/1970. The full story: I once wrote a screen capturing program (yes, there are others out there.... It's just for my own personal use and a prototype for implementing programming stuff). Video is saved as MJPEG in an AVI container. In addition, audio is recorded from the microphone (to a WAV file). This works perfectly without A/V sync problems. I haven't been using FFmpeg for this purpose so far. Encoding and muxing is done after recording is finished using AviDemux. Now I'm about to change this procedure completely by implementing real-time encoding by using FFmpeg as the encoding backend. FFmpeg has two input sources: Video via TCP as already described, and audio via FFmpeg's DirectShow capabilities from the webcam. The timestamps for audio are relativ to the system start, e.g. the last recording started at 18716.449 (~5 hours, 11 minutes). If I specify "-use_wallclock_as_timestamps 1" for video, the timestamps of the two streams are not relativ to the same point in time. To keep the story short, I'm discarding some other thoughts because it can't work this way: As FFmpeg can lag behind, my application buffers the captured screenshots before sending them to FFmpeg via TCP. Consequently, the point in time when FFmpeg reads the packet and creates a timestamp for it (if I use use_wallclock_as_timestamps), can be seconds (or minutes) /after/ the frame has been captured. The timestamp would be completely wrong, so I can't proceed this way. Conclusion: I must find a way to provide the real timestamp for every video frame. It's been recorded within my program, but I can't send it along with every frame within a mpjpeg stream. That's why I'm curious if there is any other simple streaming protocol in which I can send a jpeg frame + timestamp, and that doesn't require me reading dozends of specification documents. [sent this 3 message 3rd time now as previous ones don't seem to arrive after a longer waiting period] _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
