The docs in the header file say that the AVSEEK_FLAG_BACKWARD is ignored, and the tests I've run seem to work even when I leave it out.
Mark ------------------------- SUBJECT: Re: [Libav-user] How to seek to a given frame? DATE: Wed, 8 May 2019 13:20:17 -0700 FROM: Michael Armes TO: "This list is about using libavcodec, libavformat, libavutil, libavdevice and libavfilter." REPLY-TO: "This list is about using libavcodec, libavformat, libavutil, libavdevice and libavfilter." Use AVSEEK_FLAG_BACKWARD [1] to seek to the closest _keyframe_ having a smaller pts than the one you are seeking. You must then iterate through reading frames until you reach your desired position (if you are not seeking to a keyframe). --michael On Wed, May 8, 2019 at 10:53 AM Mark McKay wrote: I'm trying to create a video player with the ability to seek whereever I want. I'm having some trouble with av_seek_frame(), which seems to keep returning the first keyframe after the timestamp I'm looking for: int timestamp = av_rescale_q(timeMs, AV_TIME_BASE_Q, pFormatCtx->streams[videoStream]->time_base); int err = av_seek_frame(pFormatCtx, videoStream, timestamp, 0); Unfortunately, if it puts me at a position /after/ the frame where I'm seeking, I have already passed the frame I want and can't scan forward to find it. I've also tried seeking with AVSEEK_FLAG_ANY, but this it not returning frames with valid data. I'm guessing that you need to jump to the correct keyframe and then scan forward so that the frame buffers are built correctly. I'm also considering scanning the entire video when I first load it to build an index of packet information. AVSEEK_FLAG_BYTE looks like it could be useful to jump directly to the packet I want - however, I don't know where to find the byte value I would need to pass to the seek function. How can I scan to the frame that I want? Cheers, Mark --- http://www.kitfox.com [3] _______________________________________________ Libav-user mailing list [email protected] [4] https://ffmpeg.org/mailman/listinfo/libav-user [5] To unsubscribe, visit link above, or email [email protected] [6] with subject "unsubscribe". --- http://www.kitfox.com Links: ------ [1] http://ffmpeg.org/doxygen/trunk/avformat_8h.html#ac736f8f4afc930ca1cda0b43638cc678 [2] mailto:[email protected] [3] http://www.kitfox.com [4] mailto:[email protected] [5] https://ffmpeg.org/mailman/listinfo/libav-user [6] mailto:[email protected]
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