hi all! i am currently writing a little python binding to interface libavformat and libavcodec to get video infos like codec, resolution and so on and to extract single frames as thumbnails.
i used these great ressources as the basis: http://www.inb.uni-luebeck.de/~boehme/using_libavcodec.html http://code.google.com/p/pyffmpeg/ and until now everything works as expected. my problem now are matroska and theora video files. i used this mkv file as my example: http://www.matroska.org/samples/mewmew/downloads/mewmew-vorbis-ssa.mkv but this also occurs with every other mkv somehow i can get the video info but can not extract frames from it. av_seek_frame() seems to return with -1 if i try to seek to any position. also with ffmpeg this fails on the same file: ffmpeg -i mewmew-vorbis-ssa.mkv -vcodec mjpeg -vframes 1 -an -f rawvideo -ss 10 -s "test.jpg" Input #0, matroska, from 'mewmew-vorbis-ssa.mkv': Duration: 00:00:58.1, bitrate: N/A Stream #0.0: Video: mpeg4, yuv420p, 640x480, 23.98 fps(r) Stream #0.1: Audio: vorbis, 48000 Hz, stereo Incorrect frame size when opening the video i also get a lot of these errors: [matroska @ 0x7f1c791de160]Ignoring seekhead entry for ID=0x1f43b675 these seem to already indicate that there will be problems with seeking then i converted the mkv to theora with ffmpeg2theora and i still was unable to extract any frames but this time because of avcodec_decode_video() failing. the ffmpeg line from above gave nearly the same output: Input #0, ogg, from 'mewmew-vorbis-ssa.ogg': Duration: 00:00:58.1, start: 0.125125, bitrate: 976 kb/s Stream #0.0: Video: theora, yuv420p, 640x480, 23.98 fps(r) Stream #0.1: Audio: vorbis, 48000 Hz, stereo, 80 kb/s Incorrect frame size unsurprisingly other ogg files gave the same error. ffmpeg was build on ubuntu with --enable-libvorbis --enable-libtheora --enable-libogg libavutil version: 1d.49.3.0 libavcodec version: 1d.51.38.0 libavformat version: 1d.51.10.0 built on Jul 23 2008 22:37:31, gcc: 4.2.3 (Ubuntu 4.2.3-2ubuntu7) so what do i do to these errors? mkv fails with av_seek_frame() and theora fails with avcodec_decode_video() ffmpeg -vcodec mjpeg -vframes 1 -f rawvideo fails on both for any other video i tested (mostly mpeg4 avi video) ffmpeg and my self-made python binding works as expected. thx for your help josch _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
