Hello I am trying to record my screen on Xubuntu 16.04.2. While I can record both video and audio, on some software the video and audio are out of sync. When watching the video in VLC, the audio and the video are in sync, but when editing with Kdenlive or uploading directly the video to YouTube, audio and video get out of sync.
I am using a script to do this recording. The command line, considering its options, would be: env PULSE_LATENCY_MSEC=25 ffmpeg \ -vaapi_device /dev/dri/renderD128 -hwaccel vaapi -hwaccel_output_format yuv420p \ -thread_queue_size 4096 -f pulse -sample_rate 44100 -channels 2 -i alsa_output.pci-0000_00_1f.3.analog-stereo.monitor \ -thread_queue_size 1024 -f x11grab -s 1366x768 -r "30" -i :0.0 \ -acodec libfdk_aac -b:a 160k \ -vf 'format=nv12,hwupload,scale_vaapi=w=1280:h=720' -vcodec h264_vaapi -qp 24 \ -f flv -strict experimental TEST4.flv The output on terminal is: ffmpeg version N-85539-g5caaa3a Copyright (c) 2000-2017 the FFmpeg developers built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609 configuration: --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv --enable-libfdk-aac --enable-libmfx --enable-vaapi --enable-nonfree --enable-gpl --enable-libxcb --enable-libxcb-shm --enable-libxcb-xfixes --enable-libxcb-shape libavutil 55. 61.100 / 55. 61.100 libavcodec 57. 92.100 / 57. 92.100 libavformat 57. 72.101 / 57. 72.101 libavdevice 57. 7.100 / 57. 7.100 libavfilter 6. 84.101 / 6. 84.101 libavresample 3. 6. 0 / 3. 6. 0 libswscale 4. 7.101 / 4. 7.101 libswresample 2. 8.100 / 2. 8.100 libpostproc 54. 6.100 / 54. 6.100 libva info: VA-API version 0.39.0 libva info: va_getDriverName() returns 0 libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so libva info: Found init function __vaDriverInit_0_39 libva info: va_openDriver() returns 0 Guessed Channel Layout for Input Stream #0.0 : stereo Input #0, pulse, from 'alsa_output.pci-0000_00_1f.3.analog-stereo.monitor': Duration: N/A, start: 1494455796.589364, bitrate: 1411 kb/s Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s [x11grab @ 0x16073a0] Stream #0: not enough frames to estimate rate; consider increasing probesize Input #1, x11grab, from ':0.0': Duration: N/A, start: 1494455796.988299, bitrate: N/A Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1366x768, 30 fps, 1000k tbr, 1000k tbn, 1000k tbc Stream mapping: Stream #1:0 -> #0:0 (rawvideo (native) -> h264 (h264_vaapi)) Stream #0:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac)) Press [q] to stop, [?] for help [swscaler @ 0x1636ba0] Warning: data is not aligned! This can lead to a speedloss Output #0, flv, to 'TEST4.flv': Metadata: encoder : Lavf57.72.101 Stream #0:0: Video: h264 (h264_vaapi) (High) ([7][0][0][0] / 0x0007), vaapi_vld(progressive), 1280x720, q=0-31, 30 fps, 1k tbn, 30 tbc Metadata: encoder : Lavc57.92.100 h264_vaapi Stream #0:1: Audio: aac (libfdk_aac) ([10][0][0][0] / 0x000A), 44100 Hz, stereo, s16, 160 kb/s Metadata: encoder : Lavc57.92.100 libfdk_aac frame= 897 fps= 30 q=-0.0 Lsize= 3430kB time=00:00:29.83 bitrate= 941.9kbits/s speed=0.999x video:2808kB audio:583kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.157823% While I am using VAAPI, the fact audio and video get out of sync on some software happens too when using software encoding (plus 65% of CPU usage). On the output of the terminal, it can be seen that the start of pulse stream is 1494455796.589364, while the x11grab stream starts at 1494455796.988299. Can this be why video and audio are out of sync on Kdenlive and YouTube? If yes, is there a way to make the streams start at the same time? Thank you. _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".