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PODesktop audio falls behind when recording microphone + desktop audio + screen using ffmpeg
 

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  1. PODesktop audio falls behind when recording microphone + desktop audio + screen using ffmpeg
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    <p>I have put together this script for recording the microphone, the desktop audio and the screen using ffmpeg:</p> <pre><code>DATE=`which date` RESO=2560x1440 FPS=30 PRESET=ultrafast DIRECTORY=$HOME/Video/ FILENAME=videocast`$DATE +%d%m%Y_%H.%M.%S`.mkv ffmpeg -y -vsync 1 \ -f pulse -ac 2 -i alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \ -f pulse -ac 1 -ar 25000 -i alsa_input.usb-0d8c_C-Media_USB_Headphone_Set-00-Set.analog-mono \ -filter_complex aresample=async=1,amix=duration=shortest,apad \ -f x11grab -r $FPS -s $RESO -i :0.0 \ -acodec libvorbis \ -vcodec libx264 -pix_fmt yuv420p -preset $PRESET -threads 0 \ $DIRECTORY$FILENAME </code></pre> <p>Everything is recorded and between the screen and the microphone sound there are no issues what so ever, however the desktop audio falls behind badly. </p> <p>It begins in sync but gets worse over time during playback, also in ffplay. It does not matter what application playing sound: both Youtube-videos in the browser, desktop sounds and Rhythmbox (playing a couple of seconds of song then stops, wait and repeat) gets out of sync.</p> <p>The terminal output complain about </p> <pre><code>"ALSA lib pcm.c:7843:(snd_pcm_recover) overrun occurred22.73 bitrate=10384.5kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred" </code></pre> <p>and similar but I do not know what that means.</p> <p>Full terminal output here:</p> <pre><code>ffmpeg version 2.0.1 Copyright (c) 2000-2013 the FFmpeg developers built on Aug 11 2013 14:52:28 with gcc 4.8.1 (GCC) 20130725 (prerelease) configuration: --prefix=/usr --disable-debug --disable-static --enable-avresample --enable-dxva2 --enable-fontconfig --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-pic --enable-postproc --enable-runtime-cpudetect --enable-shared --enable-swresample --enable-vdpau --enable-version3 --enable-x11grab libavutil 52. 38.100 / 52. 38.100 libavcodec 55. 18.102 / 55. 18.102 libavformat 55. 12.100 / 55. 12.100 libavdevice 55. 3.100 / 55. 3.100 libavfilter 3. 79.101 / 3. 79.101 libavresample 1. 1. 0 / 1. 1. 0 libswscale 2. 3.100 / 2. 3.100 libswresample 0. 17.102 / 0. 17.102 libpostproc 52. 3.100 / 52. 3.100 Guessed Channel Layout for Input Stream #0.0 : stereo Input #0, pulse, from 'alsa_output.pci-0000_00_1b.0.analog-stereo.monitor': Duration: N/A, start: 0.014093, bitrate: 1536 kb/s Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s Guessed Channel Layout for Input Stream #1.0 : mono Input #1, pulse, from 'alsa_input.usb-0d8c_C-Media_USB_Headphone_Set-00-Set.analog-mono': Duration: N/A, start: 0.006172, bitrate: 400 kb/s Stream #1:0: Audio: pcm_s16le, 25000 Hz, mono, s16, 400 kb/s [x11grab @ 0x218a6e0] device: :0.0 -&gt; display: :0.0 x: 0 y: 0 width: 2560 height: 1440 [x11grab @ 0x218a6e0] shared memory extension found Input #2, x11grab, from ':0.0': Duration: N/A, start: 1379021580.184321, bitrate: N/A Stream #2:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 2560x1440, -2147483 kb/s, 30 tbr, 1000k tbn, 30 tbc [libx264 @ 0x21ae560] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX [libx264 @ 0x21ae560] profile Constrained Baseline, level 5.0 [libx264 @ 0x21ae560] 264 - core 133 r2339 585324f - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0 Output #0, matroska, to '/home/anders/Video/videocast12092013_23.33.00.mkv': Metadata: encoder : Lavf55.12.100 Stream #0:0: Audio: vorbis (libvorbis) (oV[0][0] / 0x566F), 25000 Hz, mono, fltp Stream #0:1: Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 2560x1440, q=-1--1, 1k tbn, 30 tbc Stream mapping: Stream #0:0 (pcm_s16le) -&gt; aresample (graph 0) Stream #1:0 (pcm_s16le) -&gt; amix:input1 (graph 0) amix (graph 0) -&gt; Stream #0:0 (libvorbis) Stream #2:0 -&gt; #0:1 (rawvideo -&gt; libx264) Press [q] to stop, [?] for help ALSA lib pcm.c:7843:(snd_pcm_recover) overrun occurred22.73 bitrate=10384.5kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred3.22 bitrate=10423.3kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) overrun occurred25.25 bitrate=11011.0kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred5.76 bitrate=11013.7kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) overrun occurred27.25 bitrate=11175.4kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred7.76 bitrate=11168.7kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred8.24 bitrate=11176.4kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) overrun occurred55.48 bitrate=11243.8kbits/s ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred ALSA lib pcm.c:7843:(snd_pcm_recover) underrun occurred frame=12871 fps= 30 q=-1.0 Lsize= 542369kB time=00:07:09.31 bitrate=10349.3kbits/s video:539762kB audio:2363kB subtitle:0 global headers:3kB muxing overhead 0.044476% [libx264 @ 0x21ae560] frame I:52 Avg QP:15.46 size:725888 [libx264 @ 0x21ae560] frame P:12819 Avg QP:18.26 size: 40172 [libx264 @ 0x21ae560] mb I I16..4: 100.0% 0.0% 0.0% [libx264 @ 0x21ae560] mb P I16..4: 2.6% 0.0% 0.0% P16..4: 18.1% 0.0% 0.0% 0.0% 0.0% skip:79.3% [libx264 @ 0x21ae560] coded y,uvDC,uvAC intra: 57.8% 49.8% 25.3% inter: 8.9% 8.7% 2.2% [libx264 @ 0x21ae560] i16 v,h,dc,p: 23% 29% 32% 16% [libx264 @ 0x21ae560] i8c dc,h,v,p: 45% 28% 18% 9% [libx264 @ 0x21ae560] kb/s:10306.26 </code></pre> <p>Please help me, I am really close to get this working! </p> <p><strong>UPDATE</strong>: The desktop audio is out of sync when skipping filter_complex and microphone also, bit in a smaller amount. Using <code>copy</code> instead of <code>libvorbis</code> does not change anything either.</p>
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      1. PODesktop audio falls behind when recording microphone + desktop audio + screen using ffmpeg
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    1. COIsolate the issue. Does the sync issue still occur if you omit the filtering and the other audio stream and use `-acodec copy` instead of `-acodec libvorbis`?
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    2. COUpdated question, skipping microphone during record does not change it.
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    3. COAnother update: nor does changeing the audio codec to `copy`.
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