ALSA buffer xrun induced by low quality source in ffmpeg capture

Question

I am attempting to transfer some old Video 8 tapes to my computer, though an EasyCap USB stick and the motherboard's sound line-in, on Ubuntu. I believe the arguments are correctly laid out below to capture from two independent streams, and encode them both into the output MP4 file.

Edit:

I can simplify the question a bit, now.

ALSA buffer overrun (or underrun?) is induced by the unreliable/noisy audio source. For instance, if ffmpeg captures the beginning of tape playback, this causes "buffer xrun" far beyond when the tape gets up to speed and playback should be normal.

It is interesting that the bitrate shown in the ffmpeg log shoots up higher than normal when it's producing a garbage output! (Is this bitrate a sum of of audio and video bitrates?)

I've tried a couple of audio encoding codecs, and had the same problem.

Using libfdk_aac:

  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 640x480, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.13.100 libx264
    Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 48000 Hz, mono, s16, 128 kb/s
    Metadata:
      encoder         : Lavc56.13.100 libfdk_aac
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
[alsa @ 0x22038a0] ALSA buffer xrun.  0kB time=00:00:00.00 bitrate=N/A    
[alsa @ 0x22038a0] ALSA buffer xrun.1934kB time=00:00:02.76 bitrate=5723.5kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.4795kB time=00:00:05.49 bitrate=7150.1kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.7668kB time=00:00:08.21 bitrate=7646.1kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.1475kB time=00:00:10.94 bitrate=8588.9kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.3822kB time=00:00:13.66 bitrate=8289.0kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.5388kB time=00:00:16.38 bitrate=7695.0kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.6896kB time=00:00:19.10 bitrate=7244.0kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.8980kB time=00:00:21.84 bitrate=7118.8kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.2032kB time=00:00:24.55 bitrate=7349.3kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.4612kB time=00:00:27.27 bitrate=7391.1kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.6660kB time=00:00:29.98 bitrate=7284.6kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.9123kB time=00:00:32.68 bitrate=7299.3kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.0641kB time=00:00:35.39 bitrate=7091.7kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.2601kB time=00:00:38.13 bitrate=7002.6kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.5828kB time=00:00:40.87 bitrate=7181.0kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.8481kB time=00:00:43.60 bitrate=7229.9kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.1461kB time=00:00:46.34 bitrate=7328.0kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.3982kB time=00:00:49.06 bitrate=7342.7kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.6565kB time=00:00:51.77 bitrate=7367.8kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.9718kB time=00:00:54.51 bitrate=7471.3kbits/s    
[alsa @ 0x22038a0] ALSA buffer xrun.2341kB time=00:00:57.25 bitrate=7489.2kbits/s    
^Cframe= 1760 fps= 29 q=-1.0 Lsize=   53946kB time=00:01:00.04 bitrate=7360.3kbits/s    
video:53880kB audio:53kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.022994%
[libx264 @ 0x2217ac0] frame I:8     Avg QP:24.00  size: 55686
[libx264 @ 0x2217ac0] frame P:1752  Avg QP:27.66  size: 31237
[libx264 @ 0x2217ac0] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x2217ac0] mb P  I16..4: 15.0%  0.0%  0.0%  P16..4: 80.2%  0.0%  0.0%  0.0%  0.0%    skip: 4.8%
[libx264 @ 0x2217ac0] coded y,uvDC,uvAC intra: 45.3% 86.6% 59.4% inter: 65.7% 81.3% 11.5%
[libx264 @ 0x2217ac0] i16 v,h,dc,p: 40% 25% 26%  9%
[libx264 @ 0x2217ac0] i8c dc,h,v,p: 45% 24% 19% 12%
[libx264 @ 0x2217ac0] kb/s:7516.07
Received signal 2: terminating.

Using libvorbis:

  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 640x480, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.13.100 libx264
    Stream #0:1: Audio: vorbis (libvorbis) ([221][0][0][0] / 0x00DD), 48000 Hz, mono, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc56.13.100 libvorbis
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (pcm_s16le (native) -> vorbis (libvorbis))
[alsa @ 0x1a948a0] ALSA buffer xrun.  0kB time=00:00:00.00 bitrate=N/A    
[alsa @ 0x1a948a0] ALSA buffer xrun. 402kB time=00:00:04.37 bitrate= 752.3kbits/s    
[alsa @ 0x1a948a0] ALSA buffer xrun.4122kB time=00:00:08.80 bitrate=3833.0kbits/s    
[alsa @ 0x1a948a0] ALSA buffer xrun.8722kB time=00:00:13.14 bitrate=5436.3kbits/s    
[alsa @ 0x1a948a0] ALSA buffer xrun.3903kB time=00:00:17.51 bitrate=6502.2kbits/s    
[alsa @ 0x1a948a0] ALSA buffer xrun.6625kB time=00:00:21.89 bitrate=6221.4kbits/s    
[alsa @ 0x1a948a0] ALSA buffer xrun.9548kB time=00:00:26.28 bitrate=6092.5kbits/s    
^Cframe=  851 fps= 26 q=-1.0 Lsize=   22018kB time=00:00:30.69 bitrate=5875.3kbits/s    
video:21996kB audio:12kB subtitle:0kB other streams:0kB global headers:4kB muxing overhead: 0.044897%
[libx264 @ 0x1aa8ac0] frame I:4     Avg QP:23.50  size: 62405
[libx264 @ 0x1aa8ac0] frame P:847   Avg QP:25.58  size: 26297
[libx264 @ 0x1aa8ac0] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x1aa8ac0] mb P  I16..4: 13.2%  0.0%  0.0%  P16..4: 72.0%  0.0%  0.0%  0.0%  0.0%    skip:14.8%
[libx264 @ 0x1aa8ac0] coded y,uvDC,uvAC intra: 40.6% 81.0% 58.6% inter: 58.8% 72.7% 8.6%
[libx264 @ 0x1aa8ac0] i16 v,h,dc,p: 41% 28% 22%  9%
[libx264 @ 0x1aa8ac0] i8c dc,h,v,p: 54% 19% 16% 11%
[libx264 @ 0x1aa8ac0] kb/s:6345.60
Received signal 2: terminating.

---

ffmpeg's detection of the ALSA stream is seemingly goofed up by the inconsistencies of the tape. In the failure case, only short blips of the tapes audio exist in the output MP4. The audio bitrate of the output file is less than 10 kbps, averaged out across the whole file. The output video seems to be fine, even though the low frames-per-second in the failure case log below.

The audio and video streams can be captured fine for short amounts of time before a source error occurs; this provides the success case log. The failure case log was created by intentionally making an error in the source streams -- turning on the camera makes a brief noisy signal.

Is there a setting that needs to be forced to keep ffmpeg recording the audio stream, even when the tape is blank or noisy?

Could it be that the libfdk_aac audio encoder is tripped up by the low quality source?

The relevant line; rawvideo stream is piped to this in script at bottom:

ffmpeg -pixel_format uyvy422 -s:v 720x480 -framerate 29.97 -f rawvideo \
-i $PIPE  -f alsa -i hw:0,0 -vf scale=w=720:h=540 -vcodec libx264 \
-preset ultrafast -shortest -c:a libfdk_aac -b:a 128k -af pan=1:c0=c0  \
-ar 96000 $OUTFILE

The ar argument was one attempt to force recording.

ffmpeg log file for (short-lived) success; high frames-per-second captured:

ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
  built on Jan 11 2015 17:53:45 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, rawvideo, from '/tmp/somagic-pipe':
  Duration: N/A, start: 0.000000, bitrate: 165722 kb/s
    Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x480, 165722 kb/s, 29.97 tbr, 29.97 tbn, 29.97 tbc
Home directory not accessible: Permission denied
Guessed Channel Layout for  Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:0,0':
  Duration: N/A, start: 1423202268.577088, bitrate: 1536 kb/s
    Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[Parsed_pan_0 @ 0x3335d60] This syntax is deprecated. Use '|' to separate the list items.
Single channel layout '1' is interpreted as a number of channels, switch to the syntax '1c' otherwise it will be interpreted as a channel layout number in a later version
[Parsed_pan_0 @ 0x3335d60] Pure channel mapping detected: 0
[libx264 @ 0x3364bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x3364bc0] profile High 4:2:2, level 3.1, 4:2:2 8-bit
[libx264 @ 0x3364bc0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - 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=3 lookahead_threads=1 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, mp4, to '/home/peterbecich/easycap/Videos/fpv_video_02_05_2015_21_57_48.mp4':
  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 720x540, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.13.100 libx264
    Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 96000 Hz, mono, s16, 128 kb/s
    Metadata:
      encoder         : Lavc56.13.100 libfdk_aac
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame=   13 fps=0.0 q=26.0 size=     187kB time=00:00:00.30 bitrate=5102.7kbits/s    
frame=   29 fps= 29 q=26.0 size=     469kB time=00:00:00.83 bitrate=4607.6kbits/s    
frame=   44 fps= 29 q=26.0 size=     755kB time=00:00:01.33 bitrate=4635.2kbits/s    
frame=   59 fps= 29 q=26.0 size=    1024kB time=00:00:01.83 bitrate=4572.1kbits/s    
frame=   74 fps= 29 q=26.0 size=    1279kB time=00:00:02.33 bitrate=4486.5kbits/s    
frame=   89 fps= 29 q=26.0 size=    1516kB time=00:00:02.83 bitrate=4378.0kbits/s    
frame=  104 fps= 29 q=26.0 size=    1752kB time=00:00:03.33 bitrate=4301.0kbits/s    
frame=  119 fps= 29 q=26.0 size=    1991kB time=00:00:03.83 bitrate=4251.1kbits/s    
frame=  135 fps= 30 q=26.0 size=    2245kB time=00:00:04.37 bitrate=4207.5kbits/s    
frame=  150 fps= 30 q=26.0 size=    2524kB time=00:00:04.87 bitrate=4245.0kbits/s    
frame=  165 fps= 30 q=26.0 size=    2808kB time=00:00:05.37 bitrate=4282.0kbits/s    
frame=  180 fps= 30 q=26.0 size=    3091kB time=00:00:05.87 bitrate=4311.5kbits/s    
[rawvideo @ 0x3350640] Invalid buffer size, packet size 65536 < expected frame_size 691200
Error while decoding stream #0:0: Invalid argument
frame=  183 fps= 29 q=-1.0 Lsize=    3247kB time=00:00:06.11 bitrate=4351.5kbits/s    
video:3142kB audio:96kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.254788%
[libx264 @ 0x3364bc0] frame I:1     Avg QP:20.00  size:  2289
[libx264 @ 0x3364bc0] frame P:182   Avg QP:25.99  size: 17664
[libx264 @ 0x3364bc0] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x3364bc0] mb P  I16..4: 78.5%  0.0%  0.0%  P16..4: 20.2%  0.0%  0.0%  0.0%  0.0%    skip: 1.4%
[libx264 @ 0x3364bc0] coded y,uvDC,uvAC intra: 84.1% 71.5% 18.9% inter: 51.9% 63.5% 0.4%
[libx264 @ 0x3364bc0] i16 v,h,dc,p: 15%  8% 69%  8%
[libx264 @ 0x3364bc0] i8c dc,h,v,p: 50% 19% 24%  7%
[libx264 @ 0x3364bc0] kb/s:4215.02

ffmpeg log for failure; low FPS captured:

ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
  built on Jan 11 2015 17:53:45 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, rawvideo, from '/tmp/somagic-pipe':
  Duration: N/A, start: 0.000000, bitrate: 165722 kb/s
    Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x480, 165722 kb/s, 29.97 tbr, 29.97 tbn, 29.97 tbc
Home directory not accessible: Permission denied
Guessed Channel Layout for  Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:0,0':
  Duration: N/A, start: 1423201999.226455, bitrate: 1536 kb/s
    Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[Parsed_pan_0 @ 0x21cad60] This syntax is deprecated. Use '|' to separate the list items.
Single channel layout '1' is interpreted as a number of channels, switch to the syntax '1c' otherwise it will be interpreted as a channel layout number in a later version
[Parsed_pan_0 @ 0x21cad60] Pure channel mapping detected: 0
[libx264 @ 0x21f9bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x21f9bc0] profile High 4:2:2, level 3.1, 4:2:2 8-bit
[libx264 @ 0x21f9bc0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - 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=3 lookahead_threads=1 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, mp4, to '/home/peterbecich/easycap/Videos/fpv_video_02_05_2015_21_53_18.mp4':
  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 720x540, q=-1--1, 29.97 fps, 11988 tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.13.100 libx264
    Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 96000 Hz, mono, s16, 128 kb/s
    Metadata:
      encoder         : Lavc56.13.100 libfdk_aac
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=1.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.7 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.5 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.4 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.3 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.3 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.2 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.2 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.2 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
frame=    1 fps=0.2 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A    
[alsa @ 0x21e5ac0] ALSA buffer xrun.
frame=    8 fps=1.3 q=19.0 size=      12kB time=00:00:06.03 bitrate=  15.9kbits/s    
frame=   23 fps=3.5 q=18.0 size=      12kB time=00:00:06.03 bitrate=  16.4kbits/s    
frame=   38 fps=5.4 q=18.0 size=      12kB time=00:00:06.03 bitrate=  16.7kbits/s    
frame=   53 fps=7.0 q=18.0 size=      12kB time=00:00:06.03 bitrate=  16.9kbits/s    
frame=   68 fps=8.4 q=26.0 size=     146kB time=00:00:06.03 bitrate= 198.8kbits/s    
frame=   83 fps=9.7 q=26.0 size=     375kB time=00:00:06.03 bitrate= 510.0kbits/s    
frame=   98 fps= 11 q=26.0 size=     608kB time=00:00:06.03 bitrate= 826.5kbits/s    
frame=  114 fps= 12 q=26.0 size=     875kB time=00:00:06.03 bitrate=1189.1kbits/s    
frame=  128 fps= 13 q=26.0 size=    1091kB time=00:00:06.03 bitrate=1481.6kbits/s    
frame=  144 fps= 14 q=26.0 size=    1339kB time=00:00:06.03 bitrate=1819.2kbits/s    
frame=  159 fps= 14 q=26.0 size=    1571kB time=00:00:06.03 bitrate=2134.6kbits/s    
frame=  174 fps= 15 q=26.0 size=    1796kB time=00:00:06.03 bitrate=2440.1kbits/s    
[alsa @ 0x21e5ac0] ALSA buffer xrun.
frame=  189 fps= 16 q=26.0 size=    2015kB time=00:00:12.04 bitrate=1370.4kbits/s    
frame=  204 fps= 16 q=26.0 size=    2238kB time=00:00:12.04 bitrate=1522.3kbits/s    
frame=  219 fps= 17 q=26.0 size=    2490kB time=00:00:12.04 bitrate=1694.2kbits/s    
frame=  235 fps= 17 q=26.0 size=    2728kB time=00:00:12.04 bitrate=1855.8kbits/s    
frame=  250 fps= 18 q=26.0 size=    2973kB time=00:00:12.04 bitrate=2022.4kbits/s    
[rawvideo @ 0x21e5640] Invalid buffer size, packet size 65536 < expected frame_size 691200
Error while decoding stream #0:0: Invalid argument
frame=  261 fps= 18 q=-1.0 Lsize=    3269kB time=00:00:12.06 bitrate=2220.1kbits/s    
video:3263kB audio:4kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.081101%
[libx264 @ 0x21f9bc0] frame I:2     Avg QP:21.50  size: 21342
[libx264 @ 0x21f9bc0] frame P:259   Avg QP:24.22  size: 12734
[libx264 @ 0x21f9bc0] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x21f9bc0] mb P  I16..4: 62.8%  0.0%  0.0%  P16..4: 14.2%  0.0%  0.0%  0.0%  0.0%    skip:22.9%
[libx264 @ 0x21f9bc0] coded y,uvDC,uvAC intra: 77.7% 61.2% 14.1% inter: 19.7% 24.8% 1.6%
[libx264 @ 0x21f9bc0] i16 v,h,dc,p: 17% 10% 65%  8%
[libx264 @ 0x21f9bc0] i8c dc,h,v,p: 52% 18% 24%  6%
[libx264 @ 0x21f9bc0] kb/s:3068.90

The whole script:

#!/bin/sh

PIPE=/tmp/somagic-pipe
OUTFILEDIR=~/easycap/Videos/
LOGDIR=~/.somagic-log/
NOW=`date +"%m_%d_%Y_%H_%M_%S"`

OUTFILE=${OUTFILEDIR}fpv_video_${NOW}.mp4

mkdir $LOGDIR

FFMPEG_LOG=${LOGDIR}ffmpeg.log
SOMAGIC_LOG=${LOGDIR}somagic.log
MPLAYER_LOG=${LOGDIR}mplayer.log

rm $PIPE >/dev/null 2>&1
rm $OUTFILE >/dev/null 2>&1

rm $FFMPEG_LOG
rm $SOMAGIC_LOG
rm $MPLAYER_LOG

mkfifo $PIPE >/dev/null 2>&1

ffmpeg -pixel_format uyvy422 -s:v 720x480 -framerate 29.97 -f rawvideo \
-i $PIPE  -f alsa -i hw:0,0 -vf scale=w=720:h=540 -vcodec libx264 \
-preset ultrafast -shortest -c:a libfdk_aac -b:a 128k -af pan=1:c0=c0  \
-ar 96000 $OUTFILE > $FFMPEG_LOG 2>&1 &

somagic-capture --ntsc -c --luminance=2 --lum-aperture=3 2> $SOMAGIC_LOG \
| tee $PIPE | \
mplayer -vf yadif,screenshot -demuxer rawvideo -rawvideo \
"ntsc:format=uyvy:fps=30000/1001" -aspect 4:3 - 2> $MPLAYER_LOG


rm $PIPE >/dev/null 2>&1 

Modified from here: https://gist.github.com/Brick85/0b327ac2d3d45e23ed33

Answer 1

I was able to solve this problem by adding the -thread_queue_size 1024 was able to solve this problem by adding the option for both the video input and the audio input. Here is my full line:

ffmpeg -f rawvideo -video_size 720x480 -thread_queue_size 1024 \
  -pixel_format uyvy422 -framerate 29.97 -i - -f alsa -thread_queue_size 1024 \
  -i hw:1 -preset slow -c:v libx264 -aspect 4:3 -strict -2 -y -threads 4 output.mp4

Answer 2

Found a partial solution in using two separate ffmpeg processes, as suggested in this thread: https://trac.ffmpeg.org/ticket/615 Specifically, this comment: https://trac.ffmpeg.org/ticket/615#comment:13

The separate audio and video files will have to be put together, later.

Recording video in ffmpeg and audio in Audacity was not useful due to sync problems, written up here: https://video.stackexchange.com/questions/14809/sync-up-ffmpeg-rawvideo-recording-and-audacity-alsa-recording

Hopefully the two ffmpeg processes record at the same rate, unlike ffmpeg and Audacity.

Edit: Two ffmpeg processes probably will not produce two files of the same length. It seems that ffmpeg automatically strips out dead space from video, but not audio.