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• Recording screencast using ffmpeg produces audio that is out of sync with the video

  7 décembre 2014, par AgilE

  I’m on Fedora 20. I got it pre-compiled from the repo.

  I use the follow command to record screencasts :

  ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1366x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -preset ultrafast -crf 0 -threads 0 filename.mkv

  The audio is perfectly synced with the video at the beginning. However, as the video progresses, the audio starts lagging behind severely (say a lag of more than 4 seconds). I’ve included a sample output that ffmpeg shows while recording a video.

  ffmpeg version 2.1.3 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jan 25 2014 15:11:42 with gcc 4.8.2 (GCC) 20131212 (Red Hat 4.8.2-7)
  
    configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-libass --enable-libcdio --enable-libcelt --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  
    libavutil      52. 48.101 / 52. 48.101
  
    libavcodec     55. 39.101 / 55. 39.101
  
    libavformat    55. 19.104 / 55. 19.104
  
    libavdevice    55.  5.100 / 55.  5.100
  
    libavfilter     3. 90.100 /  3. 90.100
  
    libavresample   1.  1.  0 /  1.  1.  0
  
    libswscale      2.  5.101 /  2.  5.101
  
    libswresample   0. 17.104 /  0. 17.104
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, alsa, from 'pulse':
  
    Duration: N/A, start: 1391533629.323015, bitrate: 1536 kb/s
  
      Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  [x11grab @ 0x153ad80] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1366 height: 768
  
  [x11grab @ 0x153ad80] shared memory extension found
  
  Input #1, x11grab, from ':0.0':
  
    Duration: N/A, start: 1391533629.365274, bitrate: 1007124 kb/s
  
      Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1366x768, 1007124 kb/s, 30 tbr, 1000k tbn, 30 tbc
  
  [swscaler @ 0x1520460] deprecated pixel format used, make sure you did set range correctly
  
  No pixel format specified, yuv444p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x1551420] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x1551420] profile High 4:4:4 Predictive, level 3.2, 4:4:4 8-bit
  
  [libx264 @ 0x1551420] 264 - core 138 r2363 c628e3b - 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=0 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 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=cqp mbtree=0 qp=0
  
  Output #0, matroska, to 'testing.mkv':
  
    Metadata:
  
      encoder         : Lavf55.19.104
  
      Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p, 1366x768, q=-1--1, 1k tbn, 30 tbc
  
      Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (rawvideo -> libx264)
  
    Stream #0:0 -> #0:1 (pcm_s16le -> pcm_s16le)
  
  Press [q] to stop, [?] for help
  
  [swscaler @ 0x1520460] Warning: data is not aligned! This can lead to a speedloss
  
  frame=  213 fps= 27 q=-1.0 Lsize=    3572kB time=00:00:08.00 bitrate=3653.6kbits/s    
  
  video:2025kB audio:1501kB subtitle:0 global headers:0kB muxing overhead 1.291094%
  
  [libx264 @ 0x1551420] frame I:1     Avg QP: 0.00  size:692585
  
  [libx264 @ 0x1551420] frame P:212   Avg QP: 0.00  size:  6509
  
  [libx264 @ 0x1551420] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x1551420] mb P  I16..4: 47.2%  0.0%  0.0%  P16..4:  0.1%  0.0%  0.0%  0.0%  0.0%    skip:52.8%
  
  [libx264 @ 0x1551420] coded y,u,v intra: 0.7% 0.7% 0.7% inter: 0.1% 0.1% 0.1%
  
  [libx264 @ 0x1551420] i16 v,h,dc,p: 100%  0%  0%  0%
  
  [libx264 @ 0x1551420] kb/s:2335.32

  Is there something I’m missing ?

• FFmpeg wrong duration(double) when convert mp4

  13 novembre 2017, par crazymxm

  The output file has the double duration :

  Source video duration :00:01:58.88

  output video duration :00:03:57.76

  （video’s duration is double ，audio’s duration is correct. So， the video looks like played twice, with no sound in the second half ）

  here is the log：

  ./ffmpeg -i /Volumes/LANKEXIN/1383.mp4 out.mp4
  ffmpeg version N-82977-g8fd3e02-tessus Copyright (c) 2000-2016 the FFmpeg developers
  built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  configuration : —cc=/usr/bin/clang —prefix=/opt/ffmpeg —extra-version=tessus —enable-avisynth —enable-fontconfig —enable-gpl —enable-libass —enable-libbluray —enable-libfreetype —enable-libgsm —enable-libmodplug —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libopus —enable-libschroedinger —enable-libsnappy —enable-libsoxr —enable-libspeex —enable-libtheora —enable-libvidstab —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libwavpack —enable-libx264 —enable-libx265 —enable-libxavs —enable-libxvid —enable-libzmq —enable-version3 —disable-ffplay —disable-indev=qtkit —disable-indev=x11grab_xcb
  

    libavutil      55. 43.100 / 55. 43.100
  
    libavcodec     57. 70.100 / 57. 70.100
  
    libavformat    57. 61.100 / 57. 61.100
  
    libavdevice    57.  2.100 / 57.  2.100
  
    libavfilter     6. 68.100 /  6. 68.100
  
    libswscale      4.  3.101 /  4.  3.101
  
    libswresample   2.  4.100 /  2.  4.100
  
    libpostproc    54.  2.100 / 54.  2.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Volumes/LANKEXIN/1383.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isom
  
      creation_time   : 2017-10-30T14:58:05.000000Z
  
      encoder         : mp4creator 1.6.1d
  
    Duration: 00:01:58.88, start: 0.000000, bitrate: 1918 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1729 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc (default)
  
      Metadata:
  
        creation_time   : 2017-10-30T14:58:05.000000Z
  
        encoder         : VC Coding
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 189 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-10-30T14:58:05.000000Z
  
  File 'out.mp4' already exists. Overwrite ? [y/N] y
  
  [libx264 @ 0x7fbaca003c00] using SAR=1/1
  
  [libx264 @ 0x7fbaca003c00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264 @ 0x7fbaca003c00] profile High, level 3.1
  
  [libx264 @ 0x7fbaca003c00] 264 - core 148 - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'out.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isom
  
      encoder         : Lavf57.61.100
  
      Stream #0:0(eng): Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc (default)
  
      Metadata:
  
        creation_time   : 2017-10-30T14:58:05.000000Z
  
        encoder         : Lavc57.70.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
      Stream #0:1(eng): Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-10-30T14:58:05.000000Z
  
        encoder         : Lavc57.70.100 aac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  
    Stream #0:1 -> #0:1 (aac (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  frame=   46 fps=0.0 q=0.0 size=       0kB time=00:00:00.93 bitrate=   0.0kbits/sframe=   64 fps= 45 q=28.0 size=     137kB time=00:00:01.66 bitrate= 672.2kbits/frame=   85 fps= 44 qframe= 5944 fps= 33 q=-1.0 Lsize=   38746kB time=00:03:57.64 bitrate=1335.7kbits/s speed=1.33x    4kB time=00:00:02.94 bitrate= 818.0kbits/s speed= 1.2x    
  
  video:36779kB audio:1846kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.311413%
  
  [libx264 @ 0x7fbaca003c00] frame I:24    Avg QP:19.49  size: 67090
  
  [libx264 @ 0x7fbaca003c00] frame P:1806  Avg QP:21.65  size: 14304
  
  [libx264 @ 0x7fbaca003c00] frame B:4114  Avg QP:25.42  size:  2484
  
  [libx264 @ 0x7fbaca003c00] consecutive B-frames:  2.2%  8.1% 25.5% 64.2%
  
  [libx264 @ 0x7fbaca003c00] mb I  I16..4: 20.6% 55.8% 23.6%
  
  [libx264 @ 0x7fbaca003c00] mb P  I16..4:  5.2%  9.3%  0.8%  P16..4: 36.0%  9.9%  4.2%  0.0%  0.0%    skip:34.5%
  
  [libx264 @ 0x7fbaca003c00] mb B  I16..4:  0.5%  1.0%  0.0%  B16..8: 27.2%  1.8%  0.2%  direct: 0.9%  skip:68.5%  L0:48.6% L1:47.6% BI: 3.8%
  
  [libx264 @ 0x7fbaca003c00] 8x8 transform intra:60.9% inter:78.2%
  
  [libx264 @ 0x7fbaca003c00] coded y,uvDC,uvAC intra: 38.3% 61.5% 12.3% inter: 6.6% 11.3% 0.6%
  
  [libx264 @ 0x7fbaca003c00] i16 v,h,dc,p: 22% 35% 10% 33%
  
  [libx264 @ 0x7fbaca003c00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 21% 24% 21%  5%  6%  6%  6%  5%  6%
  
  [libx264 @ 0x7fbaca003c00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 24% 33% 11%  4%  7%  6%  6%  4%  4%
  
  [libx264 @ 0x7fbaca003c00] i8c dc,h,v,p: 43% 30% 20%  7%
  
  [libx264 @ 0x7fbaca003c00] Weighted P-Frames: Y:0.3% UV:0.2%
  
  [libx264 @ 0x7fbaca003c00] ref P L0: 73.5%  9.0% 13.8%  3.7%  0.0%
  
  [libx264 @ 0x7fbaca003c00] ref B L0: 92.4%  6.6%  1.1%
  
  [libx264 @ 0x7fbaca003c00] ref B L1: 97.7%  2.3%
  
  [libx264 @ 0x7fbaca003c00] kb/s:1267.21
  
  [aac @ 0x7fbaca021800] Qavg: 897.576

• Recording Camlink 4k feed with ffmpeg

  5 août 2020, par Nitzan Yogev

  its my first question ! awesome !
so im new to python, and im working on some program for work
I have the Elgato CamLink 4k connected to Sony A7III.
im looking for the best way to record a video file from the camlink feed using python
I know that ffmpeg is a good way to record webcam feed. but im having trouble with it
here is my code.

  


      import ffmpeg

(
    ffmpeg
    .input('0', format='avfoundation', pix_fmt='nv12', framerate=25)
    .output('test.mp4', pix_fmt='nv12', vframes=125)
    .overwrite_output()
    .run()
)


  


  im using this ffmpeg-python module

  


  im getting a output file with only the first frame and nothing more

  


  here is what im getting in the run terminal

  


  ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.62)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[avfoundation @ 0x7ff043814600] Stream #0: not enough frames to estimate rate; consider increasing probesize
Input #0, avfoundation, from '0':
  Duration: N/A, start: 6247.240967, bitrate: N/A
    Stream #0:0: Video: rawvideo (NV12 / 0x3231564E), nv12, 3840x2160, 1000k tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[mp4 @ 0x7ff043856c00] Frame rate very high for a muxer not efficiently supporting it.
Please consider specifying a lower framerate, a different muxer or -vsync 2
[libx264 @ 0x7ff043868000] MB rate (32400000000) > level limit (16711680)
[libx264 @ 0x7ff043868000] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7ff043868000] profile High, level 6.2, 4:2:0, 8-bit
[libx264 @ 0x7ff043868000] 264 - core 160 r3011 cde9a93 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=18 lookahead_threads=3 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'test.mp4':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), nv12, 3840x2160, q=-1--1, 1000k fps, 1000k tbn, 1000k tbc
    Metadata:
      encoder         : Lavc58.91.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=  125 fps= 30 q=-1.0 Lsize=     788kB time=00:00:00.00 bitrate=52509528.5kbits/s dup=124 drop=1 speed=2.99e-05x    
video:786kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.290685%
[libx264 @ 0x7ff043868000] frame I:1     Avg QP:19.49  size:588332
[libx264 @ 0x7ff043868000] frame P:31    Avg QP:20.24  size:  4202
[libx264 @ 0x7ff043868000] frame B:93    Avg QP:33.28  size:   922
[libx264 @ 0x7ff043868000] consecutive B-frames:  0.8%  0.0%  0.0% 99.2%
[libx264 @ 0x7ff043868000] mb I  I16..4:  2.8% 86.0% 11.3%
[libx264 @ 0x7ff043868000] mb P  I16..4:  0.0%  0.0%  0.0%  P16..4:  6.9%  0.3%  0.5%  0.0%  0.0%    skip:92.3%
[libx264 @ 0x7ff043868000] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  4.4%  0.0%  0.0%  direct: 0.0%  skip:95.6%  L0:19.0% L1:81.0% BI: 0.0%
[libx264 @ 0x7ff043868000] 8x8 transform intra:86.0% inter:88.3%
[libx264 @ 0x7ff043868000] coded y,uvDC,uvAC intra: 93.8% 87.1% 55.6% inter: 0.1% 1.5% 0.0%
[libx264 @ 0x7ff043868000] i16 v,h,dc,p:  9% 10%  9% 72%
[libx264 @ 0x7ff043868000] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 15% 14% 34%  6%  5%  5%  6%  7%  7%
[libx264 @ 0x7ff043868000] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 22% 18% 16%  9%  8%  7%  8%  7%  6%
[libx264 @ 0x7ff043868000] i8c dc,h,v,p: 48% 26% 20%  6%
[libx264 @ 0x7ff043868000] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x7ff043868000] ref P L0: 82.6%  0.1% 14.0%  3.3%
[libx264 @ 0x7ff043868000] ref B L0: 99.8%  0.2%  0.0%
[libx264 @ 0x7ff043868000] ref B L1: 76.2% 23.8%
[libx264 @ 0x7ff043868000] kb/s:51475456.00


  


  if im plugging the camlink off I get a video from my macbook internal camera. so I know this should somehow work