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• ffmpeg and streaming to youtube displaying logotype and webcamera

  7 juin 2017, par DmitrySemenov

  ➜  tmp ffmpeg -version 
  
  ffmpeg version 3.1.7 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with gcc 6.3.1 (GCC) 20161221 (Red Hat 6.3.1-1)
  
  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 -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' --extra-ldflags='-Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld' --enable-bzlib --disable-crystalhd --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libcdio --enable-indev=jack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmp3lame --enable-nvenc --extra-cflags=-I/usr/include/nvenc --enable-openal --enable-opencl --enable-opengl --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --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-libmfx --enable-runtime-cpudetect
  
  libavutil      55. 28.100 / 55. 28.100
  
  libavcodec     57. 48.101 / 57. 48.101
  
  libavformat    57. 41.100 / 57. 41.100
  
  libavdevice    57.  0.101 / 57.  0.101
  
  libavfilter     6. 47.100 /  6. 47.100
  
  libavresample   3.  0.  0 /  3.  0.  0
  
  libswscale      4.  1.100 /  4.  1.100
  
  libswresample   2.  1.100 /  2.  1.100
  
  libpostproc    54.  0.100 / 54.  0.100

  I’m streaming to youtube with the following settings

  ffmpeg \
  
  -f x11grab -video_size 3840x2160 -framerate 30 -i :1.0 \
  
  -f v4l2 -video_size 320x240 -framerate 30 -i /dev/video0 \
  
  -f alsa -ac 2 -i pulse -i logo.png -filter_complex \
  
  "[0:v]scale=1920:-1,setpts=PTS-STARTPTS[bg]; \
  
   [1:v]scale=120:-1,setpts=PTS-STARTPTS[fg]; \
  
   [bg][fg]overlay=W-w-10:10[bg2]; \
  
   [bg2][3:v]overlay=W-w-10:H-h-10,format=yuv420p[out]" \
  
  -map "[out]" -map 2:a -c:v libx264 -preset veryfast \
  
  -maxrate 9000k -bufsize 12000k -c:a aac -b:a 160k -ar 44100 -b:a 128k \
  
  -f flv rtmp://a.rtmp.youtube.com/live2/TOKEN

  

  I’m getting that huge black screen that cuts a lot of visible screen canvas. How do I get rid of it keeping webcamera preview on top and logo at the bottom ?

  This is what I see in console

  https://gist.github.com/dmitry-saritasa/cc85ba6650d9bd50b28a61624711b96a

  as you can see I only get 6-9fps while I expect 24+ (per settings ?)

  frame=  101 fps=6.4 q=23.0 size=    1669kB time=00:00:11.37 bitrate=1202.2kbits/s dup=0 drop=4 speed=0.718x    
  
  frame=  105 fps=6.4 q=27.0 size=    1866kB time=00:00:12.09 bitrate=1263.7kbits/s dup=0 drop=4 speed=0.74x    
  
  frame=  107 fps=6.4 q=28.0 size=    1871kB time=00:00:12.32 bitrate=1243.0kbits/s dup=0 drop=4 speed=0.732x    
  
  frame=  111 fps=6.4 q=26.0 size=    1879kB time=00:00:12.79 bitrate=1203.4kbits/s dup=0 drop=4 speed=0.737x    

  ---

  Questions

  1. How to get rid of the top black area ? So that I can screen share my full display ?
  2. How to increase fps ?

• FFmpeg concat video and audio out of sync

  20 décembre 2020, par Xeoncross

  Joining multiple files using ffmpeg concat seems to result in a mismatch of the timestamps or offsets for the audio. I've tried with several videos and noticed the same problem for h.264 / MP4.

  



  Using concat and encoding the video seems to work fine. The audio stays in sync as ffmpeg does the full conversion calculations and seems to get everything right.

  



  However, simply concatenating the videos without any transformation or encoding results in a slowly increasing sync issue. Obviously, encoding the videos rather than simply joining them will result in a loss of information/quality so I would rather find a way around this problem.

  



  I've tried several flags to sort out this problem that appears to be based on the timestamps. None of these seem to correct the problem though.

  



  ffmpeg -f concat -fflags +genpts -async 1 -i segments.txt test.mov
ffmpeg -auto_convert 1 -f concat -fflags +genpts -async 1 -i segments.txt -c copy test2.mov
ffmpeg -f concat -i segments.txt -c copy -fflags +genpts test3.mp4
ffmpeg -f concat -fflags +genpts -async 1 -i segments.txt -copyts test4.mov
ffmpeg -f concat -i segments.txt -copyts test5.mov
ffmpeg -f concat -i segments.txt -copyts -c copy test6.mov
ffmpeg -f concat -fflags +genpts -i segments.txt -copyts -c copy test7.mov


  



  Note : all other questions that I could find on SO seem to "fix" the problem by simply encoding the videos over again. Not a good solution.

  



  Update

  



  I realized the concat wasn't the problem. The original set of clips had mis-matched timestamps. Somehow concat + encoding fixed the issue, but I don't want to re-encode the videos and loose quality each time.

  



  ffmpeg -y -ss 00:00:02.750 -i input.MOV -c copy -t 00:00:05.880 output.MOV


  



  Which resulted in the following data

  



  ffprobe -v quiet -show_entries stream=start_time,duration output.MOV

start_time=-0.247500
duration=6.131125
start_time=-0.257333
duration=6.155333


  



  Since then I've tried to use -tom and -t in different places along with -af apad -c:v copy and I've still failed to get the duration to be the same.

  



  Here is the full ffprobe output

  



  Here is the original (red) vs the segment (green)

  



  Detailed Sample Files

  



  I recorded a sample video, added the commands to chop it up, then concat it. http://davidpennington.me/share/audio_sync_test_video.zip

  


• FFmpeg concat video and audio out of sync

  16 septembre 2016, par Xeoncross

  Joining multiple files using ffmpeg concat seems to result in a mismatch of the timestamps or offsets for the audio. I’ve tried with several videos and noticed the same problem for h.264 / MP4.

  Using concat and encoding the video seems to work fine. The audio stays in sync as ffmpeg does the full conversion calculations and seems to get everything right.

  However, simply concatenating the videos without any transformation or encoding results in a slowly increasing sync issue. Obviously, encoding the videos rather than simply joining them will result in a loss of information/quality so I would rather find a way around this problem.

  I’ve tried several flags to sort out this problem that appears to be based on the timestamps. None of these seem to correct the problem though.

  ffmpeg -f concat -fflags +genpts -async 1 -i segments.txt test.mov
  
  ffmpeg -auto_convert 1 -f concat -fflags +genpts -async 1 -i segments.txt -c copy test2.mov
  
  ffmpeg -f concat -i segments.txt -c copy -fflags +genpts test3.mp4
  
  ffmpeg -f concat -fflags +genpts -async 1 -i segments.txt -copyts test4.mov
  
  ffmpeg -f concat -i segments.txt -copyts test5.mov
  
  ffmpeg -f concat -i segments.txt -copyts -c copy test6.mov
  
  ffmpeg -f concat -fflags +genpts -i segments.txt -copyts -c copy test7.mov

  Note : all other questions that I could find on SO seem to "fix" the problem by simply encoding the videos over again. Not a good solution.

  Update

  I realized the concat wasn’t the problem. The original set of clips had mis-matched timestamps. Somehow concat + encoding fixed the issue, but I don’t want to re-encode the videos and loose quality each time.

  ffmpeg -y -ss 00:00:02.750 -i input.MOV -c copy -t 00:00:05.880 output.MOV

  Which resulted in the following data

  ffprobe -v quiet -show_entries stream=start_time,duration output.MOV
  
  
  
  start_time=-0.247500
  
  duration=6.131125
  
  start_time=-0.257333
  
  duration=6.155333

  Since then I’ve tried to use -tom and -t in different places along with -af apad -c:v copy and I’ve still failed to get the duration to be the same.

  Here is the full ffprobe output

  Here is the original (red) vs the segment (green)

  Detailed Sample Files

  I recorded a sample video, added the commands to chop it up, then concat it. http://davidpennington.me/share/audio_sync_test_video.zip