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• Capture desktop screens including audio with ffmpeg

  9 mars 2019, par klaus

  After referring to the official documentation and one other blog post, I now have following script :

  A="$(pacmd list-sources | grep -PB 1 "analog.*monitor>" | head -n 1 | perl -pe 's/.* //g')"
  
  F="/home/enan/Videos/$(date --iso-8601=minutes | perl -pe 's/[^0-9]+//g').mkv"
  
  V="$(xdpyinfo | grep dimensions | perl -pe 's/.* ([0-9]+x[0-9]+) .*/$1/g')"
  
  ffmpeg -video_size "$V" -framerate 25 -f x11grab -i :0.0 -f pulse -i "$A" -f pulse -i default \
  
      -filter_complex amerge -ac 1 -preset veryfast "$F"

  Basically that script results into the following command :

  ffmpeg -video_size 1366x768 -framerate 25 -f x11grab -i :0.0 -f pulse -ac 2 -i default output.mkv

  In this case, with -ac 2, the audio that gets added with the captured video is of some mic. I’m using a laptop and don’t have a mic, so I don’t exactly know which device the outside sounds get added from but it does. But no audio from the main audio that I can hear through the headphone jack doesn’t get added to the video.

  If I use -ac 1 instead, the video now gets the outside audio as well as the internal audio. That’s good. But how do I restrict the video to only add internal audio, not add audio gotten from mic or something similar.

  I don’t know if it’ll help, but adding it anyway. From man mpv :

         -ac[:stream_specifier] channels (input/output,per-stream)
  
             Set the number of audio channels. For output streams it is set by
  
             default to the number of input audio channels. For input streams this
  
             option only makes sense for audio grabbing devices and raw demuxers and
  
             is mapped to the corresponding demuxer options.

• How to batch fade in and fade out multiple videos ffmpeg ?

  25 mars 2021, par user2826193

  I have found several tips on how to batch fade in and fade out a single video using ffprobe.
What I cannot find is how to do several videos using a batch script. I even tried using this code that I found on here :

  


  ffmpeg -i 123.mp4 -filter_complex "fade=d=3.5, reverse, fade=d=3.5, reverse" output.mp4


  


  That works for a single video only without the use of ffprobe. When I tried using it for multiple videos in a for .mp4 batch file, something goes horribly wrong and I get an error : Failed to inject frame into filter network : Cannot allocate memory ffmpeg
The files converted are about 1MB in size and the laptop freezes.

  


  Can anyone point me in the right direction ? Thanks...

  


  EDIT :

  


  This is the code I used...

  


  @echo off
if not exist "faded" mkdir faded
for %%f in ("*.mp4") do ffmpeg -i "%%f" -filter_complex "fade=d=3.5, reverse, fade=d=3.5, reverse" "faded\%%~nf.mp4"


  


  EDIT_2 :

  


  This is what I tried to manipulate to use the ffprobe and FADE instead of TRIM :

  


  @Echo Off
SetLocal
Set "ext=mp4"
Set "opts=-v quiet"
Set "opts=%opts% -print_format "compact=print_section=0:nokey=1:escape=csv""
Set "opts=%opts% -show_entries "format=duration""
If Exist *.%ext% (If Not Exist "Trimmed\" MD Trimmed)
For %%a In (*.%ext%) Do Call :Sub "%%~a"
Exit/B

:Sub
For /f "Tokens=1* Delims=." %%a In (
    'FFProbe %opts% %1') Do (Set/A "ws=%%a-8.25" & Set "ps=%%b")
rem If %ws% Lss 20 GoTo :EOF
Set/A hh=ws/(60*60), lo=ws%%(60*60), mm=lo/60, ss=lo%%60
If %hh% Lss 10 Set hh=0%hh%
If %mm% Lss 10 Set mm=0%mm%
If %ss% Lss 10 Set ss=0%ss%
FFMpeg -i %1 -ss 00:00:04.2500 -to %hh%:%mm%:%ss%.%ps:~,3% -c:v copy -c:a copy "Trimmed\%~1"


  


• USB webcam streaming in ARM board (i.MX6)

  5 septembre 2017, par Titus

  I want to streaming the camera via NETWORK. I have connected the USB webcam to i.MX6 board and want to stream in Ubuntu14.04/16.04 via network.

  Incidentally, I have installed the gstreamer and ffmpeg tools for this in i.MX6 board.

  Also I am able to stream USB webcam within Ubuntu14.04 PC using the following ffmpeg commands. But it’s also not working if I use ffplay in other Ubuntu16.04 and I am not sure why (both are same ffmpeg versions).

  ffmpeg -f v4l2 -i /dev/video0 -preset ultrafast -vcodec libx264 -tune zerolatency -b 900k -f mpegts udp://192.168.0.37:1234
  
  
  
  ffplay udp://192.168.0.37:1234

  Ubuntu 16.06 : (NOT WORKING)

  tus@titus-PC:~/workdir$ ffplay udp://192.168.0.105:1234
  
  ffplay version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2003-2017 the FFmpeg developers
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --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-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
      nan    :  0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0  

  Ubuntu 14.04 : (WORKING)

  titus@titus-laptop:~$ 
  
  titus@titus-laptop:~$ ffplay udp://127.0.0.1:1234
  
  ffplay version 3.3.2 Copyright (c) 2003-2017 the FFmpeg developers
  
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
    configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libtheora --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab --enable-libwavpack --enable-nvenc
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  [h264 @ 0xb0621660] non-existing PPS 0 referenced sq=    0B f=0/0   
  
      Last message repeated 1 times
  
  [h264 @ 0xb0621660] decode_slice_header error
  
  [h264 @ 0xb0621660] non-existing PPS 0 referenced
  
  [h264 @ 0xb0621660] decode_slice_header error
  
  [h264 @ 0xb0621660] non-existing PPS 0 referenced
  
  [h264 @ 0xb0621660] decode_slice_header error
  
  [h264 @ 0xb0621660] non-existing PPS 0 referenced
  
  [h264 @ 0xb0621660] decode_slice_header error
  
  [h264 @ 0xb0621660] no frame!
  
  [h264 @ 0xb0621660] non-existing PPS 0 referenced sq=    0B f=0/0   
  
  1751.47 M-V: -0.021 fd=   0 aq=    0KB vq=   11KB sq=    0B f=0/0   
  
  1751.63 M-V: -0.020 fd=   0 aq=    0KB vq=   11KB sq=    0B f=0/0   
  
  1751.80 M-V: -0.020 fd=   0 aq=    0KB vq=   11KB sq=    0B f=0/0 

  Finally I want to stream with different ARM boards. Am also not able to build ffplay command. Same issue with raspberry pi too. I am doing something wrong or misunderstood something here ?