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• Immidiately display first and latest frame of h264 stream which may sometimes pause

  22 septembre 2016, par jorp

  Steps to reproduce :

  1.Connect android device to linux PC via USB.
  

  2.Run command on pc :
  adb shell screenrecord --output-format=h264 - | ffplay -analyzeduration 1 -

  3.Screenrecord(an Android system tool) will start to capture Android screen, encode by MediaCodec, generate h264 stream, send stream data to ffplay via pipe.

  4.PC will pop up ffplay window, and start display Android screen graphs

  ---

  If adb command runs when Android screen graph keeps static (no pixel color changes), ffplay window won’t pop up, until I touch somewhere to make Android graph changes.

  Question 1 : how to make ffplay to immidiately display the first frame of video when Android screen keeps static and adb commmand runs ?

  I’m not talking about "latency", if Android graph keeps changing, the graphic latency is within 2 second. It’s fast enough.

  when Android graph is static, run command without ffplay :
  adb shell screenrecord --output-format=h264 -

  screenrecord will output H264 stream data immidiately then pause.(See picture below).
  stream data comes first

  Does the data contain all information of first frame graph ?
  If so, how to make ffplay to display it immidiately ?

  ---

  Question 2 : how to make ffplay to immidiately display the latest frame of video when Android screen suddenly become static ?

  When Android screen start casting and Android graph suddenly become static, H264 data stream transfer will pause, while PC graph is different with Android graph.

  For example, I make a popup menu on Android disappear, there has been a fadeoff animation, PC graph pauses and display a translucent popup menu.(See picture below)

  latest graph on pc

  The first and latest frames of stream doesn’t display in ffplay immidiately, they are "missing".
  when Android screen go on changing, the "missing" frames displays.
  So it seems like the latest frames are always in buffer.

  I’ve tried adding these params to ffplay :
  

  -noinfbuf
-fflags nobuffer
-max_delay 0
-sync ext
-preset ultrafast
-tune zerolatency

  
  They cannot solve the problems

  Modifing Android ROM or screenrecord source, making a pixel color changes every frame, may solve the problems(I guess), but it would enlarge data stream, it’s the last choise.
  Is there any solution by adding params of ffplay, or by modifing screenrecord or ffplay source code ?

  PS : mplayer also has the same problem :
  mplayer -demuxer h264es -

• how to use ffmpeg in python to record a specific window with system audio without command line and cleanly stop it

  17 juillet 2023, par Jaime

  I'm working in an application that is capturing specific window from my desktop and grabbing the system audio, it application is packaged with pyinstaller with —windowed parameter, when I start to capture video it work perfectly and in a debbug execution it stop cleanly, but when I run it from the packaged file, the ffmpeg process never stop. I'm using subprocess.popen to launch ffmpeg by this way :

  


  command = ['ffmpeg','-f', 'dshow', '-i', f'audio={device}', '-f', 'gdigrab', '-framerate', '30', '-i', f'title={device_model}', '-c:v', 'libx264', '-preset', 'slower', '-crf', '22', f'{file_path}']
subprocess.Popen(comando,stdin=subprocess.PIPE,stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=False)


  


• How to concatenate 3 mp4 files using ffmpeg (facing error in resultant video) ?

  5 février 2021, par Mayank Thapliyal

  I have 3 videos of mp4 format. They have same resolution (640 X 1280) but other properties like frame rate etc are different. I want to join them back to back.So I gave a check on internet and I used the following method

  


  :: Create File List
echo file file1.mp4 >  mylist.txt 
echo file file2.mp4 >> mylist.txt
echo file file3.mp4 >> mylist.txt

:: Concatenate Files
ffmpeg -f concat -i mylist.txt -c copy output.mp4


  


  But unfortunately it did not worked.In the resultant video, file1 part got freezed, and audio of whole video shifted (no idea how).And other methods are also not working properly

  


  I just want to join them back to back.Any idea how to do it ?

  


  Edit :- I gave a check on the output of the ffmpeg (using pause command in bat and discovered the following. Maybe it may help regarding the issue)

  


  C:\Users\Cascade_Games\Desktop\Cascade Empire\ffmpeg-4.3.1-2020-10-01-full_build\bin>ffmpeg -f concat -i mylist.txt -vcodec copy -acodec copy Mux1.mp4
ffmpeg version 4.3.1-2020-10-01-full_build-www.gyan.dev Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.0 (Rev3, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  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
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 000002a0474e6a40] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'mylist.txt':
  Duration: N/A, start: -0.023220, bitrate: 2447 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x640 [SAR 1:1 DAR 2:1], 2320 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc
    Metadata:
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s
    Metadata:
      handler_name    : SoundHandler
Output #0, mp4, to 'Mux1.mp4':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x640 [SAR 1:1 DAR 2:1], q=2-31, 2320 kb/s, 30 fps, 30 tbr, 15360 tbn, 15360 tbc
    Metadata:
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s
    Metadata:
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mov,mp4,m4a,3gp,3g2,mj2 @ 000002a04750d700] Auto-inserting h264_mp4toannexb bitstream filter
[mov,mp4,m4a,3gp,3g2,mj2 @ 000002a0474ef040] Auto-inserting h264_mp4toannexb bitstream filter
[mp4 @ 000002a0478e09c0] Non-monotonous DTS in output stream 0:1; previous: 30282976, current: 27826977; changing to 30282977. This may result in incorrect timestamps in the output file.
[mp4 @ 000002a0478e09c0] Non-monotonous DTS in output stream 0:1; previous: 30282977, current: 27828129; changing to 30282978. This may result in incorrect timestamps in the output file.
(Same Thing was getting repeated,hence I deleted it)
[mp4 @ 000002a0478e09c0] Non-monotonous DTS in output stream 0:1; previous: 30283209, current: 28095393; changing to 30283210. This may result in incorrect timestamps in the output file.
[mp4 @ 000002a0478e09c0] Non-monotonous DTS in output stream 0:1; previous: 30283210, current: 28096545; changing to 30283211. This may result in incorrect timestamps in the output file.
[mp4 @ 000002a0478e09c0] aac bitstream error
    Last message repeated 234 times
frame=18937 fps=11438 q=-1.0 Lsize=   49051kB time=00:11:26.69 bitrate= 585.2kbits/s speed= 415x
video:40720kB audio:7653kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.401324%


  


  Edit :-
Info of all files (I have changed the video name to 1.mp4,2.mp4,3.mp4)

  


  C:\Users\Cascade_Games\Desktop\Cascade Empire\ffmpeg-4.3.1-2020-10-01-full_build\bin>ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4
ffmpeg version 4.3.1-2020-10-01-full_build-www.gyan.dev Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.0 (Rev3, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  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
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:05.27, start: 0.000000, bitrate: 2337 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x640 [SAR 1:1 DAR 2:1], 2320 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from '2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:10:25.70, start: 0.000000, bitrate: 616 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x640 [SAR 1:1 DAR 2:1], 511 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 96 kb/s (default)
    Metadata:
      handler_name    : SoundHandle
Input #2, mov,mp4,m4a,3gp,3g2,mj2, from '3.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.50, start: 0.000000, bitrate: 447 kb/s
    Stream #2:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p, 1280x640 [SAR 1:1 DAR 2:1], 228 kb/s, 2 fps, 2 tbr, 16384 tbn, 4 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #2:1(und): Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 319 kb/s (default)
    Metadata:
      handler_name    : SoundHandler