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• cmdutils : replace strncpy() with direct assignment

  24 février 2021, par Anton Khirnov

  cmdutils : replace strncpy() with direct assignment
  Only one character is actually rewritten.
  Fixes truncation warnings, such as
  
  warning : ‘strncpy’ output truncated before terminating nul copying 3 bytes from a string of the same length [-Wstringop-truncation]
  
  in gcc 10.2.0
  

  • [DH] fftools/cmdutils.c

• Audio out of sync, direct capture device stream (Windows 10)

  3 mai 2020, par user3459555

  Using ffplay, the video stays in sync using this command :

  



  ffplay -f dshow -rtbufsize 702000k video="Cam Link"
ffplay version git-2020-05-01-39fb1e9 Copyright (c) 2003-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200328
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 43.100 / 56. 43.100
  libavcodec     58. 82.100 / 58. 82.100
  libavformat    58. 42.101 / 58. 42.101
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 80.100 /  7. 80.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, dshow, from 'video=Cam Link':vq=    0KB sq=    0B f=0/0
  Duration: N/A, start: 141954.961000, bitrate: N/A
    Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 1920x1080, 59.94 fps, 59.94 tbr, 10000k tbn, 10000k tbc
142992.53 M-V: -0.001 fd=   3 aq=    0KB vq=    0KB sq=    0B f=0/0


  



  Every controller button press stays in sync.

  



  The audio however :

  



  ffplay -f dshow audio="Digital Audio Interface (Cam Link)" -tune zerolatency
ffplay version git-2020-05-01-39fb1e9 Copyright (c) 2003-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200328
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 43.100 / 56. 43.100
  libavcodec     58. 82.100 / 58. 82.100
  libavformat    58. 42.101 / 58. 42.101
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 80.100 /  7. 80.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, dshow, from 'audio=Digital Audio Interface (Cam Link)':
  Duration: N/A, start: 143092.007000, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
143103.21 M-A:  0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0


  



  Is always behined by about a full second.

  



  I'm not trying to record this, just trying to directly play from the Elgato Cam Link 1:1 output to my computer screen. When this is played in the Elgato Game Capture software, the video and audio are 1:1, no issues. So I know it's not the console or the capture device.

  


• FFMPEG reduce fps for live h264 stream with direct copy

  22 avril 2020, par Daniel

  I found different articles on changing the fps with ffmpeg but none of them is matching for my exact purposes.

  



  There is an ffmpeg command like below :

  



  ffmpeg -i RTSPCAMERAPRODUCEH264 -c:v copy -an -movflags +frag_keyframe+empty_moov -f mp4


  



  This will remux my camerastream to fragmented mp4 perfectly.

  



  Is there a way to force ffmpeg to lower the FPS to save bandwidth ?

  



  I.e. camera streams 30fps, it needs 1Mbps for fmp4 (sample numbers !) :

  



  I'd like to know if it's possible to lower the FPS and get an output stream for which 500kbps (50% of original is enough) without re-encoding.

  



  ffmpeg -r 1 -i RTSPCAMERAPRODUCEH264 -c:v copy -an -movflags +frag_keyframe+empty_moov -f mp4


  



  and

  



  ffmpeg -i RTSPCAMERAPRODUCEH264 -c:v copy -an -movflags +frag_keyframe+empty_moov -r 1 -f mp4


  



  do not seem to work.