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• Reduce ffmpeg CPU usage with h265 [closed]

  23 septembre 2024, par Neskelogth

  I have a video file to convert using ffmpeg on Ubuntu 22.04. The input uses the codec h264 and I want to convert it to h265 (mainly for storage capacity reasons). The output of ffmpeg -version is

  


  ffmpeg version N-113725-g37702e2066 Copyright (c) 2000-2024 the FFmpeg developers
built with gcc 11 (Ubuntu 11.4.0-1ubuntu1~22.04)
configuration: --enable-nonfree --enable-cuda-nvcc --enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64 --disable-static --enable-shared --enable-libx265 --enable-gpl
libavutil      58. 39.100 / 58. 39.100
libavcodec     60. 39.101 / 60. 39.101
libavformat    60. 21.101 / 60. 21.101
libavdevice    60.  4.100 / 60.  4.100
libavfilter     9. 17.100 /  9. 17.100
libswscale      7.  6.100 /  7.  6.100
libswresample   4. 13.100 /  4. 13.100
libpostproc    57.  4.100 / 57.  4.100


  


  I saw online that one of the options of ffmpeg is -threads, but apparently it does not work, since using ffmpeg -i input.mp4 -c:v libx265 -c:a copy output.mp4 and ffmpeg -i input.mp4 -c:v libx265 -c:a copy -threads 2 output.mp4 seem to be exactly the same in terms of CPU usage as shown by htop. Is there something wrong in my usage of -threads ?

  


• ffmpeg does not respect the -t option and keeps recording [closed]

  21 juillet 2024, par Naman Muley

  The command I use is :

  


   ffmpeg -f avfoundation -framerate 30 -i "2:0" -vcodec libx264 -pix_fmt yuv420p -acodec aac -strict experimental -t 10 ./recordings/tmp.mp4


  


  With the above command, I expect the recording output to stop after 10 seconds. But the ffmpeg command keeps running and does not stop.
Feels like I am missing something basic but I have now spent 3 hours debugging and cannot figure out why.

  


  Usecase :
I need to record my screen's video as well as audio for a specifiable amount of time.

  


  According to the manual, putting -t before -i limits the input recording and putting it after -i limits the output recording. I believe after the -i is the correct way to go.

  


  Output of list devices :

  


   ffmpeg -v verbose -f avfoundation -list_devices true -i ""
ffmpeg version 7.0.1 Copyright (c) 2000-2024 the FFmpeg developers
  built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/7.0.1 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --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-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox
  libavutil      59.  8.100 / 59.  8.100
  libavcodec     61.  3.100 / 61.  3.100
  libavformat    61.  1.100 / 61.  1.100
  libavdevice    61.  1.100 / 61.  1.100
  libavfilter    10.  1.100 / 10.  1.100
  libswscale      8.  1.100 /  8.  1.100
  libswresample   5.  1.100 /  5.  1.100
  libpostproc    58.  1.100 / 58.  1.100
[AVFoundation indev @ 0x7fdc48f047c0] AVFoundation video devices:
[AVFoundation indev @ 0x7fdc48f047c0] [0] FaceTime HD Camera (Built-in)
[AVFoundation indev @ 0x7fdc48f047c0] [1] Screwdriver Desk View Camera
[AVFoundation indev @ 0x7fdc48f047c0] [2] Capture screen 0
[AVFoundation indev @ 0x7fdc48f047c0] [3] Capture screen 1
[AVFoundation indev @ 0x7fdc48f047c0] AVFoundation audio devices:
[AVFoundation indev @ 0x7fdc48f047c0] [0] Built-in Microphone
[AVFoundation indev @ 0x7fdc48f047c0] [1] Screwdriver Microphone
[in#0 @ 0x7fdc49904080] Error opening input: Input/output error
Error opening input file .
Error opening input files: Input/output error


  


  

  • I tried using different codecs and pix_fmt options.

  


  • Tried moving the -t before the -i option and after. no change.

  


  


  Works with only audio input :
The below command that records only the audio works out just fine.

  


  ffmpeg -f avfoundation -i ":0" -acodec libmp3lame -t 10 ./recordings/tmp.mp3


  


• Converting konvajs state to Advanced SubStation Alpha (ASS) format for subtitles

  7 juillet 2024, par Ahsan

  I am building a subtitle editor using react.js. I plan to use konvajs to build the styling feature of editor like rotate subtitles, change size etc. How do I convert resultant konva state to ass format so that ffmpeg can render these subtitles on video.

  


  If there is a better solution than using konvajs then please guide me.