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• x264/x265 options for fast decoding while preserving quality

  18 août 2024, par user3301993

  I want to encode some videos in H264 and H265, and I would like to ask for help in order to chose the adequate options in x264/x265.

  


  

  • My first priority is video quality. Lossless would be the best quality for example

  


  • My second priority is fast decoding speed (ie : I would like faster decoding without sacrificing quality)

    

    • fast decoding for me means that the decoding machine would use less CPU resources reading the resulting video

    


    • Less RAM consumption would be a plus

    


    • Latency is not important

    


    


  


  • I don't care that much if the output file ends up bigger. Also, encoding speed is not important

  


  


  I'm aware of the option -tune fastdecode in both x264 and x265. But apparently the quality gets a bit worse using it.

  


  For x264 :

  


  -tune fastdecode is equivalent to --no-cabac --no-deblock --no-weightb --weightp 0 (My source is x264 --fullhelp)

  


  Which options preserve quality ?

  


  For x265 :

  


  -tune fastdecode is equivalent to --no-deblock --no-sao --no-weightp --no-weightb --no-b-intra (according to x265 doc)

  


  Again, which options preserve quality ?

  


  I tried to read some documentation on these options, but I'm afraid I'm too stupid to understand if they preserve quality or not.

  


  To explain further what I mean by "preserving quality" :

  


  


  I don't understand what the cabac option does exactly. But let's say for example that it adds some extra lossless compression, resulting in a smaller video file, but the decoding machine would need to do extra work to decompress the file

  


  In that case, the --no-cabac option would skip that extra compression, resulting in no loss of quality, with a bigger file size, and the decoding machine would not need to decompress the extra compression, saving CPU work on the decoding side

  


  In this scenario, I would like to add the --no-cabac option, as it speeds up decoding, while preserving quality.

  


  


  I hope I could get my point across

  


  Can anyone help me pick the right options ?

  


  Thanks in advance

  


• x264/x265 options for fast decoding while preserving quality

  18 août 2024, par user3301993

  I want to encode some videos in H264 and H265, and I would like to ask for help in order to chose the adequate options in x264/x265.

  


  

  • My first priority is video quality. Lossless would be the best quality for example

  


  • My second priority is fast decoding speed (ie : I would like faster decoding without sacrificing quality)

    

    • fast decoding for me means that the decoding machine would use less CPU resources reading the resulting video

    


    • Less RAM consumption would be a plus

    


    • Latency is not important

    


    


  


  • I don't care that much if the output file ends up bigger. Also, encoding speed is not important

  


  


  I'm aware of the option -tune fastdecode in both x264 and x265. But apparently the quality gets a bit worse using it.

  


  For x264 :

  


  -tune fastdecode is equivalent to --no-cabac --no-deblock --no-weightb --weightp 0 (My source is x264 --fullhelp)

  


  Which options preserve quality ?

  


  For x265 :

  


  -tune fastdecode is equivalent to --no-deblock --no-sao --no-weightp --no-weightb --no-b-intra (according to x265 doc)

  


  Again, which options preserve quality ?

  


  I tried to read some documentation on these options, but I'm afraid I'm too stupid to understand if they preserve quality or not.

  


  To explain further what I mean by "preserving quality" :

  


  


  I don't understand what the cabac option does exactly. But let's say for example that it adds some extra lossless compression, resulting in a smaller video file, but the decoding machine would need to do extra work to decompress the file

  


  In that case, the --no-cabac option would skip that extra compression, resulting in no loss of quality, with a bigger file size, and the decoding machine would not need to decompress the extra compression, saving CPU work on the decoding side

  


  In this scenario, I would like to add the --no-cabac option, as it speeds up decoding, while preserving quality.

  


  


  I hope I could get my point across

  


  Can anyone help me pick the right options ?

  


  Thanks in advance

  


• Merge the .mp4 video file with the .srt file in Hebrew language

  18 octobre 2023, par ZONEX

  I am looking for a solution using Python or CMD with FFmpeg to merge my Hebrew language .srt file with my .mp4 file.
Thanks for everyone !.

  


  I have tried using this command

  


  ffmpeg -i show.mp4 -vf "subtitles=show.srt:force_style='FontName=Arial,FontSize=24,PrimaryColour=&H00FFFF00&'" -c:v libx264 -c:a aac -strict experimental -scodec mov_text mysubtitledmovie.mp4

  


  However, I encountered the error message : 'Invalid UTF-8 in decoded subtitles.' I understand that I need to add Hebrew encoding support, but I haven't found how to do that.

  


  it's important to me that it'll be very fast process to add the .srt Hebrew file to .mp4 file.