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• Emphasis level map with ffmpeg using NVENC

  2 novembre 2020, par ofer rubinstein

  I am trying to have different compression levels, to different regions in the video.
ffmpeg has something called "addroi", but it's just a recommendation and doesn't guarantee the absolute level of compression.
Nvidia NVENC has something called Emphasis Level Map, I am hoping this will be able to achieve an accurate level of compression per region.

  


  I am unable to find how to do this via ffmpeg executable, so I am starting to try to do this using the ffmpeg SDK.
Do you have any idea how to do this via the ffmpeg.exe, instead of using the SDK ?

  


  Here is what I am talking about in the NVIDIA documentation :

  


  https://docs.nvidia.com/video-technologies/video-codec-sdk/nvenc-video-encoder-api-prog-guide/index.html#emphasis-map

  


• Ffmpeg : Describing the audio data manually

  11 février 2015, par Dries

  I’m trying to manually create the packets from the audio that will be sent to the ffmpeg encoder. I’m trying to do this in the s16le format.

  I’m to write the audio after I’ve written the video frame like this :

  // Write a frame to the ffmpeg stream
  
  fwrite(frame, sizeof(unsigned char*) * frameWidth * frameHeight, 1, ffmpeg); 
  
  
  
  // Write multiple sound samples per written frame
  
  for (int t = 0; t < 44100/24; ++t)
  
      fwrite(&audio, sizeof(short int), 1, ffmpeg);

  I think that this should be possible but I don’t know how to describe the audio without directly using the libavformat library that does this automatically.

  Is this possible ? If so, how do I describe the audio properly ? I’m currently getting integer values from a sine wave.

• Is it possible to convert h265 video to h264 with resizing in Android app without the FFMPEG ?

  12 août 2022, par Robson

  I want to convert all videos based on h265 to h264 and at the same time reduce the resolution to for example 720p to avoid working on very big resolutions and later uploading that kind of big size files.

  


  I see docs https://developer.android.com/guide/topics/media/media-formats says that for h265 Android OS supports only decoding, not encoding.

  


  I know that FFMPEG will solve all my problems, but including FFMPEG will increase the app size very much, I'd like to avoid that. I am trying to use currently the Android MediaCodec, but it looks like it would work fine with converting h264 to h264 but not with h265 to h264.

  


  Do you have any ideas ? I don't need to support old Android versions.

  


  Thanks for any advice.