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• iOS/Safari MediaRecorder Extremely Big File sizes with FFMPEG Or issue with MediaRecorder

  13 janvier 2021, par Dean Van Greunen

  Having an issue where the output video size of the converted video is 0.

  


  however i believe that the issue is with the mediarecorder code :

  


  recorder = new MediaRecorder(this.stream, { mimeType: "video/webm;codecs=vp9" });
recorder.ondataavailable = async (e) => {
  const payload = e.data;
  let y = blob2base64(payload);
  // take y and transfer to server, (on server decode base64 string and append that to the video file)
}


  


  I have the MediaRecorder API Enabled via the safari and iOS settings.

  


  for example after processing and saving the data chunks for the video that has been captured. Weird is that the video is blank but when using ffprobe, all the info is correct. so i'm stuffed.

  


  Here is the Captured Video (Before conversion)

  


  after conversion, the new file is 0 bytes big

  


  Note :
this works fine on windows and linux.
issue is only with iOS or MacOS

  


  Not sure what i am doing long.

  


• ffmpeg - convert .exr image sequence (linear colorspace) to sRGB ?

  27 mai 2016, par Gambit2007

  I was just wondering - what would be the best way to convert an .exr sequence in a linear colorspace to an .mp4 file with an sRGB colorspace ?

  EDIT (more details)

  So the sequence i’m trying to convert is a 16bit .exr sequence with an RGB color space. I want to convert it to an H264/H265 .mp4
  My full command :

  ffmpeg -y -loglevel info -threads 0 -f lavfi -i aevalsrc=0
  -start_number 0011 -i input.%04d.exr -preset medium -vcodec libx265 -ar 48000 -acodec aac -shortest -strict experimental -sn -vsync 1 -pix_fmt yuv420p -b:v 30000000 -movflags +faststart -metadata title=’test.’ -x265-params
  hightier=0:pmode=1:wpp=1:tune=fastdecode:bitrate=30000:fps=60:colorprim=bt709:transfer=bt709:colormatrix=bt709:keyint=360:min-keyint=180:vbv-bufsize=30000:vbv-maxrate=30000:scenecut=0’

  Thanks !

• How Opensl es on android control the audio speed ?

  6 décembre 2013, par user1882379

  I use NDK+FFMPEG on android to decode an video file, and transfer the decoded pcm data to opensles for play audio .I register the opengles for the pcm format：

    SLDataFormat_PCM format_pcm;
  
      format_pcm.formatType = SL_DATAFORMAT_PCM;
  
      format_pcm.numChannels = channel;
  
      format_pcm.samplesPerSec = rate * 1000;
  
      format_pcm.bitsPerSample = SL_PCMSAMPLEFORMAT_FIXED_16;
  
      format_pcm.containerSize = SL_PCMSAMPLEFORMAT_FIXED_16;

  also I convert the decoded pcm data to AV_SAMPLE_FMT_S16 format using swr_convert(...), but the play audio speed is very fast. but if you use sdl , the play speed is normal. It would be sdl can control the play audio speed, but opensles can not. I do not know whether it is my mistake using opensles or opensles can not control audio speed(need application to control)？