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• FFmpeg decoding H264

  27 juillet 2020, par Steve McFarlin

  I am decoding a H264 stream using FFmpeg on the iPhone. I know the H264 stream is valid and the SPS/PPS are correct as VLC, Quicktime, Flash all decode the stream properly. The issue I am having on the iPhone is best shown by this picture.

  



  

  



  It is as if the motion vectors are being drawn. This picture was snapped while there was a lot of motion in the image. If the scene is static then there are dots in the corners. This always occurs with predictive frames. The blocky colors are also an issue.

  



  I have tried various build settings for FFmpeg such as turning off optimizations, asm, neon, and many other combinations. Nothing seems to alter the behavior of the decoder. I have also tried the Works with HTML, Love and Peace releases, and also the latest GIT sources. Is there maybe a setting I am missing, or maybe I have inadvertently enabled some debug setting in the decoder.

  



  Edit

  



  I am using sws_scale to convert the image to RGBA. I have tried various different pixel formats with the same results.

  



  sws_scale(convertCtx, (const uint8_t**)srcFrame->data, srcFrame->linesize, 0, codecCtx->height, dstFrame->data, dstFrame->linesize);


  



  I am using PIX_FMT_YUV420P as the source format when setting up my codec context.

  


• Audio problems when resizing video - moviepy

  17 août 2020, par Jordan

  I am resizing an mp4 video with this code (moviepy) :

  


  video_clip = VideoFileClip(url)
resized = video_clip.resize(width=720)
d = tempfile.mkdtemp()
video_path = os.path.join(d, 'output.mp4')
resized.write_videofile(video_path)


  


  The resized clip's audio works when I play it on my pc, but not on an iPhone. (The original clip's audio does work on my iPhone.)

  


  How can I fix this ?

  


  First image : Codec of resized video
  
Second image : Codec of original video

  


  


  


• Video Spec to fluent-FFMPEG settings

  26 novembre 2020, par Dean Van Greunen

  Not sure how to translate this video spec into fluent-FFmpeg. please assist.

  


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  This is the only video I have that plays on my iPhone, and I would like to reuse the video's encoding to allow other videos I have, to be converted into the same video format. resulting in having my other videos playable via iPhone and iOS. (this also happens to play on android, I would like the recommended encoding settings to also work on android)

  


  


  


  The video should also be streamable, I know theres a flag called +faststart but not sure how to use it.

  


  


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  here is my existing code

  


  function convertWebmToMp4File(input, output) {
  return new Promise(
    function (resolve, reject) {
  ffmpeg(input)
    .outputOptions([
      // Which settings should I put here, each on their own line/entry <-- Important plz read
      '-c:v libx264',
      '-pix_fmt yuv420p',
      '-profile:v baseline',
      '-level 3.0',
      '-crf 22',
      '-preset veryslow',
      '-vf scale=1280:-2',
      '-c:a aac',
      '-strict experimental',
      '-movflags +faststart',
      '-threads 0',
    ])
    .on("end", function () {
      resolve(true);
    })
    .on("error", function (err) {
      reject(err);
    })
    .saveToFile(output);
  });
}


  


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  TIA