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• Piping images to FFMPEG using stdin causes artifacts

  15 avril 2021, par Michael Joseph Aubry

  I am sending images from puppeteer as a base64 buffer to stdin childProcess.stdin.write(frame); The images are piped one frame at a time inside a loop.

  


  This works well except I am getting weird artifacts and frames flickering — here is an example https://s3.us-west-2.amazonaws.com/storycreator.v2.rendered/cknhtqu2e0016niuuqmtu5u7b?t=0

  


  I've found when hardcoding a delay between each frames being piped that the artifacts/flickering is reduced.

  


  await new Promise((resolve) => {
  setTimeout(() => {
    resolve("done");
  }, 3000);
});

// then after 3s pipe the buffer
childProcess.stdin.write(frame);


  


  Another solution I found to solve the issue is to encode it as a .h264 then convert it to a .mp4. The problem is the video timing is drastically off.

  


  // The ffmpeg command
const childProcess = spawn(ffmpeg, [
  "-y",
  "-f",
  "image2pipe",
  "-pix_fmt",
  "argb",
  "-s",
  "1920x1080",
  "-r",
  `${fps ? `${fps}` : 100}`,
  "-i",
  "async:cache:pipe:0",
  "-an",
  "-vcodec",
  "libx264",
  "-pix_fmt",
  "yuv420p",
  "-r",
  `${fps ? `${fps}` : 100}`,
  "-y",
  `/tmp/${renderId}.mp4` // using .h264 seems to solve flicker but causes a weird framerate
]);


  


• FFmpeg image2pipe write buffer wait until done

  20 décembre 2020, par Michael Joseph Aubry

  I'm extracting frames from an external source and passing it in as a buffer to FFMPEG using image2pipe and -i -

  


  const childProcess = spawn(ffmpeg, [
  "-y",
  "-f",
  "image2pipe",
  "-i",
  "-",
  "-vcodec",
  "libx264",
  "-pix_fmt",
  "yuv420p",
  output
]);


  


  Then I have a loop that does the job.

  


  for (let i = 0; i < 250; i++) {
  // ...await
}


  


  Inside the promise

  


  // ... do the job to get buffer

childProcess.stdin.write(frame); // frame === buffer

// frame done
resolve("success!");


  


  The problem is in some videos the frames jump and is janky. This is because FFmpeg is not fully done writing to the file before moving onto the next frame.

  


  Is there a way to write a buffer to a file through FFmpeg and make sure the frame is done writing before moving on ?

  


  Some more information

  


  Here is the source file https://s3.us-west-2.amazonaws.com/storycreator.v2.uploads/ckigi4kro00160vlfjmt74afp

  


  Here is the rendered file https://s3.us-west-2.amazonaws.com/storycreator.testing/607715f0-3ab9-11eb-a139-3bb84618c6c5.mp4?t=1607585343922

  


  Here are logs

  


  2020-12-10T07:28:48.942Z    0ae0c435-54d3-416f-9d1a-8ddf595a7e83    INFO    frame=  130 fps= 16 q=-1.0 Lsize=      83kB time=00:00:05.08 bitrate= 133.6kbits/s speed=0.641x    video:80kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.928688%


  


  2020-12-10T07:28:48.942Z    0ae0c435-54d3-416f-9d1a-8ddf595a7e83    INFO    [libx264 @ 0x640d6c0] frame I:1     Avg QP:15.47  size: 68227[libx264 @ 0x640d6c0] frame P:33    Avg QP:15.07  size:   246[libx264 @ 0x640d6c0] frame B:96    Avg QP:18.75  size:    56[libx264 @ 0x640d6c0] consecutive B-frames:  1.5%  0.0%  0.0% 98.5%


  


  2020-12-10T07:28:48.943Z    0ae0c435-54d3-416f-9d1a-8ddf595a7e83    INFO    [libx264 @ 0x640d6c0] mb I  I16..4: 24.6% 60.5% 14.9%[libx264 @ 0x640d6c0] mb P  I16..4:  0.0%  0.2%  0.0%  P16..4:  0.8%  0.0%  0.0%  0.0%  0.0%    skip:98.9%[libx264 @ 0x640d6c0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  0.3%  0.0%  0.0%  direct: 0.0%  skip:99.7%  L0:26.7% L1:73.3% BI: 0.0%[libx264 @ 0x640d6c0] 8x8 transform intra:62.0% inter:83.6%[libx264 @ 0x640d6c0] coded y,uvDC,uvAC intra: 49.2% 44.3% 32.1% inter: 0.0% 0.2% 0.0%[libx264 @ 0x640d6c0] i16 v,h,dc,p: 53% 38%  7%  2%[libx264 @ 0x640d6c0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 26% 24% 29%  3%  3%  3%  5%  3%  4%[libx264 @ 0x640d6c0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 37% 26% 14%  3%  4%  5%  4%  4%  3%[libx264 @ 0x640d6c0] i8c dc,h,v,p: 57% 27% 13%  3%[libx264 @ 0x640d6c0] Weighted P-Frames: Y:0.0% UV:0.0%[libx264 @ 0x640d6c0] ref P L0: 95.1%  1.2%  3.1%  0.6%[libx264 @ 0x640d6c0] ref B L0: 48.1% 51.3%  0.7%[libx264 @ 0x640d6c0] ref B L1: 97.3%  2.7%[libx264 @ 0x640d6c0] kb/s:125.75


  


  2020-12-10T07:28:48.944Z    0ae0c435-54d3-416f-9d1a-8ddf595a7e83    INFO    [cache @ 0x5f57940] Statistics, cache hits:0 cache misses:3551


  


• Flask and moviepy

  23 mars 2021, par Yoldash Reklamov

  Please help me figure out the correct logic for constructing a flask project with Moviepy.

  


  The task is to combine several audio files and several video files into one file.
With the help of the Moviepy and the method of concatenate in it, I manage to do all this.
But I just can't figure out how to do the following thing, there is :

  


  Audio1 (permanent), Audio2 (there will always be different files, selected by the user from the database using the drop-down menu on the site), Audio3 (permanent).
It's the same with video files.

  


  I am building a project on Flask, I am thinking of adding audio and video files not using the BLOB method, but by adding links to the database.

  


  I just can't figure out how to implement this system so that the user would go to the site, choose Audio2 from the list(for example i have 50 random audio files in drop down meny Audio1-Audio50) and somehow take it to AudioFileClip("Audio5.wav") or AudioFileClip("Audio8.wav")

  


  I just can't figure it out.
Thank you in advance !