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• How to run ffmpeg command from the client side ?

  12 janvier 2017, par Debraj Biswas

  I am trying to make an online examination portal. When students start the exam, their webcam will start automatically and record the stream live and store in the server. Invigilators will either watch the students live or they can watch the saved live streams later.

  After many research on various technologies I came across this link. It uses Node JS with websockets and ffmpeg. I ran the ffmpeg command and it streamed the live video successfully.

  But the problem is, in order to live stream, the students have to have ffmpeg installed in their system and they should run the command directly from the terminal. So how can I change this ? The students will live stream from their browser, because this is a web portal. If we put this command in a PHP script, then the command will run at the server side. But client side command should run in this case. How can I run command from client side ?

  Any suggestions will be helpful.

• FFmpeg UHD encoding (piping to x265)

  15 décembre 2016, par TEB

  Update based on the good answers :

  Source :
  Prores HQ 4:2:2 10bit
  4kp25
  REC:2020

  Heres my syntax now :

  ffmpeg -pix_fmt yuv422p10 -i JUNGLES_PLUTO_UHD_HDR_HLG.mov -pix_fmt yuv420p10 -f yuv4mpegpipe - | x265 --y4m - --input-res 3840x2160 --fps 25 --preset veryslow --b-adapt 2 --ref 4 --no-open-gop --keyint 50 --min-keyint 50 --no-scenecut --profile main --level-idc 5 --no-high-tier --sar 1:1 --colorprim bt709 --transfer bt709 --colormatrix bt709 --bframes 3 --hrd --vbv-bufsize 25000 --bitrate 25000 --vbv-maxrate 25000 --aud --no-info --b-pyramid -o test.h265
  
  
  
  output: Option pixel_format not found. 

  Target : (non-hdr UHD STB)

  hevc.file 
  
  rec:709

  • Question 1 : How does one pipe correctly from ffmpeg to x265 ?
  • Question 2 : How can one make sure the cpus are all taxed ? I have
    16vcores, but im getting like 2-3% usage on all
  • Question 3 : Any suggestions on the parameters to increase the
    quality ?

  • Question 4 : Since the content is BT2020, but my target device is not currently able to display/render BT2020, but BT709.. how would i change the syntax to enable this in the best way..(downscale it)
    Would :

    —colorprim bt2020 —transfer bt2020 —colormatrix bt709

  be correct ?

• PHP & FFMPEG running on AWS worker finishes 2/3 of operations properly then fails

  1er novembre 2016, par jreikes

  I have a PHP application (using the Laravel 5.3 framework) that performs several operations on video after upload (transcoding, thumbnail generation, etc.). Everything works great locally. But it works a little differently in AWS and that seems to be causing problems.

  In AWS, uploads go to S3, then the EC2 workers pull those files into a local temp folder, perform about 8 operations with FFMPEG via shell_exec() (storing the results into the temp folder), then transfer the finished files back to S3. The first 6 operations (which are related to transcoding) finish properly. The last 2 operations (which create thumbnails) usually fail (about 1/10 times I test it, the whole thing works — inexplicably).

  I have a WorkingCopy class to give me relative and fully qualified paths, as needed, and to automatically delete temp files after completion. I also have a ColdStroage class to handle the S3 data. All 8 FFMPEG operations are structured the same way using this class.

  In trying to troubleshoot the problem, I tried running the FFMPEG thumbnail generation via SSH and found that it was failing. It’s this error :

  [image2 @ 0x2e43320] Could not open file : path/filename.png
  
  av_interleaved_write_frame(): Input/output error

  https://trac.ffmpeg.org/wiki/Errors explains that this happens when the destination folder doesn’t exist. But, while testing via SSH, I was getting this error even when the destination folder existed. If I CHMOD 777 the destination folder, the operation completes successfully via SSH.

  Seems simple enough, right ? Thing is, my WorkingCopy class creates the temp folder with mkdir($folderName, 0777, true) — so the folders should already be 777. They actually don’t appear to be truly 777 when I check them via SSH, but still — why do the first 6 operations work ? Just to be sure this wasn’t the issue, I added a CHMOD to my script just before thumbnail creation and it still failed.

  Here’s one more weird thing... If I comment out those last two FFMPEG operations, then transcoding (the preceding operation) fails. Based on that, I thought maybe the file system needs a moment to finish writing the FFMPEG output before proceeding, so I added sleep(5) before the end of the script. It still doesn’t work.

  I can’t share the full code publicly, but here’s the general format of the FFMPEG calls

  $pathForLargeThumbnails = 'large_thumbnails';
  
  
  
  $thumbnailLargeWorkingCopy = new WorkingCopy($pathForLargeThumbnails);
  
  $thumbnailLarge = new ColdStorage($pathForLargeThumbnails);
  
  
  
  $shellErrors .= shell_exec(
  
        "/usr/local/bin/ffmpeg/ffmpeg"
  
      . " -loglevel error"
  
      . " -i " . "\"" . $originalVideoStream->fullPath . "\""
  
      . " -y"
  
      . " -vf thumbnail -frames:v 1"
  
      . " \"" . $thumbnailLargeWorkingCopy->fullPath . "\""
  
  );
  
  
  
  $thumbnailLarge->put($thumbnailLargeWorkingCopy->get());

  Anyone know why this succeeds 6 times and then fails twice at the end ?