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• Avconv/php priduces small gif files instead of video files (gifs are not allowed to upload)

  5 juin 2018, par Verode

  I allow users to upload the following video files :

  wmv|avi|mpg|mp4|mov|ogg|flv|3gp|3g2|m4v

  First of all my php scripts checks file extension. If it’s not one of the permitted extensions, the upload aborts.

  Second. The script checks mime type :

  $finfo = new finfo;
  
  $ftyp = $finfo->file($uploaded_file, FILEINFO_MIME_TYPE);
  
  
  
  $avava = array(
  
  "video/mp4",
  
  "video/x-ms-asf",
  
  "video/x-ms-wmv",
  
  "video/x-msvideo",
  
  "video/mpeg",
  
  "video/quicktime",
  
  "video/x-flv",
  
  "video/ogg",
  
  "video/3gpp",
  
  "video/3gpp2"
  
  );
  
  
  
  if (!in_array($ftyp, $avava)) {
  
  $file->error = $this->get_error_message('accept_file_types');
  
  return false;
  
  }

  The script also checks frame rate and dimensions etc.

  If everything is correct, the upload finishes and a cronjob every 10 minutes converts uploaded video files to mp4 and decrease dimensions if they are very large :

  $thuc = exec("avconv -y -i $fai -map 0 -c:v libx264 -crf 22 -c:a copy $fai2");
  
  
  
  if ($width > 800) {
  
  $thuc = exec("avconv -y -i $fai2 -filter:v scale=\"750:trunc(ow/a/2)*2\" -c:a copy $fai3");
  
  }

  When I access uploaded videos, most videos are fine, but a few videos are not working - video doesn’t start and doesn ; t show anything.

  All these files are small 45 bytes files that in text editor show the following lines :

  GIF89a  €  ÿÿÿ   !ù    ,       „    ;

  What is this ? Is it a gif file ? How people can upload gif files if they are not among allowed mime types ? Why these files are so small ? What causes this problem ? Php scripts allows upload gif files ? It’s a avconv problem ?

• aacdec : fix small comment, update decoder features comment

  31 octobre 2013, par Compn

  aacdec : fix small comment, update decoder features comment
  

  • [DH] libavcodec/aacdec.c

• Render a small video with low delay

  6 septembre 2024, par Makis Christou

  So I have a problem where I need to be able to render a (3s, 180 frame) video on demand and delay is important. I know that video rendering scales linearly but for some reason when using a threadpool in python (moviepy) it doesn't scale linearly at all and the CPU is underutilized. This is how I do it atm :

  


      start_time = time.time()  # Start timing the frame processing
    
    # Process frames in parallel using a persistent thread pool
    processed_frames = []
    with ThreadPoolExecutor(max_workers=num_threads) as executor:
        future_to_chunk = {executor.submit(process_frame_chunk, chunk, config): i for i, chunk in enumerate(frame_chunks)}
        for future in as_completed(future_to_chunk):
            processed_frames.extend(future.result())


    end_time = time.time()  # End timing the frame processing
    print(f"Frame processing took {end_time - start_time:.2f} seconds.")


  


  With 32 and 16 threads I get about the same time which is 2.7s and with 4 I get 3s. With 1 thread I get about 8.5s. How should I go about debugging this ? Is there overhead when starting the threads ?

  


  I tried the above and was expecting a linear speedup or close to it.