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• avformat/dashdec : Fix crash on invalid input/ENOMEM, fix leak

  20 septembre 2022, par Andreas Rheinhardt

  avformat/dashdec : Fix crash on invalid input/ENOMEM, fix leak
  In case a SupplementalProperty node exists in an adaptationset,
  
  it is searched for a "schemeIdUri" property via xmlGetProp().
  
  Whatever xmlGetProp() returns is then compared via av_strcasecmp()
  
  to a string literal. xmlGetProp() can return NULL, namely in case
  
  no "schemeIdUri" exists and (given that this string is allocated)
  
  presumably also on allocation failure. No check for NULL is done,
  
  so this may crash.
  Furthermore, the string returned by xmlGetProp() needs to be freed
  
  with xmlFree(), but this is not done either.
  This commit fixes both of these issues ; they existed since this code
  
  has been added in 10d008f0fd9e713e290f626300d66382ad786c49.
  This has been found while investigating ticket #9697. The continuous
  
  leaks might very well be the reason behind the observed slowdown.
  Reviewed-by : Steven Liu <lingjiujianke@gmail.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavformat/dashdec.c

• Is it possible to fetch some key-frames of a video by using the HTTP Range header

  9 décembre 2020, par pvd

  I've read the SO problem , and it seems not applying to my specific case.

  


  Is it possible to fetch some key-frames of a video from web server by the HTTP Range header ? For example, for a 30 seconds duration video, we'd like to analysis the I-frame around 00:00:02, 00:00:15, 00:00:28.

  


  I need to analysis the videos from internal web server to detect if there's specific watermarks in it and some other analysis.

  


  Since the first I-frame might be invalid sometimes(Logo for example), we were planning to extract the I-frame from the 00:00:02, the middle I-frame, and the last 2nd second I-frame.

  


  For example, for a 30 seconds duration video, we'd like to analysis the I-frame around 00:00:02, 00:00:15, 00:00:28.

  


  We could make it works while download the whole video, since most of the data we downloaded from the server are not being used. I was wondering if maybe we could only use the HTTP Range header to download partial data and analysis it ?

  


• How to correct crop image using FFMPEG&XILINX

  17 mai 2023, par Dmytro

  I use AWS vt1 with Xilinx SDK and FFMPEG. All from the AWS box with pre-built SDK and so on.
I need to extract frames from fullHD but scale it to 480p
I stuck with it. Could someone help with the correct options ?

  


  I have this Python-based code :

  


  
        # If the video is greater than 480p, resize the frames to 480p
        if height > 480:
            command = [
                ffmpeg_path,
                '-c:v', 'mpsoc_vcu_h264',
                '-i', temp_video,
                '-filter_complex',
                'multiscale_xma=outputs=1: out_1_width=848: out_1_height=480: out_1_rate=half:[b]; [b]xvbm_convert[b1]',
                '-pix_fmt', 'yuv420p',
                '-ss', str(median_time),
                '-map', '[b1]',
                '-vframes', '1',
                '-q:v', '2',
                '-f', 'image2pipe',
                '-vcodec', 'mjpeg',
                '-y', '-'
            ]
        else:  # Preserve the original resolution
            command = [
                ffmpeg_path,
                '-c:v', 'mpsoc_vcu_h264',
                '-i', temp_video,
                '-vf', 'xvbm_convert',
                '-pix_fmt', 'yuv420p',
                '-ss', str(median_time),
                '-vframes', '1',
                '-q:v', '2',
                '-f', 'image2pipe',
                '-vcodec', 'mjpeg',
                '-y', '-'
            ]
            output = subprocess.run(command, capture_output=True)
            frame = output.stdout



  


  The second option with '-vf', 'xvbm_convert', work perfectly.
But the issue with the first.