• Compression Techniques

  ProRes 422 HQ to H264 – bitrate problem

  Posted by Andrzej Wozniak on April 10, 2013 at 11:53 am

  Hi,
  I have an animated cartoon digitalized from PAL DIGIBETA tape onto the mov file with the ProRes 422HQ codec.
  It is an old cartoon. Here is an example episode: https://www.youtube.com/watch?v=DCWHh_mZogE

  The initial video bitrate in prores file is variable @24.5 Mbps. I need to recompess the file into h264 with the bitrate of 6-8 Mbps.
  I used Mpegstreamclip, Handbreak, FFmpeg and Compressor but I can’t get the required bitrate.

  In Handbreak, even if I choose constant quality @RF:0 (lossless), the output file is around 2 Mbps.
  In mpegstreamclip I select H.264 Multi-pass restricted to 8 Mbps and optimized for download, I get the same output bitrate of around 2 Mbps. Same with the Compresor 4. I have also tried FFMpeg for Mac, with the Force Constant Bitrate option enabled and the output was the same as above.

  Would anyone here have a solution to this problem?

  All the best!

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  Andrzej Wozniak replied 13 years, 4 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Craig Seeman

  April 13, 2013 at 12:59 am

  My hunch is the encoders are just being very efficient. There’s a lot of flat areas which means the encoder can throw out a lot of data without much loss in quality. You could try way overshooting the target in the settings but even that might not work.

  You might as well include Telestream Episode and Sorenson Squeeze in the test although I have a hunch the results won’t be that much different.

  There may be some encoders that allow you to pad data to hit a target bit rate but that doesn’t really get you anything quality wise as it’s just padding. Episode can do that with Transport Streams for example.
• 

  Andrzej Wozniak

  April 13, 2013 at 1:00 pm

  Hi Craig,
  I had the same feeling, that the problem is caused by the low complexity of the video. Telestream Episode and Sorenson Squeeze are quite expensive pieces of software so this would be my last choice. The problem is that the VOD platform will not accept video with the lower bitrate than expected. Since the expected format is a h264 video wrapped in the mov container, I am not sure if there is a way to create such a file with a constant bitrate like with the transport stream. I am fairly new to this, please excuse if I am making not much sense here 🙂 As I have mentioned, in Handbreak I even tried loosless settings which normally produces huge files. In my case it just doesn’t work.

  So I assume the question is now – how to produce a h264 video in a mov container with some sort of “forced” constant bitrate?

  Kind regards
  Andrzej

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