Ducksonfilm
Level 1 (0 points)

Q: CABAC selection results in CAVLC in 4.2

Is anyone else having trouble encoding h.264 with CABAC selected? I get a video file made with CAVLC?

 

I am encoding a prores master file (1440 x 1080 - its from HDV orginally)

Take the Apple preset "HD 1080p" from the "Video Sharing Services" group. Note the Video settings show CABAC for Entropy mode.

Start batch and encode (so no preset editing or settings change - just the standard Apple issue)

 

Analysing the transcoded file in VideoSpec or Media Inspector shows the file has been encoded with CAVLC rather than CABAC

 

Encode using the same preset but with a change of Entropy mode to CAVLC and you get a file that is identical to the first effort.

 

Furthermore...

I have the x264 codec installed and using this in the same preset results in a CABAC encoded movie. It also encodes about 30% more quickly.

 

Something not feeling right!

Thoughts?

(Yosemite 10.10.3, Mid2010 Mac Pro 16GB 2.8GHz Quad-Core Intel Xeon)

Final Cut Pro X, OS X Yosemite (10.10.3), Mac Pro 2.8GHz quad, 16GB,

Posted on May 22, 2015 3:56 AM

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Ducksonfilm

Q: CABAC selection results in CAVLC in 4.2

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  • by Russ H,

    Russ H Russ H May 22, 2015 4:39 AM in response to Ducksonfilm
    Level 7 (21,905 points)
    Quicktime
    May 22, 2015 4:39 AM in response to Ducksonfilm

    I Was just testing something similar for someone else and didn't encounter this. But I was working with square pixels so I'll try with HDV

    when I can get to my computer. I believe X.264 is CABAC by default. Wonder whether one job was single pass and the other multi pass to explain the 30% difference in times.

     

    RUss

  • by Russ H,Helpful

    Russ H Russ H May 22, 2015 6:58 AM in response to Russ H
    Level 7 (21,905 points)
    Quicktime
    May 22, 2015 6:58 AM in response to Russ H

    Was able to run two tests on a 1440x1080 HDV clip:

     

    1) the Broadband High preset gives me an mp4 file that MediaInfo reports as CABAC entropy;

     

    2) the HD 1080 preset gives me a .mov file that is also reported as CABAC.

     

    No sure what to suggest. Maybe creating a custom setting using CABAC to see if the entropy setting sticks?

     

    Russ

  • by Ducksonfilm,

    Ducksonfilm Ducksonfilm May 24, 2015 6:29 AM in response to Russ H
    Level 1 (0 points)
    May 24, 2015 6:29 AM in response to Russ H

    Thanks for those tests, Russ.

    I think I've got some work to do to get to the bottom of this!

     

    I'm keeping the question open in case others have suggestions.