Decode Movie Image & Play Movie only 8 Bit

Steps causing the bug to occur

  1. Generate a prores 4444 12 bit video file
  2. Video output information of Decode Movie Image & Play Movie show 8 bit not 12 bit or 16 bit

Other notes

  • Vuo version: 1.2.3
  • macOS version: OS X 10.9
  • How severely does this bug affect you? It prevents me from completing a specific task with Vuo.

Screen Shot 2016-08-01 at 11.34.08 pm.png

Information about ProRes AVFoundation decoding:
AVAssetReaderTrackOutput | Apple Developer Documentation  

We’ll investigate.

1 Like

I noticed this became a problem for me when using feedback image with 4444 prores with alpha channel. The 8 bit values caused banding within the feedback image (even when feedback is set to 16 bit). The content that is 4444 prores was captured at 10bit with a shogun recorder out of a GH4 (so it is real 10 bit at least). I can post an example soon.

I also completed a test with greyscale gradient generator within Vuo with feedback and there wasn’t any banding.

UPDATE: After more research the banding may not be due to 8 bit Video file playback. I will investigate further.

It would be good if the decode movie nodes could have an 8 or 16 bit toggle.  

Yeah, we do plan to provide an option to switch between 8 or 16 bpc — or “automatic”, the default.

In preliminary testing (thanks for the link to documentation you emailed), AVFoundation was only able to provide the 16bpc image on CPU, not as an OpenGL texture, so we expect 8bpc to have noticeably better performance/framerates. The toggle would allow the composition author to choose their quality/performance tradeoff.

Totally agree @jstrecker! 16 bit would only be used (for me anyway) for high quality offline rendering of video or effects.

wow, most unfortunate AVF.

@jstrecker maybe place a warning about 8 v’s 16 bit performance tradeoff in the Decode Movie Image or Play Movie info text?

@alexmitchellmus — Will do.

@krezrock @jstrecker for highspeed video decoding HAP codec is really the only way to do that currently. Prores isn’t really designed for realtime video systems.

@krezrock if you want HAP check out my FR.

HAP also allows alpha channel as well, and the video data is decoded completely on the GPU! :-)  

@krezrock just noticed you already voted for HAP! Awesome!

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@jstrecker Is HAP built on QT or AVF?  

@krezrock HAP has both a QT and AVF plugin. However QT (QuickTime) is EOL. HAP is also MIT style open source. And super fast!