[FFmpeg-user] ProRes XQ 12-bit support

Elliott Balsley elliottbalsley at gmail.com
Fri Apr 20 03:34:14 EEST 2018

> Or more likely a marketing issue.

I think maybe what is happening is that since Resolve processes images in a 32-bit space, and it’s not convenient to fit 12-bit words, it pads each word to 16-bits so then it fits better.

Anyway, on this topic, is there a way to definitely read the bit depth used to encode a file?  According to Arri, the ProRes 444 clips created by the Alexa camera are written using 12 bits.  This is documented in many places on the web, including this forum post.  But somehow, ffmpeg identifies these files as yuv444p10le and the image looks correct.
https://www.arri.com/forum/viewtopic.php?t=127&p=266 <https://www.arri.com/forum/viewtopic.php?t=127&p=266>

If the image were truly 12-bit, and ffmpeg decodes it as 10-bit, I expect the image would look wrong.

According to the MediaInfo developer, there is no way to definitely read the encoded bit depth, and therefore he has removed that info from the MediaInfo tool.
https://sourceforge.net/p/mediainfo/discussion/297610/thread/4bc21b18/#cd3a/2395/563e/1fec <https://sourceforge.net/p/mediainfo/discussion/297610/thread/4bc21b18/#cd3a/2395/563e/1fec>
 <https://sourceforge.net/p/mediainfo/discussion/297610/thread/4bc21b18/#cd3a/2395/563e/1fec> <https://sourceforge.net/p/mediainfo/discussion/297610/thread/4bc21b18/#cd3a/2395/563e/1fec> <https://sourceforge.net/p/mediainfo/discussion/297610/thread/4bc21b18/#cd3a/2395/563e/1fec>

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