Author Topic: Main/High Profile H.264 encoding  (Read 6149 times)

shanel

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Main/High Profile H.264 encoding
« on: October 03, 2012, 04:35:53 AM »
For Canon models before the 5d3, the video encoding uses only the Baseline Profile of H.264 which is significantly less efficient (=lower quality for the bitrate). There is a useful visual comparison about a third of the way down the page at http://keyj.emphy.de/video-encoder-comparison/

Can ML implement Main or High Profile H.264 on any of the Digic 4 models?

1%

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Re: Main/High Profile H.264 encoding
« Reply #1 on: October 03, 2012, 05:04:11 AM »
I'd settle for 5.2 and QPs below 10. 5DIII can do 7? Don't know how much the "profile" really counts.
I've tried to change it but can't find correct location/values. All I can do is max out the quality and lower compression.

Someone should do a comparison between 100Mbps/T3i (Q87) crop and 5dIII. Mjpeg beats both but right now its small and on 600D tethered.

shanel

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Re: Main/High Profile H.264 encoding
« Reply #2 on: October 03, 2012, 08:31:21 AM »
Hi 1%,

- I'm not sure what you are referring to when you say 5.2 and 7?

- On QP, ML already has control for QP via Qscale.

- At high bitrates, profile can be a bigger driver of quality than just bitrate. Baseline profile offers only a limited set of the technologies that make H.264 powerful (No B-Frames, no CABAC, etc.) On a encoded-quality-per-bitrate basis, the 5d3 will blow older cameras out of the water as a result.

Marvin

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Re: Main/High Profile H.264 encoding
« Reply #3 on: October 03, 2012, 10:10:45 AM »
Hi 1%,

- I'm not sure what you are referring to when you say 5.2 and 7?

- On QP, ML already has control for QP via Qscale.

- At high bitrates, profile can be a bigger driver of quality than just bitrate. Baseline profile offers only a limited set of the technologies that make H.264 powerful (No B-Frames, no CABAC, etc.) On a encoded-quality-per-bitrate basis, the 5d3 will blow older cameras out of the water as a result.

Although 5D3 uses High Profile, Canon seems intentionally crippled the quality, CABAC is turned off by default (see the bitrate thread). Without ML, 5D3 won't offer many visible advantages on codec/compression.
Film is truth 24 frames per second.

shanel

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Re: Main/High Profile H.264 encoding
« Reply #4 on: October 03, 2012, 12:22:56 PM »
1% - thanks for the heads up; I just read through that thread.
Shame about CABAC but is that simply a parameter that a future ML implementation can adjust (=fix)?
I'd say High Profile without CABAC would still improve PSNR somewhat vs. Baseline though, if B-frames are used properly.

So no luck switching a Digic 4 model to High Profile (with our without CABAC)?

1%

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Re: Main/High Profile H.264 encoding
« Reply #5 on: October 03, 2012, 04:59:42 PM »
No luck. I tried. SPS_PPS is with JPCORE_OPMR3 and the number doesn't correspond to anything for me. I'd have to see what 5dIII does... except it has a different encoder.

Qscale controls SliceQPD which controls real QP per frame in video. If you look(ed) at bit rate I/P thread you see the results, especially in raw/grading.

B frames would probably get held in the buffer and just compressed harder. Its not 1:1 what a PC H.264 implementation would do. I.e. shorter gop actually helps rather than a longer one.

5.2 - max profile level from wikipedia, we have 5.1 only on digic IV
7 - frame QP in file. My max is 10 on 600D. Read somewhere 5d3 max is 7.

That's  why I wonder how they would stack up once you take resizing out of the picture. 5DIII encoder is crippleware, atm.  BMCC eats it at 1/2 the price. If 600D is even 75% as good (as 5d3), there is a serious problem. Besides SSD, 5DIII hardware/sensor should be superior to both of those cameras.


hjfilmspeed

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Re: Main/High Profile H.264 encoding
« Reply #6 on: October 23, 2012, 04:18:32 AM »
i keep seeing all these benchmark tests and canon is for sure limiting the quality of of video from the 5d3. Unless im not understanding the tests correctly the 5d3 has some decent power. decent enought to resolve better anyways =( oh well. lovin the alpha 2 though!