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Old 31st October 2005, 19:41   #21  |  Link
akupenguin
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Quote:
Originally Posted by Manao
But only if the quantizer gets really low. And low entries means higher bitrates --> high quantizers at same bitrates, so in the overall it compensates one another ( well, almost at least )
The precision needed (and thus the version of quantization function used) depends on the entries in the CQM, not on the QP.
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Old 31st October 2005, 19:41   #22  |  Link
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Quote:
Originally Posted by Manao
But only if the quantizer gets really low. And low entries means higher bitrates --> high quantizers at same bitrates, so in the overall it compensates one another ( well, almost at least )
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Quote:
Originally Posted by Christian Heine
MMXEXT32 qaunt2x2dc can be used if cqm >= 2.
MMXEXT32 qaunt4x4dc can be used if cqm >= 4.
MMXEXT32 quant4x4 can always be used.
MMXEXT32 qaunt8x8 can be used if cqm >= 2.

MMXEXT16 qaunt2x2dc can be used if cqm >= 4.
MMXEXT16 qaunt4x4dc can be used if cqm >= 4.
MMXEXT16 quant4x4 can be used if cqm >= 4.
MMXEXT16 quant8x8 can be used if cqm >= 7.

MMX15 qaunt2x2dc can be used if cqm >= 7.
MMX15 qaunt4x4dc can be used if cqm >= 7.
MMX15 quant4x4 can be used if cqm >= 7.
MMX15 quant8x8 can be used if cqm >= 11.
And Sharktooth Matrix contains entries < 7, so the faster MMX15 routines are not used.
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Old 31st October 2005, 19:46   #23  |  Link
Manao
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Then I'm completely wrong. Strange, I would have thought it was working as the decoding process.

But then, nothing prevents you from multiplying all values by three in Sharktooth matrices , and adapting deblocking accordingly
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Old 31st October 2005, 19:54   #24  |  Link
akupenguin
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Quote:
Originally Posted by Manao
But then, nothing prevents you from multiplying all values by three in Sharktooth matrices, and adapting deblocking accordingly
That kills RD, since the lambdas depend only on QP, not CQM. Also confuses MB skip detection.
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Old 31st October 2005, 20:11   #25  |  Link
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Your remark could apply to any CQM ( edit : which differs a bit too much from the flat one ). Perhaps lambda / skip decision could be made according to matrices coefficients ( normalizing thresholds / lambdas by the sum of the coefficients or something alike )
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Old 3rd December 2005, 15:33   #26  |  Link
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Is this CQM suitable for anime? and also suitable for encoding with SAR?
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Old 3rd December 2005, 16:12   #27  |  Link
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Quote:
Originally Posted by jackiehcs
and also suitable for encoding with SAR?
sure, cqm has nothing to do with sar
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Old 3rd December 2005, 16:28   #28  |  Link
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Actually, you can take into account the SAR by tweaking the CQM, because horizontal and vertical frequencies won't behave in the same way. So theorically, CQM makes SAR usage even more suitable. Theorically only though ( creating the proper matrix is another matter, quite complicated )
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Old 3rd December 2005, 19:19   #29  |  Link
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Default quantization or flat matrices should be more appropriate for anime.
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Old 30th December 2005, 03:07   #30  |  Link
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I'm doing 720p encodes of captured HDTV material. I'm using the Sharktooth full x264 builds and x264-MeGUI using the HQ-Slow preset at about 6Mbps. Is this matrix something that would benefit me? Or is there something else I should possibly be looking at? I don't have any issues with my encodes, but am always on the lookout for improvements.
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Old 30th December 2005, 03:48   #31  |  Link
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Well, the general rule is to use low bitrate matrices with HD sources but 6mbp is relatively high for h.264.
So yes, it may be worth a try. Post your findings though
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Old 30th December 2005, 03:54   #32  |  Link
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Well, honestly, 6Mbps was just a guess, I didn't want to post a "what is a good bitrate for x264 at 720p" but since you brought it up...what might a good starting point be? The sources are all typical movies, sources are 1920x1080@29.970. I resize (and deinterlace if necessary) to 720p@23.976fps. I honestly have no idea where to begin for bitrates for these HD encodes.
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Old 30th December 2005, 04:25   #33  |  Link
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1500kbps is a good starting point for sources with good compressibility at 1280x720 @ 23.976fps.
Higher bitrates are needed if noise or grain is present or if compressibility is lower (action movies for example).
Obviosly that's subjective... but artifacts on HD stuff are much less visible.
Use a quality preset (like HQ-Slower for MeGUI) or if encoding time is a problem just rise the bitrate and use a faster preset.

Last edited by Sharktooth; 30th December 2005 at 04:27.
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Old 30th December 2005, 05:15   #34  |  Link
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Wow

I didn't realize that I could get away with such a low bitrate for HD content! Well, that'll be good, I tried the bits/pixel calculator on the bitrate tab of the newest GKnot and it showed I'd need a minimum of 3500Kbps to get the 0.190bits/pixel. I guess it's a bit outdated for x264? Either way, I'm stoked, now how about for DVD->x264 (my Emily Rose DVD is 720x288@23.976)?
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Old 30th December 2005, 12:53   #35  |  Link
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Quote:
Originally Posted by ChrisBensch
minimum of 3500Kbps to get the 0.190bits/pixel.
In general, the smaller resolution, the higher bits/pixel needed, for by downsizing you get more detail per compressed block. At least for clean sources.
Against this rule can go the fact, that with downsizing from HD to SD you can accidentally get rid of some film grain, which increases the compressibility.

As always it depends on source. I personally do not see any special reason to squeeze a full length movie 1280x??? smaller than 1 DVD size.

For instance one of my test:
wmv3 6.5Mbps 1440x820ANA -->Quite heavy denoising and deblocking --> 1280x544 --> x264 4200kbps
IIRC the avg quant was some around/below 20 with flat (not sure) w/o deblocking filter.

Last edited by redfordxx; 30th December 2005 at 13:06.
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Old 30th December 2005, 13:04   #36  |  Link
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Sharktooth,
you have obviously a lot of testing with your matrix behind.
Do you have any experience with your matrix, on which quantizer (and below) the blocking disappears (or other artifacts --- ringing, nonsharpness). With the filter deblock off if you know --- I have to encode the HD with the filter of, otherwise the playback eats too much CPU.
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Old 30th December 2005, 18:56   #37  |  Link
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It really depends on the source.
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Old 17th May 2006, 02:44   #38  |  Link
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Sharktooth, are you developing anymore AVC quantization matrices, like you said in your first post? I don't mean to be nosy or anything, I just use your matrix alot and I am curious if there is anything in development.
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Old 17th May 2006, 03:22   #39  |  Link
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Yes, im still experimenting with matrices. Im trying to fine tune HR and LR is in preliminary testing phase... but that's not as easy as for mpeg4 ASP
however i think i'll rename them... both.
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Old 17th May 2006, 03:35   #40  |  Link
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Great! I can't wait to test these babies out!
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