Official Low GOP topic

stoney

thanks @stip and @stray. no visible damage so far.

Braamokiev

Thanks

@stonebat

Mihuel

@Braamokiev
settings=@stonebat ;-)

stoney

a simple tweak on @driftwood's settings ;)

cosimo_bullo

@ stonebat

"The h setting is 110Mbps, GOP3, AQ2, X1.5 on FBs and FL. The j setting is 110Mbps, GOP3, AQ3, X1.39 on FBs and FL. Both worked. The attached diagram is from the j setting. My gut feeling is that... the B-frame seems little too big. Or is that a typical behavior from AQ3 setting?"

I think it is typical of AQ3 and 4... and to my mind it's a good thing, those big b-frames, especially with non moving shots. Going to test your latest right now.

Mihuel

@stonebat
This is a graph from settings 110Mbits, GOP3, AQ3 and 1.37 on FBs anf Fl. This was simple shot of my girlfriend.

Braamokiev

Thanks to:

@Mihuel
@Stonebat
@Drifwood
@Stip
@Stray

And special thanks for Vitaliy!

I wait the best Setting 100mbs
;-)

driftwood

@Mihuel that doent look right, close streamparser reopen it and reopen that same file.

Mihuel

@driftwood
ok, I will try again , thanks for advise :)
P.S. I'm loading patch with 1.3 FBs and Fl right now .... so after this ....

Mihuel

@driftwood
Unfortunately stream parser several times showed the same thing. Maybe this card? Maybe this is my model of camera?
When I changed FBs and Fl to 1.3 ....
Hmmm, I think I'm doing something wrong. Anyone can help me ?

driftwood

@Mihuel download Stonebat's110 aq3 (setj) and load it and confirm a test matches his with streamparser

Mihuel

@drifwood
Ok, good idea ( better then mine ) ;)

cbrandin

When you lower frame limit it will end up raising the effective QP value to accommodate the lower bandwidth allocated to I frames and do other strange things. It's sort of like clipping - not really a good thing. Better to leave frame limit a little higher and lower AQ until it works. According to my calculations (based in part on your feedback), the ideal AQ value for GOP3 at 100Mb would be between 1 and 2. It seems that 2 works pretty well, 3 is clearly too high according to my latest math. With GOP1, you probably want to use AQ1.

Chris

stoney

Mihuel, is your girlfriend a human? :) The B-frames are abnormally high.

stoney

Orly? Ok. Back to AQ2~!~!

Mihuel

@stonebat
I think so, but you know how a woman is pregnant. Maybe it is a small elephant? ;)

Mihuel

@cbrandin
My jaw dropped to the floor and I already have :-)

stoney

@Mihuel never mind :)

@cbrandin
How do we verify the clipping?

What about GOP6 for 66Mbps and 88Mbps? AQ3 is the practical limit?

cbrandin

For GOP 6 I would estimate that you could go to AQ3 at any bitrate. With GOP1 I think it's AQ 1-2 no matter the bitrate. This is because AQ is automatically scaled according to bitrate.

Chris

driftwood

@cbrandin Have you worked out a stable-ish multiplier for AQ3 at 132mbps?

@stonebat elecard buffer analysis verifys the clipping and where it will fail.

edit: still testing my buffer theory.

stoney

Interesting. Thanks Chris.

So we have a matrix?

GOP12 AQ4 for 44, 66, 88Mbps
GOP6 AQ3 for 66, 88, 110Mbps
GOP3 AQ2 for 88, 110, 132Mbps
GOP1 AQ1 for 110, 132, 154Mbps

The lower GOP, the higher bitrate range, the lower AQ.

If AQ and multiplier are set for each mode, it's basically 2-d matrix of Mbps and GOP.

Mihuel

@stonebat
I tried GOP6, AQ3 and FL and FBs x1, 5 Charter does not withstood and the Stream Parser showed a few seconds I = P = B

stoney

@cbrandin would know a multiplier for the case.

Mihuel

ok, let's wait for the opinion of the wiser of us on this issue :-)

Mihuel

@cbrandin
Do you have any suggestions for 6GOP and 88 or 110Mbits? Unfortunately, my knowledge is, at least, enough so that I can handle myself.

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