Bit rate investigation

Started by Audionut, July 19, 2012, 04:54:03 AM

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1%

Try recording wav and see how it matches up. I'll figure out how to patch all at some point.

Leon

@ N / A :  I can't think why you would be getting rolling shadows with tungsten lighting.  Are you sure you don mean fluorescent / energy saving?  A tungsten light doesn't cool down sufficiently between the phases of the alternating current to cause a visible variation in light level, whereas fluorescent does.  In any case the frame rate shouldn't matter; it is the shutter speed that can cause problems, so try a shutter speed of 1/60 (for USA and 60Hz supplies) regardless of frame rate.

mike.charal

Rush - Yeah, I had the sound disabled and was recording in 24p.

1% - Thanks for the advice. I was able to fool around with and get a better handle on the min/max bitrate settings and I raised the buffer warning level much higher and it's working pretty flawlessly, no more shooting down to slice 127 then back up to 87. Suffice it to say, I'm very excited. I've seen a lot of comparisons of shots straight out of the camera, where the differences may seem subtle, but yesterday I did a test grade on a 90 mbps medium complexity image and I noticed when I applied levels and squeezed everything in, the image remained amazingly smooth; very few (if any) compression artifacts or macroblocks were revealed. Truly amazing, thanks again!

1%

You're welcome. V 2.0 will hopefully be faster/better.

You can see it being made here: https://bitbucket.org/OtherOnePercent/tragic-lantern-2.0

So far I got most stuff in except for bit rate. xxGB limit will be selectable. Hopefully get it all done in a couple of months. Right now its tax time.

driftwood

Hi 1%
Buffer settings are generally around .70 of the bitrate settings in h264. Is there a way to set buffer bitrate yet?

Whilst on the subject of the latest encoder settings for ML - Do you have scaling tables ? Point me to the latest variables available.

Thanks

Nick
Canon 60D, Canon 5DMK3, Lexar 1000x 128GB CF, Panasonic (shhhh!) GH2s & GH3s. :-)

1%

No way to set the buffer per se, just when the buffer warning goes off. H264 buffer is different than camera write buffer. I think we only see the latter (I see H264 buffer when throwing into analysis tools).

There are 4x4 and 8x8 scaling matrices in the 5d3/6D encoder. Only the 8x8 transforms work, the 4x4s for some reason don't play back. Lots of underexplored territory.

See below for what is available in new encoder:

http://www.magiclantern.fm/forum/index.php?topic=4124.0


highest rate out of 6D I got was 400Mb/s



1%

Seems the 4x4s get used dynamically on 6D.


quant_param          : 5
pmode                : Intra_4x4
ipred Intra_4x4      :
DC           DC           DC           DC         
DC           DC           DC           Horz       
Vert         DiagDwnLeft  DiagDwnLeft  Horz       
Vert         Vert         DiagDwnLeft  Horz       
ipred chroma         : DC



kgv5

Hi
sorry for the noob question but i have to ask especially the 6d owners: what do you think is the best setting of ML encoder (newest version) to get best picture quality?
Could you please give me your settings of:

ALL-I or IPB ??

bit rate
initQP
flush rate
GOP size
Config select.

I have 45 MB/s sandisk extreme card.
In the 2.3 version (in my 550d) it looks easier, here i am little bit confused.

Do you think that improvement of picture quality is noticeble?

Thank you
www.pilotmovies.pl   5D Mark III, 6D, 550D

1%

Off, Off
Flush 6, GOP 24
IPB with rate control config set to autoload.

For sound I just leave flush stock unless I'm recording wav with it.

ALL-I is a wash just like on 600D, frames are just too big at good qps and inferior to IPB or IBB.

Rush

1%, thank you very much for porting flush control to 600D! (spotted it in latest 2.0 build)

So, I will further optimize my previous settings.
Greetings from Russia!

1%

Still needs slice and gop :)

But an interesting thing is that with flush via cache hack and gop via video parameters it might be possible to do flush 3 and longer gop. That's not something I've done on 600D yet.

kgv5

Quote from: 1% on May 04, 2013, 06:11:22 PM
Off, Off
Flush 6, GOP 24
IPB with rate control config set to autoload.

For sound I just leave flush stock unless I'm recording wav with it.

ALL-I is a wash just like on 600D, frames are just too big at good qps and inferior to IPB or IBB.

Thank you 1%, so what bitrates are you getting with such settings?
I made a quick test 1080p 24fps IPB,  (due to mediainfo) i get about 64 mbit/s with flush 6, sound off and almost the same with flush auto sound on. In the same conditions canons stock is about 30 IPB and 50 ALL-I. Fact, it is very stable but do you think it will give visible better picture quality? Does it make sense to go higher up to 120-150 and if it does, which parameter i have to change in the first place?
www.pilotmovies.pl   5D Mark III, 6D, 550D

1%

I get 62-80... it depends on scene complexity. 150+ is where issues start to happen with dropped frames and the like.

Picture quality is better than stock, it picks higher QP when I analyze it in streameye. Also CABAC vs CAVLC. Mostly you would notice it editing the files in post, they stretch further.

Ideally someone should test lvrec vs H264 at different qualities and find out what is "best".

To just jack up the bit rate set it to override and set a low initqp like 1-10 or 15. Target can be whatever its only loosely adhered to in fixed qp recording. You can decrease the gop and flush rate too if it stops. Just pick gops that are divisible into fps or it won't record.

Gop of 3 or 4 gives you IBB I think so you lose the P frame and I guess only compress between I frames. Slightly less load on the CPU. Not sure what it does to quality as nobody else has an IBB encoder.

kgv5

Got it! Thank you so much for your explanation, helped me a lot  :D
www.pilotmovies.pl   5D Mark III, 6D, 550D

DjJuvan

I didn't go all the way back in topic... mostly you're talking about GOP changes on 600D.... what about 550D?  Does this settings and tragiclantern apply to this model too?

1%

I have no 550D and 550D is limited to 4gb files. 2.0 still doesn't have it (big files, not 550D) implemented but soon.

AriLG

T3i (main), T2i
------------------
It's not about accuracy,  it's about Aesthetics

1%

TL 1- BR by sllice and extra controls.
TL -2 LV_rec + new menus - bit rate control not fully done, just have gop, flush, file size so far.

Rush

My review on new TL 2.0 flush rate and GOP control.

Seems like there is no reasons to use GOP 100 - it is only ~0-5% more effective than GOP 12 :(
So default GOP 12 is optimal with flush rate adjusted (I set it to 6 frames. I don't know really, but for me it look like low values reduces upper limit of bitrate because card become more busy).

New extreme high CBR modes is not possible with 600D sd's transfer limit. Maximum is 4.5x with GOP12 which is around 160 mbps.
It is strange, but with short GOPs 160 mbps SD limit is achieved by setting CBR 3.0x, not 4.5x.

And it looks like there is no any problems to playback video files incamera with changed GOP if it is under 60-70 mbps.
It wasn't possible to playback with old GOP-control.

It is sad that flush rate settings not compatible with audio recording, so for me I stick to GOP4+audio+CBR3.0-160mbps with default flush rate.. But wait! I can't use this settings with audio in tl-2.0 cause of buffer while it works perfectly with tl-1.0 in 25p! Something is bad with sound in tl-2.0...
Greetings from Russia!

1%

I'm working on the audio, needs a solution for all cameras. Gop 100? Gop 24 is 1/fps, should be maximum. Gop 1 is All-I... flush is independent of gop or its supposed to be. So you can have more compressed gop of 24.. or maybe try 48, this didn't work on 6D, limit is FPS.

I think the excessive X numbers just overflow so you won't gain anything from 4.5x-20x, it seems to just encode at QP10. The extra X numbers are from going off of video hacks.

You have to analyze the videos with BR viewer (or analysis tools if you have them). Gop 100 you are writing 1 iframe for 100 p frames or somewhere about there, almost all P.

More gop in reasonable steps should mean more compression across frames with QP10. In the old version couldn't set flush and gop separately.

Rush

QuoteGop 100? Gop 24 is 1/fps
I didn't expected that it works, and it showed no visible difference vs GOP12 with bitrate with fixed QScale.
But it works! I checked video in VirtualDub and it showed that I frames (K frames in VD) is every 100th frame.

Hope that audio issue will be resolved. Thank you for your effort!
Greetings from Russia!

wenen


Rush

It works!  ;)
Good quality: http://bit.ly/YFM92c


Max possible without dropped frames is 1280x400 24p or 960x540 24p but still looks awesome (I prefer 1280x400).

1%'s builds for 600D:
https://bitbucket.org/OtherOnePercent/tragic-lantern-2.0/downloads/
Greetings from Russia!

1%

I feel like even the tiny DNG raw files are better or as good as H264. The small ones will probably go to 720P at least... a 2x upres to 1080, dunno but probably close.

wenen

What is lv_rec?

I can't find in the new meny how to set the camera to slice 87. Where can i find it?