Author Topic: 600D GOP and Slice control FAQ + settings, for beginners.  (Read 22387 times)

jgharding

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600D GOP and Slice control FAQ + settings, for beginners.
« on: July 04, 2013, 06:19:57 PM »
This post is designed to answer questions about the H264 codec control in one version of Tragic Lantern in a simple and practical way.

After a few posts I made about using bitrate control on the 600D I had a bunch of messages about settings, and development threads were getting busy, so here's a new thread.

Though one could explain these concepts in greater detail, it's of no real practical use to the average user, so here they in plain English.

They are simplified, so lease don't fill the thread with highly technical responses on video encoding, that information is available elsewhere for those who are curious.

WHAT IS IT?

A balancing act of sorts. High bitrate means nicer footage but bigger files. You can adjust the colours more and remove noise more easily. Advanced control of the H264 encoder that tries to make it use as high a bitrate as possible, without fluctuating wildly or stopping recording.

WHY NOT USE RAW?

Raw can be lovely but there are also a lot of compromises (crop sensor, lower resolution, longer workflow) so perfecting H264 is a great way to get higher quality footage from your beloved camera.

H264 is limited because the encoder uses a rather soft image, but these settings will let you get the best from that image.

WHAT DO I NEED?

A 600D, a fast SD card of 45 or 95MBs will guarantee speed, and (currently) this build of 1%'s Tragic Lantern:

https://bitbucket.org/OtherOnePercent/tragic-lantern/downloads/autoexec.bin-bitrateback

The build is a little older than ones you may be used to so a few things are missing or different. GOP and slice control aren't in the new builds yet but may be at some point, and when they are let me know and alter this thread.

Some other useful things for the 600D are:

The Mosaic Engineering TXi filter, which removes most aliasing and moire, allowing you to make better use of the bitrate. Sometimes it gives Err30 butmost of the time it's amazing. You will still get some moire with exceedingly fine cloth and so on.

The Technicolor Cinestyle Picture Profile and it's LUT, which allows a flatter picture for grading. It's free.

The VisionColor picture profile, which is quite flat but has a nice natural film like tone. It's $6.99. That's a bargain, don't pirate it!

Neat Video denoising plug-in, which can make very high ISOs like 6400 usable when combined with the higher bitrates.

  ;D 8) THE SETTINGS 8) ;D

SOUND OFF
*For maximum image quality at GOP1, don't bother recording sound in camera, deactivate it in Canon menus. Use separate sound.*

IF YOU NEED SOUND use 25p mode and set GOP to 3 instead of 1.

IN SLICE CBR

Lock Slice: Disabled
Min BR: 130
Max BR: 160
Drop by 1: 140
Drop by 3: 145
Taper Rates: Enabled.

IN BITRATE MENU

Mode: CBR
DblockA: -1                  (low noise setting)
Dblockb: -1                  (low noise setting)
PicPC: 0
GOP: 1                         (3 is great too, and saves space)
Bitrate Info: On           (I find it interesting)
BuffWarnLevel: 70%    (just in case)


BUT WHAT DOES IT MEAN?!!

If you don't need to know, it's probably best to to worry. Hey, the important thing is it works! But here's some simplified explanations:

SLICE
Quality. The numbers used are weird, but not that confusing. The lowest numbers (86, 87) try and use as many bits as possible for encoding. The trouble is, if you lock the slice to 87 and give the camera a hugely complex picture the bitrate goes too high, the buffer fills up and recording stops, or quality has to drop for a while. The second of these situation makes the bitrate "bounce" up and down between loads and 40 or so, which means your image goes pixelly every so often.

Slice control lets the camera raise the slice (drop the bitrate) gradually and in a controlled manner if things get too much.

The settings I've provided here have been stress tested very heavily. They keep things at 87 a lot of  the time, but reign it in if the scene becomes too complex. The settings are designed to keep the bitrate below 160 but as high as the camera can keep it without overflowing the buffer in complex scenes.

You can push it harder, but it won't be as stable. These setting have, for me so far, been the most consistant. I recently shot for 15 hours on a fashion video and never had any buffer drops. The average bitrate of the footage was around 100mbps I-frame, which is a lot better than stock.

The buffer can still get too full (resulting in a drop to a very low bitrate and some pixellation) if you shoot a very complex high ISO scene with the slice starting at 87 or so. If you are shooting a complex scene start the slice at 115 or so using the first setting in Slice Control, and the camera will quickly level itself.

GOP

GOP is "group of pictures". To compress more video into less space, some codecs look at one frame, then compare a lot of subsequent frames to it, only storing the bits that have changed. The GOP number is how many are in this group.

So what's the practical result? A long GOP is more efficient, but to my eye tend to look more video like, motion can be a little smeared. I prefer GOP 1, also known as I-frame, as each picture is a whole picture, like a piece of film. The downside here is that file sizes are big, but hey, it looks the best and memory cheap.

GOP 3 is a good compromise and allows sound recording in 25p mode with these settings.

BUFFER

A small memory where the camera stores things before they are written to the SD card. If this fills up, recording will stop. You can use GOP 1 to let frames be written straight to the card, but for some reason GOP 3 seems less hard on buffer. This is reaching the limit of my knowledge. GOP 1 probably stresses the card a lot, but your card will probably be obsolete before it matters. Just format it ater shoots.
Zeiss primes, 600D, a lot of shadow. http://www.jgharding.com

Luzestudio

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #1 on: July 05, 2013, 02:00:38 PM »
Thank you very much for the info, much appreciated.

I have to get a faster card, because when I make the recording it just lasts a few seconds, and I think it's a problem with the sd cards I have. I will get one of ones you recommend.

Best

Xermán

Rick M

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #2 on: July 05, 2013, 03:49:51 PM »
Thanks for this guide! I noticed that topic the other day and tried to look over the last few pages to figure out what was going on, but with all those terms being thrown around, I was way lost. Might give this a try soon and see the difference.

Does this build have the audio monitoring for T3i that was added after the last stable version too? Or is this mode something where you can't do audio recording at the same time because it's too much information and stops recording?

MD87

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #3 on: July 05, 2013, 06:04:38 PM »
Great theme. I have long wanted casual, what is a "Flush rate"? ( in TL2 ) And GOP = 1 for default bit rate will change in the image?
600D+ TL. CANON 50 F1.8 II; TAMRON  17-50 F2.8 VC; CANON 18-135; MIR-1B 37 F2.8; JUPITER-37A 135 F3.5.

1%

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #4 on: July 05, 2013, 06:33:54 PM »
Flush rate is how fast to write. Gop 1 is ALL-I.. gop 3 is pretty decent middle ground if you still want P frames.

Hehe.. is sraw helping H264 or is canon not using the memory? Sraw should be in both versions.

jgharding

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #5 on: July 05, 2013, 07:19:37 PM »
Thanks for this guide! I noticed that topic the other day and tried to look over the last few pages to figure out what was going on, but with all those terms being thrown around, I was way lost. Might give this a try soon and see the difference.

Does this build have the audio monitoring for T3i that was added after the last stable version too? Or is this mode something where you can't do audio recording at the same time because it's too much information and stops recording?

Excellent, I'm glad it helped!

I saw many new users in development threads asking similar questions, so I thought it may help.

No audio with these settings I'm afraid. Thanks for pointing it out, I've added it to the post.

I will attempt optimum audio settings too...

EDIT: yes audio does technically work at 25p, but with these settings it overflows the buffer instantly, so I leave it off for best picture...
Zeiss primes, 600D, a lot of shadow. http://www.jgharding.com

jgharding

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #6 on: July 05, 2013, 07:22:43 PM »
*double post*
Zeiss primes, 600D, a lot of shadow. http://www.jgharding.com

1%

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #7 on: July 05, 2013, 07:38:20 PM »
Quote
No audio with these settings I'm afraid. Thanks for pointing it out, I've added it to the post.

TL 1 you can do audio at 25P I believe... or do wav.. but the wav seems to be synced to 25P in all modes.

CFP

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #8 on: July 05, 2013, 11:22:14 PM »
Hehe.. is sraw helping H264 or is canon not using the memory? Sraw should be in both versions.
There's no way to check the shoot_malloc size with the TL1 build, or am I missing something?

I tried it with the settings postet in the first post and the picture quality set to "RAW" and "SRAW" (Rebooted, to increase buffer. But I don't know if it worked). I couldn't see a difference. At 30 and 35 frames per second (ISO 3200 to push the bitrate) it stoped with both settings after a few seconds.

But I have a few questions: Why aren't these controls in the new builds? Will they return? Is it possible to set the flush rate with the TL1 build? If not, what's the default?

1%

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #9 on: July 06, 2013, 01:39:24 AM »
Flush rate is tied to gop in the first one. Yea, they should return. I'm still dealing w/ raw, etc.

AriLG

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #10 on: July 06, 2013, 10:40:26 PM »
1%, what are your settings with regards to the OP ?
T3i (main), T2i
------------------
It's not about accuracy,  it's about Aesthetics

jgharding

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #11 on: July 07, 2013, 02:39:20 PM »
Yes you can do audio, in that it does function at 25p but If you turn it on with these settings the buffer fills straight away, so I leave it off ;)



Zeiss primes, 600D, a lot of shadow. http://www.jgharding.com

Critical Point

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #12 on: July 07, 2013, 05:14:38 PM »
The image looks great, way better to my eye than the stock one, but the only problem I'm having is that the footage can't be played back in camera, is that normal ?
600D & GH2 / PC.

N/A

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #13 on: July 08, 2013, 01:09:43 AM »
Yeah that's normal, something to do with chroma subsampling I think.
7D. 600D. Rokinon 35 cine. Sigma 30 1.4
Audio and video recording/production, Random Photography
Want to help with the latest development but don't know how to compile?

jjproducciones

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #14 on: July 08, 2013, 03:36:12 AM »
There is something similar in the canon 550D, Thanks.

far.in.out

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #15 on: July 08, 2013, 12:30:42 PM »
Quote
the encoder uses a rather soft image
could you explain that in more detail? I saw somewhere an option to disable sharpening... this looks controversial... do you need to sharpen it or to soften???
EOS M (was 600D > 50D)

Luzestudio

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #16 on: July 09, 2013, 10:50:05 AM »
could you explain that in more detail? I saw somewhere an option to disable sharpening... this looks controversial... do you need to sharpen it or to soften???

I think that he means that the image received by the h264 encoder is soft (it's not a genuine 1920x1080, but reescaled from a smaller size).

For what I know one of the best approaches to sharpening is recording with sharpening 0 and increasing it in post-pro but maybe someone has found a better workflow.

Luzestudio

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #17 on: July 10, 2013, 02:32:47 PM »
Anyone had time to make a comparison between stock vs custom?

Critical Point

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #18 on: July 10, 2013, 08:31:52 PM »
I think that he means that the image received by the h264 encoder is soft (it's not a genuine 1920x1080, but reescaled from a smaller size).

For what I know one of the best approaches to sharpening is recording with sharpening 0 and increasing it in post-pro but maybe someone has found a better workflow.
I have done extensive testing on the sharpening issue. What I've found out, is that the cinestyle picture profile used with 0 in camera sharpening, gives a way to soft image, and if you try to sharpen it in post, you have to use very high values witch produce too much noise on the footage. So, I have learned that if you use +1 sharpening in camera, and then a low value software sharpening, you get a nice clean image, without any noise, and good enough sharpened.

Never, ever, go with the in camera sharpening beyond +1, and in the most extreme cases +2. I recommend either 0 or +1.
600D & GH2 / PC.

Luzestudio

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #19 on: July 11, 2013, 09:28:37 AM »
I have done extensive testing on the sharpening issue. What I've found out, is that the cinestyle picture profile used with 0 in camera sharpening, gives a way to soft image, and if you try to sharpen it in post, you have to use very high values witch produce too much noise on the footage. So, I have learned that if you use +1 sharpening in camera, and then a low value software sharpening, you get a nice clean image, without any noise, and good enough sharpened.

Never, ever, go with the in camera sharpening beyond +1, and in the most extreme cases +2. I recommend either 0 or +1.

Good advice, I will give it a try.

jgharding

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #20 on: July 11, 2013, 10:54:57 AM »
Yes the encoder receives a lower resolution image feed that's been rescaled a few times so it's never true 1080p

I recently started trying sharpness on 1 as well. I've not A/B tested but the idea sounded good to me, since we aren't dealing with raw we could do with a little bit of sharpness "baked in"

I used these settings on another film last weekend. It's looking good! I did find that the camera stops recording in longer takes. Must be the 4GB file limit coming up early...
Zeiss primes, 600D, a lot of shadow. http://www.jgharding.com

marekk

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #21 on: July 11, 2013, 11:09:16 AM »
When I can find source of this build ? I would like to port it to 60D..

Luzestudio

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #22 on: July 11, 2013, 11:16:06 AM »
When I can find source of this build ? I would like to port it to 60D..

Read the first post: https://bitbucket.org/OtherOnePercent/tragic-lantern/

marekk

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #23 on: July 11, 2013, 11:17:35 AM »
Yes I know ;))))
but actual source code doesn't include changes from this build.

Read the first post: https://bitbucket.org/OtherOnePercent/tragic-lantern/

Can

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Re: 600D GOP and Slice control FAQ + settings, for beginners.
« Reply #24 on: July 11, 2013, 03:53:16 PM »
When I can find source of this build ? I would like to port it to 60D..

Yes, please! 60D Nation is behind you. 8)