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.
THE SETTINGS
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.
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.
THE SETTINGS 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.