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spencer king
Cineform Datarate > Canon 7d Datarate
on Jan 27, 2012 at 2:18:52 am

Hey I think this is a pretty good question that might help some others.

I ran a .MOV/h.264 clip straight from the camera through cineform,

set to convert to a cineform intermediary- avi -
2:33/859mb clip with a total bitrate of 47.8 mbps
the result was,
2:33/2.15gb clip with a total bitrate of 145.mbps (16-Bit Apparently)

I dont understand why the bitrate is so high when the 7d shoots at 47mbps. I dont notice any difference in quality, i did direct comparisons with both clips, and both clips compared with color correction and even the color grading doesnt show any differences. This is on premiere and Im trying to find a good compression for windows that can aid in color correction and overall quality. Im not concerned with going easier on the editing route. Thanks for any help.


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Peter Burger
Re: Cineform Datarate > Canon 7d Datarate
on Jan 27, 2012 at 9:25:17 am

You need a higher bitrate with files that are less compressed.

Cineform files are much bigger, because they contain much more picture information. This is because of two reasons:

1) Cineform is an intraframe codec - which means every frame exists as a frame in the file.
H.264 is an interframe codec, which means only some frames are really existant, the rest are "interpolated".

More frames means: more information. More information lead to bigger files which need a higher bitrate.

2) The overall compression of Cineform is less strong than of H.264 (one reason the before mentioned interframe-/intraframe factor).

The tricky bit is: A cineform transcoded file does contain more information but not more *usable* information. So the 8Bit source video (H.264) is wrapped in a 16Bit file which needs more space.

Transcoding serves primarily one reason: To increase the speed of editing (or - on slower or older machines/software - make it possible), since decompression of the the transcoded files is much less processor- and RAM-heavy. A 16Bit (or 10Bit, if you transcode to say DNxHD) helps with grading, because of the 16Bit structure of the new file. This only works, if your software supports 16Bit mode (like After Effects does). You don't *have to* transcode to 16Bit - at least not when working in AE - you can change the workspace to 16Bit and use your 8Bit files.

So: If eding speed and stability of your system is no issue, IMHO you can edit the files natively with Premiere CS5 or CS5.5. In the sequence settings enable "maximum bitdepth" to avoid the grading problems (like banding etc.).

Hope this helps a bit.

------------------------------------------
"Tragedy is a close-up; comedy, a long shot." - Buster Keaton


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spencer king
Re: Cineform Datarate > Canon 7d Datarate
on Jan 28, 2012 at 12:12:19 am

Thanks for the detailed reply i really really appreciate the help.

Okay Im pretty sure I followed all of that. So if I take my 16bit cineform AVI file into after effects for color grading, its not going to show a difference in quality compared to the original 8bit h.264? - It will just help with the performance of my machine?

I havnt had any issues editing in premiere with the h.264. I am shooting my 7D with the newest technicolor picture style(big difference+)and now Im trying to find out at which point it is in post production, I can make the biggest improvement on quality. Could it be that I am converting my native video files into the wrong codec? Or should I be focused on the exporting stage.

I have been exporting my work as an h.264- for youtube. Will exporting the final product out of premiere, as a cineform file(or other), possibly be a big changer?

Thanks again


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Peter Burger
Re: Cineform Datarate > Canon 7d Datarate
on Jan 28, 2012 at 12:58:27 pm

[spencer king] "So if I take my 16bit cineform AVI file into after effects for color grading, its not going to show a difference in quality compared to the original 8bit h.264? - It will just help with the performance of my machine?"

Yes and no. :) The transcoded file will look more or less exactly like the original. You don't add picture information through transcoding and you won't lose information if you transcode to a lossles codec like Cineform. You still have the same "8Bit picture", but it's wrapped in a 16Bit codec.

Editing and postproduction speed will be improved. I also noticed stability improvement of Premiere and After Effects.

If you don't intend to do more intense postproduction you can also transcode to a lossless 8Bit codec, which will save you a lot of HDD space.

The big advancement when working in 16Bit mode is, that you'll have more possibilities for any kind of post-production work. Values (of colour or luminance) that would not be possible in 8Bit mode can be interpolated. You'll have less issues with banding etc.

[spencer king] "Could it be that I am converting my native video files into the wrong codec? Or should I be focused on the exporting stage."

No, Cineform is fine!

[spencer king] "I have been exporting my work as an h.264- for youtube. Will exporting the final product out of premiere, as a cineform file(or other), possibly be a big changer?"

I'd render the final out into a lossless codec (like Cinfecorm). This file might be huge, but it's the best as can be. You can then convert this file (with Media Encoder) to your desired output formats. It's much faster to play around with your output settings for the optimum quality with a prerendered file rather than rendering your timeline and all the effects again and again and again...

------------------------------------------
"Tragedy is a close-up; comedy, a long shot." - Buster Keaton


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spencer king
Re: Cineform Datarate > Canon 7d Datarate
on Feb 2, 2012 at 9:08:13 pm

Wow thanks so much for the replies, I have been working with this information I will definitely post a follow up shortly. Thanks again.


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Peter Burger
Re: Cineform Datarate > Canon 7d Datarate
on Feb 3, 2012 at 7:23:09 am

Glad, I helped!

------------------------------------------
"Tragedy is a close-up; comedy, a long shot." - Buster Keaton

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