CRT = 10 in v2.6.4, what does that equal in Bitrate (MB/s)?

I do a lot of Artemis - Medium quality on 1080p content.

In v2.6.4, I usually run all my files through CRT (Constant Rate Factor) = 10, what Bitrate should I set it in version 3.0.1 for Bitrate (MB/s)? I want to ensure I am getting the equivalent quality?


Those numbers have been a mystery to me as well.

I think it is named CRF = constant rate factor. It uses a bitrate that goes up and down to attempt to deliver the same quality in all parts of a movie. Dependend on the video footage the average bitrate can vary a lot.

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What bitrate should we set it for:
and 4K content?

depends on your needs. I personally would suggest 4 mbit/s - 8 mbit/s for 720p, 8mbit/s - 16 mbit/s for 1080p and 16 mbit - 32 mbit/s for 4 k.

Bitrate depends on many things including the fps and encoder. I checked one of my 1080p 30 fps encoded H264 that were done at CRF 17 and that was 28 Mb/s. I know BD discs usually come in around 20-25 Mb/s but they are also usually only 24fps. If you want to check your old files to see the bitrate they were output on, then use a tool called media info which will give you the bitrate and fps as well as the codecs used.

there is no equal bitrate. when using crf the bitrate goes up and down depending on the video footage to deliver a continous level of image quality!

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Yes it varies but getting an average bitrate since there in no longer a CRF option is the only viable way for comparative bitrates.

If you want to encode full hd 1080p video by using 32 mbit you are save. :slight_smile:

In my opinion CRT=10, is way more than you need. 16-32Mbit/s is also way more than you need.
~ 6-12Mbit/s is plenty for 1080p/30fps h264.

I would tend to agree CRF 10 does seem a bit extreme. Personally CRF 17 gave me equivalent to a good BD bitrate. I have seen 1080p at 12Mb/s and it is generally a “good” picture however 20Mb/s is superior in fast action packed scenes where a lot is going on so it depends on what you are encoding. It’s all down to personal choice. Higher bitrates give better picture quality, if you want smaller file size and don’t care so much about picture quality then go with lower bitrates. Obviously now we have the option of H265 you could reduce the bitrate by as much as 60% and still get an equivalent picture quality to the H264. It’s not unusual for 4k BD to be in the region of 50-70Mb/s and that’s using the HEVC 265 codec.

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Hopefully CRF will be brought back.
For me, it’s absolutely the way to go.

Yep totally agree. It’s far better to have a variable bitrate based on picture quality then setting a bitrate that may be way too high for some scenes and not enough for others.

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VEAI 3.0.x does not appear to have a CRF setting. (Which is disappointing.) However, If you want to control the lossiness of your video while working on it use the ProRes 422 HQ option. It will output ginormous files, which can be reprocessed without much image degradation. After all your enhancement work is done you can then do a final export to whatever compressed format you want and specify a large or small bitrate.

My preference is to use a higher bitrate to avoid compression artifacts, but depending on how the final video image is used may determine your choices.