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Old 22nd April 2020, 17:08   #1  |  Link
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Join Date: Jul 2017
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CRF use for content aware VOD streaming?


So there are a lot of discussions regarding content aware/per-title streaming for VOD nowdays, were different types of methods are used to select what bitrate is appropriate when it comes to streaming.

old, but yeah basically this:

But it seems like a lot of streaming services (i guess at least most of the smaller local ones) still just use fixed bitrates for the ladder, cause I guess they dont have resources to implement complex workflows.

So I've been wondering, why isnt CRF used (or is it?)? Cant it be in used together with vbv restrictions to create a crude method to do this?

I'm a bit out of my realm of expertise here but. Lets say you have a 1Mbps connection target preset, why not set a crf value that is close to 500Kbps in avg bitrate for your average complexity material, then set --vbv-maxrate 750 --vbv-bufsize 1000. I'm I missing something or shouldn't this be a fairly good (or at least easy) way of doing it compared to fixed bitrates?

So a ladder would look something like this:

540p24 ~500Kbps (1Mbps safe) --crf 26 --vbv-maxrate 750 --vbv-bufsize 1000

720p24 ~1250Kbps (2Mbps safe) --crf 24 --vbv-maxrate 1750 --vbv-bufsize 2500

1080p24 ~3Mbps (5Mbps safe) --crf 22 --vbv-maxrate 4500 --vbv-bufsize 6000

1080p24 ~6Mbps (10Mbps safe) --crf 19 --vbv-maxrate 9000 --vbv-bufsize 12000

So, my question is basically: is this a good or a poor way of doing it? If good, is this already in widespread use, and if not, why?

Last edited by excellentswordfight; 22nd April 2020 at 17:28.
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