Bitrate Encoding VBR vs CBR?

Forum|Forum|8 years ago
December 4, 2017
3 replies
43965 views

Should I use VBR or CBR if I'm rendering at 17Mbps? I understand the differences, etc. File sizes are not an issue either.

Thanks.

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Correct answer yairb999

OK then, here is that post on facebook by Kyle Koch:

VBR (variable bitrate) is used successfully on commercial DVDs but the engineers pay very close attention to increase the bitrate for complex visuals.

It can be used to reduce your file size, but personally, I find it delivers poor results.

From our tests, we’ve seen digital blockiness @ 10 and 15Mbps for fast motion.

20Mbps CBR is the first level that gave us solid results. You could go higher for uploads to social media but may not need to.

For videos that don’t change the pixels much, like a static shot of a person talking with a plain BG, you can go much lower on the bitrate.

Our vids are cut fast and with lots of motion so we tend to upload ProRes422 and 20Mbps h264.

For in-term client previews (like raw interviews) we will post as low as 8Mbps.

yairb999

Inspiring

Some people think CBR gives better results than VBR.
See here:

https://www.facebook.com/groups/adobepremierepro/permalink/1524466490948298/?comment_id=1524469674281313&reply_comment_id=1524478397613774&comment_tracking=%7B%22tn%22%3A%22R1%22%7D

E

excited_Genie16B8

Legend

I'm not a member of Facebook.

But you can always run your own tests with your material. My guess is that you'll find little quality difference, only a size difference.

yairb999Correct answer

Inspiring

OK then, here is that post on facebook by Kyle Koch:

VBR (variable bitrate) is used successfully on commercial DVDs but the engineers pay very close attention to increase the bitrate for complex visuals.

It can be used to reduce your file size, but personally, I find it delivers poor results.

From our tests, we’ve seen digital blockiness @ 10 and 15Mbps for fast motion.

20Mbps CBR is the first level that gave us solid results. You could go higher for uploads to social media but may not need to.

For videos that don’t change the pixels much, like a static shot of a person talking with a plain BG, you can go much lower on the bitrate.

Our vids are cut fast and with lots of motion so we tend to upload ProRes422 and 20Mbps h264.

For in-term client previews (like raw interviews) we will post as low as 8Mbps.

E

excited_Genie16B8

Legend

My preference is for VBR 1 pass. It offers a size advantage over CBR and doesn't unnecessarily add to export times.

Killertom63Author

Inspiring

I don't mind the size difference, nor export times really as they're like 5/10 minutes.

My issue is I feel like more can go wrong with VBR, as it has to constantly change the bitrate. I rather it get the full bandwidth per frame, to maximise quality.

The only reason why I'm asking this is because I had a video that had a bad, bad encoding glitch and it made the footage unviewable. And I'm starting to wonder if that is because of how VBR works, because the footage would only break when something new would happen on screen, etc.

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excited_Genie16B8

Legend

My issue is I feel like more can go wrong with VBR, as it has to constantly change the bitrate. I rather it get the full bandwidth per frame, to maximise quality.

I think that's an unfounded concern. If a frame only needs 10 bits, why use 20?

Certainly there's nothing wrong with CBR. But the overwhelming majority of video you watch is VBR.