Compares the quality of Constrained VBR and Capped VBR

Best SVT-AV1 Bitrate Control Technique for Live Streaming

There are four bitrate control techniques worth considering for live encoding/transcoding using the SVT-AV1 codec. These are:

  • Capped CRF
  • VBR
  • Capped VBR
  • Constrained VBR

Here’s what I found: Overall:

  • Capped CRF shows promise with significant bitrate savings, good quality retention, and the best overall performance by ~10 – 25% (meaning more streams from the same hardware).
  • VBR was generally the best of the three VBR variants.
  • Capped VBR was very similar to VBR with no significant advantages (again, in the live use case).
  • Constrained VBR produced a more consistent bitrate, but had:
    • The highest peak bitrates (potential deliverability issues).
    • The lowest average VMAF score of the three VBR variants.
    • The lowest low-frame quality scores, indicating the potential for transient quality issues.
  • Bottom line: Either use VBR or capped CRF.

You can download a report detailing these findings here. No registration is required.

About Jan Ozer

Avatar photo
I help streaming and video technology companies solve complex technical and market-facing problems in practical business terms. Engagements range from fixed-scope audits and codec strategy reviews to product testing and technical content that helps customers, prospects, and internal teams connect technical performance to business outcomes. I am a contributing editor to Streaming Media Magazine, writing about codecs and encoding tools. I have written multiple authoritative books on video encoding, including Video Encoding by the Numbers: Eliminate the Guesswork from your Streaming Video (https://amzn.to/3kV6R1j) and Learn to Produce Video with FFmpeg: In Thirty Minutes or Less (https://amzn.to/3ZJih7e). I have multiple courses relating to streaming media production, all available at https://bit.ly/slc_courses.

Check Also

VVC On The Rise

The thing about codec adoption is that years of hard work and development must occur …

Munich FRAND Royalty Guidelines: More Questions than Answers

On August 13, 2026, the 7th Civil Chamber of the Munich I Regional Court issued …

Bitmovin Releases 10th Edition of the Video Developer Report

Each year, I write about Bitmovin’s Video Developer Report because it’s one of the few …

Leave a Reply

Your email address will not be published. Required fields are marked *