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

Media over QUIC (MoQ), What It Takes to Deploy It, and When It Matters (From CDN77)

The IETF’s MoQ Transport draft is on its 21th version. According to Michal Hošna of …

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 …

Leave a Reply

Your email address will not be published.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