Compares the quality of Constrained VBR and Capped VBR

Best SVT-AV1 Bitrate Control Technique for Live Streaming

Jan Ozer September 18, 2023 Articles Leave a comment 1,633 Views

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.

SVT-AV1 Bitrate Control Modes for Live Streaming (2295 downloads )

About Jan Ozer

Avatar photo
I help companies train new technical hires in streaming media-related positions; I also help companies optimize their codec selections and encoding stacks and evaluate new encoders and codecs. 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. I currently work as www.netint.com as a Senior Director in Marketing.

Check Also

How AdCurate Helps Publishers Improve Ad Quality and Boost Revenue

In this conversation, Jan Ozer from the Streaming Learning Center interviews Gabe Thomas, VP of …

How Witbe Measured Super Bowl Streaming Performance — Insights on Latency, QoE, and 4K Quality

On March 11, 2025, I (Jan Ozer) from the Streaming Learning Center interviewed Yoann Hinard, …

Review of Multi-Resolution Encoding for HTTP Adaptive Streaming using VVenC

In their paper entitled, Multi-resolution Encoding for HTTP Adaptive Streaming using VVenC, Kamran Qureshi, Hadi …

Leave a Reply

Your email address will not be published.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

© Copyright 2025 Streaming Learning Center, All Rights Reserved