Changes between Version 40 and Version 41 of Encode/AV1

Timestamp:

Nov 13, 2022, 8:52:23 AM (4 years ago)

Author:

veikk0

Comment:

Update on CRF/CQ behavior.

Encode/AV1

@@ -36 +36 @@
 libaom-av1 has a constant quality (CQ) mode (like CRF in x264 and x265) which will ensure that every frame gets the number of bits it deserves to achieve a certain (perceptual) quality level, rather than encoding each frame to meet a bit rate target. This results in better overall quality. If you do not need to achieve a fixed target file size, this should be your method of choice.
 
-To trigger this mode, you must use a combination of -crf and -b:v 0. -b:v '''MUST''' be 0. 
+To trigger this mode, simply use the `-crf` switch along with the desired numerical value. 
 
 {{{
-ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 0 av1_test.mkv
+ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 av1_test.mkv
 }}}
 
 The CRF value can be from 0–63. Lower values mean better quality and greater file size. 0 means lossless. A CRF value of 23 yields a quality level corresponding to CRF 19 for x264 ([https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11842/2595598/Towards-much-better-SVT-AV1-quality-cycles-tradeoffs-for-VOD/10.1117/12.2595598.full?SSO=1 source]), which would be considered visually lossless.
+
+Note that in FFmpeg versions prior to 4.3, triggering the CRF mode also requires setting the bitrate to 0 with `-b:v 0`. If this is not done, the `-crf` switch triggers the constrained quality mode with a default bitrate of 256kbps.
 
 == Constrained Quality ==