qaac v3.03, using the --cvbr 256 parameter in foobar2000, convert to m4a file, and open the file with MediaInfo, It display as Constant Bit Rate (CBR)

[JDF2026]

--cvbr is working correctly as CVBR. If you play the file with a player such as foobar2000, you should be able to see that the bitrate varies during playback.

However, due to the change in the MP4 library, the values written to maxBitrate and avgBitrate in the DecoderConfigDescriptor of the esds box in the MP4 file are now different from what they were before.

In version 3.00, we write the contents of the DecoderConfigDescriptor generated by the encoder as-is. Previously, maxBitrate was based on the measured bitrate.

I don't know what heuristic MediaInfo uses, but it is probably looking at the maxBitrate and avgBitrate values and reporting the bitrate mode as "Constant."

Originally posted by @nu774 in #129

I downloaded qaac 3.03 and modified the parameters of the AAC (Apple) encoder qaac64.exe in foobar2000 to --ignorelength -s --no-optimize --cvbr 256 -o %d -
I converted the flac file back to an m4a file and opened the m4a file with MediaInfo. It still displayed as Constant Bit Rate (CBR). I don't know what the reason is?

foobar2000 v1.6.10
Win10 x64

[nu774]

Fixed on v3.04

[JDF2026]

Fixed on v3.04

Thanks a lot, Can i both use -v 256 or --cvbr 256 to make it as CVBR ?

[nu774]

-v and --cvbr have the same meaning.
Also, the behavior of bitrate modes such as TVBR/CVBR/ABR/CBR themselves has not changed since before version 3.00. They are encoded in the same way as before.

What changed in version 3.00 is that the resulting bitrate values (average bitrate and maximum bitrate) are no longer set as metadata in a specific location within the MP4 container, which changed the behavior of whether MediaInfo interprets that value and displays it as "Constant." That's the only change.

In version 3.04, the actual measured values of the average bitrate and maximum bitrate are now written, so under normal circumstances MediaInfo should no longer display "Constant" for something that is actually CVBR.

[JDF2026]

-v and --cvbr have the same meaning. Also, the behavior of bitrate modes such as TVBR/CVBR/ABR/CBR themselves has not changed since before version 3.00. They are encoded in the same way as before.

What changed in version 3.00 is that the resulting bitrate values (average bitrate and maximum bitrate) are no longer set as metadata in a specific location within the MP4 container, which changed the behavior of whether MediaInfo interprets that value and displays it as "Constant." That's the only change.

In version 3.04, the actual measured values of the average bitrate and maximum bitrate are now written, so under normal circumstances MediaInfo should no longer display "Constant" for something that is actually CVBR.

You're amazing, God bless you.