[FFmpeg-devel] [PATCH] doc/encoders: ffaacenc does not output CBR

[Lynne]

May 11, 2020, 14:34 by guillaume.kh.alt at gmail.com:

> The documentation and wiki imply the native AAC encoder can output CBR and VBR files :
> >b
> >Set bit rate in bits/s. Setting this automatically activates constant bit rate (CBR) mode. If this option is unspecified it is set to 128kbps.
>
>>
>>
> >q
> >Set quality for variable bit rate (VBR) mode. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
>

The twoloop coder (not the default) does CBR. The fast coder for now tries to approximate it.
So the documentation is correct. If you do need more accurate CBR just use the twoloop coder for now.
I'm working on the encoder now and that should improve its CBR constraints with the fast coder.