AuI ConverteR has default mp3 conversion settings to provide better sound quality.
However, you may be need custom settings of mp3 encoding.
and get Extra Warranty 1-year period for FREE.
THE PROMO LICENSE NUMBER IS LIMITED.
* - This promo is valid from 4 December 2023 00:00GMT to 6 December 2023 00:00GMT. This Extra Warranty 1-year period is applied to this purchased promo license only.

If you buy "AuI ConverteR PROduce-RD" (2023/12.x version) from 24 August 2023 to 24 October 2023, you will get free update to version 2024 (13.x) after its release.
To assign custom bitrate, set desirable parameters in command line of mp3 encoder.
- Open Settings > Output formats.
- At left upper corner, select Output file format "mp3".
-
In the field "Output converter command line params" find something like (without quotes):
- for constant bitrate: "-b:a 320k" ("-ab 320k") or
- for variable bitrate: "-q:a 9" ("-aq 9"). -
Replace found parameter to:
- for constant bitrate: -ab N (N is desirable bitrate 64k, 128k, 256k, 320k) or
- for variable bitrate: -aq M (M is digit from 0 to 9; 9 is maximum sound quality).
EXAMPLES:
Constant bitrate 320k, variant 1
-y -i %inputfile% %metadataartworkfilef% -ab 320k -metadata genre=%genre% -metadata date=%year% -metadata track=%tracknumber% -metadata title=%tracktitle% -metadata album=%album% -metadata artist=%artist% -metadata copyright=%copyright% -metadata TIT3=%description% -metadata album_artist=%albumartist% -metadata publisher=%publisher% -metadata composer=%composer% -metadata performer=%conductor% -metadata TIT1=%groupdescription% -metadata disc=%disknumber% -metadata TKEY=%initialkey% -metadata TBPM=%beatsperminute% -metadata language=%language% -metadata encoder=%encoder% -metadata encoded_by=%encodedby% -id3v2_version 3 -write_id3v1 1 %outputfile%
Constant bitrate 320k, variant 2
-y -i %inputfile% %metadataartworkfilef% -b:a 320k -metadata genre=%genre% -metadata date=%year% -metadata track=%tracknumber% -metadata title=%tracktitle% -metadata album=%album% -metadata artist=%artist% -metadata copyright=%copyright% -metadata TIT3=%description% -metadata album_artist=%albumartist% -metadata publisher=%publisher% -metadata composer=%composer% -metadata performer=%conductor% -metadata TIT1=%groupdescription% -metadata disc=%disknumber% -metadata TKEY=%initialkey% -metadata TBPM=%beatsperminute% -metadata language=%language% -metadata encoder=%encoder% -metadata encoded_by=%encodedby% -id3v2_version 3 -write_id3v1 1 %outputfile%
Variable bitrate (level 9, maximum sound quality), variant 1
-y -i %inputfile% %metadataartworkfilef% -aq 9 -metadata genre=%genre% -metadata date=%year% -metadata track=%tracknumber% -metadata title=%tracktitle% -metadata album=%album% -metadata artist=%artist% -metadata copyright=%copyright% -metadata TIT3=%description% -metadata album_artist=%albumartist% -metadata publisher=%publisher% -metadata composer=%composer% -metadata performer=%conductor% -metadata TIT1=%groupdescription% -metadata disc=%disknumber% -metadata TKEY=%initialkey% -metadata TBPM=%beatsperminute% -metadata language=%language% -metadata encoder=%encoder% -metadata encoded_by=%encodedby% -id3v2_version 3 -write_id3v1 1 %outputfile%
Variable bitrate (level 9, maximum sound quality), variant 2
-y -i %inputfile% %metadataartworkfilef% -q:a 9 -metadata genre=%genre% -metadata date=%year% -metadata track=%tracknumber% -metadata title=%tracktitle% -metadata album=%album% -metadata artist=%artist% -metadata copyright=%copyright% -metadata TIT3=%description% -metadata album_artist=%albumartist% -metadata publisher=%publisher% -metadata composer=%composer% -metadata performer=%conductor% -metadata TIT1=%groupdescription% -metadata disc=%disknumber% -metadata TKEY=%initialkey% -metadata TBPM=%beatsperminute% -metadata language=%language% -metadata encoder=%encoder% -metadata encoded_by=%encodedby% -id3v2_version 3 -write_id3v1 1 %outputfile%
Read more information about ffmpeg mp3 bitrate settings