maikmerten

Here's another patch approach: This makes -q4 the lowest quality setting (providing the best quality) for CBR and ABR. This is similar how for the new VBR mode, some quality settings are disallowed as well (a few lines prior).

The problem of q0/q1/q2/q3 producing worse results for CBR/ABR was introduced with this change: https://sourceforge.net/p/lame/svn/6147/ This enabled the new VBR-psymodel for CBR and ABR, which happened to help with https://sourceforge.net/p/lame/bugs/392/ (which also is about lower speed settings introducing artifacts).

ABR seems to be affected similarly to CBR. Here's a slightly expanded trivial patch to disable noise_shaping_amp for ABR as well.

Here's a trivial patch that sets noise_shaping_amp to 0 for CBR encoding.

For some reason, I accidentally filed this in group "Compatibility". More fitting would be "Quality", of course.

CBR: High quality settings (e.g, -q 0) degrade quality over -q 4