I had noticed fdk is specifically looking for the qscale flag, and otherwise does not do anything with global_quality. I suppose the change is risky for anyone who is setting both global quality and qscale, but with the current code, it seems incorrect to have a conditional based on the scaled option and not account for the scaling.
if (avctx->flags & AV_CODEC_FLAG_QSCALE || s->vbr) { int mode = s->vbr ? s->vbr : avctx->global_quality; On Wed, Feb 22, 2023 at 9:16 AM Timo Rothenpieler <t...@rothenpieler.org> wrote: > On 22.02.2023 17:46, Gyan Doshi wrote: > > > > > > On 2023-02-22 10:12 pm, Timo Rothenpieler wrote: > >> On 22.02.2023 17:33, Gyan Doshi wrote: > >>> From > >>> > >>> fftools\ffmpeg_mux_init.c > >>> 619: ost->enc_ctx->global_quality = FF_QP2LAMBDA * qscale > >>> > >>> Regards, > >>> Gyan > >> > >> But that's only if you set the old qscale CLI options. > >> If you set the global_quality option directly, there is no factor > >> applied. > >> > >> By dividing by FF_QP2LAMBDA you break setting this value via > >> global_quality, and instead add support for setting it via the old and > >> pretty much abandoned qscale interface. > > > > FWIW, that's what LAME does. > > > > libavcodec\libmp3lame.c > > 119: lame_set_VBR_quality(s->gfp, avctx->global_quality / > > (float)FF_QP2LAMBDA); > > > > global_quality semantics seem overloaded. Maybe we should just redirect > > user to priv vbr and error out in fdk init. > > > > Regards, > > Gyan > > It's pretty much a matter of "what did this code always do in the past". > It then got to stick to it, cause otherwise we break downstream API and > CLI consumers. > > The mp3lame code is probably old enough that qscale was still the > default at the time. > Nowadays it's global_quality. > > Both of those options mapping to the same field in avctx, one with a > magic factor applies, is definitely and oddity. > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".