la, 2024-09-14 kello 00:15 +0300, Pauli Virtanen kirjoitti: [clip] > - it appears the resulting frame_bits depends also on some other state > than s->lambda. iteration with lambda1, lambda2>lambda1, and then again > with lambda1 can produce different frame_bits on the two lambda1 > iterations. Is there some state that is modified across iterations?
Looking at the code, there seem to be at least a few things: 1. aacpsy analyze internal state, AacPsyChannel.prev_band AacPsyContext.pe.previous, get updated on each re-encode iteration of the same frame 2. avoid_clipping() is applied on coeffs only on first iteration, in later iterations coeffs can get overwritten by pcoeffs 3. adjust_frame_information() changes sce->ics.max_sfb which would affect clipping The aacpsy prev state is documented to relate to previous frame, but it seems it can here be overwritten by that from the previous re-encode iteration. This looks a bit suspicious. Probably the clipping factor also should be re-applied on re-encodes. Maybe s->psy.model->analyze() should be done only on the first encode iteration, and the same bitres.alloc result be used for all potential re-encodes of the same frame? -- Pauli Virtanen _______________________________________________ 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".
