Chiebot-Mirror/FFmpeg - FFmpeg - Gitea: Git with a cup of tea

Author	SHA1	Message	Date
Claudio Freire	ca203e9985	AAC encoder: improve SF range utilization This patch does 4 things, all of which interact and thus it woudln't be possible to commit them separately without causing either quality regressions or assertion failures. Fate comparison targets don't all reflect improvements in quality, yet listening tests show substantially improved quality and stability. 1. Increase SF range utilization. The spec requires SF delta values to be constrained within the range -60..60. The previous code was applying that range to the whole SF array and not only the deltas of consecutive values, because doing so requires smarter code: zeroing or otherwise skipping a band may invalidate lots of SF choices. This patch implements that logic to allow the coders to utilize the full dynamic range of scalefactors, increasing quality quite considerably, and fixing delta-SF-related assertion failures, since now the limitation is enforced rather than asserted. 2. PNS tweaks The previous modification makes big improvements in twoloop's efficiency, and every time that happens PNS logic needs to be tweaked accordingly to avoid it from stepping all over twoloop's decisions. This patch includes modifications of the sort. 3. Account for lowpass cutoff during PSY analysis The closer PSY's allocation is to final allocation the better the quality is, and given these modifications, twoloop is now very efficient at avoiding holes. Thus, to compute accurate thresholds, PSY needs to account for the lowpass applied implicitly during twoloop (by zeroing high bands). This patch makes twoloop set the cutoff in psymodel's context the first time it runs, and makes PSY account for it during threshold computation, making PE and threshold computations closer to the final allocation and thus achieving better subjective quality. 4. Tweaks to RC lambda tracking loop in relation to PNS Without this tweak some corner cases cause quality regressions. Basically, lambda needs to react faster to overall bitrate efficiency changes since now PNS can be quite successful in enforcing maximum bitrates, when PSY allocates too many bits to the lower bands, suppressing the signals RC logic uses to lower lambda in those cases and causing aggressive PNS. This tweak makes PNS much less aggressive, though it can still use some further tweaks. Also update MIPS specializations and adjust fuzz Also in lavc/mips/aacpsy_mips.h: remove trailing whitespace	9 years ago
Claudio Freire	01ecb7172b	AAC encoder: Extensive improvements This finalizes merging of the work in the patches in ticket #2686. Improvements to twoloop and RC logic are extensive. The non-exhaustive list of twoloop improvments includes: - Tweaks to distortion limits on the RD optimization phase of twoloop - Deeper search in twoloop - PNS information marking to let twoloop decide when to use it (turned out having the decision made separately wasn't working) - Tonal band detection and priorization - Better band energy conservation rules - Strict hole avoidance For rate control: - Use psymodel's bit allocation to allow proper use of the bit reservoir. Don't work against the bit reservoir by moving lambda in the opposite direction when psymodel decides to allocate more/less bits to a frame. - Retry the encode if the effective rate lies outside a reasonable margin of psymodel's allocation or the selected ABR. - Log average lambda at the end. Useful info for everyone, but especially for tuning of the various encoder constants that relate to lambda feedback. Psy: - Do not apply lowpass with a FIR filter, instead just let the coder zero bands above the cutoff. The FIR filter induces group delay, and while zeroing bands causes ripple, it's lost in the quantization noise. - Experimental VBR bit allocation code - Tweak automatic lowpass filter threshold to maximize audio bandwidth at all bitrates while still providing acceptable, stable quality. I/S: - Phase decision fixes. Unrelated to #2686, but the bugs only surfaced when the merge was finalized. Measure I/S band energy accounting for phase, and prevent I/S and M/S from being applied both. PNS: - Avoid marking short bands with PNS when they're part of a window group in which there's a large variation of energy from one window to the next. PNS can't preserve those and the effect is extremely noticeable. M/S: - Implement BMLD protection similar to the specified in ISO-IEC/13818:7-2003, Appendix C Section 6.1. Since M/S decision doesn't conform to section 6.1, a different method had to be implemented, but should provide equivalent protection. - Move the decision logic closer to the method specified in ISO-IEC/13818:7-2003, Appendix C Section 6.1. Specifically, make sure M/S needs less bits than dual stereo. - Don't apply M/S in bands that are using I/S Now, this of course needed adjustments in the compare targets and fuzz factors of the AAC encoder's fate tests, but if wondering why the targets go up (more distortion), consider the previous coder was using too many bits on LF content (far more than required by psy), and thus those signals will now be more distorted, not less. The extra distortion isn't audible though, I carried extensive ABX testing to make sure. A very similar patch was also extensively tested by Kamendo2 in the context of #2686.	9 years ago
Rostislav Pehlivanov	1956cfbaed	aacenc_is: take absolute coefficient value upon energy calculations This was an oversight when the IS system was being first implemented. The ener01 part was largely a result of trial and error and the fact that the sum of coef0 and coef1 could result in a zero was overlooked. Once ener01 turns to zero it's used to divide the left channel energy which doesn't turn out so well as it fills IS[] with -nan's and inf's which in turn confused the quantize_band_cost. Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	9 years ago
Rostislav Pehlivanov	a71f7de95b	aacenc_is: ignore PNS band types It's better to trust that the coefficients generated will be closer than the coefficients derived, and the new PNS implementation makes sure that this happens. Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	9 years ago
Rostislav Pehlivanov	4565611b04	aacenc_is: add a flag to use pure coefficients instead This commit adds a flag to use the pure coefficients instead of the processed ones (sce->coeffs). This is needed because IS will apply the changes to the coefficients immediately before the adjust_common_prediction function and it doesn't make sense to measure stereo channel coefficient difference when one of the channels coefficients are all zero. Therefore add a flag to use pure coefficients in that case. TNS is the only thing touching the coefficients before IS so common window prediction will not take that into account but the effect of the TNS filter per coefficient can be small (a few percent) so to some approximation it's fine to just ignore that. Also fixed a small error which doesn't alter the results that much. pow(sqrt(number), 3.0/4.0) == pow(number, 3.0/8.0) != pow(number, 3.0/4.0). Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	9 years ago
Rostislav Pehlivanov	2c94e45fad	aacenc_is: rename struct to follow guidelines Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	9 years ago
Timothy Gu	21dd5279c3	aacenc: Add missing ff_ prefixes Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com> Reviewed-by: Ganesh Ajjanagadde <gajjanag@mit.edu>	9 years ago
Rostislav Pehlivanov	d1ca7142ac	aaccoder: move the Intensity Stereo implementation out This commit moves the intensity stereo implementation out from aaccoder and into a separate file. This was possible using the previous commits. This commit also drastically improves the IS implementation by making it phase invariant e.g. it will always choose the best possible phase regardless of whether M/S coding is on or most of the coefficients have identical phases. This also increases the quality and reduces any distortions introduced by enablind intensity stereo. Users are encouraged to test it out using the -aac_is 1 parameter as it has always been. Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	9 years ago