Hello! I have noticed if decode https://samples.ffmpeg.org/A-codecs/ATRAC1/Test%20tones%20disc%20-%20Chirp.aea file by ffmpeg we got aliasing near 11025Hz. Screenshots: https://yadi.sk/i/r-95jZkKkSnbu https://yadi.sk/i/PV92LNESkSnby
I was tried to solve it: ATRAC1 - hybrid codec, has two stacked QMF and splits the signal into 3 band before MDCT. Thereby we need to compensate delay of one QMF to achieve reconstruction. There is a delay line but it looks like delay for 23 sample is not correct. I have done some experiments and got 39 should be right delay. Results of decoding with patch: https://yadi.sk/i/yooaIQrmkSncB https://yadi.sk/i/CUXsH7-CkSncK To be honest I am not a prof in math and it would be great if someone recheck it from math perspective. There is a patch in attach. Best Regards, -- Daniil Cherednik
0001-ffmpeg_atrac1_decoder_delay.patch
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