> Gpsycho: based on the ISO model2 demonstration. It uses predictability. If > amplitude and position of a sound can be accurately preticted from the 2 > previous granules data, then the sound is considered tonal. It is a good > idea, but the problem is that it can't detect the tonality of the sound > before the 3rd granule where the sound is present. So the 2 first granules > are wrongs. > It's a little like the ISO short block estimation, were iso model needed > data from previous granule, and then was switching 1 granule too late. > Perhaps this could be fixed by doing tonality estimation of further 2 > granules, and when a sound is detected as tonal, mark it as also tonal in > the 2 previous granules. (as obviously it's already tonal since 2 granules) > The second problem is that in the case of a tonal with rapid change in > frequency, like a sine sweep, we miss it everytime.
You can predict from both the past and future two frames and choose the one with the smallest prediction error for calculating the unpredictability measure. This way you can also handle tonality estimation of first 2 frames (then you'll just use prediction from 2 future frames). And it should give quite some extra coding efficiency (according to some paper by Nokia). Menno http://www.audiocoding.com _______________________________________________ mp3encoder mailing list [EMAIL PROTECTED] http://minnie.tuhs.org/mailman/listinfo/mp3encoder
