[vorbis] MP3/Vorbis comparision

[Giuliano Pochini]

> I can see this ripple in your files too. The mp3-files has no ripple.
> And the pre/post echos are much lower as ogg. But it is audible?

I can hear the pre-echo, but not the post-echo in that audio samples. It
sounds like a "ch" just before the sound and I have to isolate a peice
of the sample to hear it clearly. If I remove the pre-echo I can very
hardly ABX the rippled ogg file from the original. The ripple has a
period between 2 and 4ms and it's quite low measured in dB. But at -q0
it's wider in both time and amplitude and more audible.

> I have generated a sinus tone sweep from 20Hz up to 22KHz at -6dB with
> 30sec length. After encoding with ogg q4, the ripple is always visible,
> but it is not audible. At every frequency, i can not hear this ripple.

Did you measure the frequency of the ripple ? It's very fast, don't
expect to hear a remolo. It sounds like in interference between two
sine waves that differ about 300Hz in frequency.

> Maybe a test with pure sine tones is a test, which is too hard for
> lossy encoding with mp3 and ogg.

Yes, it's just a test. But if you encode music from your C=64
collection... :)

> In normal music, pure sine tones and
> abrupt level changes from digital silence to -6dB should never occur.

Percussions do it, but they're noisy and usually you don't notice it.

> Ogg's main problem is the high frequency boost, but besides this,
> music encoded with ogg sounds very well.

I agree.

Bye.

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