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Topic: Lowpass, too much lower (Read 13332 times) previous topic - next topic
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Lowpass, too much lower

Reply #25 –
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5. if you can consistenly hear a difference move up the lowpass (13kHz, 14kHz etc. etc.) until you can't.
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I've tried this test. There is a problem with the samples. The lowpass filter is a brickwall one, and the ringing is obviously audible at 12 and 13 kHz for me. I can ABX them easily, but if the lowpass filter had been softer, there would not have been any audible ringing, and maybe I could not have ABXed the samples relying only on treble loss.
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I agree. The 14khz sample has the ringing too.
You messed up, now I gotta mess you up. It's the law!

Lowpass, too much lower

Reply #26 –
Quote
Quote
5. if you can consistenly hear a difference move up the lowpass (13kHz, 14kHz etc. etc.) until you can't.
[a href="index.php?act=findpost&pid=321292"][{POST_SNAPBACK}][/a]


I've tried this test. There is a problem with the samples. The lowpass filter is a brickwall one, and the ringing is obviously audible at 12 and 13 kHz for me. I can ABX them easily, but if the lowpass filter had been softer, there would not have been any audible ringing, and maybe I could not have ABXed the samples relying only on treble loss.
[a href="index.php?act=findpost&pid=321574"][{POST_SNAPBACK}][/a]


Excuse my ignorance, but is this the kind of filter generally used in lossy codecs or is it different?
If this is the kind of filter that creates the worst artifacts then I assume one can be safe of one's lowpass threshold using this method, I mean in the worst case one's lowpass threshold would be lower than the one found using samples lowpassed with this so called brickwall filter. But, as I've seen before one should never assume... 

Lowpass, too much lower

Reply #27 –
Quote
Quote
Quote
5. if you can consistenly hear a difference move up the lowpass (13kHz, 14kHz etc. etc.) until you can't.
[a href="index.php?act=findpost&pid=321292"][{POST_SNAPBACK}][/a]


I've tried this test. There is a problem with the samples. The lowpass filter is a brickwall one, and the ringing is obviously audible at 12 and 13 kHz for me. I can ABX them easily, but if the lowpass filter had been softer, there would not have been any audible ringing, and maybe I could not have ABXed the samples relying only on treble loss.
[a href="index.php?act=findpost&pid=321574"][{POST_SNAPBACK}][/a]


Excuse my ignorance, but is this the kind of filter generally used in lossy codecs or is it different?
If this is the kind of filter that creates the worst artifacts then I assume one can be safe of one's lowpass threshold using this method, I mean in the worst case one's lowpass threshold would be lower than the one found using samples lowpassed with this so called brickwall filter. But, as I've seen before one should never assume... 
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As far as I know, all major lossy encoders use smooth filters instead of brickwall filters.
 

Lowpass, too much lower

Reply #28 –
I've uploaded some new samples, using cosine filters instead of brickwall ones. See this thread.