[vorbis-dev] vorbis-utils features ;)

[Kevin Marks]

At 9:04 pm -0500 15/3/01, Kenneth Arnold wrote:
>On Wed, Mar 14, 2001 at 08:48:50PM -0800, Monty wrote:
>>
>>
>>  > (*) At silent areas in a song (extracted digitally with cdparanoia) the
>>  > bitrate holds around 200 kps (-b 192).. That seems like a waste 
>>of bits to me
>>
>>  Then it's not actually digital silence, most likely.  Very very low
>>  amplitude hiss (and even the best microphones have this) is difficult
>>  to model in a transform encoder precisely.  There *is* signal
>>  there... and hard to encode signal at that, because it's truly random
>>  :-)
>
>Still shouldn't be needing 200 kbps to code this though; if it's below
>the threshold of hearing it shouldn't matter whether it's random or
>not; Vorbis should be throwing it out! Or is there a major mistake in
>the psycoacoustic model?

Conversely, if it is random, you don't have to model it precisely, 
just use an RNG and scale down. Or, even better, filter it out with a 
noise gate before moving to frequency space.

Non-random noise (like the NASA ionosphere sample I posted earlier) 
is trickier, especially for a frequency-domain codec.

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