[vorbis-dev] When can we expect low bitrate encoding?

MC Spanky mcspanky at mac.com
Mon Dec 11 07:22:08 PST 2000

On Fri, 8 Dec 2000, Monty wrote:

> Oggenc just doesn't know how to lowpass or downsample; if you feed it
> an input source that's lower than 44.1kHz, it will Do The Right Thing
> (tm); 11kHz inputs currently compress down to as low as 16kbit/s.
> That said, the encoder modes are not yet well tuned for lower sampling
> rates; specifically, the preecho handling doesn't yet scale down so
> preecho will be slightly more annoying at 22kHz, and fairly pronounced
> at 11kHz sampling rates.  That, obviously, will be corrected in the
> not too distant future.

Hmm.  So to encode a mono stream at less than 64 kbit/s, i need to start
by reducing it to 22kHz sample rate, i.e. dropping frequencies above 11
kHz.  Is this optimal?  i.e. would a fancy pants psycho-acousical
genius, given the 44.1kHz version, start by filtering out those high
frequencies anyway?  If not, are there are plans to implement 44 kHz ->
less than 64 kbit/sec for mono streams?


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