[vorbis] Realtime resampling/encoding with oggenc

[Ross Levis]

On Tue, 15 May 2001, Beni Cherniavsky wrote:
> I get a nasty 19kHz feedback spike or something that confuses
> vorbis.  Now that I'm cutting it out, vorbis doesn't have to
> waste bits trying to replicate that nasty high pitch spike.

That 19khz tone is the stereo pilot that tells your receiver that a stereo
signal is being received.  Receivers should not be passing that through the
audio but most seem to.

> As for AM, I'm not sure, but I'd probably throw out everything above
> 10kHz and below 100Hz.  If I'm not mistaken it doesn't go above or
> below that. Maybe someone knows what AM is optimzed for exactly.

There is a 10khz upper limit but I'm not sure of the 100hz limit.

> I only use vorbis to record live sources as well because for 
> some reason,
> if the channels are not centered, lame's joint stereo gets 
> confused and
> introduces artifacts without fail (could use true stereo... but hey, 
> vorbis kicks its ass).  Every single time.

Yes I've heard this with old 70's recordings as well when the left & right
channels are slightly out of phase.  Lame appears to be a lot better with
this problem these days than it use to be.  Lame has had mods in the area
where it decides to encode a frame at joint-stereo or plain stereo.  Monty
will have to test his joint-stereo algorithm with recordings of this nature.

Ross.

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.