Vorbis - Nov 2005 - Mono encoding w/ a stereo source.

Crew,

I've run into something a little odd with the vorbis encoder and would 
like some input.

I use SpacialAudio's SAM3 Broadcaster and am having problems with the 
ogg encoder when I create a mono output stream.  It seems as if the 
signal level of the left and right sides are being combined before the 
encoding process, leaving the sound muddy and overdriven.  As such, if I 
reduce the output level by 6db, the combined streams are at the right 
level.  The settings I'm using are Quality -1, 32kbps/44kHz.

SpacialAudio suggested that they are passing the audio info to the 
library as required.

Ideas?

-I

On 11/16/05, Ian A. Underwood <agentgrn@dcne.net>
wrote:
> Crew,
>
> I've run into something a little odd with the vorbis encoder and would
> like some input.
>
> I use SpacialAudio's SAM3 Broadcaster and am having problems with the
> ogg encoder when I create a mono output stream.  It seems as if the
> signal level of the left and right sides are being combined before the
> encoding process, leaving the sound muddy and overdriven.  As such, if I
> reduce the output level by 6db, the combined streams are at the right
> level.  The settings I'm using are Quality -1, 32kbps/44kHz.
>
> SpacialAudio suggested that they are passing the audio info to the
> library as required.
If you're encoding in mono, then the data being passed to the encoder
library is in mono - libvorbis does not do downmixing internally. It
sounds, from your description, like SAM3 is internally doing
downmixing to mono, but in a way that produces poor quality audio. Is
that possible?

Mike