[Vorbis] encoding vorbis in windows using on multi-core cpu

[xiphmont at xiph.org]

On 7/23/07, Patrick Byrne <pbyrne at frontier.co.uk> wrote:
> Hi,
>
> I have just realised that the otherwise-excellent lancer vorbis encoders
> do not actually use multiple cores when encoding mono streams*. It looks
> as though stereo streams get a core each, but mono stream encodes only
> run at 50% cpu.

Stereo streams still use only a single core, assuming we're talking
about the reference encoder.  I assume Lancer is using [mostly]
reference code.

> Does anyone know if work has been done previously on encoding mono
> streams across multiple cores? We stand to save a lot of time!

Yes, but too many steps strictly rely on preceeding steps, and
encoding a block requires the results of the encoding analysis for the
block that preceeds it.  There have been multithreaded encoder
projects in the past, but each one compromised output quality and as
such did not catch on.

Monty