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    SubjectRe: Surround via SPDIF with ALSA/emu10k1?
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    On Sat, Aug 27, 2005 at 05:47:08PM -0400, Lee Revell wrote:
    > For the best S/N ratio and dynamic range all mixer controls SHOULD be at
    > 100%, assuming the volume control in your driver only attenuates
    > signals. This is the case for the emu10k1 which implements all mixer
    > controls via DSP programs that run on the soundcard anyway, and handles
    > overflow itself.

    Well I don't want them all at 100% since I do want to be able to have
    even levels between the cd, midi and wave, which isn't always the case
    at 100%. They sure sounded worse.

    I certainly know some simpler sound cards would have more distrosion
    when you ran the amplifiers on the card at 100%.

    > Think about it, if you lower the mixer controls to 75%, you're not
    > getting the full 16 bits of dynamic range, it's probably more like 14 or
    > 15. 16 bits is barely enough headroom anyway, so you really don't want
    > this.

    Bit 16 is used as soon as the signal passes 50%. After all it is
    required when the signal goes past 32767 and is on all the way to 65535.

    So at 75% depending on how things are done internally I will be either
    using the full range just not amplified to the same amount, or if truly
    done entirely digitally, then I will be using 75% of the range, which is
    still more than even 15bit could handle (since 15 bit has half the range
    of 16bit).

    > Anyway the problem here is a bug in the emu10k1 driver, see alsa-devel
    > for the resolution.

    Well that probably helps.

    Len Sorensen
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