[mythtv] [mythtv-commits] Ticket #7517: Separate Volume control from Audio Output

[Peter Stokes]

On 16 Aug 2010, at 22:56, Ed W wrote:

> 
>> The second feature is provided by the "software" volume control. Whilst it results in potentially lower quality audio, software volume control is generally favourably to no volume control at all and is therefore provided as a fallback.
> 
> Actually, I think you will find very few soundcards actually have a mixer which operates in the analogue domain?  In general when you adjust your alsa mixer levels the soundcard is doing a software volume control on the card...

I am not an expert on the hardware design of PC soundcards, so I cannot comment. By way of explanation, I do have what I consider to be the optimal, in terms of volume control, audio configuration. I use a PC soundcard connected to an external audio amplifier via SPDIF. I have written an ALSA plugin ("arcam-av"), that controls the amplification of the external amplifier via RS232 control. This configuration provides full-scale audio samples to the amplifier and then the level of amplification is controlled in the analogue domain, post digital-to-analogue conversion, within the external amplifier. It is this configuration, with the audio samples passing as unmolested as possible through the PC, that I seek to maintain.

Peter