>>>> Can you tell me if hw:0,0 is exactly equivalent to the "default" ALSA
>>>> device *if* dmix is disabled with the following in /etc/asound.conf:
>>>>
>>>> pcm.!default {
>>>> type plug
>>>> slave.pcm hw
>>>> }
>>>
>>> No hw:0,0 talks directly to hardware (without conversions. Plug is a
>>> plugin to
>>> convert the format and sampling rate in order to connect the input to the
>>> output.
>>> So the conf you wrote is equivalent to plughw:0,0 not to hw:0,0.
>>>
>>> Anyway I recomend to use the conf you quoted or something like the
>>> following
>>> (which is more readable) as a default device in order to let applications
>>> play
>>> any kind of sound (44khz, 48khz, 8bit and so on)
>>>
>>> pcm.digital
>>> {
>>> type hw
>>> card 0
>>> device 0
>>> }
>>>
>>> pcm.!default {
>>> type plug
>>> slave.pcm digital
>>> }
>>
>> I think I'm starting to figure this out. Please correct me if I'm
>> wrong, but I think the default device converts both format and sample
>> rate, and plughw converts only format. This is what I've seen from my
>> tests and observing the LEDs on my USB DAC. Does plughw do anything
>> besides converting the format?
>
> plughw will do any conversion that's needed between the device and the
> source, if the sample rate conversion is needed it's done, otherwise not.
> However, "default" device, depending on your setup/distribution, may be
> using software mixing with either dmix or PulseAudio, which will likely
> output at a fixed sample rate at all times.
What other changes might be made to the signal? The default device
and plughw both upmix or downmix to stereo if necessary, right?
I'm using the default device and the following config:
# cat /etc/asound.conf
defaults.pcm.rate_converter "samplerate_best"
pcm.!default {
type plug
slave.pcm hw
}
This way, if the sample rate, format, or number of channels is not
supported, they are converted, otherwise they are not. If the sample
rate is converted, it is converted with samplerate_best. I think this
results in the highest possible quality in all situations. Is that
right?
- Grant
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