ALC1150 can't playback SND_PCM_FORMAT_FLOAT without dmix

ALC1150 can't playback SND_PCM_FORMAT_FLOAT without dmix

[Madura Anushanga]

Hi,

MSI z87-GD65 GAMING motherboard's ALC1150 plays SND_PCM_FORMAT_FLOAT with
noise[1] other non float formats work well. As soon as I changed
/etc/asound.conf from

pcm.!default{
   type hw
   card 1
}

to

pcm.dmixed {
        type asym
        playback.pcm {
                type dmix
                ipc_key 5678293
                ipc_perm 0660
                ipc_gid audio

                slave {
                        channels 2 # make 6 or 5.1 channel
                        pcm {
                                format S16_LE # S32_LE
                                rate 48000 # can also be 44100
                                type hw
                                card 1 # your card
                                device 0 # your device
                                subdevice 0 #important?
                        }

                        period_size 1024
                        buffer_size 8192
                }

                bindings {
                        0 0
                        1 1
# Uncomment below if using 6 channel
#                       2 2
#                       3 3
#                       4 4
#                       5 5
                }
        }
        capture.pcm "hw:0"
}

pcm.!default {
        type plug
        slave.pcm "dmixed"
}

SND_PCM_FORMAT_FLOAT plays without a problem.

1. https://github.com/manushanga/vrok/blob/master/outs/alsa.cpp

            - Madura A.

Re: ALC1150 can't playback SND_PCM_FORMAT_FLOAT without dmix

[Daniel Mack]

Hi,

On 05/04/2014 09:27 AM, Madura Anushanga wrote:
> MSI z87-GD65 GAMING motherboard's ALC1150 plays SND_PCM_FORMAT_FLOAT with
> noise[1] other non float formats work well. As soon as I changed
> /etc/asound.conf from
> 
> pcm.!default{
>    type hw
>    card 1
> }

The 'hw' plugin requires the audio hardward to support the configured
format natively, matching the exact sample format, alignment and
endianess, as well as the sample rate and channel number etc.

I don't know of any consumer-class Codec that supports float on the
hardware wire.

> pcm.dmixed {
>         type asym
>         playback.pcm {
>                 type dmix

...

> 1. https://github.com/manushanga/vrok/blob/master/outs/alsa.cpp

In general, you should use the 'plughw' plugin for generic applications,
which does the implicit sample format conversion for you.


Daniel