Re: Broken ALSA surround sound with OpenALSoft 1.12 and newer

On Monday, February 27, 2012 11:00:20 AM Martin Egge wrote:
> What has changed beetween 1.11 and 1.12 and might have broken the 5.1 output
> here?

The only related thing that changed is that, instead of setting the number of 
periods and the period size in sample frames (or the nearest possible; the 
buffer size is then inferred from period_size * periods), it sets the buffer 
size and period size in microseconds (or the nearest possible; periods is then 
inferred from buffer_size / period_size) so that it better scales if the 
sample rate was changed.

I don't see any reason for the changes to cause a failure, though. The 
functions snd_pcm_hw_params_set_buffer_time_near and 
snd_pcm_hw_params_set_period_time_near are supposed to set values closest to 
what the device is capable of.

> > You can try modifying the 'periods' setting in alsoft.conf. The default is
> > 4, but you can try setting it to 2 or 3 to reduce the buffer size.
> 
> That didn't change anything.

What about setting 'mmap' to 'false' under the [alsa] section?

Do you have a ~/.alsoftrc (and if so, what's in it)?

> > Out of curiousity, what audio hardware do you have?
> 
> Output of lspci -vv
> 
> 07:00.0 Multimedia audio controller: Creative Labs CA0106 Soundblaster
>         Subsystem: Creative Labs SB0410 SBLive! 24-bit

Okay, so you have a real sound card. Pretty sure that does hardware mixing, so 
you don't need dmix.

> Yes, please send me an example.

I've attached an /etc/asound.conf I use to define a 'dmix6' device. It plays 
back at 48khz and has an 18ms period size and 90ms buffer size, and accepts 
CARD, DEV, and SUBDEV arguments similar the the default dmix.

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pcm.dmix6 {
    @args [ CARD DEV SUBDEV ]
    @args.CARD {
        type string
        default {
            @func refer
            name defaults.pcm.dmix.card
        }
    }
    @args.DEV {
        type integer
        default {
            @func refer
            name defaults.pcm.dmix.device
        }
    }
    @args.SUBDEV {
        type integer
        default 0
    }

    type dmix
    ipc_key 1024
    ipc_key_add_uid false # let multiple users share
    ipc_perm 0660 # IPC permissions (octal, default 0600)
    slave {
        pcm {
            type hw
            card $CARD
            device $DEV
            subdevice $SUBDEV
        }
        rate 48000
        channels 6
        period_time 18000
        buffer_time 90000
    }

    hint {
        show on
        description "Direct sample mixing device (5.1 Surround)"
        device $DEV
    }
}

ctl.dmix6 {
    @args [ CARD ]
    @args.CARD {
        type string
        default {
            @func refer
            name defaults.pcm.dmix.card
        }
    }   

    type hw
    card $CARD
}