[alsa-devel] [PATCH] Re: iec958 switch uneffective while playing ac3 stream

Dag Lem dag at nimrod.no
Sun Apr 22 13:01:30 CEST 2007

Takashi Iwai <tiwai at suse.de> writes:


> The fix is already in HG tree, so please test the latest HG version
> to confirm whether it's fixed.

I finally got around to test the code in the HG tree.

The S/PDIF output still works perfectly on the ALC882M. I ran PCM
tests using all available frame rates (44.1kHz, 48kHz, 96kHz, 192kHz).
I also tested AC3 (at 48kHz) and DTS (at 44.1kHz and 48kHz).

Good work! That goes for Dominique as well, of course :-)

The only fly in the ointment for the average user will be, I think,
that HDA-Intel.pcm.default is using dmix. This effectively cuts most
non-experts off from using anything but 48kHz, resulting in inferior
sound quality (and unavailability to play back 44.1KHz DTS over
S/PDIF) due to resampling.

Perhaps dmix could be configured with more than one destination frame
rate, so that resampling would only be used if absolutely necessary?
Just a thought.

Best regards,

Dag Lem

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