[alsa-devel] HDMI audio: TV vs. codec supported sample rates

[Jaroslav Kysela]

On Tue, 3 Aug 2010, Stephen Warren wrote:

> A user has the following setup:
>
> A GPU which supports audio-over-HDMI. The codec supports sample rates 
> 32000 44100 48000 88200 96000 176400 192000 (from 
> /proc/asound/card1/codec#1). However, the user's TV supports only sample 
> rates 44100 48000 88200 (from /proc/asound/card1/eld*).
>
> When the user plays sound with sample rate 22050, they hear nothing. 
> Sound with sample rates supported by the TV works OK.
>
> My question: Is the HDA codec driver supposed to dynamically adjust its 
> list of supported sample rates based on the ELD content, or is the ALSA 
> library somehow supposed to detect the subset of rates supported in HW 
> and convert the sample rate in SW before sending the audio to the 
> driver?

The driver must return the correct list of supported sample rates. 
Otherwise alsa-lib thinks that the invalid sample rate is supported in the 
hardware or driver.

 					Jaroslav

-----
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.