[pulseaudio-discuss] [PATCH] alsa: Add extra HDMI mappings

David Henningsson david.henningsson at canonical.com
Thu Jul 31 01:46:07 PDT 2014

On 2014-07-30 20:36, Alexander E. Patrakov wrote:
> Add DTS-encoded profiles (they need dcaenc from git).
> The use cases for DTS over HDMI are:
> 1. Radeon driver on old kernels, with no support for multichannel PCM HDMI
>     audio.
> 2. A TV that acts as a converter between an HDMI-connected computer and
>     an SPDIF-connected receiver, with no other way to connect the components.

You never mentioned this before, and I haven't heard anyone asking for 
it either.

OTOH, dts encoders are probably not installed by default on any common 
distro except very media focused ones (e g OpenElec, XBMC and such), and 
if you're manually installing the dts encoder or running a media center 
distro then maybe this is interesting.

Also, there are probably HDMI cards out there that only support stereo 
LPCM in hardware but I'm not sure how common it is.

So I guess it's okay, but it wouldn't hurt with more opinions about how 
common dts really is over HDMI.

Also, have you tried this yourself so you know that pulseaudio works 
well enough with the dca encoder? We don't want crashes.

> +[Mapping hdmi-dts-surround]
> +description = Digital Surround 5.1 (HDMI/DTS)
> +device-strings = dcahdmi:%f
> +paths-output = hdmi-output-0
> +channel-map = front-left,front-right,rear-left,rear-right,front-center,lfe
> +priority = 1
> +direction = output

Just a question about the dcahdmi:%f stuff - isn't the "dca" definition 
flexible enough that you can just use dca:hdmi:%f instead of dcahdmi:%f 
? That way it should work with earlier versions of dcaenc too?

David Henningsson, Canonical Ltd.

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