[pulseaudio-discuss] [WIP] Passthrough support

Arun Raghavan arun.raghavan at collabora.co.uk
Tue Mar 15 22:49:51 PDT 2011


On Tue, 2011-03-15 at 23:13 -0600, Kelly Anderson wrote:
> On 03/15/11 22:04, Arun Raghavan wrote:
> > On Tue, 2011-03-15 at 18:50 -0600, Kelly Anderson wrote:
> >> On 03/09/11 03:10, Arun Raghavan wrote:
> >>> Hello all,
> >>> Based on the RFC I posted earlier, I've implemented basic passthrough
> >>> support in some usable shape. It's up on the passthrough branch of each
> >>> of:
> >>>
> >>> PulseAudio:
> >>> http://git.collabora.co.uk/?p=user/arun/pulseaudio.git;a=shortlog;h=refs/heads/passthrough
> >>> gst-plugins-base:
> >>> http://git.collabora.co.uk/?p=user/arun/gst-plugins-base.git;a=shortlog;h=refs/heads/passthrough
> >>> gst-plugins-good:
> >>> http://git.collabora.co.uk/?p=user/arun/gst-plugins-good.git;a=shortlog;h=refs/heads/passthrough
> >>>
> >>
> 
> Hey Arun,
> 
> I've built and installed the passthrough branch.

Great! Thanks for testing this out. :)

> Isn't changing sample rates supported yet?  So far I can only 
> passthrough sample rates that match the default-sample-rate in 
> daemon.conf.  Changeable rates is critical to being able to support for 
> example dts-hd at 192khz, when standard dts will be 48khz.
> 
> I'm using paplay for basic functionality checks.

It will work, but not with paplay, only with the extended API when you
create a non-PCM stream. I will rationalise the check for passthrough
sink inputs in a bit, but for now, could you change the checks (there
are 2) in alsa-sink sink_process_msg() from:

    if (PA_LIKELY(pa_format_info_is_pcm(i->format)))

to:

    if (PA_LIKELY(!(i->flags & PA_SINK_INPUT_PASSTHROUGH)))

This should make the sample-rate reconfiguration work for paplay as
well.

I'll apply your HDMI-related patch and push it to my tree (we should
really be probing - I'll look into this once the other bits are done).

Cheers,
Arun




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