On Thu, 2014-10-02 at 15:58 +0200, David Henningsson wrote:
> The drain speed increase done a while ago, only worked when directly connected
> to ALSA sinks. Playing through an module-virtual-sink would cause slower drains.
What about other virtual sinks? Shouldn't the same fix be applied to
those too?
> This fix has two parts:
> 1) We now refuse to process handed out silence. This has the effect
> that it tells ALSAs sink input that we're draining, and that we want to
s/ALSAs sink input/the ALSA sink/ ?
> be woken up exactly at this sample based point in time.
> 2) When we're being called to process input underruns, we know this has
> happened, so we can just forward the call up the sink chain to get
> to protocol-native, which can acknowledge that the drain has completed.
>
> This fix is incomplete, because if more than one sink input is playing back
> into the sink, only the last one will be drained in time. But it's better
> than nothing.
A comment about this shortcoming in the code would be good.
> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> ---
>
> Happy for testing of this patch - Ubuntu runs HDA-intel with 64K buffers instead of the 2M that
> some distros use, so I'm not seeing that much difference that you do anyway.
The buffer size can be changed at runtime:
echo 2048 > /proc/asound/card0/pcm0p/sub0/prealloc
> Also, when I was testing, I also noticed a bigger startup latency when playing
> back through a virtual sink. This is nothing I have looked deeper at.
>
> src/modules/module-virtual-sink.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/src/modules/module-virtual-sink.c b/src/modules/module-virtual-sink.c
> index 66fd8a9..c1e5969 100644
> --- a/src/modules/module-virtual-sink.c
> +++ b/src/modules/module-virtual-sink.c
> @@ -216,6 +216,10 @@ static int sink_input_pop_cb(pa_sink_input *i, size_t nbytes, pa_memchunk *chunk
> pa_memchunk nchunk;
>
> pa_sink_render(u->sink, nbytes, &nchunk);
> + if (nchunk.memblock == u->sink->silence.memblock) {
> + pa_memblock_unref(nchunk.memblock);
> + return -1;
> + }
I think this needs a comment explaining what it implies if
pa_sink_render() returns silence and why it makes sense to return -1 in
that case.
--
Tanu
