[alsa-devel] parameter for pulse device?

[Takashi Iwai]

On Fri, 20 Sep 2019 09:35:59 +0200,
Tanu Kaskinen wrote:
> 
> On Thu, 2019-09-19 at 14:12 -0700, frederik at ofb.net wrote:
> > Thank you for the tips.
> > 
> > I don't know if my input is still needed, but I figured out from
> > looking at some of the syntax you linked to that I can put this in
> > ~/.asoundrc and it does the job (this is what I had had in mind when
> > I asked about "magic with macros", it is somewhat advanced for me):
> > 
> >     pcm.!pulse {
> >         @args [ DEV ]
> >         @args.DEV {
> >             type string
> >             default "default"
> >         }
> >         type pulse;
> >         device $DEV
> >     }               
> > 
> > Now I can set up a filter like this:
> > 
> >     ecasound -i alsa,pulse:mic -o alsa,pulse:monitor
> > 
> > Is something like this going into the alsa-plugins repo?
> 
> I'm sure something like this will be accepted if you submit a patch. I
> got the impression that Takashi isn't willing to write the patch
> himself, and nor am I, so you're in the best position to make this
> happen.

I have a test patch but had no chance to test the stuff at all
currently as I am (and will be for the next few weeks) traveling.

> Note that
> 
>             default "default"
> 
> doesn't do the intended thing with the current pcm_pulse.c code. With
> the current code the plugin will request PulseAudio to use a device
> named "default", which most likely won't exist and playback or
> recording will fail. The plugin code needs to pass NULL as the device
> name to pa_stream_connect_playback() and pa_stream_connect_record()
> when it detects that the default device is requested, so you'll need to
> modify pcm_pulse.c in order to make this work. Instead of "default" as
> the special string in the configuration, I suggested using "".

Below is the totally untested patch (even not build-tested!)
If anyone interested, feel free to cook it.


thanks,

Takashi

---
diff --git a/pulse/50-pulseaudio.conf b/pulse/50-pulseaudio.conf
index 62da207af9ca..916258d942af 100644
--- a/pulse/50-pulseaudio.conf
+++ b/pulse/50-pulseaudio.conf
@@ -1,7 +1,13 @@
 # Add a specific named PulseAudio pcm and ctl (typically useful for testing)
 
 pcm.pulse {
+	@args [ DEVICE ]
+	@args.DEVICE {
+		type string
+		default ""
+	}
 	type pulse
+	device $DEVICE
 	hint {
 		show {
 			@func refer
diff --git a/pulse/ctl_pulse.c b/pulse/ctl_pulse.c
index fbb6eae2ec76..9b820fd04b15 100644
--- a/pulse/ctl_pulse.c
+++ b/pulse/ctl_pulse.c
@@ -664,6 +664,8 @@ SND_CTL_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &server) < 0) {
 				SNDERR("Invalid type for %s", id);
 				return -EINVAL;
+			} else if (!*server) {
+				server = NULL;
 			}
 			continue;
 		}
@@ -671,6 +673,8 @@ SND_CTL_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &device) < 0) {
 				SNDERR("Invalid type for %s", id);
 				return -EINVAL;
+			} else if (!*device) {
+				device = NULL;
 			}
 			continue;
 		}
@@ -678,6 +682,8 @@ SND_CTL_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &source) < 0) {
 				SNDERR("Invalid type for %s", id);
 				return -EINVAL;
+			} else if (!*source) {
+				source = NULL;
 			}
 			continue;
 		}
@@ -685,6 +691,8 @@ SND_CTL_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &sink) < 0) {
 				SNDERR("Invalid type for %s", id);
 				return -EINVAL;
+			} else if (!*sink) {
+				sink = NULL;
 			}
 			continue;
 		}
diff --git a/pulse/pcm_pulse.c b/pulse/pcm_pulse.c
index 283174357e8b..869c9b674c6b 100644
--- a/pulse/pcm_pulse.c
+++ b/pulse/pcm_pulse.c
@@ -1069,6 +1069,8 @@ SND_PCM_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &server) < 0) {
 				SNDERR("Invalid type for %s", id);
 				return -EINVAL;
+			} else if (!*server) {
+				server = NULL;
 			}
 			continue;
 		}
@@ -1076,6 +1078,8 @@ SND_PCM_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &device) < 0) {
 				SNDERR("Invalid type for %s", id);
 				return -EINVAL;
+			} else if (!*device) {
+				device = NULL;
 			}
 			continue;
 		}
@@ -1091,6 +1095,8 @@ SND_PCM_PLUGIN_DEFINE_FUNC(pulse)
 			if (snd_config_get_string(n, &fallback_name) < 0) {
 				SNDERR("Invalid value for %s", id);
 				return -EINVAL;
+			} else if (!*fallback_name) {
+				fallback_name = NULL;
 			}
 			continue;
 		}