OK, I've implemented the first draft of this idea.
It works OK (well, doesn't seem to crash!) but has a couple issues.
If it's loaded at startup and no other sinks are created, it will
automatically create a null-sink for you. You can play sound and as soon
as you add another sink (could be your own null-sink or a real sound
device e.g. from usb etc) it will automatically unload the null-sink it
started. The idea is that module-recover-streams should take over and
move all the streams from the null-sink to the new sink added. This
doesn't seem to work in my tests. I get a blip of audio and then mplayer
just freezes. I'm not sure that's my fault (the audio does start afterall).
The other way round seems to work fine, e.g. starting playing with a
real sink, and removing the said sink, a null-sink is automatically
loaded and the recover-streams kicks in and works.
I would have thought that the case where it fails should have been more
successful and the case where it works could have failed (as it uses one
of the same hooks as recover-streams, tho' I *was* careful to load my
module first).
Can someone please comment on the code and the ideas and if I'm doing
something fundamentally stupid?
The whole "u->ignore" flag in there seems a bit wrong and I've maybe
missed something obvious there.
Cheers
Col
Colin Guthrie wrote:
> Hi,
>
> I've been running into some problems testing Mandriva One KDE 2008.1 RC1
> (live CD).
>
> I've been using VirtualBox and the default setup is to not include any
> sound hardware, so when the system boots pulseaudio starts fine but
> module-hal-detect (unsurprisingly) doesn't find anything and no sinks
> are loaded.
>
> This actually causes quite a few problems. pavucontrol seems to segv and
> paplay has a stream error. Strangely after loading and then unloading
> module-null-sink, things are less critical - e.g. pavucontrol runs fine...
>
> As a side note, artd seems to crash repeatedly (seems to go on forever)
> which IMO is a KDE session related bug but what I'm about to suggest
> would inadvertently fix this too.
>
>
>
> While I've been using virtualbox, this could be useful on any system
> without built in sound (or if it's just disabled) to which you
> subsequently plugin USB sound device. Sound could play to no where and
> when a real device is plugged in all streams playing on the null sink
> could be automatically moved over and null-sink removed. If/when the
> real device is remmoved, we could load up module-null-sink.
>
> module-rescue-streams could actually take care of the moving of streams
> around so all we really need is a module to watch for when sinks are
> added or removed and take appropriate action with regards to loading or
> unloading module-null-sink etc.
>
> What do you think, is this sensible?
Index: src/modules/module-always-sink.c
===================================================================
--- src/modules/module-always-sink.c (revision 0)
+++ src/modules/module-always-sink.c (revision 0)
@@ -0,0 +1,175 @@
+/* $Id: module-always-sink.c 2043 2007-11-09 18:25:40Z lennart $ */
+
+/***
+ This file is part of PulseAudio.
+
+ Copyright 2008 Colin Guthrie
+
+ PulseAudio is free software; you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2 of the License,
+ or (at your option) any later version.
+
+ PulseAudio is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with PulseAudio; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/core.h>
+#include <pulsecore/sink-input.h>
+#include <pulsecore/modargs.h>
+#include <pulsecore/log.h>
+#include <pulsecore/namereg.h>
+
+#include "module-always-sink-symdef.h"
+
+PA_MODULE_AUTHOR("Colin Guthrie");
+PA_MODULE_DESCRIPTION("Always keeps at least one sink loaded even if it's a
null one");
+PA_MODULE_VERSION(PACKAGE_VERSION);
+PA_MODULE_LOAD_ONCE(TRUE);
+
+static const char* const valid_modargs[] = {
+ NULL,
+};
+
+struct userdata {
+ pa_hook_slot *new_slot, *unlink_slot;
+ pa_module* m;
+ pa_bool_t ignore;
+};
+
+void load_null_sink_if_needed(pa_core *c, pa_sink *sink, struct userdata* u) {
+ pa_sink *target;
+ uint32_t idx;
+ pa_bool_t have_a_sink = FALSE;
+ pa_module *m;
+
+ pa_assert(c);
+ pa_assert(u);
+
+ // Loop through all sinks and check to see if we have *any* sinks
+ // Ignore the sink passed in (if it's not null)
+ for (target = pa_idxset_first(c->sinks, &idx); target; target =
pa_idxset_next(c->sinks, &idx)) {
+ if (sink && target == sink)
+ continue;
+ have_a_sink = TRUE;
+ break;
+ }
+
+ if (!have_a_sink) {
+ pa_log_debug("Autoloading null-sink as no other sinks detected.");
+
+ u->ignore = TRUE;
+ m = pa_module_load(c, "module-null-sink", "sink_name=AutoNullSink");
+ u->ignore = FALSE;
+
+ if (!m) {
+ pa_log_warn("Unable to auto-load module-null-sink");
+ } else {
+ u->m = m;
+ }
+ }
+
+}
+
+static pa_hook_result_t new_hook_callback(pa_core *c, pa_sink *sink, void*
userdata) {
+ struct userdata *u = userdata;
+
+ pa_assert(c);
+ pa_assert(sink);
+ pa_assert(u);
+
+ // Is this mini-mutex thing the best way to do this?
+ if (u->ignore) {
+ // This is us detecting ourselves on load... just ignore this.
+ return PA_HOOK_OK;
+ } else if (!u->m) {
+ pa_log_debug("Auto-loaded null-sink not active, so ignoring newly
detected sink.");
+ return PA_HOOK_OK;
+ } else if (sink->module == u->m) {
+ // This is us detecting ourselves on load in a different way... just
ignore this.
+ return PA_HOOK_OK;
+ }
+
+ pa_log_info("A new sink has been discovered. Unloading null-sink.");
+
+ pa_module_unload(c, u->m);
+ // Don't reset this here as the callback below will detect this and
+ // set it itself.
+ //u->m = NULL;
+
+ return PA_HOOK_OK;
+}
+
+static pa_hook_result_t unlink_hook_callback(pa_core *c, pa_sink *sink, void*
userdata) {
+ struct userdata *u = userdata;
+
+ pa_assert(c);
+ pa_assert(sink);
+ pa_assert(u);
+
+ // First check to see if it's our own null-sink that's been removed...
+ if (sink->module && sink->module == u->m) {
+ pa_log_debug("Autoloaded null-sink removed");
+ u->m = NULL;
+ return PA_HOOK_OK;
+ }
+
+ load_null_sink_if_needed(c, sink, u);
+
+ return PA_HOOK_OK;
+}
+
+int pa__init(pa_module*m) {
+ pa_modargs *ma = NULL;
+ struct userdata *u;
+
+ pa_assert(m);
+
+ if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
+ pa_log("Failed to parse module arguments");
+ return -1;
+ }
+
+ m->userdata = u = pa_xnew(struct userdata, 1);
+ u->new_slot = pa_hook_connect(&m->core->hooks[PA_CORE_HOOK_SINK_NEW_POST],
(pa_hook_cb_t) new_hook_callback, u);
+ u->unlink_slot =
pa_hook_connect(&m->core->hooks[PA_CORE_HOOK_SINK_UNLINK], (pa_hook_cb_t)
unlink_hook_callback, u);
+ u->m = NULL;
+ u->ignore = FALSE;
+
+ pa_modargs_free(ma);
+
+ load_null_sink_if_needed(m->core, NULL, u);
+ return 0;
+}
+
+void pa__done(pa_module*m) {
+ struct userdata *u;
+
+ pa_assert(m);
+
+ if (!m->userdata)
+ return;
+
+ u = m->userdata;
+ if (u->new_slot)
+ pa_hook_slot_free(u->new_slot);
+ if (u->unlink_slot)
+ pa_hook_slot_free(u->unlink_slot);
+ if (u->m)
+ pa_module_unload(m->core, u->m);
+
+ pa_xfree(u);
+}
Property changes on: src/modules/module-always-sink.c
___________________________________________________________________
Name: svn:keywords
- Id
Name: svn:mime-type
+ text/plain
Name: svn:eol-style
+ native
Index: src/Makefile.am
===================================================================
--- src/Makefile.am (revision 2115)
+++ src/Makefile.am (working copy)
@@ -986,6 +986,7 @@
module-detect.la \
module-volume-restore.la \
module-default-device-restore.la \
+ module-always-sink.la \
module-rescue-streams.la \
module-suspend-on-idle.la \
module-http-protocol-tcp.la \
@@ -1156,6 +1157,7 @@
modules/module-jack-source-symdef.h \
modules/module-volume-restore-symdef.h \
modules/module-default-device-restore-symdef.h \
+ modules/module-always-sink-symdef.h \
modules/module-rescue-streams-symdef.h \
modules/module-suspend-on-idle-symdef.h \
modules/module-hal-detect-symdef.h \
@@ -1401,6 +1403,12 @@
module_default_device_restore_la_LIBADD = $(AM_LIBADD) libpulsecore.la
module_default_device_restore_la_CFLAGS = $(AM_CFLAGS)
+# Always Sink module
+module_always_sink_la_SOURCES = modules/module-always-sink.c
+module_always_sink_la_LDFLAGS = -module -avoid-version
+module_always_sink_la_LIBADD = $(AM_LIBADD) libpulsecore.la
+module_always_sink_la_CFLAGS = $(AM_CFLAGS)
+
# Rescue streams module
module_rescue_streams_la_SOURCES = modules/module-rescue-streams.c
module_rescue_streams_la_LDFLAGS = -module -avoid-version
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