Pulseaudio, selecting Audio Device + multiple Audio

dfrizel · September 15, 2014, 5:22pm

I just did some work with audio on SDL2. I had some troubles with selecting an audio device on pulseaudio. Somehow it always seemed to fall back to the default device.
A had a quick look over the code and fixed the problem (at least for me). Additionally it adds support for multi-device audio and device detection. If you are interested here is the patch for (SDL2-2.0.3) but I found no difference with the current repo.

Code:

diff -r 5bf21e9e191f src/audio/pulseaudio/SDL_pulseaudio.c
— a/src/audio/pulseaudio/SDL_pulseaudio.c Sun Sep 14 19:44:53 2014 +0200
+++ b/src/audio/pulseaudio/SDL_pulseaudio.c Sun Sep 14 21:40:27 2014 +0200
@@ -106,6 +106,7 @@

static int load_pulseaudio_syms(void);

+pa_operation* (*PULSEAUDIO_pa_context_get_sink_info_list)(pa_context *c, pa_sink_info_cb_t cb, void *userdata);

#ifdef SDL_AUDIO_DRIVER_PULSEAUDIO_DYNAMIC

@@ -202,11 +203,31 @@
SDL_PULSEAUDIO_SYM(pa_stream_disconnect);
SDL_PULSEAUDIO_SYM(pa_stream_unref);
SDL_PULSEAUDIO_SYM(pa_channel_map_init_auto);

SDL_PULSEAUDIO_SYM(pa_context_get_sink_info_list);
SDL_PULSEAUDIO_SYM(pa_strerror);
return 0;
}

+static void DeInit(struct SDL_PrivateAudioData *pulse_local_server)
+{

if (pulse_local_server != NULL)
{

  if (pulse_local_server->context != NULL)

```
  {
```

  	PULSEAUDIO_pa_context_disconnect(pulse_local_server->context);

  	PULSEAUDIO_pa_context_unref(pulse_local_server->context);

```
  	pulse_local_server->context = NULL;
```
```
  }
```

  if (pulse_local_server->mainloop != NULL) {

  	PULSEAUDIO_pa_mainloop_free(pulse_local_server->mainloop);

  	pulse_local_server->mainloop = NULL;

```
  }
```
```
  SDL_free(pulse_local_server);
```
}
+}+

/* Check to see if we can connect to PulseAudio */
static SDL_bool
CheckPulseAudioAvailable()
@@ -307,16 +328,7 @@
PULSEAUDIO_pa_stream_unref(this->hidden->stream);
this->hidden->stream = NULL;
}

   if (this->hidden->context != NULL) {

       PULSEAUDIO_pa_context_disconnect(this->hidden->context);

       PULSEAUDIO_pa_context_unref(this->hidden->context);

```
       this->hidden->context = NULL;
```
```
   }
```

   if (this->hidden->mainloop != NULL) {

       PULSEAUDIO_pa_mainloop_free(this->hidden->mainloop);

```
       this->hidden->mainloop = NULL;
```
```
   }
```
```
   SDL_free(this->hidden);
```

```
  DeInit(this->hidden);
   this->hidden = NULL;
```
}
}
@@ -344,6 +356,53 @@
return “SDL Application”; /* oh well. */
}

+static struct SDL_PrivateAudioData *ThreadInit()
+{

struct SDL_PrivateAudioData *h = NULL;
int state = 0;
struct SDL_PrivateAudioData *pulse_local_server = SDL_malloc((sizeof *pulse_local_server));
if (pulse_local_server == NULL) {
```
   return 0;
```
}
SDL_memset(pulse_local_server, 0, (sizeof *pulse_local_server));
h = pulse_local_server;
/* Set up a new main loop */
if (!(h->mainloop = PULSEAUDIO_pa_mainloop_new())) {
```
  DeInit(pulse_local_server);
```
```
  return 0;
```
}
h->mainloop_api = PULSEAUDIO_pa_mainloop_get_api(h->mainloop);
h->context = PULSEAUDIO_pa_context_new(h->mainloop_api, getAppName());
if (!h->context) {
```
  DeInit(pulse_local_server);
```
```
  return 0;
```
}
/* Connect to the PulseAudio server */
if (PULSEAUDIO_pa_context_connect(h->context, NULL, 0, NULL) < 0) {
```
  DeInit(pulse_local_server);
```
```
  return 0;
```
}
do {

  if (PULSEAUDIO_pa_mainloop_iterate(h->mainloop, 1, NULL) < 0) {

```
  	DeInit(pulse_local_server);
```
```
  	return 0;
```
```
  }
```

  state = PULSEAUDIO_pa_context_get_state(h->context);

```
  if (!PA_CONTEXT_IS_GOOD(state)) {
```
```
  	DeInit(pulse_local_server);
```
```
  	return 0;
```
```
  }
```
} while (state != PA_CONTEXT_READY);
return pulse_local_server;
+}

static int
PULSEAUDIO_OpenDevice(_THIS, const char *devname, int iscapture)
{
@@ -356,12 +415,12 @@
int state = 0;

 /* Initialize all variables that we clean on shutdown */

this->hidden = (struct SDL_PrivateAudioData *)
```
   SDL_malloc((sizeof *this->hidden));
```

this->hidden = ThreadInit();
if (this->hidden == NULL) {
return SDL_OutOfMemory();
}

SDL_memset(this->hidden, 0, (sizeof *this->hidden));

h = this->hidden;

paspec.format = PA_SAMPLE_INVALID;
@@ -448,36 +507,6 @@
PA_CHANNEL_MAP_WAVEEX);

/* Set up a new main loop */

if (!(h->mainloop = PULSEAUDIO_pa_mainloop_new())) {
```
   PULSEAUDIO_CloseDevice(this);
```

   return SDL_SetError("pa_mainloop_new() failed");

}
h->mainloop_api = PULSEAUDIO_pa_mainloop_get_api(h->mainloop);
h->context = PULSEAUDIO_pa_context_new(h->mainloop_api, getAppName());
if (!h->context) {
```
   PULSEAUDIO_CloseDevice(this);
```

   return SDL_SetError("pa_context_new() failed");

}
/* Connect to the PulseAudio server */
if (PULSEAUDIO_pa_context_connect(h->context, NULL, 0, NULL) < 0) {
```
   PULSEAUDIO_CloseDevice(this);
```

   return SDL_SetError("Could not setup connection to PulseAudio");

}
do {

   if (PULSEAUDIO_pa_mainloop_iterate(h->mainloop, 1, NULL) < 0) {

```
       PULSEAUDIO_CloseDevice(this);
```

       return SDL_SetError("pa_mainloop_iterate() failed");

```
   }
```

   state = PULSEAUDIO_pa_context_get_state(h->context);

```
   if (!PA_CONTEXT_IS_GOOD(state)) {
```
```
       PULSEAUDIO_CloseDevice(this);
```

       return SDL_SetError("Could not connect to PulseAudio");

```
   }
```
} while (state != PA_CONTEXT_READY);
h->stream = PULSEAUDIO_pa_stream_new(
h->context,
“Simple DirectMedia Layer”, /* stream description */
@@ -490,7 +519,7 @@
return SDL_SetError(“Could not set up PulseAudio stream”);
}
if (PULSEAUDIO_pa_stream_connect_playback(h->stream, NULL, &paattr, flags,

if (PULSEAUDIO_pa_stream_connect_playback(h->stream, devname, &paattr, flags,
NULL, NULL) < 0) {
PULSEAUDIO_CloseDevice(this);
return SDL_SetError(“Could not connect PulseAudio stream”);
@@ -519,6 +548,58 @@
UnloadPulseAudioLibrary();
}

+typedef struct
+{

uint8_t last;
SDL_AddAudioDevice addfn;
+} sink_struct;

+static void get_sink_info_callback(pa_context *c, const pa_sink_info *i, int is_last, void *userdata)
+{

sink_struct *a = (sink_struct *) userdata;
a->last = is_last;
if(i)
{
```
  a->addfn(i->name);
```
}
+}

+void PULSEAUDIO_DetectDevices(int iscapture, SDL_AddAudioDevice addfn)
+{

struct SDL_PrivateAudioData *h = NULL;
struct SDL_PrivateAudioData *pulse_local_server = ThreadInit();
if(pulse_local_server == NULL)
{
```
   //Out of Memory
```
```
   return;
```
}
sink_struct a;
h = pulse_local_server;
if(iscapture != 1)
{
```
  a.last = 0;
```
```
  a.addfn = addfn;
```

  pa_operation* o = PULSEAUDIO_pa_context_get_sink_info_list(h->context, get_sink_info_callback, &a);

```
  while(!a.last)
```
```
  {
```

  	if(PULSEAUDIO_pa_operation_get_state(o) == PA_OPERATION_CANCELLED)

```
  	{
```
```
  		break;
```
```
  	}
```

  	if (PULSEAUDIO_pa_mainloop_iterate(h->mainloop, 1, NULL) < 0) {

```
  		break;
```
```
  	}
```
```
  }
```
}
DeInit(pulse_local_server);
+}

static int
PULSEAUDIO_Init(SDL_AudioDriverImpl * impl)
{
@@ -530,8 +611,9 @@
UnloadPulseAudioLibrary();
return 0;
}

/* Set the function pointers */
impl->DetectDevices = PULSEAUDIO_DetectDevices;
impl->OpenDevice = PULSEAUDIO_OpenDevice;
impl->PlayDevice = PULSEAUDIO_PlayDevice;
impl->WaitDevice = PULSEAUDIO_WaitDevice;
@@ -539,7 +621,7 @@
impl->CloseDevice = PULSEAUDIO_CloseDevice;
impl->WaitDone = PULSEAUDIO_WaitDone;
impl->Deinitialize = PULSEAUDIO_Deinitialize;

impl->OnlyHasDefaultOutputDevice = 1;

impl->OnlyHasDefaultOutputDevice = 0;

return 1; /* this audio target is available. /
}
diff -r 5bf21e9e191f src/audio/pulseaudio/SDL_pulseaudio.h
— a/src/audio/pulseaudio/SDL_pulseaudio.h Sun Sep 14 19:44:53 2014 +0200
+++ b/src/audio/pulseaudio/SDL_pulseaudio.h Sun Sep 14 21:40:27 2014 +0200
@@ -30,6 +30,7 @@
/ Hidden “this” pointer for the audio functions */
#define _THIS SDL_AudioDevice *this

struct SDL_PrivateAudioData
{
/* pulseaudio structures */

And I assume it is necessary to add: It is ok the add it to the SDL2 Codebase under the zlib license

void (*segfault)(void) = 0;
int main(int argc, char **argv){segfault(); return 0;}
//Should not work, but does what told

dfrizel · September 16, 2014, 5:39pm

Added it to bugzilla - have only found it today [Embarassed]------------------------
void (*segfault)(void) = 0;
int main(int argc, char **argv){segfault(); return 0;}
//Should not work, but does what told

Daniel_Holth · September 16, 2014, 8:20pm

That’s great, I’ve found it very frustrating trying to use HDMI audio -
maybe this will fix it.On Tue, Sep 16, 2014 at 1:39 PM, dfrizel <dominik.frizel at gmx.at> wrote:

Added it to bugzilla - have only found it today [image: Embarassed]

void (*segfault)(void) = 0;
int main(int argc, char **argv){segfault(); return 0;}
//Should not work, but does what told [image: Smile]

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Pulseaudio, selecting Audio Device + multiple Audio

static int PULSEAUDIO_Init(SDL_AudioDriverImpl * impl) { @@ -530,8 +611,9 @@ UnloadPulseAudioLibrary(); return 0; }

static int
PULSEAUDIO_Init(SDL_AudioDriverImpl * impl)
{
@@ -530,8 +611,9 @@
UnloadPulseAudioLibrary();
return 0;
}