AC3 passthrough support

Second version after Tanu's feedback

TODO:
    - notify client that volume control is disabled
    - change sink rate in passthrough mode if needed
    - automatic detection of passthrough mode instead of hard
    coded profile names

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@intel.com>

src/pulsecore/protocol-native.c

@@ -1873,7 +1873,9 @@ static void command_create_playback_stream(pa_pdispatch *pd, uint32_t command, u
         dont_inhibit_auto_suspend = FALSE,
         muted_set = FALSE,
         fail_on_suspend = FALSE,
-        relative_volume = FALSE;
+        relative_volume = FALSE,
+        passthrough = FALSE;
+
     pa_sink_input_flags_t flags = 0;
     pa_proplist *p;
     pa_bool_t volume_set = TRUE;
@@ -1975,6 +1977,15 @@ static void command_create_playback_stream(pa_pdispatch *pd, uint32_t command, u
         }
     }
 
+    if (c->version >= 18) {
+
+        if (pa_tagstruct_get_boolean(t, &passthrough) < 0 ) {
+            protocol_error(c);
+            pa_proplist_free(p);
+            return;
+        }
+    }
+
     if (!pa_tagstruct_eof(t)) {
         protocol_error(c);
         pa_proplist_free(p);
@@ -2008,7 +2019,8 @@ static void command_create_playback_stream(pa_pdispatch *pd, uint32_t command, u
         (no_move ?  PA_SINK_INPUT_DONT_MOVE : 0) |
         (variable_rate ?  PA_SINK_INPUT_VARIABLE_RATE : 0) |
         (dont_inhibit_auto_suspend ? PA_SINK_INPUT_DONT_INHIBIT_AUTO_SUSPEND : 0) |
-        (fail_on_suspend ? PA_SINK_INPUT_NO_CREATE_ON_SUSPEND|PA_SINK_INPUT_KILL_ON_SUSPEND : 0);
+        (fail_on_suspend ? PA_SINK_INPUT_NO_CREATE_ON_SUSPEND|PA_SINK_INPUT_KILL_ON_SUSPEND : 0) |
+        (passthrough ? PA_SINK_INPUT_PASSTHROUGH : 0);
 
     /* Only since protocol version 15 there's a seperate muted_set
      * flag. For older versions we synthesize it here */

src/pulsecore/sink-input.c

@@ -55,6 +55,39 @@ static void sink_input_volume_ramping(pa_sink_input* i, pa_memchunk* chunk);
 static void sink_input_rewind_ramp_info(pa_sink_input *i, size_t nbytes);
 static void sink_input_release_envelope(pa_sink_input *i);
 
+static int check_passthrough_connection(pa_sink_input_flags_t flags, pa_sink *dest) {
+
+    if (dest->flags & PA_SINK_PASSTHROUGH) {
+
+        if (pa_idxset_size(dest->inputs) > 0) {
+
+            pa_sink_input *alt_i;
+            uint32_t idx;
+
+            alt_i = pa_idxset_first(dest->inputs, &idx);
+
+            /* only need to check the first input is not PASSTHROUGH */
+            if (alt_i->flags & PA_SINK_INPUT_PASSTHROUGH) {
+                pa_log_warn("Sink is already connected to PASSTHROUGH input");
+                return -PA_ERR_BUSY;
+            }
+
+            /* Current inputs are PCM, check new input is not PASSTHROUGH */
+            if (flags & PA_SINK_INPUT_PASSTHROUGH) {
+                pa_log_warn("Sink is already connected, cannot accept new PASSTHROUGH INPUT");
+                return -PA_ERR_BUSY;
+            }
+        }
+
+    } else {
+         if (flags & PA_SINK_INPUT_PASSTHROUGH) {
+             pa_log_warn("Cannot connect PASSTHROUGH sink input to sink without PASSTHROUGH capabilities");
+             return -PA_ERR_INVALID;
+         }
+    }
+    return PA_OK;
+}
+
 pa_sink_input_new_data* pa_sink_input_new_data_init(pa_sink_input_new_data *data) {
     pa_assert(data);
 
@@ -183,6 +216,9 @@ int pa_sink_input_new(
     pa_return_val_if_fail(PA_SINK_IS_LINKED(pa_sink_get_state(data->sink)), -PA_ERR_BADSTATE);
     pa_return_val_if_fail(!data->sync_base || (data->sync_base->sink == data->sink && pa_sink_input_get_state(data->sync_base) == PA_SINK_INPUT_CORKED), -PA_ERR_INVALID);
 
+    r = check_passthrough_connection(data->flags, data->sink);
+    pa_return_val_if_fail(r == PA_OK, r);
+
     if (!data->sample_spec_is_set)
         data->sample_spec = data->sink->sample_spec;
 
@@ -1020,6 +1056,11 @@ static void set_real_ratio(pa_sink_input *i, const pa_cvolume *v) {
 
 /* Called from main context */
 void pa_sink_input_set_volume(pa_sink_input *i, const pa_cvolume *volume, pa_bool_t save, pa_bool_t absolute) {
+
+    /* Do not allow for volume changes for non-audio types */
+    if (i->flags & PA_SINK_INPUT_PASSTHROUGH)
+        return;
+
     /* test ramping -> return pa_sink_input_set_volume_with_ramping(i, volume, save, absolute, 2000 * PA_USEC_PER_MSEC); */
     return pa_sink_input_set_volume_with_ramping(i, volume, save, absolute, 0);
 }
@@ -1162,6 +1203,9 @@ pa_bool_t pa_sink_input_may_move_to(pa_sink_input *i, pa_sink *dest) {
         return FALSE;
     }
 
+    if (check_passthrough_connection(i->flags, dest) < 0)
+        return FALSE;
+
     if (i->may_move_to)
         if (!i->may_move_to(i, dest))
             return FALSE;

src/pulsecore/sink-input.h

@@ -61,7 +61,8 @@ typedef enum pa_sink_input_flags {
     PA_SINK_INPUT_FIX_CHANNELS = 128,
     PA_SINK_INPUT_DONT_INHIBIT_AUTO_SUSPEND = 256,
     PA_SINK_INPUT_NO_CREATE_ON_SUSPEND = 512,
-    PA_SINK_INPUT_KILL_ON_SUSPEND = 1024
+    PA_SINK_INPUT_KILL_ON_SUSPEND = 1024,
+    PA_SINK_INPUT_PASSTHROUGH = 2048
 } pa_sink_input_flags_t;
 
 struct pa_sink_input {

src/pulsecore/sink.c

@@ -1393,6 +1393,24 @@ void pa_sink_set_volume(
     pa_assert(volume || (s->flags & PA_SINK_FLAT_VOLUME));
     pa_assert(!volume || volume->channels == 1 || pa_cvolume_compatible(volume, &s->sample_spec));
 
+    /* make sure we don't change the volume when a PASSTHROUGH input is connected */
+    if (s->flags & PA_SINK_PASSTHROUGH) {
+        pa_sink_input *alt_i;
+        uint32_t idx;
+
+        /* one and only one PASSTHROUGH input can possibly be connected */
+        if (pa_idxset_size(s->inputs) == 1) {
+
+            alt_i = pa_idxset_first(s->inputs, &idx);
+
+            if (alt_i->flags & PA_SINK_INPUT_PASSTHROUGH) {
+                /* FIXME: Need to notify client that volume control is disabled */
+                pa_log_warn("Cannot change volume, Sink is connected to PASSTHROUGH input");
+                return;
+            }
+        }
+    }
+
     /* As a special exception we accept mono volumes on all sinks --
      * even on those with more complex channel maps */