From 409f627cf80b7a00752085b4321e590d8e2c8cfc Mon Sep 17 00:00:00 2001
From: Matthias Ringwald <matthias@ringwald.ch>
Date: Tue, 14 May 2024 12:19:55 +0200
Subject: [PATCH] portaudio: allow to select sink/source audio device

---
 platform/posix/btstack_audio_portaudio.c | 84 +++++++++++++++++++-----
 src/btstack_audio.h                      |  4 ++
 2 files changed, 70 insertions(+), 18 deletions(-)

diff --git a/platform/posix/btstack_audio_portaudio.c b/platform/posix/btstack_audio_portaudio.c
index 5683f0e64..44d1c6c1e 100644
--- a/platform/posix/btstack_audio_portaudio.c
+++ b/platform/posix/btstack_audio_portaudio.c
@@ -64,6 +64,9 @@ static int                    num_channels_source;
 static int                    num_bytes_per_sample_sink;
 static int                    num_bytes_per_sample_source;
 
+static const char * sink_device_name;
+static const char * source_device_name = "4-chan";
+
 // portaudio
 static int portaudio_initialized;
 
@@ -227,24 +230,42 @@ static int btstack_audio_portaudio_sink_init(
         portaudio_initialized = 1;        
     }
 
-    /* -- setup output -- */
-    PaStreamParameters theOutputParameters;
-    theOutputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */
-    theOutputParameters.channelCount = channels;
-    theOutputParameters.sampleFormat = PA_SAMPLE_TYPE;
-    theOutputParameters.suggestedLatency = Pa_GetDeviceInfo( theOutputParameters.device )->defaultHighOutputLatency;
-    theOutputParameters.hostApiSpecificStreamInfo = NULL;
+    /* -- find output device by name if requested -- */
+    PaDeviceIndex device_index = -1;
+    const PaDeviceInfo *output_device_info;
+    if (sink_device_name != NULL){
+        int num_devices = Pa_GetDeviceCount();
+        for (int i = 0; i < num_devices; i++) {
+            output_device_info = Pa_GetDeviceInfo(i);
+            // Match device by prefix
+            if (strncmp(output_device_info->name, sink_device_name, strlen(sink_device_name)) == 0) {
+                device_index = i;
+                break;
+            }
+        }
+    }
 
-    const PaDeviceInfo *outputDeviceInfo;
-    outputDeviceInfo = Pa_GetDeviceInfo( theOutputParameters.device );
-    log_info("PortAudio: sink device: %s", outputDeviceInfo->name);
-    UNUSED(outputDeviceInfo);
+    /* -- use default device otherwise -- */
+    if (device_index < 0){
+        device_index = Pa_GetDefaultOutputDevice();
+        output_device_info = Pa_GetDeviceInfo(device_index );
+    }
+    /* -- setup output -- */
+    PaStreamParameters output_parameters;
+    output_parameters.device = device_index;
+    output_parameters.channelCount = channels;
+    output_parameters.sampleFormat = PA_SAMPLE_TYPE;
+    output_parameters.suggestedLatency = output_device_info->defaultHighOutputLatency;
+    output_parameters.hostApiSpecificStreamInfo = NULL;
+
+    log_info("PortAudio: sink device: %s", output_device_info->name);
+    UNUSED(output_device_info);
 
     /* -- setup stream -- */
     err = Pa_OpenStream(
            &stream_sink,
            NULL,
-           &theOutputParameters,
+           &output_parameters,
            samplerate,
            NUM_FRAMES_PER_PA_BUFFER,
            paClipOff,           /* we won't output out of range samples so don't bother clipping them */
@@ -300,18 +321,37 @@ static int btstack_audio_portaudio_source_init(
         portaudio_initialized = 1;        
     }
 
+    /* -- find input device by name if requested -- */
+    PaDeviceIndex device_index = -1;
+    const PaDeviceInfo *input_device_info;
+    if (source_device_name != NULL){
+        int num_devices = Pa_GetDeviceCount();
+        for (int i = 0; i < num_devices; i++) {
+            input_device_info = Pa_GetDeviceInfo(i);
+            // Match device by prefix
+            if (strncmp(input_device_info->name, source_device_name, strlen(source_device_name)) == 0) {
+                device_index = i;
+                break;
+            }
+        }
+    }
+
+    /* -- use default device otherwise -- */
+    if (device_index < 0){
+        device_index = Pa_GetDefaultInputDevice();
+        input_device_info = Pa_GetDeviceInfo(device_index );
+    }
+
     /* -- setup input -- */
     PaStreamParameters theInputParameters;
-    theInputParameters.device = Pa_GetDefaultInputDevice(); /* default input device */
+    theInputParameters.device = device_index;
     theInputParameters.channelCount = channels;
     theInputParameters.sampleFormat = PA_SAMPLE_TYPE;
-    theInputParameters.suggestedLatency = Pa_GetDeviceInfo( theInputParameters.device )->defaultHighInputLatency;
+    theInputParameters.suggestedLatency = input_device_info->defaultHighInputLatency;
     theInputParameters.hostApiSpecificStreamInfo = NULL;
 
-    const PaDeviceInfo *inputDeviceInfo;
-    inputDeviceInfo = Pa_GetDeviceInfo( theInputParameters.device );
-    log_info("PortAudio: source device: %s", inputDeviceInfo->name);
-    UNUSED(inputDeviceInfo);
+    log_info("PortAudio: source device: %s", input_device_info->name);
+    UNUSED(input_device_info);
 
     /* -- setup stream -- */
     err = Pa_OpenStream(
@@ -512,4 +552,12 @@ const btstack_audio_source_t * btstack_audio_portaudio_source_get_instance(void)
     return &btstack_audio_portaudio_source;
 }
 
+void btstack_audio_portaudio_sink_set_device(const char * device_name){
+    sink_device_name = device_name;
+}
+
+void btstack_audio_portaudio_source_set_device(const char * device_name){
+    source_device_name = device_name;
+}
+
 #endif
diff --git a/src/btstack_audio.h b/src/btstack_audio.h
index 6c669ac2c..e19099837 100644
--- a/src/btstack_audio.h
+++ b/src/btstack_audio.h
@@ -177,6 +177,10 @@ const btstack_audio_source_t * btstack_audio_embedded_source_get_instance(void);
 const btstack_audio_sink_t *    btstack_audio_esp32_sink_get_instance(void);
 const btstack_audio_source_t *  btstack_audio_esp32_source_get_instance(void);
 
+// platform-specific extension
+void btstack_audio_portaudio_sink_set_device(const char * device_name);
+void btstack_audio_portaudio_source_set_device(const char * device_name);
+
 /* API_END */
 
 #if defined __cplusplus