Automatically select audio source

If --audio-source is not specified, select the default value
according to the video source:
 - for display mirroring, use device audio by default;
 - for camera mirroring, use microphone by default.

PR #4213 <https://github.com/Genymobile/scrcpy/pull/4213>

app/src/cli.c

@@ -2219,6 +2219,16 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
         return false;
     }
 
+    if (opts->audio && opts->audio_source == SC_AUDIO_SOURCE_AUTO) {
+        // Select the audio source according to the video source
+        if (opts->video_source == SC_VIDEO_SOURCE_DISPLAY) {
+            opts->audio_source = SC_AUDIO_SOURCE_OUTPUT;
+        } else {
+            opts->audio_source = SC_AUDIO_SOURCE_MIC;
+            LOGI("Camera video source: microphone audio source selected");
+        }
+    }
+
     if (opts->record_format && !opts->record_filename) {
         LOGE("Record format specified without recording");
         return false;

app/src/options.c

@@ -17,7 +17,7 @@ const struct scrcpy_options scrcpy_options_default = {
     .video_codec = SC_CODEC_H264,
     .audio_codec = SC_CODEC_OPUS,
     .video_source = SC_VIDEO_SOURCE_DISPLAY,
-    .audio_source = SC_AUDIO_SOURCE_OUTPUT,
+    .audio_source = SC_AUDIO_SOURCE_AUTO,
     .record_format = SC_RECORD_FORMAT_AUTO,
     .keyboard_input_mode = SC_KEYBOARD_INPUT_MODE_INJECT,
     .mouse_input_mode = SC_MOUSE_INPUT_MODE_INJECT,

app/src/options.h

@@ -50,6 +50,7 @@ enum sc_video_source {
 };
 
 enum sc_audio_source {
+    SC_AUDIO_SOURCE_AUTO, // OUTPUT for video DISPLAY, MIC for video CAMERA
     SC_AUDIO_SOURCE_OUTPUT,
     SC_AUDIO_SOURCE_MIC,
 };

app/src/server.c

@@ -253,8 +253,7 @@ execute_server(struct sc_server *server,
         assert(params->video_source == SC_VIDEO_SOURCE_CAMERA);
         ADD_PARAM("video_source=camera");
     }
-    if (params->audio_source != SC_AUDIO_SOURCE_OUTPUT) {
-        assert(params->audio_source == SC_AUDIO_SOURCE_MIC);
+    if (params->audio_source == SC_AUDIO_SOURCE_MIC) {
         ADD_PARAM("audio_source=mic");
     }
     if (params->max_size) {