UI: Allow outputs to use different audio codecs

Allows an output to automatically specify which audio codec it requires
and use it instead of AAC.  This change is intended to be
behind-the-scenes and seamless to the user.

UI/window-basic-auto-config-test.cpp

@@ -268,6 +268,16 @@ void AutoConfigTestPage::TestBandwidthThread()
 	obs_output_release(output);
 	obs_output_update(output, output_settings);
 
+	const char *audio_codec =
+		obs_output_get_supported_audio_codecs(output);
+
+	if (strcmp(audio_codec, "aac") != 0) {
+		const char *id = FindAudioEncoderFromCodec(audio_codec);
+		aencoder = obs_audio_encoder_create(id,
+				"test_audio", nullptr, 0, nullptr);
+		obs_encoder_release(aencoder);
+	}
+
 	/* -----------------------------------*/
 	/* connect encoders/services/outputs  */