Decode Opus and play using Alsa

CMakeLists.txt

@@ -16,9 +16,11 @@ find_package(Threads)
 find_package(CURL)
 find_package(OpenSSL)
 find_package(EXPAT)
+find_package(ALSA)
+find_package(Opus)
 
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(EVDEV libevdev)
 
-include_directories(./moonlight-common-c ${EVDEV_INCLUDE_DIRS})
+include_directories(./moonlight-common-c ${OPUS_INCLUDE_DIRS} ${EVDEV_INCLUDE_DIRS})
-target_link_libraries (moonlight PUBLIC ${CMAKE_THREAD_LIBS_INIT} ${CURL_LIBRARIES} ${OPENSSL_LIBRARIES} ${EXPAT_LIBRARIES} ${EVDEV_LIBRARIES})
+target_link_libraries (moonlight PUBLIC ${CMAKE_THREAD_LIBS_INIT} ${CURL_LIBRARIES} ${OPENSSL_LIBRARIES} ${EXPAT_LIBRARIES} ${EVDEV_LIBRARIES} ${ALSA_LIBRARY} ${OPUS_LIBRARY})

README.md

@@ -31,6 +31,7 @@ implementation.
 
 * Download [GeForce Experience](http://www.geforce.com/geforce-experience) and install on your Windows PC
 * Download the compiled version from the [GitHub releases page](https://github.com/irtimmer/moonlight-embedded/releases)
+* Install libopus0 (Debian/Raspbian) or opus (Arch Linux/Fedora/Pidora)
 * [Configure sound](http://elinux.org/R-Pi_Troubleshooting#Sound)
 
 ##Requirements
@@ -55,6 +56,7 @@ implementation.
 
 * Install cmake
 * Install cryptographics libraries libssl-dev (Debian/Raspbian) or openssl-devel (Fedora/Pidora) or openssl (Arch Linux)
+* Install audio libraries libopus-dev and libasound2-dev (Debian/Raspbian) or opus-devel and alsa-lib-devel (Fedora/Pidora) or opus and alsa-lib (Arch Linux)
 * Initialize the git submodules ``git submodule update --init``
 
 ```

src/audio.c

@@ -20,30 +20,91 @@
 #include "audio.h"
 
 #include <stdio.h>
+#include <opus.h>
+#include <alsa/asoundlib.h>
 
-static FILE* fd;
+#define CHECK_RETURN(f) if ((rc = f) < 0) { printf("Alsa error code %d\n", rc); exit(-1); }
-static const char* fileName = "fake.opus";
 
-void audio_renderer_init() {
+#define SAMPLE_RATE 48000
+#define CHANNEL_COUNT 2
+#define FRAME_SIZE 240
+
+static const char* device = "default";
+
+static snd_pcm_t *handle;
+static OpusDecoder* decoder;
+static short pcmBuffer[FRAME_SIZE * CHANNEL_COUNT];
+
+static void audio_renderer_init() {
   printf("audio_renderer_init\n");
-  fd = fopen(fileName, "w");
+  int rc;
+  decoder = opus_decoder_create(SAMPLE_RATE, CHANNEL_COUNT, &rc);
+
+  snd_pcm_hw_params_t *hw_params;
+  snd_pcm_sw_params_t *sw_params;
+  snd_pcm_uframes_t period_size = FRAME_SIZE * CHANNEL_COUNT * 2;
+  snd_pcm_uframes_t buffer_size = 12 * period_size;
+  unsigned int sampleRate = SAMPLE_RATE;
+
+  /* Open PCM device for playback. */
+  CHECK_RETURN(snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK))
+
+  /* Set hardware parameters */
+  CHECK_RETURN(snd_pcm_hw_params_malloc(&hw_params));
+  CHECK_RETURN(snd_pcm_hw_params_any(handle, hw_params));
+  CHECK_RETURN(snd_pcm_hw_params_set_access(handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED));
+  CHECK_RETURN(snd_pcm_hw_params_set_format(handle, hw_params, SND_PCM_FORMAT_S16_LE));
+  CHECK_RETURN(snd_pcm_hw_params_set_rate_near(handle, hw_params, &sampleRate, NULL));
+  CHECK_RETURN(snd_pcm_hw_params_set_channels(handle, hw_params, CHANNEL_COUNT));
+  CHECK_RETURN(snd_pcm_hw_params_set_buffer_size_near(handle, hw_params, &buffer_size));
+  CHECK_RETURN(snd_pcm_hw_params_set_period_size_near(handle, hw_params, &period_size, NULL));
+  CHECK_RETURN(snd_pcm_hw_params(handle, hw_params));
+  snd_pcm_hw_params_free(hw_params);
+
+  /* Set software parameters */
+  CHECK_RETURN(snd_pcm_sw_params_malloc(&sw_params));
+  CHECK_RETURN(snd_pcm_sw_params_current(handle, sw_params));
+  CHECK_RETURN(snd_pcm_sw_params_set_start_threshold(handle, sw_params, buffer_size - period_size));
+  CHECK_RETURN(snd_pcm_sw_params_set_avail_min(handle, sw_params, period_size));
+  CHECK_RETURN(snd_pcm_sw_params(handle, sw_params));
+  snd_pcm_sw_params_free(sw_params);
+
+  CHECK_RETURN(snd_pcm_prepare(handle));
 }
 
-void audio_renderer_start() {
+static void audio_renderer_start() {
   printf("audio_renderer_start\n");
 }
 
-void audio_renderer_stop() {
+static void audio_renderer_stop() {
   printf("audio_renderer_stop\n");
 }
 
-void audio_renderer_release() {
+static void audio_renderer_release() {
   printf("audio_renderer_release\n");
-  fclose(fd);
+  if (decoder != NULL)
+    opus_decoder_destroy(decoder);
+
+  if (handle != NULL) {
+    snd_pcm_drain(handle);
+    snd_pcm_close(handle);
+  }
 }
 
-void audio_renderer_decode_and_play_sample(char* data, int length) {
+static void audio_renderer_decode_and_play_sample(char* data, int length) {
-  fwrite(data, length, 1, fd);
+  int decodeLen = opus_decode(decoder, data, length, pcmBuffer, FRAME_SIZE, 0);
+  if (decodeLen > 0) {
+    int rc = snd_pcm_writei(handle, pcmBuffer, decodeLen);
+    if (rc == -EPIPE)
+      snd_pcm_recover(handle, rc, 1);
+
+    if (rc<0)
+      printf("Alsa error from writei: %d\n", rc);
+    else if (decodeLen != rc)
+      printf("Alsa shortm write, write %d frames\n", rc);
+  } else {
+    printf("Opus error from decode: %d\n", decodeLen);
+  }
 }
 
 AUDIO_RENDERER_CALLBACKS audio_callbacks = {