Replace Javax Sound with direct alsa access

build.xml

@@ -9,6 +9,7 @@
   
   <property name="libs.opus.dir" location="${basedir}/jni/nv_opus_dec/"/>
   <property name="libs.omx.dir" location="${basedir}/jni/nv_omx_dec/"/>
+  <property name="libs.alsa.dir" location="${basedir}/jni/nv_alsa/"/>
   
   <property name="lib.dir" location="${basedir}/lib"/>
   <property name="build.dir" location="${basedir}/build"/>
@@ -38,6 +39,7 @@
   <target name="compile-native">
 	  <exec executable="./build.sh" dir="${libs.omx.dir}"/>
 	  <exec executable="./build.sh" dir="${libs.opus.dir}"/>
+	  <exec executable="./build.sh" dir="${libs.alsa.dir}"/>
   </target>
   
   <target name="compile-java" depends="init">
@@ -81,6 +83,7 @@
       <binlib>
         <fileset dir="${libs.opus.dir}" includes="*.so"/>
         <fileset dir="${libs.omx.dir}" includes="*.so"/>
+		<fileset dir="${libs.alsa.dir}" includes="*.so"/>
       </binlib>
     </one-jar>
   </target>

jni/nv_alsa/build.sh

@@ -0,0 +1,4 @@
+rm *.o libnv_alsa.so
+gcc -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -I /opt/vc/include -I/opt/vc/include/interface/vcos/pthreads -I/opt/vc/include/interface/vmcs_host/linux -I ./inc -fPIC -L. -c *.c
+gcc -shared -Wl,-soname,libnv_alsa.so -Wl,--no-undefined -o libnv_alsa.so *.o -L. -lasound
+rm *.o

jni/nv_alsa/nv_alsa.c

@@ -0,0 +1,54 @@
+/* Use the newer ALSA API */
+#define ALSA_PCM_NEW_HW_PARAMS_API
+
+/* All of the ALSA library API is defined
+ * in this header */
+#include <alsa/asoundlib.h>
+
+snd_pcm_t *handle;
+
+int nv_alsa_init(unsigned int channelCount, unsigned int sampleRate) {
+	int rc;
+	snd_pcm_hw_params_t *params;
+	int dir;
+	
+	/* Open PCM device for playback. */
+	if ((rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0)) != 0)
+		return rc;
+	
+	snd_pcm_hw_params_alloca(&params);
+	snd_pcm_hw_params_any(handle, params);
+	
+	snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
+	snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);
+	snd_pcm_hw_params_set_channels(handle, params, channelCount);
+	snd_pcm_hw_params_set_rate_near(handle, params, &sampleRate, &dir);
+	
+	snd_pcm_uframes_t frames = 32;
+	snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);
+	
+	if ((rc = snd_pcm_hw_params(handle, params)) != 0)
+		return rc;
+}
+
+int nv_alsa_play(const unsigned char* indata, int data_len) {
+	int frames = data_len/4; /* 2 bytes/sample, 2 channels */
+	int rc = snd_pcm_writei(handle, indata, frames);
+	if (rc == -EPIPE) {
+		/* EPIPE means underrun */
+		fprintf(stderr, "underrun occurred\n");
+		snd_pcm_prepare(handle);
+	} else if (rc < 0) {
+		fprintf(stderr,
+			"error from writei: %s\n",
+			snd_strerror(rc));
+	} else if (rc != (int) frames) {
+		fprintf(stderr,
+			"short write, write %d frames\n", rc);
+	}	
+}
+
+int nv_alsa_close(void) {
+	snd_pcm_drain(handle);
+	snd_pcm_close(handle);
+}

jni/nv_alsa/nv_alsa.h

@@ -0,0 +1,5 @@
+#include <jni.h>
+
+int nv_alsa_init(unsigned int channelCount, unsigned int sampleRate);
+int nv_alsa_play(unsigned char* indata, int inlen);
+void nv_alsa_close(void);

jni/nv_alsa/nv_alsa_jni.c

@@ -0,0 +1,36 @@
+#include "nv_alsa.h"
+
+#include <stdlib.h>
+#include <jni.h>
+
+// This function must be called before
+// any other decoding functions
+JNIEXPORT jint JNICALL
+Java_com_limelight_binding_audio_AlsaAudio_init(JNIEnv *env, jobject this, jint channelCount, jint sampleRate)
+{
+	return nv_alsa_init(channelCount, sampleRate);
+}
+
+JNIEXPORT void JNICALL
+Java_com_limelight_binding_audio_AlsaAudio_close(JNIEnv *env, jobject this)
+{
+	nv_alsa_close();
+}
+
+JNIEXPORT jint JNICALL
+Java_com_limelight_binding_audio_AlsaAudio_play(
+	JNIEnv *env, jobject this, // JNI parameters
+	jbyteArray indata, jint inoff, jint inlen)
+{
+	jint ret;
+	jbyte* jni_input_data;
+
+	jni_input_data = (*env)->GetByteArrayElements(env, indata, 0);
+
+	ret = nv_alsa_play(&jni_input_data[inoff], inlen);
+
+	// The input data isn't changed so it can be safely aborted
+	(*env)->ReleaseByteArrayElements(env, indata, jni_input_data, JNI_ABORT);
+	
+	return ret;
+}

src/com/limelight/binding/PlatformBinding.java

@@ -3,7 +3,7 @@ package com.limelight.binding;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 
-import com.limelight.binding.audio.JavaxAudioRenderer;
+import com.limelight.binding.audio.AlsaAudioRenderer;
 import com.limelight.binding.video.OmxDecoderRenderer;
 import com.limelight.nvstream.av.audio.AudioRenderer;
 import com.limelight.nvstream.av.video.VideoDecoderRenderer;
@@ -40,6 +40,6 @@ public class PlatformBinding {
 	 * @return an audio decoder and renderer
 	 */
 	public static AudioRenderer getAudioRenderer() {
-		return new JavaxAudioRenderer();
+		return new AlsaAudioRenderer();
 	}
 }

src/com/limelight/binding/audio/AlsaAudio.java

@@ -0,0 +1,17 @@
+package com.limelight.binding.audio;
+
+/**
+ * JNI Alsa bindings
+ * @author Iwan Timmer
+ */
+public class AlsaAudio {
+	static {
+		System.loadLibrary("nv_alsa");
+	}
+	
+	public static native int init(int channelCount, int sampleRate);
+	
+	public static native void close();
+	
+	public static native int play(byte[] indata, int inoff, int inlen);
+}

src/com/limelight/binding/audio/AlsaAudioRenderer.java

@@ -0,0 +1,26 @@
+package com.limelight.binding.audio;
+
+import com.limelight.nvstream.av.audio.AudioRenderer;
+
+/**
+ * Audio renderer implementation
+ * @author Iwan Timmer
+ */
+public class AlsaAudioRenderer implements AudioRenderer {
+
+	@Override
+	public void streamInitialized(int channelCount, int sampleRate) {
+		AlsaAudio.init(channelCount, sampleRate);
+	}
+
+	@Override
+	public void playDecodedAudio(byte[] bytes, int offset, int length) {
+		AlsaAudio.play(bytes, offset, length);
+	}
+
+	@Override
+	public void streamClosing() {
+		AlsaAudio.close();
+	}
+	
+}

src/com/limelight/binding/audio/JavaxAudioRenderer.java

@@ -1,87 +0,0 @@
-package com.limelight.binding.audio;
-
-import javax.sound.sampled.AudioFormat;
-import javax.sound.sampled.AudioSystem;
-import javax.sound.sampled.DataLine;
-import javax.sound.sampled.LineUnavailableException;
-import javax.sound.sampled.SourceDataLine;
-
-import com.limelight.nvstream.av.audio.AudioRenderer;
-import java.nio.ByteOrder;
-
-/**
- * Audio renderer implementation
- * @author Cameron Gutman<br>
- * Iwan Timmer
- */
-public class JavaxAudioRenderer implements AudioRenderer {
-
-	private SourceDataLine soundLine;
-	private int channelCount;
-	private int sampleRate;
-	
-	public static final int DEFAULT_BUFFER_SIZE = 4096;
-	
-	/**
-	 * Takes some audio data and writes it out to the renderer.
-	 * @param pcmData the array that contains the audio data
-	 * @param offset the offset at which the data starts in the array
-	 * @param length the length of data to be rendered
-	 */
-	@Override
-	public void playDecodedAudio(byte[] pcmData, int offset, int length) {
-		soundLine.write(pcmData, offset, length);
-	}
-
-	/**
-	 * Callback for when the stream session is closing and the audio renderer should stop.
-	 */
-	@Override
-	public void streamClosing() {
-		if (soundLine != null) {
-			soundLine.close();
-		}
-	}
-
-	private void createSoundLine(int bufferSize) {
-		AudioFormat audioFormat = new AudioFormat(sampleRate, 16, channelCount, true, ByteOrder.nativeOrder()==ByteOrder.BIG_ENDIAN);
-		
-		DataLine.Info info;
-		
-		if (bufferSize == DEFAULT_BUFFER_SIZE) {
-			info = new DataLine.Info(SourceDataLine.class, audioFormat);
-		}
-		else {
-			info = new DataLine.Info(SourceDataLine.class, audioFormat, bufferSize);
-		}
-		
-		try {
-			soundLine = (SourceDataLine) AudioSystem.getLine(info);
-			
-			if (bufferSize == DEFAULT_BUFFER_SIZE) {
-				soundLine.open(audioFormat);
-			}
-			else {
-				soundLine.open(audioFormat, bufferSize);
-			}
-			
-			soundLine.start();
-		} catch (LineUnavailableException e) {
-			soundLine = null;
-		}
-	}
-
-	/**
-	 * The callback for the audio stream being initialized and starting to receive.
-	 * @param channelCount the number of channels in the audio
-	 * @param sampleRate the sample rate for the audio.
-	 */
-	@Override
-	public void streamInitialized(int channelCount, int sampleRate) {
-		this.channelCount = channelCount;
-		this.sampleRate = sampleRate;
-		
-		createSoundLine(DEFAULT_BUFFER_SIZE);
-	}
-
-}