ebiten/audio/internal/driver/driver_android.go

// Copyright 2016 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package driver

/*

#cgo LDFLAGS: -llog

#include <android/log.h>
#include <jni.h>
#include <stdlib.h>

// __android_log_print(ANDROID_LOG_ERROR, "NativeCode", "foo", "bar");

static char* initAudioTrack(uintptr_t java_vm, uintptr_t jni_env,
    int sampleRate, int channelNum, int bytesPerSample, jobject* audioTrack, int* bufferSize) {
  *bufferSize = 0;
  JavaVM* vm = (JavaVM*)java_vm;
  JNIEnv* env = (JNIEnv*)jni_env;

  const jclass android_media_AudioFormat =
      (*env)->FindClass(env, "android/media/AudioFormat");
  const jclass android_media_AudioManager =
      (*env)->FindClass(env, "android/media/AudioManager");
  const jclass android_media_AudioTrack =
      (*env)->FindClass(env, "android/media/AudioTrack");

  const jint android_media_AudioManager_STREAM_MUSIC =
      (*env)->GetStaticIntField(
          env, android_media_AudioManager,
          (*env)->GetStaticFieldID(env, android_media_AudioManager, "STREAM_MUSIC", "I"));
  const jint android_media_AudioTrack_MODE_STREAM =
      (*env)->GetStaticIntField(
          env, android_media_AudioTrack,
          (*env)->GetStaticFieldID(env, android_media_AudioTrack, "MODE_STREAM", "I"));
  const jint android_media_AudioTrack_WRITE_BLOCKING =
      (*env)->GetStaticIntField(
          env, android_media_AudioTrack,
          (*env)->GetStaticFieldID(env, android_media_AudioTrack, "WRITE_BLOCKING", "I"));
  const jint android_media_AudioFormat_CHANNEL_OUT_MONO =
      (*env)->GetStaticIntField(
          env, android_media_AudioFormat,
          (*env)->GetStaticFieldID(env, android_media_AudioFormat, "CHANNEL_OUT_MONO", "I"));
  const jint android_media_AudioFormat_CHANNEL_OUT_STEREO =
      (*env)->GetStaticIntField(
          env, android_media_AudioFormat,
          (*env)->GetStaticFieldID(env, android_media_AudioFormat, "CHANNEL_OUT_STEREO", "I"));
  const jint android_media_AudioFormat_ENCODING_PCM_8BIT =
      (*env)->GetStaticIntField(
          env, android_media_AudioFormat,
          (*env)->GetStaticFieldID(env, android_media_AudioFormat, "ENCODING_PCM_8BIT", "I"));
  const jint android_media_AudioFormat_ENCODING_PCM_16BIT =
      (*env)->GetStaticIntField(
          env, android_media_AudioFormat,
          (*env)->GetStaticFieldID(env, android_media_AudioFormat, "ENCODING_PCM_16BIT", "I"));

  jint channel = android_media_AudioFormat_CHANNEL_OUT_MONO;
  switch (channelNum) {
  case 1:
    channel = android_media_AudioFormat_CHANNEL_OUT_MONO;
    break;
  case 2:
    channel = android_media_AudioFormat_CHANNEL_OUT_STEREO;
    break;
  default:
    return "invalid channel";
  }

  jint encoding = android_media_AudioFormat_ENCODING_PCM_8BIT;
  switch (bytesPerSample) {
  case 1:
    encoding = android_media_AudioFormat_ENCODING_PCM_8BIT;
    break;
  case 2:
    encoding = android_media_AudioFormat_ENCODING_PCM_16BIT;
    break;
  default:
    return "invalid bytesPerSample";
  }

  *bufferSize =
      (*env)->CallStaticIntMethod(
          env, android_media_AudioTrack,
          (*env)->GetStaticMethodID(env, android_media_AudioTrack, "getMinBufferSize", "(III)I"),
          sampleRate, channel, encoding);

  const jobject tmpAudioTrack =
      (*env)->NewObject(
          env, android_media_AudioTrack,
          (*env)->GetMethodID(env, android_media_AudioTrack, "<init>", "(IIIIII)V"),
          android_media_AudioManager_STREAM_MUSIC,
          sampleRate, channel, encoding, *bufferSize,
          android_media_AudioTrack_MODE_STREAM);
  // Note that *audioTrack will never be released.
  *audioTrack = (*env)->NewGlobalRef(env, tmpAudioTrack);

  // Enqueue empty bytes before playing to avoid underrunning.
  // TODO: Is this really needed? At least, SDL doesn't do the same thing.
  jint writtenBytes = 0;
  do {
    const int length = 1024;
    jbyteArray arr = (*env)->NewByteArray(env, length);
    writtenBytes =
        (*env)->CallIntMethod(
            env, *audioTrack,
            (*env)->GetMethodID(env, android_media_AudioTrack, "write", "([BIII)I"),
            arr, 0, length, android_media_AudioTrack_WRITE_BLOCKING);
  } while (writtenBytes != 0);
  // TODO: Check if writtenBytes < 0

  (*env)->CallVoidMethod(
      env, *audioTrack,
      (*env)->GetMethodID(env, android_media_AudioTrack, "play", "()V"));

  return NULL;
}

static char* writeToAudioTrack(uintptr_t java_vm, uintptr_t jni_env,
    jobject audioTrack, int bytesPerSample, void* data, int length) {
  JavaVM* vm = (JavaVM*)java_vm;
  JNIEnv* env = (JNIEnv*)jni_env;

  const jclass android_media_AudioTrack =
      (*env)->FindClass(env, "android/media/AudioTrack");
  const jint android_media_AudioTrack_WRITE_NON_BLOCKING =
      (*env)->GetStaticIntField(
          env, android_media_AudioTrack,
          (*env)->GetStaticFieldID(env, android_media_AudioTrack, "WRITE_NON_BLOCKING", "I"));

  jbyteArray arrInBytes;
  jshortArray arrInShorts;
  switch (bytesPerSample) {
  case 1:
    arrInBytes = (*env)->NewByteArray(env, length);
    (*env)->SetByteArrayRegion(env, arrInBytes, 0, length, data);
    break;
  case 2:
    arrInShorts = (*env)->NewShortArray(env, length);
    (*env)->SetShortArrayRegion(env, arrInShorts, 0, length, data);
    break;
  }
  int i = 0;
  for (i = 0; i < length;) {
    jint result = 0;
    switch (bytesPerSample) {
    case 1:
      result =
          (*env)->CallIntMethod(
              env, audioTrack,
              (*env)->GetMethodID(env, android_media_AudioTrack, "write", "([BIII)I"),
              arrInBytes, i, length - i, android_media_AudioTrack_WRITE_NON_BLOCKING);
      break;
    case 2:
      result =
          (*env)->CallIntMethod(
              env, audioTrack,
              (*env)->GetMethodID(env, android_media_AudioTrack, "write", "([SIII)I"),
              arrInShorts, i, length - i, android_media_AudioTrack_WRITE_NON_BLOCKING);
      break;
    }
    i += result;
  }

  // TODO: Check the result.
  return NULL;
}

*/
import "C"

import (
	"errors"
	"unsafe"

	"github.com/hajimehoshi/ebiten/internal/jni"
)

type Player struct {
	sampleRate     int
	channelNum     int
	bytesPerSample int
	audioTrack     C.jobject
	buffer         []byte
	bufferSize     int
	chErr          chan error
	chBuffer       chan []byte
}

func NewPlayer(sampleRate, channelNum, bytesPerSample int) (*Player, error) {
	p := &Player{
		sampleRate:     sampleRate,
		channelNum:     channelNum,
		bytesPerSample: bytesPerSample,
		buffer:         []byte{},
		chErr:          make(chan error),
		chBuffer:       make(chan []byte),
	}
	if err := jni.RunOnJVM(func(vm, env, ctx uintptr) error {
		audioTrack := C.jobject(nil)
		bufferSize := C.int(0)
		if msg := C.initAudioTrack(C.uintptr_t(vm), C.uintptr_t(env),
			C.int(sampleRate), C.int(channelNum), C.int(bytesPerSample),
			&audioTrack, &bufferSize); msg != nil {
			return errors.New("driver: " + C.GoString(msg))
		}
		p.audioTrack = audioTrack
		p.bufferSize = int(bufferSize)
		return nil
	}); err != nil {
		return nil, err
	}
	go p.loop()
	return p, nil
}

func (p *Player) loop() {
	for bufInBytes := range p.chBuffer {
		var bufInShorts []int16
		if p.bytesPerSample == 2 {
			bufInShorts = make([]int16, len(bufInBytes)/2)
			for i := 0; i < len(bufInShorts); i++ {
				bufInShorts[i] = int16(bufInBytes[2*i]) | (int16(bufInBytes[2*i+1]) << 8)
			}
		}

		if err := jni.RunOnJVM(func(vm, env, ctx uintptr) error {
			msg := (*C.char)(nil)
			switch p.bytesPerSample {
			case 1:
				msg = C.writeToAudioTrack(C.uintptr_t(vm), C.uintptr_t(env),
					p.audioTrack, C.int(p.bytesPerSample),
					unsafe.Pointer(&bufInBytes[0]), C.int(len(bufInBytes)))
			case 2:
				msg = C.writeToAudioTrack(C.uintptr_t(vm), C.uintptr_t(env),
					p.audioTrack, C.int(p.bytesPerSample),
					unsafe.Pointer(&bufInShorts[0]), C.int(len(bufInShorts)))
			}
			if msg != nil {
				return errors.New(C.GoString(msg))
			}
			return nil
		}); err != nil {
			p.chErr <- err
			return
		}
	}
}

func (p *Player) Proceed(data []byte) error {
	p.buffer = append(p.buffer, data...)
	if len(p.buffer) < p.bufferSize {
		return nil
	}
	buf := p.buffer[:p.bufferSize]
	select {
	case p.chBuffer <- buf:
	case err := <-p.chErr:
		return err
	}
	p.buffer = p.buffer[p.bufferSize:]
	return nil
}

func (p *Player) Close() error {
	return nil
}