我有工作代码将 wav 转换为 m4a。无论如何通过修改我现有的代码将 mp3 转换为 m4a。我不想使用 ffmpeg 或本机代码。下面的函数适用于 wav 到 m4a 的转换，但不是为 mp3 到 m4a 工作
public void convertAudio(final String filename) {
final String AUDIO_RECORDING_FILE_NAME = Config.mp3Audio; // Input PCM file
final String COMPRESSED_AUDIO_FILE_NAME = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC).getPath()
+ "/convertedmp4.m4a"; // Output MP4/M4A file
final String COMPRESSED_AUDIO_FILE_MIME_TYPE = "audio/mp4a-latm";
final int COMPRESSED_AUDIO_FILE_BIT_RATE = 320000; // 64kbps
final int SAMPLING_RATE = 22050;
final int BUFFER_SIZE = 22050;
final int CODEC_TIMEOUT_IN_MS = 5000;
String LOGTAG = "CONVERT AUDIO";
try {
File inputFile = new File(filename);
FileInputStream fis = new FileInputStream(inputFile);
File outputFile = new File(COMPRESSED_AUDIO_FILE_NAME);
if (outputFile.exists()) outputFile.delete();
MediaMuxer mux = new MediaMuxer(outputFile.getAbsolutePath(), MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
MediaFormat outputFormat = MediaFormat.createAudioFormat(COMPRESSED_AUDIO_FILE_MIME_TYPE, SAMPLING_RATE, 1);
outputFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
outputFormat.setInteger(MediaFormat.KEY_BIT_RATE, COMPRESSED_AUDIO_FILE_BIT_RATE);
outputFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 16384);
MediaCodec codec = MediaCodec.createEncoderByType(COMPRESSED_AUDIO_FILE_MIME_TYPE);
codec.configure(outputFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
codec.start();
ByteBuffer[] codecInputBuffers = codec.getInputBuffers(); // Note: Array of buffers
ByteBuffer[] codecOutputBuffers = codec.getOutputBuffers();
MediaCodec.BufferInfo outBuffInfo = new MediaCodec.BufferInfo();
byte[] tempBuffer = new byte[BUFFER_SIZE];
boolean hasMoreData = true;
double presentationTimeUs = 0;
int audioTrackIdx = 0;
int totalBytesRead = 0;
int percentComplete = 0;
do {
int inputBufIndex = 0;
while (inputBufIndex != -1 && hasMoreData) {
inputBufIndex = codec.dequeueInputBuffer(CODEC_TIMEOUT_IN_MS);
if (inputBufIndex >= 0) {
ByteBuffer dstBuf = codecInputBuffers[inputBufIndex];
dstBuf.clear();
int bytesRead = fis.read(tempBuffer, 0, dstBuf.limit());
if (bytesRead == -1) { // -1 implies EOS
hasMoreData = false;
codec.queueInputBuffer(inputBufIndex, 0, 0, (long) presentationTimeUs, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
} else {
totalBytesRead += bytesRead;
dstBuf.put(tempBuffer, 0, bytesRead);
codec.queueInputBuffer(inputBufIndex, 0, bytesRead, (long) presentationTimeUs, 0);
presentationTimeUs = 1000000l * (totalBytesRead / 2) / SAMPLING_RATE;
}
}
}
int outputBufIndex = 0;
while (outputBufIndex != MediaCodec.INFO_TRY_AGAIN_LATER) {
outputBufIndex = codec.dequeueOutputBuffer(outBuffInfo, CODEC_TIMEOUT_IN_MS);
if (outputBufIndex >= 0) {
ByteBuffer encodedData = codecOutputBuffers[outputBufIndex];
encodedData.position(outBuffInfo.offset);
encodedData.limit(outBuffInfo.offset + outBuffInfo.size);
if ((outBuffInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0 && outBuffInfo.size != 0) {
codec.releaseOutputBuffer(outputBufIndex, false);
} else {
mux.writeSampleData(audioTrackIdx, codecOutputBuffers[outputBufIndex], outBuffInfo);
codec.releaseOutputBuffer(outputBufIndex, false);
}
} else if (outputBufIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
outputFormat = codec.getOutputFormat();
audioTrackIdx = mux.addTrack(outputFormat);
mux.start();
} else if (outputBufIndex == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
} else if (outputBufIndex == MediaCodec.INFO_TRY_AGAIN_LATER) {
// NO OP
} else {
}
}
percentComplete = (int) Math.round(((float) totalBytesRead / (float) inputFile.length()) * 100.0);
} while (outBuffInfo.flags != MediaCodec.BUFFER_FLAG_END_OF_STREAM);
fis.close();
mux.stop();
mux.release();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}