将音频线性pcm转换为mp3(使用LAME)低、中、高音频质量设置

Question

我正在iOS中将LinearPCM编码为MP3。我正在尝试使用AudioToolbox框架和Lame将麦克风的原始PCM数据编码为MP3，尽管如果我录制音频，一切似乎都很好，但在Lame编码概念的帮助下，它被转换为MP3，同时播放录制的MP3音频文件。现在我想转换音频（使用Lame），如低、中、，高品质mp3文件。当lame转换过程时，我不知道确切的设置（采样率、比特深度、比特率、chennal、质量）

void AQRecorder::MyInputBufferHandler(  void *                              inUserData,
                                AudioQueueRef                       inAQ,
                                AudioQueueBufferRef                 inBuffer,
                                const AudioTimeStamp *              inStartTime,
                                UInt32                              inNumPackets,
                                const AudioStreamPacketDescription* inPacketDesc)
  {
  AQRecorder *aqr = (AQRecorder *)inUserData;
  //    NSLog(@"%f",inStartTime->mSampleTime);
  try
  {
    if (inNumPackets > 0)
    {
        AudioFileWritePackets(aqr->mRecordFile, FALSE, inBuffer->mAudioDataByteSize, inPacketDesc, aqr->mRecordPacket, &inNumPackets, inBuffer->mAudioData);
        aqr->mRecordPacket += inNumPackets;
        int MP3_SIZE =inBuffer->mAudioDataByteSize * 4;
        unsigned char mp3_buffer[MP3_SIZE];
        lame_t lame = lame_init();
        lame_set_in_samplerate(lame, 44100);
        lame_set_VBR(lame, vbr_default);
        lame_init_params(lame);
  //                int encodedBytes=lame_encode_buffer_interleaved(lame, (short int *)inBuffer->mAudioData , inNumPackets, mp3_buffer, MP3_SIZE);

        int encodedBytes = lame_encode_buffer(lame, (short*)inBuffer->mAudioData,  (short*)inBuffer->mAudioData, inNumPackets, mp3_buffer, MP3_SIZE);
        [delegate.mp3AudioData appendBytes:mp3_buffer length:encodedBytes];
        if (inBuffer->mAudioDataByteSize != 0) {
        }
        else
        {
            int encode=lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
            [delegate.mp3AudioData appendBytes:mp3_buffer length:encode];
        }
        lame_close(lame);
    }
    if (aqr->IsRunning())
    {
        AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL);
    }
  } catch (CAXException e)
 {
 char buf[256];
 fprintf(stderr, "Error: %s (%s)n", e.mOperation, e.FormatError(buf));
}
}

Answer 1

试试这个，

低质量：

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];
        NSMutableDictionary *dictAudioQuality =[[NSMutableDictionary alloc]init];
        [dictAudioQuality setValue:@"Low" forKey:@"audioquality"];
        [dictAudioQuality setValue:@"11025" forKey:@"samplerate"];
        [dictAudioQuality setValue:@"16" forKey:@"bitdepth"];
        [dictAudioQuality setValue:@"120" forKey:@"bitrate"];
        [dictAudioQuality setValue:@"1" forKey:@"channel"];

中等质量：

 AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];
        NSMutableDictionary *dictAudioQuality =[[NSMutableDictionary alloc]init];
        [dictAudioQuality setValue:@"Medium" forKey:@"audioquality"];
        [dictAudioQuality setValue:@"22050" forKey:@"samplerate"];
        [dictAudioQuality setValue:@"16" forKey:@"bitdepth"];
        [dictAudioQuality setValue:@"240" forKey:@"bitrate"];
        [dictAudioQuality setValue:@"1" forKey:@"channel"];

高质量：

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];
        NSMutableDictionary *dictAudioQuality =[[NSMutableDictionary alloc]init];
        [dictAudioQuality setValue:@"High" forKey:@"audioquality"];
        [dictAudioQuality setValue:@"44100" forKey:@"samplerate"];
        [dictAudioQuality setValue:@"24" forKey:@"bitdepth"];
        [dictAudioQuality setValue:@"320" forKey:@"bitrate"];
        [dictAudioQuality setValue:@"2" forKey:@"channel"];

AQRecorder.m开始记录

void AQRecorder::StartRecord(CFStringRef inRecordFile)
{
int i, bufferByteSize;
UInt32 size;
delegate =[[UIApplication sharedApplication]delegate];
nSampleRate =[[delegate.dictMP3Quality valueForKey:@"samplerate"] intValue];
nBitRate =[[delegate.dictMP3Quality valueForKey:@"bitrate"] intValue];
nChannel =[[delegate.dictMP3Quality valueForKey:@"channel"] intValue];
try {
    UInt32 category = kAudioSessionCategory_RecordAudio;
    OSStatus error = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category), &category);
    if (error) printf("couldn't set audio category!");
    // specify the recording format
    SetupAudioFormat(kAudioFormatLinearPCM);
    // create the queue
    XThrowIfError(AudioQueueNewInput(
                                     &mRecordFormat,
                                     MyInputBufferHandler,
                                     this /* userData */,
                                     NULL /* run loop */, NULL /* run loop mode */,
                                     0 /* flags */, &mQueue), "AudioQueueNewInput failed");
    // get the record format back from the queue's audio converter --
    // the file may require a more specific stream description than was necessary to create the encoder.
    mRecordPacket = 0;
    size = sizeof(mRecordFormat);
    XThrowIfError(AudioQueueGetProperty(mQueue, kAudioQueueProperty_StreamDescription,
                                        &mRecordFormat, &size), "couldn't get queue's format");
    // copy the cookie first to give the file object as much info as we can about the data going in
    // not necessary for pcm, but required for some compressed audio
    CopyEncoderCookieToFile();
    // allocate and enqueue buffers
    bufferByteSize = ComputeRecordBufferSize(&mRecordFormat, kBufferDurationSeconds);   // enough bytes for half a second
    for (i = 0; i < kNumberRecordBuffers; ++i) {
        XThrowIfError(AudioQueueAllocateBuffer(mQueue, bufferByteSize, &mBuffers[i]),
                      "AudioQueueAllocateBuffer failed");
        XThrowIfError(AudioQueueEnqueueBuffer(mQueue, mBuffers[i], 0, NULL),
                      "AudioQueueEnqueueBuffer failed");
    }
    // start the queue
    mIsRunning = true;
    XThrowIfError(AudioQueueStart(mQueue, NULL), "AudioQueueStart failed");
    lame = lame_init();
    lame_set_in_samplerate(lame, mRecordFormat.mSampleRate);
    lame_set_out_samplerate(lame, nSampleRate);
    lame_set_num_channels(lame, nChannel);
    //  lame_set_brate(lame, nBitRate);
    lame_set_VBR(lame, vbr_default);
    lame_init_params(lame);
}
catch (CAXException e) {
    char buf[256];
    fprintf(stderr, "Error: %s (%s)n", e.mOperation, e.FormatError(buf));
}
catch (...) {
    fprintf(stderr, "An unknown error occurredn");;
}
}

AQRecorder:：MyInputBufferHandler

void AQRecorder::MyInputBufferHandler(  void *                              inUserData,
                                  AudioQueueRef                     inAQ,
                                  AudioQueueBufferRef                   inBuffer,
                                  const AudioTimeStamp *                inStartTime,
                                  UInt32                                inNumPackets,
                                  const AudioStreamPacketDescription*   inPacketDesc)
{
AQRecorder *aqr = (AQRecorder *)inUserData;
try
{
    if (inNumPackets > 0)
    {
        AudioFileWritePackets(aqr->mRecordFile, FALSE, inBuffer->mAudioDataByteSize, inPacketDesc, aqr->mRecordPacket, &inNumPackets, inBuffer->mAudioData);
        aqr->mRecordPacket += inNumPackets;
        int MP3_SIZE =inNumPackets * 4;
        unsigned char mp3_buffer[MP3_SIZE];
        memset(mp3_buffer, 0, sizeof(mp3_buffer));
    //  int encodedBytes=lame_encode_buffer_interleaved(lame, (short int*)inBuffer->mAudioData , inNumPackets, mp3_buffer, MP3_SIZE);
        int encodedBytes = lame_encode_buffer(aqr->lame, (short int*)inBuffer->mAudioData,  (short int*)inBuffer->mAudioData, inNumPackets, mp3_buffer, MP3_SIZE);
        [aqr->delegate.mp3AudioData appendBytes:mp3_buffer length:encodedBytes];
        if (inBuffer->mAudioDataByteSize != 0) {
        }
        else
        {
            int encode=lame_encode_flush(aqr->lame, mp3_buffer, MP3_SIZE);
            [aqr->delegate.mp3AudioData appendBytes:mp3_buffer length:encode];
        }
        {
            NSLog(@"------------");
            NSLog(@"%d",encodedBytes);
            NSLog(@"%lu",inNumPackets);
            NSLog(@"%d",MP3_SIZE);
            NSLog(@"------------");
        }
    }
    if (aqr->IsRunning())
    {
        AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL);
    }
} catch (CAXException e)
{
    char buf[256];
    fprintf(stderr, "Error: %s (%s)n", e.mOperation, e.FormatError(buf));
}
}