OSStatus 错误 -50（参数无效）AudioQueueNewInput 在 iOS 上录制音频

Question

我已经在互联网上搜索了很长时间，试图找到这个错误的原因，但我被卡住了。我一直在关注有关使用音频服务录制音频的 Apple Developer 文档，但无论我做什么，我都会收到此错误。

我可以使用 AVAudioRecorder 将音频录制成任何格式，但我的最终目标是从输入数据中获取标准化的浮点数组，以便对其应用 FFT（抱歉我的菜鸟措辞我对音频编程还很陌生）。

这是我的代码：

- (void)beginRecording
{
    // Initialise session
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];
    [[AVAudioSession sharedInstance] setActive:YES error:nil];

    state.dataFormat.mFormatID = kAudioFormatLinearPCM;
    state.dataFormat.mSampleRate = 8000.0f;
    state.dataFormat.mChannelsPerFrame = 1;
    state.dataFormat.mBitsPerChannel = 16;
    state.dataFormat.mBytesPerPacket = state.dataFormat.mChannelsPerFrame * sizeof(SInt16);
    state.dataFormat.mFramesPerPacket = 1;

    //AudioFileTypeID fileID = kAudioFileAIFFType;

    state.dataFormat.mFormatFlags = kLinearPCMFormatFlagIsBigEndian | kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked;

    OSStatus err = AudioQueueNewInput(&state.dataFormat, handleInputBuffer, &state, CFRunLoopGetMain(), kCFRunLoopCommonModes, 0, &state.queue);
    printf("%i", err); // this is always -50 i.e. invalid parameters error

    deriveBufferSize(state.queue, state.dataFormat, 0.5, &state.bufferByteState);

    for (int i = 0; i < kNumberOfBuffers; i++) {
        AudioQueueAllocateBuffer(state.queue, state.bufferByteState, &state.buffers[i]);
        AudioQueueEnqueueBuffer(state.queue, state.buffers[i], 0, NULL);
    }

    state.currentPacket = 0;
    state.isRunning = YES;

    AudioQueueStart(state.queue, NULL);
}

- (void)endRecording
{
    AudioQueueStop(state.queue, YES);
    state.isRunning = NO;

    AudioQueueDispose(state.queue, YES);

    // Close the audio file here...
}

#pragma mark - CoreAudio

// Core Audio Callback Function
static void handleInputBuffer(void *agData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer, const AudioTimeStamp *inStartTime, UInt32 inNumPackets, const AudioStreamPacketDescription *inPacketDesc) {

    AQRecorderState *state = (AQRecorderState *)agData;

    if (inNumPackets == 0 && state->dataFormat.mBytesPerPacket != 0) {
        inNumPackets = inBuffer->mAudioDataByteSize / state->dataFormat.mBytesPerPacket;
    }

    printf("Called");

    /*
    if (AudioFileWritePackets(state->audioFile, false, inBuffer->mAudioDataByteSize, inPacketDesc, state->currentPacket, &inNumPackets, inBuffer->mAudioData) == noErr) {
        state->currentPacket += inNumPackets;
    }
     */

    if (state->isRunning) {
        AudioQueueEnqueueBuffer(state->queue, inBuffer, 0, NULL);
    }
}

void deriveBufferSize(AudioQueueRef audioQueue, AudioStreamBasicDescription ABSDescription, Float64 secs, UInt32 *outBufferSize) {

    static const int maxBufferSize = 0x50000;

    int maxPacketSize = ABSDescription.mBytesPerPacket;
    if (maxPacketSize == 0) {
        UInt32 maxVBRPacketSize = sizeof(maxPacketSize);
        AudioQueueGetProperty(audioQueue, kAudioConverterPropertyMaximumOutputPacketSize, &maxPacketSize, &maxVBRPacketSize);
    }

    Float64 numBytesForTime = ABSDescription.mSampleRate * maxPacketSize * secs;
    UInt32 x = (numBytesForTime < maxBufferSize ? numBytesForTime : maxBufferSize);
    *outBufferSize = x;
}

如果有人知道这里发生了什么，我将不胜感激。 Here is the apple docs for the error

Answer 1

你得到 -50 (kAudio_ParamError) 因为你还没有初始化 AudioStreamBasicDescription 的 mBytesPerFrame 字段:

asbd.mBytesPerFrame = asbd.mFramesPerPacket*asbd.mBytesPerPacket;

其中 asbd 是 state.dataFormat 的缩写。在你的情况下 mBytesPerFrame = 2.

我也不会指定 kLinearPCMFormatFlagIsBigEndian，让记录器 return 你本机字节顺序样本。

OSStatus 错误 -50（参数无效）AudioQueueNewInput 在 iOS 上录制音频

OSStatus error -50 (invalid parameters) AudioQueueNewInput recording audio on iOS

objective-c

core-audio

ios