Question

我正在尝试以40ms的段录制音频。音频队列接口可以处理40ms音频帧吗？如果'是'那么我们怎样才能实现呢？

感谢。

Answer 1

是的，它可能，您需要设置配置AudioQueue相应地，

基本上AudioQueue Buffer的大小，必须设置为40ms，所以它会在，

int AQRecorder::ComputeRecordBufferSize(const AudioStreamBasicDescription *format, float seconds)
{
    int packets, frames, bytes = 0;
    try {
        frames = (int)ceil(seconds * format->mSampleRate);

        if (format->mBytesPerFrame > 0)
            bytes = frames * format->mBytesPerFrame;
        else {
            UInt32 maxPacketSize;
            if (format->mBytesPerPacket > 0)
                maxPacketSize = format->mBytesPerPacket;    // constant packet size
            else {
                UInt32 propertySize = sizeof(maxPacketSize);
                XThrowIfError(AudioQueueGetProperty(mQueue, kAudioQueueProperty_MaximumOutputPacketSize, &maxPacketSize,
                                                    &propertySize), "couldn't get queue's maximum output packet size");
            }
            if (format->mFramesPerPacket > 0)
                packets = frames / format->mFramesPerPacket;
            else
                packets = frames;   // worst-case scenario: 1 frame in a packet
            if (packets == 0)       // sanity check
                packets = 1;
            bytes = packets * maxPacketSize;
        }
    } catch (CAXException e) {
        char buf[256];
        return 0;
    }   
    return bytes;
}

并设置格式

void AQRecorder::SetupAudioFormat(UInt32 inFormatID)
{
    AudioStreamBasicDescription sRecordFormat;
    FillOutASBDForLPCM (sRecordFormat,
                        SAMPLING_RATE,
                        1,
                        8*BYTES_PER_PACKET,
                        8*BYTES_PER_PACKET,
                        false,
                        false
                        );
    memset(&mRecordFormat, 0, sizeof(mRecordFormat));

    mRecordFormat.SetFrom(sRecordFormat);
}

对于我的情况，这些宏的值是，

#define SAMPLING_RATE 16000
#define kNumberRecordBuffers    3
#define BYTES_PER_PACKET 2

音频队列接口可以处理40ms音频帧吗？

1 个答案: