快速使用AVCaptureAudioDataOutputSampleBufferDelegate捕获音量级别 [英] Capturing volume levels with AVCaptureAudioDataOutputSampleBufferDelegate in swift
本文介绍了快速使用AVCaptureAudioDataOutputSampleBufferDelegate捕获音量级别的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试使用AVCaptureDevice等编译并运行的实时音量级别,但这些值似乎是随机的,并且我还会不断出现溢出错误.
RMS范围在0到20000左右也正常吗?
if let audioCaptureDevice : AVCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeAudio){
try audioCaptureDevice.lockForConfiguration()
let audioInput = try AVCaptureDeviceInput(device: audioCaptureDevice)
audioCaptureDevice.unlockForConfiguration()
if(captureSession.canAddInput(audioInput)){
captureSession.addInput(audioInput)
print("added input")
}
let audioOutput = AVCaptureAudioDataOutput()
audioOutput.setSampleBufferDelegate(self, queue: GlobalUserInitiatedQueue)
if(captureSession.canAddOutput(audioOutput)){
captureSession.addOutput(audioOutput)
print("added output")
}
//supposed to start session not on UI queue coz it takes a while
dispatch_async(GlobalUserInitiatedQueue) {
print("starting captureSession")
self.captureSession.startRunning()
}
}
...
func captureOutput(captureOutput: AVCaptureOutput!, let didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {
// Needs to be initialized somehow, even if we take only the address
var audioBufferList = AudioBufferList(mNumberBuffers: 1,
mBuffers: AudioBuffer(mNumberChannels: 1, mDataByteSize: 0, mData: nil))
//this needs to be in method otherwise only runs 125 times?
var blockBuffer: CMBlockBuffer?
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
sampleBuffer,
nil,
&audioBufferList,
sizeof(audioBufferList.dynamicType),
nil,
nil,
UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
&buffer
)
let abl = UnsafeMutableAudioBufferListPointer(&audioBufferList)
for buffer in abl{
let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(buffer.mData),
count: Int(buffer.mDataByteSize)/sizeof(Int16))
var sum:Int = 0
for sample in samples {
sum = sum + Int(sample*sample)
}
let rms = sqrt(Double(sum)/count)
}
解决方案
看来我正在使用它.在进行任何操作之前,我已将sample
强制转换为Int64
.
for buffer in abl{
let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(buffer.mData),
count: Int(buffer.mDataByteSize)/sizeof(Int16))
var sum:Int64 = 0
for sample in samples {
let s = Int64(sample)
sum +=s*s
}
dispatch_async(dispatch_get_main_queue()) {
self.volLevel.text = String(sqrt(Float(sum/Int64(samples.count))))
}
I'm trying to live volume levels using AVCaptureDevice etc it compiles and runs but the values just seem to be random and I keep getting overflow errors as well.
EDIT:
also is it normal for the RMS range to be 0 to about 20000?
if let audioCaptureDevice : AVCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeAudio){
try audioCaptureDevice.lockForConfiguration()
let audioInput = try AVCaptureDeviceInput(device: audioCaptureDevice)
audioCaptureDevice.unlockForConfiguration()
if(captureSession.canAddInput(audioInput)){
captureSession.addInput(audioInput)
print("added input")
}
let audioOutput = AVCaptureAudioDataOutput()
audioOutput.setSampleBufferDelegate(self, queue: GlobalUserInitiatedQueue)
if(captureSession.canAddOutput(audioOutput)){
captureSession.addOutput(audioOutput)
print("added output")
}
//supposed to start session not on UI queue coz it takes a while
dispatch_async(GlobalUserInitiatedQueue) {
print("starting captureSession")
self.captureSession.startRunning()
}
}
...
func captureOutput(captureOutput: AVCaptureOutput!, let didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {
// Needs to be initialized somehow, even if we take only the address
var audioBufferList = AudioBufferList(mNumberBuffers: 1,
mBuffers: AudioBuffer(mNumberChannels: 1, mDataByteSize: 0, mData: nil))
//this needs to be in method otherwise only runs 125 times?
var blockBuffer: CMBlockBuffer?
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
sampleBuffer,
nil,
&audioBufferList,
sizeof(audioBufferList.dynamicType),
nil,
nil,
UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
&buffer
)
let abl = UnsafeMutableAudioBufferListPointer(&audioBufferList)
for buffer in abl{
let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(buffer.mData),
count: Int(buffer.mDataByteSize)/sizeof(Int16))
var sum:Int = 0
for sample in samples {
sum = sum + Int(sample*sample)
}
let rms = sqrt(Double(sum)/count)
}
解决方案
It appears I have it working. I casted sample
to an Int64
before doing any manipulations.
for buffer in abl{
let samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(buffer.mData),
count: Int(buffer.mDataByteSize)/sizeof(Int16))
var sum:Int64 = 0
for sample in samples {
let s = Int64(sample)
sum +=s*s
}
dispatch_async(dispatch_get_main_queue()) {
self.volLevel.text = String(sqrt(Float(sum/Int64(samples.count))))
}
这篇关于快速使用AVCaptureAudioDataOutputSampleBufferDelegate捕获音量级别的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文