blocks|key|783827|text|您应该能够从sampleBuffRef获取音频缓冲区，然后迭代这些值以构建波形：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|783828|CMBlockBufferRef+buffer+=+CMSampleBufferGetDataBuffer(+sampleBufferRef+);
CMItemCount+numSamplesInBuffer+=+CMSampleBufferGetNumSamples(sampleBufferRef);
AudioBufferList+audioBufferList;
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++sampleBufferRef,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++NULL,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++&audioBufferList,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++sizeof(audioBufferList),
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++NULL,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++NULL,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++&buffer
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++);

//+this+copies+your+audio+out+to+a+temp+buffer+but+you+should+be+able+to+iterate+through+this+buffer+instead
SInt32*+readBuffer+=+(SInt32+*)malloc(numSamplesInBuffer+*+sizeof(SInt32));
memcpy(+readBuffer,+audioBufferList.mBuffers[0].mData,+numSamplesInBuffer*sizeof(SInt32));|code-block|syntax|javascript|783829|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You should be able to get a buffer of audio from your sampleBuffRef and then iterate through those values to build your waveform:

<pre><code>CMBlockBufferRef buffer = CMSampleBufferGetDataBuffer( sampleBufferRef );
CMItemCount numSamplesInBuffer = CMSampleBufferGetNumSamples(sampleBufferRef);
AudioBufferList audioBufferList;
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
 sampleBufferRef,
 NULL,
 &amp;audioBufferList,
 sizeof(audioBufferList),
 NULL,
 NULL,
 kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment,
 &amp;buffer
 );

// this copies your audio out to a temp buffer but you should be able to iterate through this buffer instead
SInt32* readBuffer = (SInt32 *)malloc(numSamplesInBuffer * sizeof(SInt32));
memcpy( readBuffer, audioBufferList.mBuffers[0].mData, numSamplesInBuffer*sizeof(SInt32));
</code></pre>

blocks|key|783857|text|另一种使用Swift+5并使用AVAudioFile的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|783858|///Gets+the+audio+file+from+an+URL,+downsaples+and+draws+into+the+sound+layer.
func+drawSoundWave(fromURL+url:URL,+fromPosition:Int64,+totalSeconds:UInt32,+samplesSecond:CGFloat)+throws{

++++print("\(logClassName)+Drawing+sound+from+\(url)")

++++do{
++++++++waveViewInfo.samplesSeconds+=+samplesSecond

++++++++//Get+audio+file+and+format+from+URL
++++++++let+audioFile+=+try+AVAudioFile(forReading:+url)

++++++++waveViewInfo.format+=+audioFile.processingFormat
++++++++audioFile.framePosition+=+fromPosition+*+Int64(waveViewInfo.format.sampleRate)

++++++++//Getting+the+buffer
++++++++let+frameCapacity:UInt32+=+totalSeconds+*+UInt32(waveViewInfo.format.sampleRate)

++++++++guard+let+audioPCMBuffer+=+AVAudioPCMBuffer(pcmFormat:+waveViewInfo.format,+frameCapacity:+frameCapacity)+else{+throw+AppError("Unable+to+get+the+AVAudioPCMBuffer")+}
++++++++try+audioFile.read(into:+audioPCMBuffer,+frameCount:+frameCapacity)
++++++++let+audioPCMBufferFloatValues:[Float]+=+Array(UnsafeBufferPointer(start:+audioPCMBuffer.floatChannelData?.pointee,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++count:+Int(audioPCMBuffer.frameLength)))

++++++++waveViewInfo.points+=+[]
++++++++waveViewInfo.maxValue+=+0
++++++++for+index+in+stride(from:+0,+to:+audioPCMBufferFloatValues.count,+by:+Int(audioFile.fileFormat.sampleRate)+/+Int(waveViewInfo.samplesSeconds)){

++++++++++++let+aSample+=+CGFloat(audioPCMBufferFloatValues[index])
++++++++++++waveViewInfo.points.append(aSample)
++++++++++++let+fix+=+abs(aSample)
++++++++++++if+fix+>+waveViewInfo.maxValue{
++++++++++++++++waveViewInfo.maxValue+=+fix
++++++++++++}

++++++++}

++++++++print("\(logClassName)+Finished+the+points+-+Count+=+\(waveViewInfo.points.count)+/+Max+=+\(waveViewInfo.maxValue)")

++++++++populateSoundImageView(with:+waveViewInfo)

++++}
++++catch{

++++++++throw+error

++++}

}

///Converts+the+sound+wave+in+to+a+UIImage
func+populateSoundImageView(with+waveViewInfo:WaveViewInfo){

++++let+imageSize:CGSize+=+CGSize(width:+CGFloat(waveViewInfo.points.count),//CGFloat(waveViewInfo.points.count)+*+waveViewInfo.sampleSpace,
++++++++++++++++++++++++++++++++++height:+frame.height)
++++let+drawingRect+=+CGRect(origin:+.zero,+size:+imageSize)

++++UIGraphicsBeginImageContextWithOptions(imageSize,+false,+0)
++++defer+{
++++++++UIGraphicsEndImageContext()
++++}
++++print("\(logClassName)+Converting+sound+view+in+rect+\(drawingRect)")

++++guard+let+context:CGContext+=+UIGraphicsGetCurrentContext()+else{+return+}

++++context.setFillColor(waveViewInfo.backgroundColor.cgColor)
++++context.setAlpha(1.0)
++++context.fill(drawingRect)
++++context.setLineWidth(1.0)
++++//++++++++context.setLineWidth(waveViewInfo.lineWidth)

++++let+sampleAdjustFactor+=+imageSize.height+/+waveViewInfo.maxValue
++++for+pointIndex+in+waveViewInfo.points.indices{

++++++++let+pixel+=+waveViewInfo.points[pointIndex]+*+sampleAdjustFactor

++++++++context.move(to:+CGPoint(x:+CGFloat(pointIndex),+y:+middleY+-+pixel))
++++++++context.addLine(to:+CGPoint(x:+CGFloat(pointIndex),+y:+middleY+%2B+pixel))

++++++++context.setStrokeColor(waveViewInfo.strokeColor.cgColor)
++++++++context.strokePath()

++++}

+++++//++++++++for+pointIndex+in+waveViewInfo.points.indices{
++++//
++++//++++++++++++let+pixel+=+waveViewInfo.points[pointIndex]+*+sampleAdjustFactor
++++//
++++//++++++++++++context.move(to:+CGPoint(x:+CGFloat(pointIndex)+*+waveViewInfo.sampleSpace,+y:+middleY+-+pixel))
++++//++++++++++++context.addLine(to:+CGPoint(x:+CGFloat(pointIndex)+*+waveViewInfo.sampleSpace,+y:+middleY+%2B+pixel))
++++//
++++//++++++++++++context.setStrokeColor(waveViewInfo.strokeColor.cgColor)
++++//++++++++++++context.strokePath()
++++//
++++//++++++++}

++++//++++++++var+xIncrement:CGFloat+=+0
++++//++++++++for+point+in+waveViewInfo.points{
++++//
++++//++++++++++++let+normalizedPoint+=+point+*+sampleAdjustFactor
++++//
++++//++++++++++++context.move(to:+CGPoint(x:+xIncrement,+y:+middleY+-+normalizedPoint))
++++//++++++++++++context.addLine(to:+CGPoint(x:+xIncrement,+y:+middleX+%2B+normalizedPoint))
++++//++++++++++++context.setStrokeColor(waveViewInfo.strokeColor.cgColor)
++++//++++++++++++context.strokePath()
++++//
++++//++++++++++++xIncrement+%2B=+waveViewInfo.sampleSpace
++++//
++++//++++++++}

++++guard+let+soundWaveImage+=+UIGraphicsGetImageFromCurrentImageContext()+else{+return+}

++++soundWaveImageView.image+=+soundWaveImage
++++//++++++++//In+case+of+handling+sample+space+in+for
++++//++++++++updateWidthConstraintValue(soundWaveImage.size.width)
++++updateWidthConstraintValue(soundWaveImage.size.width+*+waveViewInfo.sampleSpace)

}|code-block|syntax|javascript|783859|哪里|783860|class+WaveViewInfo+{

++++var+format:AVAudioFormat!
++++var+samplesSeconds:CGFloat+=+50
++++var+lineWidth:CGFloat+=+0.20
++++var+sampleSpace:CGFloat+=+0.20

++++var+strokeColor:UIColor+=+.red
++++var+backgroundColor:UIColor+=+.clear

++++var+maxValue:CGFloat+=+0
++++var+points:[CGFloat]+=+[CGFloat]()

}|783861|目前只打印一个声波，但它可以扩展。好处是你可以按部分打印音轨。|783862|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Another approach using Swift 5 and using AVAudioFile:

<pre><code>///Gets the audio file from an URL, downsaples and draws into the sound layer.
func drawSoundWave(fromURL url:URL, fromPosition:Int64, totalSeconds:UInt32, samplesSecond:CGFloat) throws{

 print("\(logClassName) Drawing sound from \(url)")

 do{
 waveViewInfo.samplesSeconds = samplesSecond

 //Get audio file and format from URL
 let audioFile = try AVAudioFile(forReading: url)

 waveViewInfo.format = audioFile.processingFormat
 audioFile.framePosition = fromPosition * Int64(waveViewInfo.format.sampleRate)

 //Getting the buffer
 let frameCapacity:UInt32 = totalSeconds * UInt32(waveViewInfo.format.sampleRate)

 guard let audioPCMBuffer = AVAudioPCMBuffer(pcmFormat: waveViewInfo.format, frameCapacity: frameCapacity) else{ throw AppError("Unable to get the AVAudioPCMBuffer") }
 try audioFile.read(into: audioPCMBuffer, frameCount: frameCapacity)
 let audioPCMBufferFloatValues:[Float] = Array(UnsafeBufferPointer(start: audioPCMBuffer.floatChannelData?.pointee,
 count: Int(audioPCMBuffer.frameLength)))

 waveViewInfo.points = []
 waveViewInfo.maxValue = 0
 for index in stride(from: 0, to: audioPCMBufferFloatValues.count, by: Int(audioFile.fileFormat.sampleRate) / Int(waveViewInfo.samplesSeconds)){

 let aSample = CGFloat(audioPCMBufferFloatValues[index])
 waveViewInfo.points.append(aSample)
 let fix = abs(aSample)
 if fix &gt; waveViewInfo.maxValue{
 waveViewInfo.maxValue = fix
 }

 }

 print("\(logClassName) Finished the points - Count = \(waveViewInfo.points.count) / Max = \(waveViewInfo.maxValue)")

 populateSoundImageView(with: waveViewInfo)

 }
 catch{

 throw error

 }

}

///Converts the sound wave in to a UIImage
func populateSoundImageView(with waveViewInfo:WaveViewInfo){

 let imageSize:CGSize = CGSize(width: CGFloat(waveViewInfo.points.count),//CGFloat(waveViewInfo.points.count) * waveViewInfo.sampleSpace,
 height: frame.height)
 let drawingRect = CGRect(origin: .zero, size: imageSize)

 UIGraphicsBeginImageContextWithOptions(imageSize, false, 0)
 defer {
 UIGraphicsEndImageContext()
 }
 print("\(logClassName) Converting sound view in rect \(drawingRect)")

 guard let context:CGContext = UIGraphicsGetCurrentContext() else{ return }

 context.setFillColor(waveViewInfo.backgroundColor.cgColor)
 context.setAlpha(1.0)
 context.fill(drawingRect)
 context.setLineWidth(1.0)
 // context.setLineWidth(waveViewInfo.lineWidth)

 let sampleAdjustFactor = imageSize.height / waveViewInfo.maxValue
 for pointIndex in waveViewInfo.points.indices{

 let pixel = waveViewInfo.points[pointIndex] * sampleAdjustFactor

 context.move(to: CGPoint(x: CGFloat(pointIndex), y: middleY - pixel))
 context.addLine(to: CGPoint(x: CGFloat(pointIndex), y: middleY + pixel))

 context.setStrokeColor(waveViewInfo.strokeColor.cgColor)
 context.strokePath()

 }

 // for pointIndex in waveViewInfo.points.indices{
 //
 // let pixel = waveViewInfo.points[pointIndex] * sampleAdjustFactor
 //
 // context.move(to: CGPoint(x: CGFloat(pointIndex) * waveViewInfo.sampleSpace, y: middleY - pixel))
 // context.addLine(to: CGPoint(x: CGFloat(pointIndex) * waveViewInfo.sampleSpace, y: middleY + pixel))
 //
 // context.setStrokeColor(waveViewInfo.strokeColor.cgColor)
 // context.strokePath()
 //
 // }

 // var xIncrement:CGFloat = 0
 // for point in waveViewInfo.points{
 //
 // let normalizedPoint = point * sampleAdjustFactor
 //
 // context.move(to: CGPoint(x: xIncrement, y: middleY - normalizedPoint))
 // context.addLine(to: CGPoint(x: xIncrement, y: middleX + normalizedPoint))
 // context.setStrokeColor(waveViewInfo.strokeColor.cgColor)
 // context.strokePath()
 //
 // xIncrement += waveViewInfo.sampleSpace
 //
 // }

 guard let soundWaveImage = UIGraphicsGetImageFromCurrentImageContext() else{ return }

 soundWaveImageView.image = soundWaveImage
 // //In case of handling sample space in for
 // updateWidthConstraintValue(soundWaveImage.size.width)
 updateWidthConstraintValue(soundWaveImage.size.width * waveViewInfo.sampleSpace)

}
</code></pre>

WHERE

<pre><code>class WaveViewInfo {

 var format:AVAudioFormat!
 var samplesSeconds:CGFloat = 50
 var lineWidth:CGFloat = 0.20
 var sampleSpace:CGFloat = 0.20

 var strokeColor:UIColor = .red
 var backgroundColor:UIColor = .clear

 var maxValue:CGFloat = 0
 var points:[CGFloat] = [CGFloat]()

}
</code></pre>

At the moment only prints one sound wave but it can be extended. The good part is that you can print an audio track by parts

I reading song from iPod library using assetUrl (in code it named audioUrl)
I can play it many ways, I can cut it, I can make some precessing with this but...
I really don't understand what I gonna do with this CMSampleBufferRef to get data for drawing waveform! I need info about peak values, how I can get it this (maybe another) way? 

<pre><code> AVAssetTrack * songTrack = [audioUrl.tracks objectAtIndex:0];
 AVAssetReaderTrackOutput * output = [[AVAssetReaderTrackOutput alloc] initWithTrack:songTrack outputSettings:nil];
 [reader addOutput:output];
 [output release];

 NSMutableData * fullSongData = [[NSMutableData alloc] init];
 [reader startReading];

 while (reader.status == AVAssetReaderStatusReading){

 AVAssetReaderTrackOutput * trackOutput = 
 (AVAssetReaderTrackOutput *)[reader.outputs objectAtIndex:0];

 CMSampleBufferRef sampleBufferRef = [trackOutput copyNextSampleBuffer];

 if (sampleBufferRef){/* what I gonna do with this? */}
</code></pre>

Please help me!

Drawing waveform with AVAssetReader

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我使用assetUrl (代码名为audioUrl)从iPod库中读取歌曲，我可以用多种方式播放它，我可以剪切它，我可以用它进行一些处理，但是……我真的不明白我该怎么用这个CMSampleBufferRef来获取绘制波形的数据！我需要关于峰值的信息，我如何才能以这种(也许是另一种)方式获得它？    AVAssetTr...

问用AVAssetReader绘制波形
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