Question

我正在寻找如何绘制声音幅度。

我发现http://supermegaultragroovy.com/2009/10/06/drawing-waveforms/但我遇到了一些问题。如何获得表示音频的浮点值列表？

Answer 1

谢谢大家。

我在这里找到了这个例子：Drawing waveform with AVAssetReader，改变它并开发了一个基于。

的新类

此类返回UIImageView。

//.h file
#import <UIKit/UIKit.h>

@interface WaveformImageVew : UIImageView{

}
-(id)initWithUrl:(NSURL*)url;
- (NSData *) renderPNGAudioPictogramLogForAssett:(AVURLAsset *)songAsset;
@end


//.m file
#import "WaveformImageVew.h"

#define absX(x) (x<0?0-x:x)
#define minMaxX(x,mn,mx) (x<=mn?mn:(x>=mx?mx:x))
#define noiseFloor (-50.0)
#define decibel(amplitude) (20.0 * log10(absX(amplitude)/32767.0))
#define imgExt @"png"
#define imageToData(x) UIImagePNGRepresentation(x)

@implementation WaveformImageVew

-(id)initWithUrl:(NSURL*)url{
    if(self = [super init]){
        AVURLAsset * urlA = [AVURLAsset URLAssetWithURL:url options:nil];
        [self setImage:[UIImage imageWithData:[self renderPNGAudioPictogramLogForAssett:urlA]]];
    }
    return self;
}

-(UIImage *) audioImageLogGraph:(Float32 *) samples
                   normalizeMax:(Float32) normalizeMax
                    sampleCount:(NSInteger) sampleCount 
                   channelCount:(NSInteger) channelCount
                    imageHeight:(float) imageHeight {

    CGSize imageSize = CGSizeMake(sampleCount, imageHeight);
    UIGraphicsBeginImageContext(imageSize);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [UIColor blackColor].CGColor);
    CGContextSetAlpha(context,1.0);
    CGRect rect;
    rect.size = imageSize;
    rect.origin.x = 0;
    rect.origin.y = 0;

    CGColorRef leftcolor = [[UIColor whiteColor] CGColor];
    CGColorRef rightcolor = [[UIColor redColor] CGColor];

    CGContextFillRect(context, rect);

    CGContextSetLineWidth(context, 1.0);

    float halfGraphHeight = (imageHeight / 2) / (float) channelCount ;
    float centerLeft = halfGraphHeight;
    float centerRight = (halfGraphHeight*3) ; 
    float sampleAdjustmentFactor = (imageHeight/ (float) channelCount) / (normalizeMax - noiseFloor) / 2;

    for (NSInteger intSample = 0 ; intSample < sampleCount ; intSample ++ ) {
        Float32 left = *samples++;
        float pixels = (left - noiseFloor) * sampleAdjustmentFactor;
        CGContextMoveToPoint(context, intSample, centerLeft-pixels);
        CGContextAddLineToPoint(context, intSample, centerLeft+pixels);
        CGContextSetStrokeColorWithColor(context, leftcolor);
        CGContextStrokePath(context);

        if (channelCount==2) {
            Float32 right = *samples++;
            float pixels = (right - noiseFloor) * sampleAdjustmentFactor;
            CGContextMoveToPoint(context, intSample, centerRight - pixels);
            CGContextAddLineToPoint(context, intSample, centerRight + pixels);
            CGContextSetStrokeColorWithColor(context, rightcolor);
            CGContextStrokePath(context); 
        }
    }

    // Create new image
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    // Tidy up
    UIGraphicsEndImageContext();   

    return newImage;
}



- (NSData *) renderPNGAudioPictogramLogForAssett:(AVURLAsset *)songAsset {

    NSError * error = nil;    

    AVAssetReader * reader = [[AVAssetReader alloc] initWithAsset:songAsset error:&error];

    AVAssetTrack * songTrack = [songAsset.tracks objectAtIndex:0];

    NSDictionary* outputSettingsDict = [[NSDictionary alloc] initWithObjectsAndKeys:

                                        [NSNumber numberWithInt:kAudioFormatLinearPCM],AVFormatIDKey,
                                        //     [NSNumber numberWithInt:44100.0],AVSampleRateKey, /*Not Supported*/
                                        //     [NSNumber numberWithInt: 2],AVNumberOfChannelsKey,    /*Not Supported*/

                                        [NSNumber numberWithInt:16],AVLinearPCMBitDepthKey,
                                        [NSNumber numberWithBool:NO],AVLinearPCMIsBigEndianKey,
                                        [NSNumber numberWithBool:NO],AVLinearPCMIsFloatKey,
                                        [NSNumber numberWithBool:NO],AVLinearPCMIsNonInterleaved,

                                        nil];


    AVAssetReaderTrackOutput* output = [[AVAssetReaderTrackOutput alloc] initWithTrack:songTrack outputSettings:outputSettingsDict];

    [reader addOutput:output];
    [output release];

    UInt32 sampleRate,channelCount;

    NSArray* formatDesc = songTrack.formatDescriptions;
    for(unsigned int i = 0; i < [formatDesc count]; ++i) {
        CMAudioFormatDescriptionRef item = (CMAudioFormatDescriptionRef)[formatDesc objectAtIndex:i];
        const AudioStreamBasicDescription* fmtDesc = CMAudioFormatDescriptionGetStreamBasicDescription (item);
        if(fmtDesc ) {

            sampleRate = fmtDesc->mSampleRate;
            channelCount = fmtDesc->mChannelsPerFrame;

            //    NSLog(@"channels:%u, bytes/packet: %u, sampleRate %f",fmtDesc->mChannelsPerFrame, fmtDesc->mBytesPerPacket,fmtDesc->mSampleRate);
        }
    }

    UInt32 bytesPerSample = 2 * channelCount;
    Float32 normalizeMax = noiseFloor;
    NSLog(@"normalizeMax = %f",normalizeMax);
    NSMutableData * fullSongData = [[NSMutableData alloc] init];
    [reader startReading];    

    UInt64 totalBytes = 0; 

    Float64 totalLeft = 0;
    Float64 totalRight = 0;
    Float32 sampleTally = 0;

    NSInteger samplesPerPixel = sampleRate / 50;    

    while (reader.status == AVAssetReaderStatusReading){

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

        if (sampleBufferRef){
            CMBlockBufferRef blockBufferRef = CMSampleBufferGetDataBuffer(sampleBufferRef);

            size_t length = CMBlockBufferGetDataLength(blockBufferRef);
            totalBytes += length;


            NSAutoreleasePool *wader = [[NSAutoreleasePool alloc] init];

            NSMutableData * data = [NSMutableData dataWithLength:length];
            CMBlockBufferCopyDataBytes(blockBufferRef, 0, length, data.mutableBytes);


            SInt16 * samples = (SInt16 *) data.mutableBytes;
            int sampleCount = length / bytesPerSample;
            for (int i = 0; i < sampleCount ; i ++) {

                Float32 left = (Float32) *samples++;
                left = decibel(left);
                left = minMaxX(left,noiseFloor,0);

                totalLeft  += left;



                Float32 right;
                if (channelCount==2) {
                    right = (Float32) *samples++;
                    right = decibel(right);
                    right = minMaxX(right,noiseFloor,0);

                    totalRight += right;
                }

                sampleTally++;

                if (sampleTally > samplesPerPixel) {

                    left  = totalLeft / sampleTally; 
                    if (left > normalizeMax) {
                        normalizeMax = left;
                    }                    
                    // NSLog(@"left average = %f, normalizeMax = %f",left,normalizeMax);                    

                    [fullSongData appendBytes:&left length:sizeof(left)];

                    if (channelCount==2) {
                        right = totalRight / sampleTally; 


                        if (right > normalizeMax) {
                            normalizeMax = right;
                        }                        

                        [fullSongData appendBytes:&right length:sizeof(right)];
                    }

                    totalLeft   = 0;
                    totalRight  = 0;
                    sampleTally = 0;

                }
            }                        

            [wader drain];            

            CMSampleBufferInvalidate(sampleBufferRef);

            CFRelease(sampleBufferRef);
        }
    }    

    NSData * finalData = nil;

    if (reader.status == AVAssetReaderStatusFailed || reader.status == AVAssetReaderStatusUnknown){
        // Something went wrong. Handle it.
    }

    if (reader.status == AVAssetReaderStatusCompleted){
        // You're done. It worked.

        NSLog(@"rendering output graphics using normalizeMax %f",normalizeMax);

        UIImage *test = [self audioImageLogGraph:(Float32 *) fullSongData.bytes 
                                    normalizeMax:normalizeMax 
                                     sampleCount:fullSongData.length / (sizeof(Float32) * 2) 
                                    channelCount:2
                                     imageHeight:100];

        finalData = imageToData(test);
    }        

    [fullSongData release];
    [reader release];

    return finalData;
}

@end

Answer 2

一直在阅读你的问题并为此创建了一个控件。看起来像这样：

enter image description here

代码在这里：

https://github.com/fulldecent/FDWaveformView

在这里讨论：

https://www.cocoacontrols.com/controls/fdwaveformview

更新2015-01-29 ：这个项目非常强大并且发布了一致的版本。感谢所有曝光的SO！

Answer 3

这是我用来将音频数据（音频文件）转换为浮点表示并保存到数组中的代码。

-(void) PrintFloatDataFromAudioFile {

NSString *  name = @"Filename";  //YOUR FILE NAME
NSString * source = [[NSBundle mainBundle] pathForResource:name ofType:@"m4a"]; // SPECIFY YOUR FILE FORMAT

const char *cString = [source cStringUsingEncoding:NSASCIIStringEncoding];

CFStringRef str = CFStringCreateWithCString(
                                            NULL,
                                            cString,
                                            kCFStringEncodingMacRoman
                                            );
CFURLRef inputFileURL = CFURLCreateWithFileSystemPath(
                                                      kCFAllocatorDefault,
                                                      str,
                                                      kCFURLPOSIXPathStyle,
                                                      false
                                                      );

ExtAudioFileRef fileRef;
ExtAudioFileOpenURL(inputFileURL, &fileRef);


  AudioStreamBasicDescription audioFormat;
audioFormat.mSampleRate = 44100;   // GIVE YOUR SAMPLING RATE 
audioFormat.mFormatID = kAudioFormatLinearPCM;
audioFormat.mFormatFlags = kLinearPCMFormatFlagIsFloat;
audioFormat.mBitsPerChannel = sizeof(Float32) * 8;
audioFormat.mChannelsPerFrame = 1; // Mono
audioFormat.mBytesPerFrame = audioFormat.mChannelsPerFrame * sizeof(Float32);  // == sizeof(Float32)
audioFormat.mFramesPerPacket = 1;
audioFormat.mBytesPerPacket = audioFormat.mFramesPerPacket * audioFormat.mBytesPerFrame; // = sizeof(Float32)

// 3) Apply audio format to the Extended Audio File
ExtAudioFileSetProperty(
                        fileRef,
                        kExtAudioFileProperty_ClientDataFormat,
                        sizeof (AudioStreamBasicDescription), //= audioFormat
                        &audioFormat);

int numSamples = 1024; //How many samples to read in at a time
UInt32 sizePerPacket = audioFormat.mBytesPerPacket; // = sizeof(Float32) = 32bytes
UInt32 packetsPerBuffer = numSamples;
UInt32 outputBufferSize = packetsPerBuffer * sizePerPacket;

// So the lvalue of outputBuffer is the memory location where we have reserved space
UInt8 *outputBuffer = (UInt8 *)malloc(sizeof(UInt8 *) * outputBufferSize);



AudioBufferList convertedData ;//= malloc(sizeof(convertedData));

convertedData.mNumberBuffers = 1;    // Set this to 1 for mono
convertedData.mBuffers[0].mNumberChannels = audioFormat.mChannelsPerFrame;  //also = 1
convertedData.mBuffers[0].mDataByteSize = outputBufferSize;
convertedData.mBuffers[0].mData = outputBuffer; //

UInt32 frameCount = numSamples;
float *samplesAsCArray;
int j =0;
    double floatDataArray[882000]   ; // SPECIFY YOUR DATA LIMIT MINE WAS 882000 , SHOULD BE EQUAL TO OR MORE THAN DATA LIMIT

while (frameCount > 0) {
    ExtAudioFileRead(
                     fileRef,
                     &frameCount,
                     &convertedData
                     );
    if (frameCount > 0)  {
        AudioBuffer audioBuffer = convertedData.mBuffers[0];
        samplesAsCArray = (float *)audioBuffer.mData; // CAST YOUR mData INTO FLOAT

       for (int i =0; i<1024 /*numSamples */; i++) { //YOU CAN PUT numSamples INTEAD OF 1024

            floatDataArray[j] = (double)samplesAsCArray[i] ; //PUT YOUR DATA INTO FLOAT ARRAY
              printf("\n%f",floatDataArray[j]);  //PRINT YOUR ARRAY'S DATA IN FLOAT FORM RANGING -1 TO +1
            j++;


        }
    }
}}

Answer 4

这是我的答案，所有的极客

obj-c

这是代码：

-(void) listenerData:(NSNotification *) notify
{
int resnum=112222;
unsigned int bitsum=0;
for(int i=0;i<4;i++)
{
    bitsum+=(resnum>>(i*8))&0xff;
}
bitsum=bitsum&0xff;
NSString * check=[NSString stringWithFormat:@"%x %x",resnum,bitsum];
check=nil; 
self.drawData=notify.object;``
[self setNeedsDisplay];
}

-(void)drawRect:(CGRect)rect
{
NSArray *data=self.drawData;
NSData *tdata=[data objectAtIndex:0];
double *srcdata=(double*)tdata.bytes;
int datacount=tdata.length/sizeof(double);
tdata=[data objectAtIndex:1];
double *coveddata=(double*)tdata.bytes;

CGContextRef context=UIGraphicsGetCurrentContext();
CGRect bounds=self.bounds;
CGContextClearRect(context, bounds);
CGFloat midpos=bounds.size.height/2;
CGContextBeginPath(context);

const double scale=1.0/100;
CGFloat step=bounds.size.width/(datacount-1);
CGContextMoveToPoint(context, 0, midpos);
CGFloat xpos=0;
for(int i=0;i<datacount;i++)
{
    CGContextAddLineToPoint(context, xpos, midpos-srcdata[i]*scale);
    xpos+=step;
}
CGContextAddLineToPoint(context, bounds.size.width, midpos);

CGContextClosePath(context);
CGContextSetRGBFillColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextFillPath(context);

CGContextBeginPath(context);

const double scale2=1.0/100;
CGContextMoveToPoint(context, 0, midpos);
xpos=0;
for(int i=0;i<datacount;i++)
{
    CGContextAddLineToPoint(context, xpos, midpos+coveddata[i]*scale2);
    xpos+=step;
}
CGContextAddLineToPoint(context, bounds.size.width, midpos);

CGContextClosePath(context);
CGContextSetRGBFillColor(context, 1.0, 0.0, 1.0, 1.0);
CGContextFillPath(context);
}

IOS上的WaveForm

4 个答案: