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    <p>Thank all. </p> <p>I found this example here: <a href="https://stackoverflow.com/questions/5032775/drawing-waveform-with-avassetreader">Drawing waveform with AVAssetReader</a> , changed it and developed a new class based on.</p> <p>This class returns UIImageView.</p> <pre><code>//.h file #import &lt;UIKit/UIKit.h&gt; @interface WaveformImageVew : UIImageView{ } -(id)initWithUrl:(NSURL*)url; - (NSData *) renderPNGAudioPictogramLogForAssett:(AVURLAsset *)songAsset; @end //.m file #import "WaveformImageVew.h" #define absX(x) (x&lt;0?0-x:x) #define minMaxX(x,mn,mx) (x&lt;=mn?mn:(x&gt;=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 &lt; 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:&amp;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 &lt; [formatDesc count]; ++i) { CMAudioFormatDescriptionRef item = (CMAudioFormatDescriptionRef)[formatDesc objectAtIndex:i]; const AudioStreamBasicDescription* fmtDesc = CMAudioFormatDescriptionGetStreamBasicDescription (item); if(fmtDesc ) { sampleRate = fmtDesc-&gt;mSampleRate; channelCount = fmtDesc-&gt;mChannelsPerFrame; // NSLog(@"channels:%u, bytes/packet: %u, sampleRate %f",fmtDesc-&gt;mChannelsPerFrame, fmtDesc-&gt;mBytesPerPacket,fmtDesc-&gt;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 &lt; 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 &gt; samplesPerPixel) { left = totalLeft / sampleTally; if (left &gt; normalizeMax) { normalizeMax = left; } // NSLog(@"left average = %f, normalizeMax = %f",left,normalizeMax); [fullSongData appendBytes:&amp;left length:sizeof(left)]; if (channelCount==2) { right = totalRight / sampleTally; if (right &gt; normalizeMax) { normalizeMax = right; } [fullSongData appendBytes:&amp;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 </code></pre>
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    1. COExcellent code here. Had to import <CoreMedia/CoreMedia.h> and <AVFoundation/AVFoundation.h> into the .h file to get this up and running
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