Wellenform mit AVAssetReader zeichnen

81

Ich lese Songs aus der iPod-Bibliothek mit AssetUrl (im Code AudioUrl). Ich kann sie auf viele Arten abspielen, ich kann sie schneiden, ich kann damit etwas verarbeiten, aber ... ich verstehe wirklich nicht, was ich damit machen werde CMSampleBufferRef zum Abrufen von Daten zum Zeichnen von Wellenformen! Ich benötige Informationen zu Spitzenwerten. Wie kann ich diese (möglicherweise andere) Methode erhalten?

    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? */}

Bitte hilf mir!

iFreeman
quelle

Antworten:

261

Ich suchte nach einer ähnlichen Sache und beschloss, "meine eigene zu rollen". Mir ist klar, dass dies ein alter Beitrag ist, aber falls jemand anderes danach sucht, hier ist meine Lösung. Es ist relativ schnell und schmutzig und normalisiert das Bild auf "Vollausschlag". Die von ihm erstellten Bilder sind "breit", dh Sie müssen sie in eine UIScrollView einfügen oder die Anzeige auf andere Weise verwalten.

Dies basiert auf einigen Antworten auf diese Frage

Beispielausgabe

Beispielwellenform

BEARBEITEN: Ich habe eine logarithmische Version der Mittelungs- und Rendermethoden hinzugefügt. Die alternativen Versions- und Vergleichsausgaben finden Sie am Ende dieser Nachricht. Ich persönlich bevorzuge die ursprüngliche lineare Version, habe mich aber entschlossen, sie zu veröffentlichen, falls jemand den verwendeten Algorithmus verbessern kann.

Sie benötigen diese Importe:

#import <MediaPlayer/MediaPlayer.h>
#import <AVFoundation/AVFoundation.h>

Zunächst eine generische Rendering-Methode, die einen Zeiger auf gemittelte Beispieldaten verwendet
und ein UIImage zurückgibt. Beachten Sie, dass diese Samples keine abspielbaren Audio-Samples sind.

-(UIImage *) audioImageGraph:(SInt16 *) samples
                normalizeMax:(SInt16) 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) / (float) normalizeMax;

    for (NSInteger intSample = 0 ; intSample < sampleCount ; intSample ++ ) {
        SInt16 left = *samples++;
        float pixels = (float) left;
        pixels *= sampleAdjustmentFactor;
        CGContextMoveToPoint(context, intSample, centerLeft-pixels);
        CGContextAddLineToPoint(context, intSample, centerLeft+pixels);
        CGContextSetStrokeColorWithColor(context, leftcolor);
        CGContextStrokePath(context);

        if (channelCount==2) {
            SInt16 right = *samples++;
            float pixels = (float) right;
            pixels *= 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;
}

Als nächstes eine Methode, die ein AVURLAsset verwendet und PNG-Bilddaten zurückgibt

- (NSData *) renderPNGAudioPictogramForAsset:(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;
    SInt16 normalizeMax = 0;

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

    UInt64 totalBytes = 0;         
    SInt64 totalLeft = 0;
    SInt64 totalRight = 0;
    NSInteger 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 ++) {

                SInt16 left = *samples++;
                totalLeft  += left;

                SInt16 right;
                if (channelCount==2) {
                    right = *samples++;
                    totalRight += right;
                }

                sampleTally++;

                if (sampleTally > samplesPerPixel) {

                    left  = totalLeft / sampleTally; 

                    SInt16 fix = abs(left);
                    if (fix > normalizeMax) {
                        normalizeMax = fix;
                    }

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

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

                        SInt16 fix = abs(right);
                        if (fix > normalizeMax) {
                            normalizeMax = fix;
                        }

                        [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. return nil

        return nil;
    }

    if (reader.status == AVAssetReaderStatusCompleted){

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

        UIImage *test = [self audioImageGraph:(SInt16 *) 
                         fullSongData.bytes 
                                 normalizeMax:normalizeMax 
                                  sampleCount:fullSongData.length / 4 
                                 channelCount:2
                                  imageHeight:100];

        finalData = imageToData(test);
    }        

    [fullSongData release];
    [reader release];

    return finalData;
}

Erweiterte Option: Wenn Sie das Audio mit AVAudioPlayer abspielen möchten, müssen Sie es im Bundle-Cache-Ordner Ihrer Apps zwischenspeichern. Da ich das getan habe, habe ich beschlossen, auch die Bilddaten zwischenzuspeichern und das Ganze in eine UIImage-Kategorie zu packen. Sie müssen dieses Open-Source-Angebot einschließen , um das Audio zu extrahieren, und Code von hier , um einige Hintergrund-Threading-Funktionen zu handhaben.

Zunächst einige Definitionen und einige generische Klassenmethoden für den Umgang mit Pfadnamen usw.

//#define imgExt @"jpg"
//#define imageToData(x) UIImageJPEGRepresentation(x,4)

#define imgExt @"png"
#define imageToData(x) UIImagePNGRepresentation(x)

+ (NSString *) assetCacheFolder  {
    NSArray  *assetFolderRoot = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    return [NSString stringWithFormat:@"%@/audio", [assetFolderRoot objectAtIndex:0]];
 }

+ (NSString *) cachedAudioPictogramPathForMPMediaItem:(MPMediaItem*) item {
    NSString *assetFolder = [[self class] assetCacheFolder];
    NSNumber * libraryId = [item valueForProperty:MPMediaItemPropertyPersistentID];
    NSString *assetPictogramFilename = [NSString stringWithFormat:@"asset_%@.%@",libraryId,imgExt];
    return [NSString stringWithFormat:@"%@/%@", assetFolder, assetPictogramFilename];
}

+ (NSString *) cachedAudioFilepathForMPMediaItem:(MPMediaItem*) item {
    NSString *assetFolder = [[self class] assetCacheFolder];

    NSURL    * assetURL = [item valueForProperty:MPMediaItemPropertyAssetURL];
    NSNumber * libraryId = [item valueForProperty:MPMediaItemPropertyPersistentID];

    NSString *assetFileExt = [[[assetURL path] lastPathComponent] pathExtension];
    NSString *assetFilename = [NSString stringWithFormat:@"asset_%@.%@",libraryId,assetFileExt];
    return [NSString stringWithFormat:@"%@/%@", assetFolder, assetFilename];
}

+ (NSURL *) cachedAudioURLForMPMediaItem:(MPMediaItem*) item {
    NSString *assetFilepath = [[self class] cachedAudioFilepathForMPMediaItem:item];
    return [NSURL fileURLWithPath:assetFilepath];
}

Nun die Init-Methode, die "das Geschäft" macht

- (id) initWithMPMediaItem:(MPMediaItem*) item 
           completionBlock:(void (^)(UIImage* delayedImagePreparation))completionBlock  {

    NSFileManager *fman = [NSFileManager defaultManager];
    NSString *assetPictogramFilepath = [[self class] cachedAudioPictogramPathForMPMediaItem:item];

    if ([fman fileExistsAtPath:assetPictogramFilepath]) {

        NSLog(@"Returning cached waveform pictogram: %@",[assetPictogramFilepath lastPathComponent]);

        self = [self initWithContentsOfFile:assetPictogramFilepath];
        return self;
    }

    NSString *assetFilepath = [[self class] cachedAudioFilepathForMPMediaItem:item];

    NSURL *assetFileURL = [NSURL fileURLWithPath:assetFilepath];

    if ([fman fileExistsAtPath:assetFilepath]) {

        NSLog(@"scanning cached audio data to create UIImage file: %@",[assetFilepath lastPathComponent]);

        [assetFileURL retain];
        [assetPictogramFilepath retain];

        [NSThread MCSM_performBlockInBackground: ^{

            AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:assetFileURL options:nil];
            NSData *waveFormData = [self renderPNGAudioPictogramForAsset:asset]; 

            [waveFormData writeToFile:assetPictogramFilepath atomically:YES];

            [assetFileURL release];
            [assetPictogramFilepath release];

            if (completionBlock) {

                [waveFormData retain];
                [NSThread MCSM_performBlockOnMainThread:^{

                    UIImage *result = [UIImage imageWithData:waveFormData];

                    NSLog(@"returning rendered pictogram on main thread (%d bytes %@ data in UIImage %0.0f x %0.0f pixels)",waveFormData.length,[imgExt uppercaseString],result.size.width,result.size.height);

                    completionBlock(result);

                    [waveFormData release];
                }];
            }
        }];

        return nil;

    } else {

        NSString *assetFolder = [[self class] assetCacheFolder];

        [fman createDirectoryAtPath:assetFolder withIntermediateDirectories:YES attributes:nil error:nil];

        NSLog(@"Preparing to import audio asset data %@",[assetFilepath lastPathComponent]);

        [assetPictogramFilepath retain];
        [assetFileURL retain];

        TSLibraryImport* import = [[TSLibraryImport alloc] init];
        NSURL    * assetURL = [item valueForProperty:MPMediaItemPropertyAssetURL];

         [import importAsset:assetURL toURL:assetFileURL completionBlock:^(TSLibraryImport* import) {
            //check the status and error properties of
            //TSLibraryImport

            if (import.error) {

                NSLog (@"audio data import failed:%@",import.error);

            } else{
                NSLog (@"Creating waveform pictogram file: %@", [assetPictogramFilepath lastPathComponent]);
                AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:assetFileURL options:nil];
                NSData *waveFormData = [self renderPNGAudioPictogramForAsset:asset]; 

                [waveFormData writeToFile:assetPictogramFilepath atomically:YES];

                if (completionBlock) {
                     [waveFormData retain];
                    [NSThread MCSM_performBlockOnMainThread:^{

                        UIImage *result = [UIImage imageWithData:waveFormData];
                        NSLog(@"returning rendered pictogram on main thread (%d bytes %@ data in UIImage %0.0f x %0.0f pixels)",waveFormData.length,[imgExt uppercaseString],result.size.width,result.size.height);

                        completionBlock(result);

                        [waveFormData release];
                    }];
                }
            }

            [assetPictogramFilepath release];
            [assetFileURL release];

        }  ];

        return nil;
    }
}

Ein Beispiel für das Aufrufen:

-(void) importMediaItem {

    MPMediaItem* item = [self mediaItem];

    // since we will be needing this for playback, save the url to the cached audio.
    [url release];
    url = [[UIImage cachedAudioURLForMPMediaItem:item] retain];

    [waveFormImage release];

    waveFormImage = [[UIImage alloc ] initWithMPMediaItem:item completionBlock:^(UIImage* delayedImagePreparation){

        waveFormImage = [delayedImagePreparation retain];
        [self displayWaveFormImage];
    }];

    if (waveFormImage) {
        [waveFormImage retain];
        [self displayWaveFormImage];
    }
}

Logarithmische Version von Mittelungs- und Rendermethoden

#define absX(x) (x<0?0-x:x)
#define minMaxX(x,mn,mx) (x<=mn?mn:(x>=mx?mx:x))
#define noiseFloor (-90.0)
#define decibel(amplitude) (20.0 * log10(absX(amplitude)/32767.0))

-(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 *) renderPNGAudioPictogramLogForAsset:(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;
}

Vergleichsausgaben

Linear
Lineare Darstellung zum Start von "Warm It Up" von Acme Swing Company

logarithmisch
Logarithmischer Plot zum Start von "Warm It Up" von Acme Swing Company

nicht synchronisiert
quelle
22
Dies ist eine sehr vollständige und nützliche Antwort. Es ist eigentlich ein Borderline-Tutorial, das Sie in ein Blog oder ähnliches einfügen könnten. Ich würde dich auf 10 stimmen, wenn ich könnte.
Daniel G. Wilson
3
Ja, du solltest wirklich ein Tutorial oder einen Blogeintrag schreiben ... auch mit einem Beispielprojekt;)
Daniel
2
Keine Ahnung wie schnell es geht, aber es funktioniert! Ich musste einige Dinge hinzufügen / ändern, da Sie einige Annahmen wie 2-Kanal-Audio fest codiert haben. Ich fand auch das folgende praktisch für die Berechnung von SamplesPerPixel (die Art und Weise, wie Sie es zugewiesen haben, schien willkürlich? / 50 ??) NSTimeInterval duration = (float) songAsset.duration.value / (float) songAsset.duration.timescale; NSLog (@ "Aufnahmedauer:% f Sek.", Dauer);
Hufeisen7
Ich möchte es auch für Retina-Grafiken aktualisieren und möglicherweise die UIImage * -Methode in eine drawRect: -Methode verwandeln und in der Lage sein, einen hervorgehobenen Bereich hinzuzufügen. DANKE für den tollen Ausgangspunkt. AVFoundation und Bibliotheken auf niedrigerer Ebene sind für die relativ Unerfahrenen immer noch etwas beängstigend
Hufeisen7
3
Danke dafür. Ich habe dies als Ausgangspunkt für eine Kakaokontrolle verwendet, die einige andere Funktionen wie das
Anzeigen des Spielfortschritts
5

Sie sollten in der Lage sein, einen Audiopuffer von Ihrem sampleBuffRef abzurufen und diese Werte dann zu durchlaufen, um Ihre Wellenform zu erstellen:

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));
Joel
quelle
3

Ein anderer Ansatz mit Swift 5 und AVAudioFile:

///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 + 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)

}

WO

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]()

}

Im Moment wird nur eine Schallwelle gedruckt, diese kann jedoch erweitert werden. Das Gute daran ist, dass Sie eine Audiospur nach Teilen drucken können

Reimond Hill
quelle
Was ist mit Live-Audio-Streaming?
Mojtaba al Moussawi
der Ansatz aber anders sein. Ihr bester Ansatz wäre es, einen Datenpuffer zu füllen und zu zeichnen, aber es ist mein Gast.
Reimond Hill