// // HBAudio.m // HandBrake // // Created on 2010-08-30. // #import "HBAudio.h" #import "HBAudioController.h" #import "hb.h" NSString *keyAudioCodecName = @"keyAudioCodecName"; NSString *keyAudioMP4 = @"keyAudioMP4"; NSString *keyAudioMKV = @"keyAudioMKV"; NSString *keyAudioSampleRateName = @"keyAudioSampleRateName"; NSString *keyAudioBitrateName = @"keyAudioBitrateName"; NSString *keyAudioMustMatchTrack = @"keyAudioMustMatchTrack"; NSString *keyAudioMixdownName = @"keyAudioMixdownName"; NSString *keyAudioMixdownLimitsToTrackBitRate = @"keyAudioMixdownLimitsToTrackBitRate"; NSString *keyAudioMixdownCanBeDefault = @"keyAudioMixdownCanBeDefault"; NSString *keyAudioCodec = @"codec"; NSString *keyAudioMixdown = @"mixdown"; NSString *keyAudioSamplerate = @"samplerate"; NSString *keyAudioBitrate = @"bitrate"; static NSMutableArray *masterCodecArray = nil; static NSMutableArray *masterSampleRateArray = nil; static NSMutableArray *masterBitRateArray = nil; @interface NSArray (HBAudioSupport) - (NSDictionary *) dictionaryWithObject: (id) anObject matchingKey: (NSString *) aKey; - (NSDictionary *) lastDictionaryWithObject: (id) anObject matchingKey: (NSString *) aKey; @end @implementation NSArray (HBAudioSupport) - (NSDictionary *) dictionaryWithObject: (id) anObject matchingKey: (NSString *) aKey reverse: (BOOL) reverse { NSDictionary *retval = nil; NSEnumerator *enumerator = reverse ? [self reverseObjectEnumerator] : [self objectEnumerator]; NSDictionary *dict; id aValue; while (nil != (dict = [enumerator nextObject]) && nil == retval) { if (nil != (aValue = [dict objectForKey: aKey]) && YES == [aValue isEqual: anObject]) { retval = dict; } } return retval; } - (NSDictionary *) dictionaryWithObject: (id) anObject matchingKey: (NSString *) aKey { return [self dictionaryWithObject: anObject matchingKey: aKey reverse: NO]; } - (NSDictionary *) lastDictionaryWithObject: (id) anObject matchingKey: (NSString *) aKey { return [self dictionaryWithObject: anObject matchingKey: aKey reverse: YES]; } @end @implementation HBAudio #pragma mark - #pragma mark Object Setup + (void) load { if ([HBAudio class] == self) { int i; NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSDictionary *dict; masterCodecArray = [[NSMutableArray alloc] init]; // knowingly leaked [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"AAC (CoreAudio)", @"AAC (CoreAudio)"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_CA_AAC], keyAudioCodec, [NSNumber numberWithBool: YES], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithBool: NO], keyAudioMustMatchTrack, nil]]; [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"AAC (faac)", @"AAC (faac)"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_FAAC], keyAudioCodec, [NSNumber numberWithBool: YES], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithBool: NO], keyAudioMustMatchTrack, nil]]; [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"MP3 (lame)", @"MP3 (lame)"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_LAME], keyAudioCodec, [NSNumber numberWithBool: YES], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithBool: NO], keyAudioMustMatchTrack, nil]]; [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"AC3 Passthru", @"AC3 Passthru"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_AC3_PASS], keyAudioCodec, [NSNumber numberWithBool: YES], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithInt: HB_ACODEC_AC3], keyAudioMustMatchTrack, nil]]; [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"AC3", @"AC3"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_AC3], keyAudioCodec, [NSNumber numberWithBool: YES], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithBool: NO], keyAudioMustMatchTrack, nil]]; [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"DTS Passthru", @"DTS Passthru"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_DCA_PASS], keyAudioCodec, [NSNumber numberWithBool: NO], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithInt: HB_ACODEC_DCA], keyAudioMustMatchTrack, nil]]; [masterCodecArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"Vorbis (vorbis)", @"Vorbis (vorbis)"), keyAudioCodecName, [NSNumber numberWithInt: HB_ACODEC_VORBIS], keyAudioCodec, [NSNumber numberWithBool: NO], keyAudioMP4, [NSNumber numberWithBool: YES], keyAudioMKV, [NSNumber numberWithBool: NO], keyAudioMustMatchTrack, nil]]; // Note that for the Auto value we use 0 for the sample rate because our controller will give back the track's // input sample rate when it finds this 0 value as the selected sample rate. We do this because the input // sample rate depends on the track, which means it depends on the title, so cannot be nicely set up here. masterSampleRateArray = [[NSMutableArray alloc] init]; // knowingly leaked [masterSampleRateArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"Auto", @"Auto"), keyAudioSampleRateName, [NSNumber numberWithInt: 0], keyAudioSamplerate, nil]]; for (i = 0; i < hb_audio_rates_count; i++) { [masterSampleRateArray addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_rates[i].string], keyAudioSampleRateName, [NSNumber numberWithInt: hb_audio_rates[i].rate], keyAudioSamplerate, nil]]; } masterBitRateArray = [[NSMutableArray alloc] init]; // knowingly leaked for (i = 0; i < hb_audio_bitrates_count; i++) { int rate = hb_audio_bitrates[i].rate; dict = [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_bitrates[i].string], keyAudioBitrateName, [NSNumber numberWithInt: rate], keyAudioBitrate, nil]; [masterBitRateArray addObject: dict]; } [pool release]; } return; } // Ensure the list of codecs is accurate // Update the current value of codec based on the revised list - (void) updateCodecs { NSMutableArray *permittedCodecs = [NSMutableArray array]; unsigned int count = [masterCodecArray count]; NSDictionary *dict; NSString *keyThatAllows = nil; // Determine which key we use to see which codecs are permitted switch ([videoContainerTag intValue]) { case HB_MUX_MP4: keyThatAllows = keyAudioMP4; break; case HB_MUX_MKV: keyThatAllows = keyAudioMKV; break; default: keyThatAllows = @"error condition"; break; } // First get a list of the permitted codecs based on the internal rules if (nil != track && YES == [self enabled]) { BOOL goodToAdd; for (unsigned int i = 0; i < count; i++) { dict = [masterCodecArray objectAtIndex: i]; // First make sure only codecs permitted by the container are here goodToAdd = [[dict objectForKey: keyThatAllows] boolValue]; // Now we make sure if DTS or AC3 is not available in the track it is not put in the codec list, but in a general way if (YES == [[dict objectForKey: keyAudioMustMatchTrack] boolValue]) { if ([[dict objectForKey: keyAudioMustMatchTrack] intValue] != [[[self track] objectForKey: keyAudioInputCodec] intValue]) { goodToAdd = NO; } } if (YES == goodToAdd) { [permittedCodecs addObject: dict]; } } } // Now make sure the permitted list and the actual ones matches [self setCodecs: permittedCodecs]; // Ensure our codec is on the list of permitted codecs if (nil == [self codec] || NO == [permittedCodecs containsObject: [self codec]]) { if (0 < [permittedCodecs count]) { [self setCodec: [permittedCodecs objectAtIndex: 0]]; // This should be defaulting to Core Audio } else { [self setCodec: nil]; } } return; } // The rules here are provided as-is from the original -[Controller audioTrackPopUpChanged:mixdownToUse:] routine // with the comments taken from there as well. - (void) updateMixdowns { NSMutableArray *retval = [NSMutableArray array]; int trackCodec = [[track objectForKey: keyAudioInputCodec] intValue]; int codecCodec = [[codec objectForKey: keyAudioCodec] intValue]; if (HB_ACODEC_AC3 == trackCodec && HB_ACODEC_AC3_PASS == codecCodec) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"AC3 Passthru", @"AC3 Passthru"), keyAudioMixdownName, [NSNumber numberWithInt: HB_ACODEC_AC3_PASS], keyAudioMixdown, [NSNumber numberWithBool: YES], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } else if (HB_ACODEC_DCA == trackCodec && HB_ACODEC_DCA_PASS == codecCodec) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"DTS Passthru", @"DTS Passthru"), keyAudioMixdownName, [NSNumber numberWithInt: HB_ACODEC_DCA_PASS], keyAudioMixdown, [NSNumber numberWithBool: YES], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } else { int audioCodecsSupport6Ch = (trackCodec && HB_ACODEC_LAME != codecCodec); int channelLayout = [[track objectForKey: keyAudioInputChannelLayout] intValue]; int layout = channelLayout & HB_INPUT_CH_LAYOUT_DISCRETE_NO_LFE_MASK; /* add a mono option? */ [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[0].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: hb_audio_mixdowns[0].amixdown], keyAudioMixdown, [NSNumber numberWithBool: NO], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; /* offer stereo if we have a stereo-or-better source */ if (layout >= HB_INPUT_CH_LAYOUT_STEREO) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[1].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: hb_audio_mixdowns[1].amixdown], keyAudioMixdown, [NSNumber numberWithBool: NO], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } /* do we want to add a dolby surround (DPL1) option? */ if (HB_INPUT_CH_LAYOUT_3F1R == layout || HB_INPUT_CH_LAYOUT_3F2R == layout || HB_INPUT_CH_LAYOUT_DOLBY == layout) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[2].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: hb_audio_mixdowns[2].amixdown], keyAudioMixdown, [NSNumber numberWithBool: NO], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } /* do we want to add a dolby pro logic 2 (DPL2) option? */ if (HB_INPUT_CH_LAYOUT_3F2R == layout) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[3].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: hb_audio_mixdowns[3].amixdown], keyAudioMixdown, [NSNumber numberWithBool: NO], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } /* do we want to add a 6-channel discrete option? */ if (1 == audioCodecsSupport6Ch && HB_INPUT_CH_LAYOUT_3F2R == layout && (channelLayout & HB_INPUT_CH_LAYOUT_HAS_LFE)) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[4].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: hb_audio_mixdowns[4].amixdown], keyAudioMixdown, [NSNumber numberWithBool: NO], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: (HB_ACODEC_AC3 == codecCodec) ? YES : NO], keyAudioMixdownCanBeDefault, nil]]; } // based on the fact that we are in an else section where the ifs before hand would have detected the following two // situations, the following code will never add anything to the returned array. I am leaving this in place for // historical reasons. /* do we want to add an AC-3 passthrough option? */ if (HB_ACODEC_AC3 == trackCodec && HB_ACODEC_AC3_PASS == codecCodec) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[5].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: HB_ACODEC_AC3_PASS], keyAudioMixdown, [NSNumber numberWithBool: YES], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } /* do we want to add a DTS Passthru option ? HB_ACODEC_DCA*/ if (HB_ACODEC_DCA == trackCodec && HB_ACODEC_DCA_PASS == codecCodec) { [retval addObject: [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithUTF8String: hb_audio_mixdowns[5].human_readable_name], keyAudioMixdownName, [NSNumber numberWithInt: HB_ACODEC_DCA_PASS], keyAudioMixdown, [NSNumber numberWithBool: YES], keyAudioMixdownLimitsToTrackBitRate, [NSNumber numberWithBool: YES], keyAudioMixdownCanBeDefault, nil]]; } } if (NO == [self enabled]) { retval = nil; } // Now make sure the permitted list and the actual ones matches [self setMixdowns: retval]; // Ensure our mixdown is on the list of permitted ones if (YES == [[NSUserDefaults standardUserDefaults] boolForKey: @"CodecDefaultsMixdown"] || nil == [self mixdown] || NO == [retval containsObject: [self mixdown]]) { [self setMixdown: [retval lastDictionaryWithObject: [NSNumber numberWithBool: YES] matchingKey: keyAudioMixdownCanBeDefault]]; } return; } - (void) updateBitRates: (BOOL) shouldSetDefault { NSMutableArray *permittedBitRates = [NSMutableArray array]; int count; NSDictionary *dict; count = [masterBitRateArray count]; int minBitRate; int maxBitRate; NSString *defaultBitRate; int currentBitRate; int trackInputBitRate = [[[self track] objectForKey: keyAudioInputBitrate] intValue]; BOOL limitsToTrackInputBitRate = [[[self mixdown] objectForKey: keyAudioMixdownLimitsToTrackBitRate] boolValue]; BOOL shouldAdd; int theSampleRate = [[[self sampleRate] objectForKey: keyAudioSamplerate] intValue]; if (0 == theSampleRate) { // this means Auto theSampleRate = [[[self track] objectForKey: keyAudioInputSampleRate] intValue]; } int ourCodec = [[codec objectForKey: keyAudioCodec] intValue]; int ourMixdown = [[[self mixdown] objectForKey: keyAudioMixdown] intValue]; hb_get_audio_bitrate_limits(ourCodec, theSampleRate, ourMixdown, &minBitRate, &maxBitRate); int theDefaultBitRate = hb_get_default_audio_bitrate(ourCodec, theSampleRate, ourMixdown); defaultBitRate = [NSString stringWithFormat: @"%d", theDefaultBitRate]; for (unsigned int i = 0; i < count; i++) { dict = [masterBitRateArray objectAtIndex: i]; currentBitRate = [[dict objectForKey: keyAudioBitrate] intValue]; // First ensure the bitrate falls within range of the codec shouldAdd = (currentBitRate >= minBitRate && currentBitRate <= maxBitRate); // Now make sure the mixdown is not limiting us to the track input bitrate if (YES == shouldAdd && YES == limitsToTrackInputBitRate) { if (currentBitRate != trackInputBitRate) { shouldAdd = NO; } } if (YES == shouldAdd) { [permittedBitRates addObject: dict]; } } // There is a situation where we have a mixdown requirement to match the track input bit rate, // but it does not fall into the range the codec supports. Therefore, we force it here. if (YES == limitsToTrackInputBitRate && 0 == [permittedBitRates count]) { NSDictionary *missingBitRate = [masterBitRateArray dictionaryWithObject: [NSNumber numberWithInt: trackInputBitRate] matchingKey: keyAudioBitrate]; if (nil == missingBitRate) { // We are in an even worse situation where the requested bit rate does not even exist in the underlying // library of supported bitrates. Of course since this value is ignored we can freely make a bogus one // for the UI just to make the user a little more aware. missingBitRate = [NSDictionary dictionaryWithObjectsAndKeys: [NSString stringWithFormat: @"%d", trackInputBitRate], keyAudioBitrateName, [NSNumber numberWithInt: trackInputBitRate], keyAudioBitrate, nil]; } [permittedBitRates addObject: missingBitRate]; } if (NO == [self enabled]) { permittedBitRates = nil; } // Make sure we are updated with the permitted list [self setBitRates: permittedBitRates]; // Select the proper one if (YES == shouldSetDefault) { [self setBitRateFromName: defaultBitRate]; } if (nil == [self bitRate] || NO == [permittedBitRates containsObject: [self bitRate]]) { [self setBitRate: [permittedBitRates lastObject]]; } return; } - (id) init { if (self = [super init]) { [self addObserver: self forKeyPath: @"videoContainerTag" options: 0 context: NULL]; [self addObserver: self forKeyPath: @"track" options: NSKeyValueObservingOptionOld context: NULL]; [self addObserver: self forKeyPath: @"codec" options: 0 context: NULL]; [self addObserver: self forKeyPath: @"mixdown" options: 0 context: NULL]; [self addObserver: self forKeyPath: @"sampleRate" options: 0 context: NULL]; } return self; } #pragma mark - #pragma mark Accessors @synthesize track; @synthesize codec; @synthesize mixdown; @synthesize sampleRate; @synthesize bitRate; @synthesize drc; @synthesize videoContainerTag; @synthesize controller; @synthesize codecs; @synthesize mixdowns; @synthesize bitRates; - (NSArray *) tracks { return [controller masterTrackArray]; } - (NSArray *) sampleRates { return masterSampleRateArray; } - (void) dealloc { [self removeObserver: self forKeyPath: @"videoContainerTag"]; [self removeObserver: self forKeyPath: @"track"]; [self removeObserver: self forKeyPath: @"codec"]; [self removeObserver: self forKeyPath: @"mixdown"]; [self removeObserver: self forKeyPath: @"sampleRate"]; [self setTrack: nil]; [self setCodec: nil]; [self setMixdown: nil]; [self setSampleRate: nil]; [self setBitRate: nil]; [self setDrc: nil]; [self setVideoContainerTag: nil]; [self setCodecs: nil]; [self setMixdowns: nil]; [self setBitRates: nil]; [super dealloc]; return; } #pragma mark - #pragma mark KVO - (void) observeValueForKeyPath: (NSString *) keyPath ofObject: (id) object change: (NSDictionary *) change context: (void *) context { if (YES == [keyPath isEqualToString: @"videoContainerTag"]) { [self updateCodecs]; } else if (YES == [keyPath isEqualToString: @"track"]) { if (nil != [self track]) { [self updateCodecs]; if (YES == [self enabled]) { [self setSampleRate: [[self sampleRates] objectAtIndex: 0]]; // default to Auto } if (YES == [[controller noneTrack] isEqual: [change objectForKey: NSKeyValueChangeOldKey]]) { [controller switchingTrackFromNone: self]; } if (YES == [[controller noneTrack] isEqual: [self track]]) { [controller settingTrackToNone: self]; } } } else if (YES == [keyPath isEqualToString: @"codec"]) { [self updateMixdowns]; [self updateBitRates: YES]; } else if (YES == [keyPath isEqualToString: @"mixdown"]) { [self updateBitRates: YES]; [[NSNotificationCenter defaultCenter] postNotificationName: HBMixdownChangedNotification object: self]; } else if (YES == [keyPath isEqualToString: @"sampleRate"]) { [self updateBitRates: NO]; } return; } #pragma mark - #pragma mark Special Setters - (void) setTrackFromIndex: (int) aValue { [self setTrack: [[self tracks] dictionaryWithObject: [NSNumber numberWithInt: aValue] matchingKey: keyAudioTrackIndex]]; return; } // This returns whether it is able to set the actual codec desired. - (BOOL) setCodecFromName: (NSString *) aValue { NSDictionary *dict = [[self codecs] dictionaryWithObject: aValue matchingKey: keyAudioCodecName]; if (nil != dict) { [self setCodec: dict]; } return (nil != dict); } - (void) setMixdownFromName: (NSString *) aValue { NSDictionary *dict = [[self mixdowns] dictionaryWithObject: aValue matchingKey: keyAudioMixdownName]; if (nil != dict) { [self setMixdown: dict]; } return; } - (void) setSampleRateFromName: (NSString *) aValue { NSDictionary *dict = [[self sampleRates] dictionaryWithObject: aValue matchingKey: keyAudioSampleRateName]; if (nil != dict) { [self setSampleRate: dict]; } return; } - (void) setBitRateFromName: (NSString *) aValue { NSDictionary *dict = [[self bitRates] dictionaryWithObject: aValue matchingKey: keyAudioBitrateName]; if (nil != dict) { [self setBitRate: dict]; } return; } #pragma mark - #pragma mark Validation // Because we have indicated that the binding for the drc validates immediately we can implement the // key value binding method to ensure the drc stays in our accepted range. - (BOOL) validateDrc: (id *) ioValue error: (NSError *) outError { BOOL retval = YES; if (nil != *ioValue) { if (0.0 < [*ioValue floatValue] && 1.0 > [*ioValue floatValue]) { *ioValue = [NSNumber numberWithFloat: 1.0]; } } return retval; } #pragma mark - #pragma mark Bindings Support - (BOOL) enabled { return (nil != track) ? (NO == [track isEqual: [controller noneTrack]]) : NO; } - (BOOL) mixdownEnabled { BOOL retval = [self enabled]; if (YES == retval) { int myMixdown = [[[self mixdown] objectForKey: keyAudioMixdown] intValue]; if (HB_ACODEC_AC3_PASS == myMixdown || HB_ACODEC_DCA_PASS == myMixdown) { retval = NO; } } return retval; } - (BOOL) AC3Enabled { BOOL retval = [self enabled]; if (YES == retval) { int myTrackCodec = [[[self track] objectForKey: keyAudioInputCodec] intValue]; if (HB_ACODEC_AC3 != myTrackCodec) { retval = NO; } } return retval; } + (NSSet *) keyPathsForValuesAffectingValueForKey: (NSString *) key { NSSet *retval = nil; if (YES == [key isEqualToString: @"enabled"] || YES == [key isEqualToString: @"AC3Enabled"]) { retval = [NSSet setWithObjects: @"track", nil]; } else if (YES == [key isEqualToString: @"mixdownEnabled"]) { retval = [NSSet setWithObjects: @"track", @"mixdown", nil]; } return retval; } @end