jak pobrać szczegóły pliku audio w iPhone'ie

Question

Zrobiłem niestandardowy odtwarzacz przy użyciu AVAudioPlayer. Teraz chcę pobrać szczegóły pliku audio, takie jak nazwa wykonawcy, nazwa albumu itp., Które jest dodawane do folderu zasobów.

MPMusicPlayer udostępnia interfejs API do pobierania danych, ale z biblioteki iPoda i nieodebrania zasobów z piaskownicy aplikacji. Tak więc MPMusicPlayer nie będzie działał w tym scenariuszu.

W jaki sposób możemy pobrać szczegóły pliku audio w telefonie iPhone.

Answer 1

Możesz uzyskać te informacje za pośrednictwem AudioToolbox.framework. AudioToolbox.framework jest API C, więc pisał opakowanie Cel C na nim:

ID3TAG .h:

@interface ID3Tag : NSObject <NSCoding> { 
    NSString* title_; 
    NSString* album_; 
    NSString* artist_; 
    NSNumber* trackNumber_; 
    NSNumber* totalTracks_; 
    NSString* genre_; 
    NSString* year_; 
    NSNumber* approxDuration_; 
    NSString* composer_; 
    NSString* tempo_; 
    NSString* keySignature_; 
    NSString* timeSignature_; 
    NSString* lyricist_; 
    NSString* recordedDate_; 
    NSString* comments_; 
    NSString* copyright_; 
    NSString* sourceEncoder_; 
    NSString* encodingApplication_; 
    NSString* bitRate_; 
    NSStream* sourceBitRate_; 
    NSString* channelLayout_; 
    NSString* isrc_; 
    NSString* subtitle_; 
} 

@property (nonatomic, retain) NSString *title; 
@property (nonatomic, retain) NSString *album; 
@property (nonatomic, retain) NSString *artist; 
@property (nonatomic, retain) NSNumber *trackNumber; 
@property (nonatomic, retain) NSNumber *totalTracks; 
@property (nonatomic, retain) NSString *genre; 
@property (nonatomic, retain) NSString *year; 
@property (nonatomic, retain) NSNumber *approxDuration; 
@property (nonatomic, retain) NSString *composer; 
@property (nonatomic, retain) NSString *tempo; 
@property (nonatomic, retain) NSString *keySignature; 
@property (nonatomic, retain) NSString *timeSignature; 
@property (nonatomic, retain) NSString *lyricist; 
@property (nonatomic, retain) NSString *recordedDate; 
@property (nonatomic, retain) NSString *comments; 
@property (nonatomic, retain) NSString *copyright; 
@property (nonatomic, retain) NSString *sourceEncoder; 
@property (nonatomic, retain) NSString *encodingApplication; 
@property (nonatomic, retain) NSString *bitRate; 
@property (nonatomic, retain) NSStream *sourceBitRate; 
@property (nonatomic, retain) NSString *channelLayout; 
@property (nonatomic, retain) NSString *isrc; 
@property (nonatomic, retain) NSString *subtitle; 

@end 

ID3TagParser.h

#import <Foundation/Foundation.h> 
#import "ID3Tag.h" 

@interface ID3Parser : NSObject { 

} 

- (ID3Tag*) parseAudioFileForID3Tag:(NSURL*) url; 

@end 

ID3TagParser.m

#import "ID3Parser.h" 
#import <AudioToolbox/AudioToolbox.h> 

@implementation ID3Parser 

- (ID3Tag*) parseAudioFileForID3Tag:(NSURL*) url { 
    if (url == nil) { 
     return nil; 
    } 

    AudioFileID fileID = nil; 
    OSStatus err = noErr; 

    err = AudioFileOpenURL((CFURLRef) url, kAudioFileReadPermission, 0, &fileID); 
    if(err != noErr) { 
     NSLog(@"AudioFileOpenURL failed"); 
     return nil; 
    } else { 
     UInt32 id3DataSize = 0; 
     char* rawID3Tag = NULL; 

     // Reads in the raw ID3 tag info 
     err = AudioFileGetPropertyInfo(fileID, kAudioFilePropertyID3Tag, &id3DataSize, NULL); 
     if(err != noErr) { 
      return nil; 
     } 

     // Allocate the raw tag data 
     rawID3Tag = (char *) malloc(id3DataSize); 

     if(rawID3Tag == NULL) { 
      return nil; 
     } 

     err = AudioFileGetProperty(fileID, kAudioFilePropertyID3Tag, &id3DataSize, rawID3Tag); 
     if(err != noErr) { 
      return nil; 
     } 

     UInt32 id3TagSize = 0; 
     UInt32 id3TagSizeLength = 0; 
     err = AudioFormatGetProperty(kAudioFormatProperty_ID3TagSize, id3DataSize, rawID3Tag, &id3TagSizeLength, &id3TagSize); 

     if(err != noErr) { 
      switch(err) { 
       case kAudioFormatUnspecifiedError: 
        NSLog(@"err: audio format unspecified error"); 
        return nil; 
       case kAudioFormatUnsupportedPropertyError: 
        NSLog(@"err: audio format unsupported property error"); 
        return nil; 
       case kAudioFormatBadPropertySizeError: 
        NSLog(@"err: audio format bad property size error"); 
        return nil; 
       case kAudioFormatBadSpecifierSizeError: 
        NSLog(@"err: audio format bad specifier size error"); 
        return nil; 
       case kAudioFormatUnsupportedDataFormatError: 
        NSLog(@"err: audio format unsupported data format error"); 
        return nil; 
       case kAudioFormatUnknownFormatError: 
        NSLog(@"err: audio format unknown format error"); 
        return nil; 
       default: 
        NSLog(@"err: some other audio format error"); 
        return nil; 
      } 
     } 

     CFDictionaryRef piDict = nil; 
     UInt32 piDataSize = sizeof(piDict); 

     // Populates a CFDictionary with the ID3 tag properties 
     err = AudioFileGetProperty(fileID, kAudioFilePropertyInfoDictionary, &piDataSize, &piDict); 
     if(err != noErr) { 
      NSLog(@"AudioFileGetProperty failed for property info dictionary"); 
      return nil; 
     } 

     // Toll free bridge the CFDictionary so that we can interact with it via objc 
     NSDictionary* nsDict = (NSDictionary*)piDict; 

     ID3Tag* tag = [[[ID3Tag alloc] init] autorelease]; 

     tag.album = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Album]]; 
     tag.approxDuration = [NSNumber numberWithInt:[[nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_ApproximateDurationInSeconds]] intValue]]; 
     tag.artist = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Artist]]; 
     tag.bitRate = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_NominalBitRate]]; 
     tag.channelLayout = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_ChannelLayout]]; 
     tag.comments = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Comments]]; 
     tag.composer = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Composer]]; 
     tag.copyright = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Copyright]]; 
     tag.encodingApplication = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_EncodingApplication]]; 
     tag.genre = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Genre]]; 
     tag.isrc = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_ISRC]]; 
     tag.keySignature = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_KeySignature]]; 
     tag.lyricist = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Lyricist]]; 
     tag.recordedDate = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_RecordedDate]]; 
     tag.sourceBitRate = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_SourceBitDepth]]; 
     tag.sourceEncoder = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_SourceEncoder]]; 
     tag.subtitle = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_SubTitle]]; 
     tag.tempo = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Tempo]]; 
     tag.timeSignature = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_TimeSignature]]; 
     tag.title = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Title]]; 
     tag.year = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_Year]]; 

     /* 
     * We're going to parse tracks differently so that we can perform queries on the data. This means we need to look 
     * for a '/' so that we can seperate out the track from the total tracks on the source compilation (if it's there). 
     */ 
     NSString* tracks = [nsDict objectForKey:[NSString stringWithUTF8String: kAFInfoDictionary_TrackNumber]]; 

     int slashLocation = [tracks rangeOfString:@"/"].location; 

     if (slashLocation == NSNotFound) { 
      tag.trackNumber = [NSNumber numberWithInt:[tracks intValue]]; 
     } else { 
      tag.trackNumber = [NSNumber numberWithInt:[[tracks substringToIndex:slashLocation] intValue]]; 
      tag.totalTracks = [NSNumber numberWithInt:[[tracks substringFromIndex:(slashLocation+1 < [tracks length] ? slashLocation+1 : 0)] intValue]]; 
     } 

     // ALWAYS CLEAN UP! 
     CFRelease(piDict); 
     nsDict = nil; 
     free(rawID3Tag); 

     return tag; 
    } 
} 

@end 

Answer 2

Widzę, że kod odczytywania znaczników Wayne posts jest wklejany za dużo. Jeśli używasz kAudioFilePropertyInfoDictionary, nie potrzebujesz id3DataSize, nie musisz czytać surowych danych ID3Tag i id3TagSizeLength id3TagSize nie są również używane. Wystarczy otworzyć plik i odczytać tag:

- (NSDictionary *)id3TagsForURL:(NSURL *)resourceUrl 
{ 
    AudioFileID fileID; 
    OSStatus result = AudioFileOpenURL((CFURLRef)resourceUrl, kAudioFileReadPermission, 0, &fileID); 

    if (result != noErr) { 
     NSLog(@"Error reading tags: %li", result); 
     return nil; 
    } 

    CFDictionaryRef piDict = nil; 
    UInt32 piDataSize = sizeof(piDict); 

    result = AudioFileGetProperty(fileID, kAudioFilePropertyInfoDictionary, &piDataSize, &piDict); 
    if (result != noErr) 
     NSLog(@"Error reading tags. AudioFileGetProperty failed"); 

    AudioFileClose(fileID); 

    NSDictionary *tagsDictionary = [NSDictionary dictionaryWithDictionary:(NSDictionary*)piDict]; 
    CFRelease(piDict); 

    return tagsDictionary; 
} 

klucze Dicionary są zdefiniowane w AudioFile.h, począwszy kAFInfoDictionary.

Jednak istnieje inny tag czytania klucz, który będzie zwracać różne wyniki (wraz z innymi klawiszami):

- (NSDictionary *)id3TagsForURL:(NSURL *)resourceUrl 
{ 
    AudioFileID fileID; 
    OSStatus result = AudioFileOpenURL((CFURLRef)resourceUrl, kAudioFileReadPermission, 0, &fileID); 

    if (result != noErr) { 
     return nil; 
    } 

    //read raw ID3Tag size 
    UInt32 id3DataSize = 0; 
    char *rawID3Tag = NULL; 
    result = AudioFileGetPropertyInfo(fileID, kAudioFilePropertyID3Tag, &id3DataSize, NULL); 
    if (result != noErr) { 
     AudioFileClose(fileID); 
     return nil; 
    } 

    rawID3Tag = (char *)malloc(id3DataSize); 

    //read raw ID3Tag 
    result = AudioFileGetProperty(fileID, kAudioFilePropertyID3Tag, &id3DataSize, rawID3Tag); 
    if (result != noErr) { 
     free(rawID3Tag); 
     AudioFileClose(fileID); 
     return nil; 
    } 

    CFDictionaryRef piDict = nil; 
    UInt32 piDataSize = sizeof(piDict); 

    //this key returns some other dictionary, which works also in iPod library 
    result = AudioFormatGetProperty(kAudioFormatProperty_ID3TagToDictionary, id3DataSize, rawID3Tag, &piDataSize, &piDict); 
    if (result != noErr) { 
     return nil; 
    } 

    free(rawID3Tag); 
    AudioFileClose(fileID); 

    NSDictionary *tagsDictionary = [NSDictionary dictionaryWithDictionary:(NSDictionary*)piDict]; 
    CFRelease(piDict); 

    return tagsDictionary; 
}