ios - m3u8 解析組裝

前言: 之前有專案要實現m3u8本地播放，後面自己寫了一個多執行緒下載的demo，裡面坑很多。因為時間問題，也沒時間去填坑，後面還是採用單執行緒下載。但想了下m3u8本地快取播放這個需求，每個公司的需求可能有所差異。但m3u8是協議好的東西，解析跟組裝的部分應該都差不多。所以下面就記錄下這部分的內容。

定義模型儲存資訊

@class ZBLM3u8TsInfo;

@interface ZBLM3u8Info : NSObject
@property (nonatomic, copy) NSString *targetduration;
@property (nonatomic, copy) NSString *version;
@property (nonatomic, copy) NSString *mediaSequence;

///key資訊
@property (nonatomic, copy) NSString *keyMethod;
@property (nonatomic, copy) NSString *keyUri;
@property (nonatomic, copy) NSString *keyLocalUri;
@property (nonatomic, copy) NSString *keyIv;
@property (nonatomic, strong) NSMutableArray <ZBLM3u8TsInfo*> *tsInfos;
@end

@interface ZBLM3u8TsInfo : NSObject
@property (nonatomic, copy) NSString *duration;
@property (nonatomic, copy) NSString *oriUrlString;
@property (nonatomic, copy) NSString *localUrlString;
@property (nonatomic, assign) NSInteger index;
@property (nonatomic, assign,getter = isHasDiscontiunity) BOOL hasDiscontiunity;
@end
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定義處理類，根據m3u8文字資訊把資訊儲存到模型中並做相關的容錯處理

.h定義

@class ZBLM3u8Info;

typedef void (^ZBLM3u8AnalysiseCompletaionHandler)(ZBLM3u8Info *m3u8Info,NSError *error);

@interface ZBLM3u8Analysiser : NSObject

/**
 m3u8解析

 @param urlStr m3u8網路url
 @param completaionHandler 回撥
 */
+ (void)analysisWithUrlString:(NSString*)urlStr completaionHandler:(ZBLM3u8AnalysiseCompletaionHandler)completaionHandler;

/**
 m3u8文字組裝

 @param m3u8Info m3u8資訊模型
 @return m3u8文字
 */
+ (NSString*)synthesisLocalM3u8Withm3u8Info:(ZBLM3u8Info *)m3u8Info;

FOUNDATION_EXPORT NSString * const ZBLM3u8AnalysiserResponeErrorDomain;
FOUNDATION_EXPORT NSString * const ZBLM3u8AnalysiserAnalysisErrorDomain;

@end

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.m實現

/*解析m3u8 和組裝m3u8*/

NSString * const ZBLM3u8AnalysiserResponeErrorDomain = @"error.m3u8.analysiser.respone";
NSString * const ZBLM3u8AnalysiserAnalysisErrorDomain = @"error.m3u8.analysiser.analysis";

@implementation ZBLM3u8Analysiser

+ (void)analysisWithUrlString:(NSString*)urlStr completaionHandler:(ZBLM3u8AnalysiseCompletaionHandler)completaionHandler
{
    NSLog(@"analysis start");
    //判斷m3u8文字是否已經儲存到本地，因為下載m3u8文字是耗時操作
    NSString *oriM3u8String = [NSString stringWithContentsOfFile:[[ZBLM3u8Setting fullCommonDirPrefixWithUrl:urlStr] stringByAppendingPathComponent:[ZBLM3u8Setting oriM3u8InfoFileName]] encoding:0 error:nil];
    
    __block BOOL happenException = NO;
    if (oriM3u8String.length) {
        NSLog(@"use local oriM3u8Info");
        //處理有可能失敗，所有需要加try-catch-finally，保護程式
        @try {
            [self analysisWithM3u8String:oriM3u8String completaionHandler:completaionHandler];
        } @catch (NSException *exception) {
            happenException = YES;
            [[ZBLM3u8FileManager shareInstance]removeFileWithPath:[[ZBLM3u8Setting fullCommonDirPrefixWithUrl:urlStr] stringByAppendingPathComponent:[ZBLM3u8Setting oriM3u8InfoFileName]]];
            completaionHandler(nil,[[NSError alloc]initWithDomain:ZBLM3u8AnalysiserAnalysisErrorDomain code:NSURLErrorUnknown userInfo:@{@"info":exception.reason}]);
        } @finally {
            
        }
        if (!happenException) {
            return;
        }
    }
    
    happenException = NO;
    //非同步獲取
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSString *m3u8Str = nil;
        //處理有可能失敗，所有需要加try-catch-finally，保護程式
        @try {
            NSError *error = nil;
            //根據url請求獲取m3u8文字，耗時操作
            m3u8Str = [[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:urlStr] usedEncoding:0 error:&error];
            
            if (error)
            {
                completaionHandler(nil,error);
                return ;
            }
            
            
            if (m3u8Str.length == 0)
            {
                completaionHandler(nil,[[NSError alloc]initWithDomain:ZBLM3u8AnalysiserResponeErrorDomain code:NSURLErrorBadServerResponse userInfo:nil]);
                return;
            }
            
            //解析
            [self analysisWithM3u8String:m3u8Str completaionHandler:completaionHandler];
            
        } @catch (NSException *exception) {
            happenException = YES;
            completaionHandler(nil,[[NSError alloc]initWithDomain:ZBLM3u8AnalysiserAnalysisErrorDomain code:NSURLErrorUnknown userInfo:@{@"info":exception.reason}]);
        } @finally {
            
        }
        
        if (!happenException) {
            //儲存原m3u8文字，方便二次利用
            [[ZBLM3u8FileManager shareInstance]saveDate:[m3u8Str dataUsingEncoding:NSUTF8StringEncoding] ToFile:[[ZBLM3u8Setting fullCommonDirPrefixWithUrl:urlStr] stringByAppendingPathComponent:[ZBLM3u8Setting oriM3u8InfoFileName]] completaionHandler:nil];
        }
    });
}


/**
 private method
 m3u8文字解析

 @param m3u8String m3u8文字
 @param completaionHandler 回撥
 */
+ (void)analysisWithM3u8String:(NSString*)m3u8String completaionHandler:(ZBLM3u8AnalysiseCompletaionHandler)completaionHandler
{
    
    ZBLM3u8Info *info = [ZBLM3u8Info new];
    info.version = [[m3u8String subStringFrom:@"#EXT-X-VERSION:" to:@"#"] removeSpaceAndNewline];
    info.targetduration = [[m3u8String subStringFrom:@"#EXT-X-TARGETDURATION:" to:@"#"] removeSpaceAndNewline];
    info.mediaSequence = [[m3u8String subStringFrom:@"#EXT-X-MEDIA-SEQUENCE:" to:@"#"] removeSpaceAndNewline];
    
    info.keyMethod = [m3u8String subStringFrom:@"#EXT-X-KEY:METHOD=" to:@","];
    info.keyUri = [m3u8String subStringFrom:@"URI=\"" to:@"\""];
    info.keyIv = [[m3u8String subStringFrom:@"IV=" to:@"#"] removeSpaceAndNewline];
    
    NSRange tsRange = [m3u8String rangeOfString:@"#EXTINF:"];
    if (tsRange.location == NSNotFound) {
        completaionHandler(nil,[[NSError alloc]initWithDomain:ZBLM3u8AnalysiserAnalysisErrorDomain code:NSURLErrorUnknown userInfo:@{@"info":@"none downloadUrl for .ts file"}]);
        return;
    }
    NSInteger index = 0;
    NSMutableArray *tsInfos = @[].mutableCopy;
    m3u8String = [m3u8String substringFromIndex:tsRange.location];
    while (tsRange.location != NSNotFound) {
        ZBLM3u8TsInfo *tsInfo = [ZBLM3u8TsInfo new];
        tsInfo.duration = [m3u8String subStringFrom:@"#EXTINF:" to:@","];
        m3u8String = [m3u8String subStringForm:@"," offset:1];
        tsInfo.oriUrlString = [[m3u8String subStringTo:@"#"] removeSpaceAndNewline];
        
        NSRange exRange = [m3u8String rangeOfString:@"#EX"];
        NSRange discontinuityRange = [m3u8String rangeOfString:@"#EXT-X-DISCONTINUITY"];
        if (exRange.location == discontinuityRange.location) {
            tsInfo.hasDiscontiunity = YES;
        }
        tsInfo.index = index ++;
        [tsInfos addObject:tsInfo];
        tsRange = [m3u8String rangeOfString:@"#EXTINF:"];
        if (tsRange.location != NSNotFound) {
            m3u8String = [m3u8String subStringForm:@"#EXTINF:" offset:0];
        }
    }
    NSLog(@"analysis compelte");
    info.tsInfos = tsInfos;
    NSParameterAssert(completaionHandler);
    completaionHandler(info,nil);
}

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根據本地儲存的ts資訊更新模型，並重新組裝m3u8文字資訊

 + (NSString*)synthesisLocalM3u8Withm3u8Info:(ZBLM3u8Info *)m3u8Info
{
    NSString *newM3u8String = @"";
    
    NSString *header = @"#EXTM3U\n";
    if (m3u8Info.version.length) {
        header = [header stringByAppendingString:[NSString stringWithFormat:@"#EXT-X-VERSION:%ld\n",(long)m3u8Info.version.integerValue]];
    }
    if (m3u8Info.targetduration.length) {
        header = [header stringByAppendingString:[NSString stringWithFormat:@"#EXT-X-TARGETDURATION:%ld\n",(long)m3u8Info.targetduration.integerValue]];
    }
    if (m3u8Info.mediaSequence.length) {
        header = [header stringByAppendingString:[NSString stringWithFormat:@"#EXT-X-MEDIA-SEQUENCE:%ld\n",(long)m3u8Info.mediaSequence.integerValue]];
    }
    
    NSString *keyStr = @"";
    if(m3u8Info.keyUri.length)
    {
        keyStr = [NSString stringWithFormat:@"#EXT-X-KEY:METHOD=%@,URI=\"%@\",IV=%@\n",m3u8Info.keyMethod,m3u8Info.keyLocalUri,m3u8Info.keyIv];
    }
    
    __block NSString *body = @"";
    [m3u8Info.tsInfos enumerateObjectsUsingBlock:^(ZBLM3u8TsInfo * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        NSString *tsInfo = [NSString stringWithFormat:@"#EXTINF:%.6lf,\n%@\n",obj.duration.floatValue,obj.localUrlString];
        body =  [body stringByAppendingString:tsInfo];
        if (obj.isHasDiscontiunity) body = [body stringByAppendingString:@"#EXT-X-DISCONTINUITY\n"];
    }];
    
    newM3u8String = [[[[newM3u8String stringByAppendingString:header] stringByAppendingString:keyStr] stringByAppendingString:body] stringByAppendingString:@"#EXT-X-ENDLIST"];
    
    return newM3u8String;
    }
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demo: github.com/zmubai/ZBLM…

ios - m3u8 解析組裝

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