iOS 笔记-SRT视频字幕的解析与同步

srt字幕的格式

1
00:00:31,788 --> 00:00:34,020
{a3}下面我给大家分享第四个问题

2
00:00:34,412 --> 00:00:35,740
{a3}如何开办企业

3
00:00:36,140 --> 00:00:37,684
{a3}如何开办企业呢

4
00:00:37,964 --> 00:00:39,060
{a3}在这个问题当中

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00:00:39,268 --> 00:00:41,692
{a3}我将给大家讲两个方面的内容

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00:00:41,892 --> 00:00:43,868
{a3}第一个方面就是开办企业的流程

7
00:00:44,260 --> 00:00:45,500
{a3}第二个方面的内容


这是我的视频字幕。
首先解析出来视频字幕的时间和字幕内容。

    NSString *appendStr = @"http://192.168.1.60:5080/Mooc/caption/dc05f541-269c-4f1b-ad99-782f5adcefdf_1447910856426.srt";
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:appendStr]];
    
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionTask *dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (!error) {
            // GBK编码
            NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
            
            // 解码
            NSString *string = [[NSString alloc] initWithData:data encoding:enc];
            
            //按行分割存放到数组中
            NSArray *singlearray = [string componentsSeparatedByString:@"
"];
            
            
            _subtitlesarray = [NSMutableArray array];
            _begintimearray = [NSMutableArray array];
            _endtimearray = [NSMutableArray array];
            
            //遍历存放所有行的数组
            for (NSString *ss in singlearray) {
                
                NSRange range = [ss rangeOfString:@"{\a3}"];
                
                NSRange range2 = [ss rangeOfString:@" --> "];
                
                if (range.location != NSNotFound) {
                    [_subtitlesarray addObject:[ss substringFromIndex:range.location + range.length]];
                }
                if (range2.location != NSNotFound) {
                    
                    NSString *beginstr = [ss substringToIndex:range2.location];
                    NSString *endstr = [ss substringFromIndex:range2.location+range2.length];
                    

                    NSArray * arr = [beginstr componentsSeparatedByString:@":"];
                    NSArray * arr1 = [arr[2] componentsSeparatedByString:@","];
                    
                    //将开始时间数组中的时间换化成秒为单位的
                    float teim=[arr[0] floatValue] * 60*60 + [arr[1] floatValue]*60 + [arr1[0] floatValue] + [arr1[1] floatValue]/1000;
                    //将float类型转化成NSNumber类型才能存入数组
                    NSNumber *beginnum = [NSNumber numberWithFloat:teim];
                    [_begintimearray addObject:beginnum];
                    
                    NSArray * array = [endstr componentsSeparatedByString:@":"];
                    NSArray * arr2 = [array[2] componentsSeparatedByString:@","];
                    
                    //将结束时间数组中的时间换化成秒为单位的
                    float fl=[array[0] floatValue] * 60*60 + [array[1] floatValue]*60 + [arr2[0] floatValue] + [arr2[1] floatValue]/1000;
                    NSNumber *endnum = [NSNumber numberWithFloat:fl];
                    [_endtimearray addObject:endnum];
                }
            }
            NSLog(@" 开始时间数组-=-=-==-=%@",_begintimearray);
            NSLog(@" 结束时间数组-=-=-==-=%@",_endtimearray);
            NSLog(@" 字幕数组-=-=-==-=%@",_subtitlesarray);
            
        }else{
            NSLog(@"error  is  %@",error.localizedDescription);
        }
    }];
    [dataTask resume];

上面代码已经把开始时间，结束时间，字幕分别放到三个数组中了。

把时间换成秒为单位的，为了能与获取的当前时间相匹配然后再比较。

视频播放时开个定时器，监控当前时间，与开始时间，结束时间比较，在之间的就把相应的字幕放进去显示就对了

self.timer = [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(timeAction) userInfo:nil repeats:YES];

- (void)timeAction
{
    
    //判断播放状态

    if (_player.rate != 1) {
        return;
    }
    NSInteger currentSecond = CMTimeGetSeconds(_player.currentItem.currentTime);

    for (int i = 0; i<_begintimearray.count ; i++) {
        NSInteger beginarr =  [_begintimearray[i] integerValue];
        NSInteger endarr = [_endtimearray[i]integerValue];
        if (currentSecond > beginarr && currentSecond< endarr) {
            //同步字幕
            _subtitlesLabel.text = _subtitlesarray[i];
            NSLog(@" 字幕  %@",_subtitlesarray[i]);
        }
    }
    
    //播放完成 暂停
    if (currentSecond == (int)CMTimeGetSeconds(self.player.currentItem.duration)) {
        [self.player pause];
        [self updateUI];
    }
}

这里提醒注意下，把时间都转为NSInteger类型进行比较，一开始使用的NSNumber比较，字幕显示混乱=。=

这样字幕显示出来了，如果字幕和视频的对话有偏差，就把定时器的时间调整的再小一点应该就好了~