正文
众所周知，基于OpenGL的GPUImage是一个很出名的框架。使用GPUImage，我们能很轻易的做出美颜效果。其中有多达120多种效果提供给大家使用。今天，我只讲如何使用GPUImage，对于GPUImage的研究，网上有很多资料，大家可以很方便的学习，以后我也会会出个关于GPUImage的专题。
1.美颜的流程为：移除之前所有的处理链->创建美颜滤镜->设置GPUImage处理链。代码如下：
- (void)beautyClick{
beautyBtn.selected =!beautyBtn.selected;
if (beautyBtn.selected) {
// 移除之前所有的处理链
[videoCamera removeAllTargets];
// 创建美颜滤镜
filter = [[GPUImageBilateralFilter alloc] init];
// 设置GPUImage处理链，从数据->滤镜->界面展示
[videoCamera addTarget:filter];
[filter addTarget:filterView];
}else{
// 移除之前所有的处理链
[videoCamera removeAllTargets];
[videoCamera addTarget:filterView];
}
}
2.断点拍摄的流程：开始拍摄时启动一个定时器，到了时间后则停止计时关闭拍摄即可。代码如下：
- (void)starWrite{
deleteBtn.hidden =NO;
beautyBtn.hidden =YES;
[self initProgressView];
isRecording =YES;
seconds =0.00;
[self initMovieWriter];
dispatch_async(dispatch_get_main_queue(), ^{
[movieWriter startRecording];
[self gcdTimer];
});
}
为了精准计时，我使用的是GCD计时器：
- (void)gcdTimer{
//使用GCD定时器
NSTimeInterval period =floatTime;
dispatch_queue_t queue =dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
_GCDtimer =dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
dispatch_source_set_timer(_GCDtimer, DISPATCH_TIME_NOW, period * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
dispatch_source_set_event_handler(_GCDtimer, ^{
dispatch_async(dispatch_get_main_queue(), ^{
//回到主线程
seconds +=floatTime;
totalTime +=floatTime;
UIView *view =[self.viewArray lastObject];
view.frame =CGRectMake(viewX,viewY,seconds*(ScreenWidth/timeSeconds),viewHight);
NSNumber *number =[NSNumber numberWithFloat:totalTime];
// NSInteger integer =(NSInteger)totalTime;
if ([number integerValue] >=timeSeconds) {
NSLog(@"结束时间%f%ld",totalTime,timeSeconds);
[self stopWrite];
}
});
});
dispatch_resume(_GCDtimer);
}
譬如计时10秒后关闭计时器停止拍摄：
- (void)stopWrite{
//因为GCDtimer较为精准 务必先调用移除定时器的方法 再调用停止录制的方法
[self removeTimer];
dispatch_async(dispatch_get_main_queue(), ^{
//注意顺序
[movieWriter finishRecording];
[filter removeTarget:movieWriter];
videoCamera.audioEncodingTarget = nil;
});
beautyBtn.hidden =NO;
[self.secondsArray addObject:[NSString stringWithFormat:@"%f",seconds]];
[self saveModelToVideoArray];
recordBtn.selected =NO;
isRecording =NO;
[self savePhotosAlbum:videoURL];
NSLog(@"录制时间为%f 当前时间为%f",seconds,totalTime);
}
注意：拍摄视频中可能有多次拍摄，在删除不想要的视频时也应该移除相应的时间，确保整个视频的时间是我们设定的时间。还有在保存视频到相册中时需要调用延时的方法，否则可能出现保存失败的情况。
//保存到手机相册
- (void)savePhotosAlbum:(NSURL *)videoPathURL{
//必须调用延时的方法 否则可能出现保存失败的情况
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:videoPathURL])
{
[library writeVideoAtPathToSavedPhotosAlbum:videoPathURL completionBlock:^(NSURL *assetURL, NSError *error)
{
/*
dispatch_async(dispatch_get_main_queue(), ^{
if (error) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"保存失败"
delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success" message:@"保存成功"
delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}
});
*/
}];
}
});
}
3.视频合成即把多个视频合成为一个视频，这需要用到AVFoundation中的AVMutableComposition去处理音频轨和视频轨。需要注意的是：要遍历videosPathArray里的视频，然后取出视频轨和音频轨在首尾处连接，导出视频的用到的是AVAssetExportSession，具体代码如下：
/* 合成视频|转换视频格式
@param videosPathArray:合成视频的路径数组
@param outpath:输出路径
@param outputFileType:视频格式
@param presetName:分辨率
@param completeBlock mergeFileURL:合成后新的视频URL
*/
+ (void)mergeAndExportVideos:(NSArray *)videosPathArray withOutPath:(NSString *)outPath outputFileType:(NSString *)outputFileType presetName:(NSString *)presetName didComplete:(void(^)(NSError *error,NSURL *mergeFileURL) )completeBlock{
if (videosPathArray.count ==0) {
NSLog(@"请添加视频");
NSError *error =[NSError errorWithDomain:NSCocoaErrorDomain code:0 userInfo:@{NSLocalizedDescriptionKey:@"视频数目不能为0"}];
if (completeBlock) {
completeBlock(error,nil);
}
return;
}
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
CMTime totalDuration = kCMTimeZero;
for (int i = 0; i < videosPathArray.count; i++) {
NSDictionary* options = @{AVURLAssetPreferPreciseDurationAndTimingKey:@YES
};
AVURLAsset *asset =[AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:videosPathArray[i]] options:options];
NSError *erroraudio = nil;
//获取AVAsset中的音频 或者视频
AVAssetTrack *assetAudioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] firstObject];
//向通道内加入音频或者视频
BOOL ba = [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
ofTrack:assetAudioTrack
atTime:totalDuration
error:&erroraudio];
NSLog(@"erroraudio:%@%d",erroraudio,ba);
NSError *errorVideo = nil;
AVAssetTrack *assetVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] firstObject];
BOOL bl = [videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
ofTrack:assetVideoTrack
atTime:totalDuration
error:&errorVideo];
NSLog(@"errorVideo:%@%d",errorVideo,bl);
totalDuration = CMTimeAdd(totalDuration, asset.duration);
}
unlink([outPath UTF8String]);
NSURL *mergeFileURL = [NSURL fileURLWithPath:outPath];
if ([[NSFileManager defaultManager] fileExistsAtPath:outPath]) {
[[NSFileManager defaultManager] removeItemAtPath:outPath error:nil];
}
//输出
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:presetName];
exporter.outputURL = mergeFileURL;
exporter.outputFileType = outputFileType;
exporter.shouldOptimizeForNetworkUse = YES;
//因为exporter.progress不可以被监听 所以在这里可以开启定时器取 exporter的值查看进度
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
switch (exporter.status) {
case AVAssetExportSessionStatusFailed:{
if (completeBlock) {
completeBlock(exporter.error,mergeFileURL);
}
break;
}
case AVAssetExportSessionStatusCancelled:{
NSLog(@"Export Status: Cancell");
break;
}
case AVAssetExportSessionStatusCompleted: {
if (completeBlock) {
completeBlock(nil,mergeFileURL);
}
break;
}
case AVAssetExportSessionStatusUnknown: {
NSLog(@"Export Status: Unknown");
break;
}
case AVAssetExportSessionStatusExporting : {
NSLog(@"Export Status: Exporting");
break;
}
case AVAssetExportSessionStatusWaiting: {
NSLog(@"Export Status: Wating");
break;
}
};
});
}];
}
大家注意CMTimeAdd的概念，即相当于加法。音视频中的时间 CMTime是一个用c语言定义的结构体，在音视频中有很重要的用途，下面会专门写篇文章介绍，毕竟这个是基础。在合成视频时，也可以设置视频的格式以及分辨率用来转格式和压缩视频。
