#前言
我最近在接手一個智慧盒子的iOS應用，上面有一個功能是這樣的。把你本地的照片和視訊可以甩屏到你繫結的盒子上。
我的上一位前輩做的時候必須要求再同一個區域網，但是當我做的時候要求不同的區域網也要實現這樣的一個功能，優化使用者的使用感受。
#那麼 我們下面就進入正題。
#內容一：圖片上傳
我做的圖片上傳是用的AF，原理就是把你想上傳的照片取出來，如果有檔案大小的要求就先做相應的圖片壓縮。
然後用AFHTTPSessionManager 類去做的上傳，下面就是程式碼：
AFHTTPSessionManager *session = [AFHTTPSessionManager manager];
[session.requestSerializer willChangeValueForKey:@"timeoutInterval"];
session.requestSerializer.timeoutInterval = 60.f;
[session.requestSerializer didChangeValueForKey:@"timeoutInterval"];
session.responseSerializer = [AFHTTPResponseSerializer serializer];
NSString *imageTitle =_imageSource[pageIndex].title;
imageTitle = [imageTitle substringToIndex:imageTitle.length-4];
NSDictionary *params = @{
@"fileType":@"jpg",
@"fileName":imageTitle
};
[session POST:@"你上傳的介面地址" parameters:params constructingBodyWithBlock:^(id<AFMultipartFormData> _Nonnull formData) {
for (NSString *key in dict.allKeys) {
[formData appendPartWithFileData:[dict objectForKey:key] name:@"myFile" fileName:[NSString stringWithFormat:@"%@.jpg",key] mimeType:@"image/jpeg"];
}
} progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) {
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
}];複製程式碼這裡主要就是和你們的後臺確認好相應的引數設定就好了。
#內容二：視訊上傳
視訊上傳和圖片上傳其實是類似的，只不過就是引數的設定不一樣而已。也是用上面的方法。關鍵也是設定好引數。
在這裡我想說的是，有的時候視訊太大要做相應的壓縮處理。因為我之前對視訊這面接觸的比較少，也上網找了一些資料然後看到這樣的一個方法：
- (void)lowQuailtyWithInputURL:(NSURL*)inputURL
outputURL:(NSURL*)outputURL
blockHandler:(void (^)(AVAssetExportSession*))handler
{
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];
AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetMediumQuality];
session.outputURL = outputURL;
session.outputFileType = AVFileTypeQuickTimeMovie;
[session exportAsynchronouslyWithCompletionHandler:^(void)
{
handler(session);
}];
}複製程式碼通過這個方法就可以對視訊進行相應的壓縮處理。
#下面就是視訊內容的旋轉問題了。
一開始我聽到了這個需求的時候我的腦子裡真的是瞬間萬馬飛奔啊！！ 這是什麼鬼需求啊！鬼知道我經歷了什麼？
我想，那我就上網找一下吧！我找了一下，還真的有這麼樣的技術部落格。但是一上來就是把他的程式碼網上一貼。我先大概的瀏覽了一下那程式碼的長度。寫的我實在是沒有耐心去仔細的看到底是怎麼實現的。我就關掉了。可是後來一看，也沒有別的什麼部落格供我參考了。在我走投無路的時候，我看到了這麼一個部落格，說是Apple自己就有Demo，我就抱著好奇的態度去看了看。下載了那個Demo仔細的研究了一下。果然就好使了。 那麼，接下來就說一下。
再旋轉視訊之前我們先要確認一下，這個視訊是要旋轉多少度。
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];
NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
NSInteger degress;
if([tracks count] > 0) {
AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
CGAffineTransform t = videoTrack.preferredTransform;//這裡的矩陣有旋轉角度，轉換一下即可
if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0){
// Portrait
degress = 90;
}else if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0){
// PortraitUpsideDown
degress = 270;
}else if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0){
// LandscapeRight
degress = 0;
}else if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0){
// LandscapeLeft
degress = 180;
}
}複製程式碼這樣我們就可以通過degress來確認旋轉的角度了。
那麼我們接下來就開始旋轉視訊
AVMutableVideoCompositionInstruction *instruction = nil;
AVMutableVideoCompositionLayerInstruction *layerInstruction = nil;
CGAffineTransform t1;
CGAffineTransform t2;
AVAssetTrack *assetVideoTrack = nil;
AVAssetTrack *assetAudioTrack = nil;
// Check if the asset contains video and audio tracks
if ([[asset tracksWithMediaType:AVMediaTypeVideo] count] != 0) {
assetVideoTrack = [asset tracksWithMediaType:AVMediaTypeVideo][0];
}
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {
assetAudioTrack = [asset tracksWithMediaType:AVMediaTypeAudio][0];
}
CMTime insertionPoint = kCMTimeZero;
NSError *error = nil;
// Step 1
// Create a composition with the given asset and insert audio and video tracks into it from the asset
if (!mutableComposition) {
// Check whether a composition has already been created, i.e, some other tool has already been applied
// Create a new composition
mutableComposition = [AVMutableComposition composition];
// Insert the video and audio tracks from AVAsset
if (assetVideoTrack != nil) {
AVMutableCompositionTrack *compositionVideoTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetVideoTrack atTime:insertionPoint error:&error];
}
if (assetAudioTrack != nil) {
AVMutableCompositionTrack *compositionAudioTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetAudioTrack atTime:insertionPoint error:&error];
}
}
// // Step 2
// // Translate the composition to compensate the movement caused by rotation (since rotation would cause it to move out of frame)
// t1 = CGAffineTransformMakeTranslation(assetVideoTrack.naturalSize.height, 0.0);
// // Rotate transformation
// t2 = CGAffineTransformRotate(t1, degreesToRadians(90));
if (degress == 0) {
t1 = CGAffineTransformMakeTranslation(0.0, 0.0);
t2 = CGAffineTransformRotate(t1, degreesToRadians(0));
}else if (degress == 90){
t1 = CGAffineTransformMakeTranslation(assetVideoTrack.naturalSize.height, 0.0);
t2 = CGAffineTransformRotate(t1, degreesToRadians(90));
}else if (degress == 180){
t1 = CGAffineTransformMakeTranslation(assetVideoTrack.naturalSize.width, assetVideoTrack.naturalSize.height);
t2 = CGAffineTransformRotate(t1, degreesToRadians(180));
}else if (degress == 270){
t1 = CGAffineTransformMakeTranslation(0,assetVideoTrack.naturalSize.height*1.78);
t2 = CGAffineTransformRotate(t1, degreesToRadians(-90));
}
// Step 3
// Set the appropriate render sizes and rotational transforms
if (!mutableVideoComposition) {
// Create a new video composition
mutableVideoComposition = [AVMutableVideoComposition videoComposition];
if (degress == 0 || degress == 180) {
mutableVideoComposition.renderSize = CGSizeMake(assetVideoTrack.naturalSize.width,assetVideoTrack.naturalSize.height);
}else{
mutableVideoComposition.renderSize = CGSizeMake(assetVideoTrack.naturalSize.height,assetVideoTrack.naturalSize.width);
}
mutableVideoComposition.frameDuration = CMTimeMake(1, 30);
// The rotate transform is set on a layer instruction
instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mutableComposition duration]);
layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:(mutableComposition.tracks)[0]];
[layerInstruction setTransform:t2 atTime:kCMTimeZero];
} else {
mutableVideoComposition.renderSize = CGSizeMake(mutableVideoComposition.renderSize.height, mutableVideoComposition.renderSize.width);
// Extract the existing layer instruction on the mutableVideoComposition
instruction = (mutableVideoComposition.instructions)[0];
layerInstruction = (instruction.layerInstructions)[0];
// Check if a transform already exists on this layer instruction, this is done to add the current transform on top of previous edits
CGAffineTransform existingTransform;
if (![layerInstruction getTransformRampForTime:[mutableComposition duration] startTransform:&existingTransform endTransform:NULL timeRange:NULL]) {
[layerInstruction setTransform:t2 atTime:kCMTimeZero];
} else {
// Note: the point of origin for rotation is the upper left corner of the composition, t3 is to compensate for origin
CGAffineTransform t3 = CGAffineTransformMakeTranslation(-1*assetVideoTrack.naturalSize.height/2, 0.0);
CGAffineTransform newTransform = CGAffineTransformConcat(existingTransform, CGAffineTransformConcat(t2, t3));
[layerInstruction setTransform:newTransform atTime:kCMTimeZero];
}
}
// Step 4
// Add the transform instructions to the video composition
instruction.layerInstructions = @[layerInstruction];
mutableVideoComposition.instructions = @[instruction];複製程式碼到這個時候呢視訊的旋轉已經完成了。
上面我們不是寫了一個視訊壓縮的方法嗎？把這個時候生成的mutableVideoComposition賦值給session.videoComposition = mutableVideoComposition;就好了。這樣就是先旋轉視訊然後直接壓縮完成我們的需求。