使用iOS广播扩展录制视频

我正在尝试调整iOS广播扩展功能来录制视频，而不是直播。 这似乎是可能的，因为您可以在

processSampleBuffer:withType:

方法中获取像素缓冲区

然后我编写了如下代码，但在附加缓冲区时失败

我既不熟悉AVAssetWriter，也不熟悉应用程序扩展编程，所以我无法找出这里出了什么问题

我在做我们在分机里不该做的事吗？或者AVAssetWriter的用法是错误的

任何想法都是有用的。谢谢

//
//  SampleHandler.m
//  The main class of the App Extension
//
#import "SampleHandler.h"
#import <AVFoundation/AVFoundation.h>

@implementation SampleHandler {
    VideoExporter *exporter;
    NSDate *startDate;
}

- (void)broadcastStartedWithSetupInfo:(NSDictionary<NSString *,NSObject *> *)setupInfo {
    // User has requested to start the broadcast. Setup info from the UI extension can be supplied but optional.
    [self setupWriter];    
}

- (void)setupWriter {
    NSFileManager *fm = [NSFileManager defaultManager];

    // Set video path into shared container
    NSURL *containerURL = [fm containerURLForSecurityApplicationGroupIdentifier:@"group.com.mycompany"];
    NSURL *libraryURL = [containerURL URLByAppendingPathComponent:@"Library" isDirectory: true];
    BOOL isDir = false;
    NSURL *cachesURL = [libraryURL URLByAppendingPathComponent:@"Caches" isDirectory: true];    
    NSURL *outVideoURL = [cachesURL URLByAppendingPathComponent:@"output.mov"];

    if([[NSFileManager defaultManager] fileExistsAtPath:[outVideoURL path]]){
        [[NSFileManager defaultManager] removeItemAtPath:[outVideoURL path] error:nil];
    }

    exporter = [[VideoExporter alloc] initWithOutputURL:outVideoURL size:CGSizeMake(1280, 720) frameRate:30];
    exporter.delegate = self;
    [exporter beginExport];

    startDate = [NSDate date];
}

- (void)broadcastPaused {
    // User has requested to pause the broadcast. Samples will stop being delivered.
}

- (void)broadcastResumed {
    // User has requested to resume the broadcast. Samples delivery will resume.
}

- (void)broadcastFinished {
    // User has requested to finish the broadcast.
    NSLog(@"User requested finish writing");
    [exporter finishWriting];
}

- (void)processSampleBuffer:(CMSampleBufferRef)sampleBuffer withType:(RPSampleBufferType)sampleBufferType {

    switch (sampleBufferType) {
        case RPSampleBufferTypeVideo:
            // Handle video sample buffer
            [exporter addCMSampleBuffer:sampleBuffer];
            break;
        case RPSampleBufferTypeAudioApp:
            // Handle audio sample buffer for app audio
            break;
        case RPSampleBufferTypeAudioMic:
            // Handle audio sample buffer for mic audio
            break;            
        default:
            break;
    }
}
@end


//
//  VideoExporter.m
//  Helper class to write the video
//
#import "VideoExporter.h"

@implementation VideoExporter

@synthesize width, height;
@synthesize framesPerSecond;
@synthesize outputURL;
@synthesize delegate;

- (id)initWithOutputURL:(NSURL *)aURL size:(CGSize)size frameRate:(uint64_t)fps {
    if ((self = [super init])) {
        width = (int)round(size.width);
        height = (int)round(size.height);
        framesPerSecond = fps;
        outputURL = aURL;
    }
    return self;
}

- (void)beginExport {    
    NSError *error = nil;
    writer = [[AVAssetWriter alloc] initWithURL:outputURL
                                       fileType:AVFileTypeQuickTimeMovie
                                          error:&error];
    NSAssert(writer != nil, @"Writer should not be nil");

    NSDictionary * outSettings = [NSDictionary dictionaryWithObjectsAndKeys:AVVideoCodecTypeH264, AVVideoCodecKey,
                                  [NSNumber numberWithInt:width], AVVideoWidthKey,
                                  [NSNumber numberWithInt:height], AVVideoHeightKey, nil];
    writerInput = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeVideo outputSettings:outSettings];

    NSDictionary * pixelAttributes = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange], kCVPixelBufferPixelFormatTypeKey, nil];
    adaptor = [[AVAssetWriterInputPixelBufferAdaptor alloc] initWithAssetWriterInput:writerInput sourcePixelBufferAttributes:pixelAttributes];

    [writer addInput:writerInput];

    BOOL started = [writer startWriting];
    NSAssert(started, @"Should start writing!");

    [writer startSessionAtSourceTime:kCMTimeZero];
}

- (void)addCMSampleBuffer:(CMSampleBufferRef)buf {
    if(writer.status==0) {
        NSLog(@"Writer status unknown!!");
    }    
    [self appendCMSampleBuffer:buf];
}

- (void)finishWriting {        
    [writerInput markAsFinished];
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);

    int64_t longDuration = 1000;
    CMTime cmTime = CMTimeMake(longDuration, 1);
    [writer endSessionAtSourceTime:cmTime];

    [writer finishWritingWithCompletionHandler:^{
        // Call delegate method here
        dispatch_semaphore_signal(semaphore);
    }];
    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);    
}

#pragma mark - Private -

- (void)appendCMSampleBuffer:(CMSampleBufferRef)bufferRef {
    if(![writerInput isReadyForMoreMediaData]) {
        NSLog(@"WriterInput not ready! status = %ld, error=%@", (long)writer.status, writer.error);
        return;
    }    
    BOOL success = [adaptor appendPixelBuffer:(CVPixelBufferRef)bufferRef withPresentationTime:CMTimeMake(frameCount++, (int32_t) framesPerSecond)];
    if(success == NO) {
        NSLog(@"Append buffer failed! status = %ld, error=%@", (long)writer.status, writer.error);  // Always gets here
    }
}
@end

//
//SampleHandler.m
//应用程序扩展的主类
//
#导入“SampleHandler.h”
#进口
@实现SampleHandler{
视频出口商*出口商；
NSDate*起始日期；
}
-（无效）广播已启动，设置信息：（NSDictionary*）设置信息{
//用户已请求启动广播。可以提供UI扩展的设置信息，但这是可选的。
[自编]；
}
-（无效）作者{
NSFileManager*fm=[NSFileManager defaultManager]；
//将视频路径设置到共享容器中
NSURL*containerURL=[fm ContainerUrlForSecurity应用程序组标识符：@“group.com.mycompany”]；
NSURL*libraryURL=[ContainerUrlByAppendingPathComponent:@“Library”是目录：true]；
BOOL-isDir=false；
NSURL*cachesURL=[libraryURL URLByAppendingPathComponent:@“Caches”是目录：true]；
NSURL*outVideoURL=[CacheSurlByAppendingPathComponent:@“output.mov”]；
如果（[[NSFileManager defaultManager]文件ExistSatPath:[outVideoURL路径]]）{
[[NSFileManager defaultManager]removeItemAtPath:[outVideoURL path]错误：nil]；
}
exporter=[[VideoExporter alloc]initWithOutputURL:outVideoURL大小：CGSizeMake（1280720）帧速率：30]；
exporter.delegate=self；
[出口商开始出口]；
startDate=[NSDate日期]；
}
-（无效）广播暂停{
//用户已请求暂停广播。样本将停止发送。
}
-（无效）恢复广播{
//用户已请求恢复广播。将继续发送样本。
}
-（无效）广播结束{
//用户已请求完成广播。
NSLog（@“用户请求完成写入”）；
[出口商完成写作]；
}
-（void）processSampleBuffer:（CMSampleBufferRef）SampleBufferWithType:（RPSampleBufferType）sampleBufferType{
开关（sampleBufferType）{
案例RPSampleBufferTypeVideo：
//处理视频采样缓冲区
[导出器addCMSampleBuffer:sampleBuffer]；
打破
案例RPSampleBufferTypeAudioApp：
//处理应用程序音频的音频采样缓冲区
打破
案例RPSampleBufferTypeAudioMic：
//处理麦克风音频的音频采样缓冲区
打破
违约：
打破
}
}
@结束
//
//视频出口商
//帮助类来编写视频
//
#导入“VideoExporter.h”
@实施视频导出器
@综合宽度、高度；
@合成帧秒；
@合成输出URL；
@综合代表；
-（id）initWithOutputURL:（NSURL*）aURL size:（CGSize）size帧速率：（uint64_t）fps{
if（（self=[super init]））{
宽度=（int）圆形（size.width）；
高度=（整数）圆形（大小.高度）；
framesPerSecond=fps；
outputURL=aURL；
}
回归自我；
}
-（void）beginExport{
n错误*错误=nil；
writer=[[AVAssetWriter alloc]initWithURL:outputURL
文件类型：AVFileTypeQuickTimeMovie
错误：&错误]；
NSAssert（writer！=nil，@“writer不应为nil”）；
NSDictionary*outSettings=[NSDictionary Dictionary WithObjectsAndKeys:AVVideoCodeTypeH264，AVVideoCodeKey，
[NSNumber numberWithInt:width]、AVVideoWidthKey、，
[NSNumber numberWithInt:height]，AVVideoHeightKey，无]；
writerInput=[[AVAssetWriterInput alloc]initWithMediaType:AvMediaType视频输出设置：outSettings]；
NSDictionary*pixelAttributes=[NSDictionary Dictionary WithObjectsSandKeys:[NSNumber numberWithInt:kCVPixelFormatType_420YPCBCRCR8BIPLANARVIDERANGE]，kCVPixelBufferPixelFormatTypeKey，无]；
适配器=[[AvassetWriterInputPixelBufferAdapter alloc]initWithAssetWriterInput:writerInput sourcePixelBufferAttributes:pixelAttributes]；
[writer addInput:writerInput]；
BOOL start=[writer startWriting]；
NSAssert（已开始，@“应开始编写！”）；
[writer startSessionAtSourceTime:kCMTimeZero]；
}
-（void）addCMSampleBuffer:（CMSampleBufferRef）buf{
if（writer.status==0）{
NSLog（@“写入程序状态未知！！”）；
}    
[self-appendCMSampleBuffer:buf]；
}
-（无效）完成写入{
[writerInput markAsFinished]；
dispatch\u semaphore\u t semaphore=dispatch\u semaphore\u create（0）；
int64_t longDuration=1000；
CMTime CMTime=CMTimeMake（长持续时间，1）；
[编写器EndSessionSourceTime:cmTime]；
[编写器使用CompletionHandler完成编写：^{
//在此调用委托方法
调度信号灯（信号灯）；
}];
调度信号灯等待（信号灯，调度时间永远）；
}
#布拉格马克-私人-
-（void）appendCMSampleBuffer:（CMSampleBufferRef）bufferRef{
如果（！[writerInput isReadyForMoreMediaData]）{
NSLog（@“WriterInput not ready！状态=%ld，错误=%@”，（长）writer.status，writer.error）；
返回；
}    
BOOL success=[Adapter appendPixelBuffer:（CVPixelBufferRef）bufferRef with PresentationTime:CMTimeMake（frameCount++，（int32_t）framesPerSecond）]；
如果（成功==否）{
NSLog（@“追加缓冲区失败！状态=%ld，错误=%@”，（长）writer.status，writer.error）；//始终位于此处
}
}
@结束

我在iOS 13.7（17H35）上测试了这种行为

似乎

AVAssetWriter

需要前台特权，而扩展没有前台特权。（）

startWriting

met

Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo={
    NSLocalizedFailureReason=An unknown error occurred (-17508),
    NSLocalizedDescription=The operation could not be completed,
    NSUnderlyingError=0x282a80120 {
        Error Domain=NSOSStatusErrorDomain Code=-17508 "(null)"
    }
}