AVFoundation 视频导出 - 无故出错 [Objective-C]

Question

我正在尝试使用 AVFoundation 为视频颜色应用程序编码视频（您可以查看 here）。导出编解码器将是 H264 或 ProRes 或 HEVC（取决于用户的选择），如果这对解决我的问题有帮助的话。

我已经根据答案编写了我的代码：Make movie file with picture Array and song file, using AVAsset

来自 github 的代码：https://github.com/caferrara/img-to-video/blob/master/img-to-video/ViewController.m#L29

这是我得到的（有一些外部变量和函数调用，但我认为很清楚发生了什么）：

NSURL * outURL = [NSURL fileURLWithPath:[NSString stringWithFormat: @"%s", path]];

NSLog(outURL.absoluteString);

NSError * error = nil;
AVAssetWriter * videoWriter = [[AVAssetWriter alloc] initWithURL: outURL
                              fileType:AVFileTypeQuickTimeMovie
                                                          error:&error];

NSDictionary * videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               encoder->codec, AVVideoCodecKey,
                               [NSNumber numberWithInt:encoder->width], AVVideoWidthKey,
                               [NSNumber numberWithInt:encoder->height], AVVideoHeightKey,
                               nil ];

AVAssetWriterInput * videoWriterInput = [AVAssetWriterInput
                                        assetWriterInputWithMediaType:AVMediaTypeVideo
                                        outputSettings:videoSettings];


AVAssetWriterInputPixelBufferAdaptor * adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                 assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
                                                 sourcePixelBufferAttributes:nil];

videoWriterInput.expectsMediaDataInRealTime = YES;
[videoWriter addInput:videoWriterInput];

//Start a session:
[videoWriter startWriting];
NSLog(@"Write Started");
[videoWriter startSessionAtSourceTime:kCMTimeZero];


//Video encoding

CVPixelBufferRef buffer = NULL;

setMlvAlwaysUseAmaze(App->videoMLV);

for(uint64_t f = 0; f < getMlvFrames(App->videoMLV); ++f)
{
    getMlvProcessedFrame16(App->videoMLV, f, encoder->data);
    CVReturn success = CVPixelBufferCreateWithBytes( kCFAllocatorDefault,
                                                     encoder->width,
                                                     encoder->height,
                                                     kCVPixelFormatType_48RGB,
                                                     encoder->data,
                                                     sizeof(uint16_t) * encoder->width * 3,
                                                     NULL,
                                                     NULL,
                                                     NULL,
                                                     &buffer );
    if (success != kCVReturnSuccess || buffer == NULL) NSLog(@"Failed to create pixel buffer.");
    NSDictionary * colour_attachment = @{(id)kCVImageBufferICCProfileKey : (id)encoder->colour_profile_data};
    CVBufferSetAttachments(buffer, (CFDictionaryRef)colour_attachment, kCVAttachmentMode_ShouldPropagate);

    BOOL append_ok = NO;
    int j = 0;
    while (!append_ok && j < 30) {
        if (adaptor.assetWriterInput.readyForMoreMediaData)  {
            //print out status:
            NSLog(@"Processing video frame (%d, attempt %d)", (int)f, j);

            CMTime frameTime = CMTimeMake(f * 5000.0, (int32_t)(encoder->fps * 1000.0));
            append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];
            if(!append_ok){
                NSError *error = videoWriter.error;
                if(error!=nil) {
                    NSLog(@"Unresolved error %@,%@.", error, [error userInfo]);
                }
            }
            while(!adaptor.assetWriterInput.readyForMoreMediaData) [NSThread sleepForTimeInterval:0.0001];
        }
        else {
            printf("adaptor not ready %d, %d\n", (int)f, j);
            while(!adaptor.assetWriterInput.readyForMoreMediaData) [NSThread sleepForTimeInterval:0.0001];
        }
        j++;
    }
    if (!append_ok) {
        printf("error appending image %d times %d\n, with error.", (int)f, j);
    }
}

[videoWriterInput markAsFinished];
[videoWriter finishWriting];

[videoWriterInput release];
[videoWriter release];

NSLog(@"Write Ended");

但是，每当我尝试运行时，它都会打印以下错误：

2017-11-15 20:54:40.532 MLV App[21801:3488295] Unresolved error Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo={NSLocalizedFailureReason=An unknown error occurred (-12905), NSLocalizedDescription=The operation could not be completed, NSUnderlyingError=0x7fd446adeb70 {Error Domain=NSOSStatusErrorDomain Code=-12905 "(null)"}},{
NSLocalizedDescription = "The operation could not be completed";
NSLocalizedFailureReason = "An unknown error occurred (-12905)";
NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-12905 \"(null)\""; }.

我在网上查了很多关于这个错误代码的含义，但一直没用。

我在这里使用 AVFoundation 有什么大问题吗？我也尝试过切换到 8 位 RGB 帧，但没有解决问题。

Answer 1

并非列出的每种像素格式实际上都受框架支持。不支持您选择的那个。坚持 kCVPixelFormatType_32ARGB、kCVPixelFormatType_422YpCbCr8 等标准格式

kVTPixelTransferNotSupportedErr = -12905 通过 https://www.osstatus.com/

关于 Core Video 支持的像素格式的技术问答： https://developer.apple.com/library/content/qa/qa1501/_index.html

请注意，您可能需要运行代码来查找给定 OS 版本的最新支持格式列表。此外，并非每个框架中的每个路径都支持每种格式。换句话说，在像素格式之间进行转换的 VideoToolbox 可能不支持格式 X，即使您可以创建该格式的 CVPixelBuffer。

对于您的情况，请尝试 kCVPixelFormatType_4444AYpCbCr16、kCVPixelFormatType_422YpCbCr16、kCVPixelFormatType_422YpCbCr10 或 kCVPixelFormatType_64ARGB，因为它们至少在解码端受支持： https://developer.apple.com/documentation/avfoundation/avassetreadertrackoutput

AVFoundation 视频导出 - 无故出错 [Objective-C]

AVFoundation video export - error for no reason [Objective-C]

macos

video

export

objective-c

avfoundation