Question

我正在使用此代码创建CMVideoFormatDescriptionRef：

  CMVideoDimensions dimensions = {
    .width = width,
    .height = height
  };

  CMVideoFormatDescriptionRef videoInfo = NULL;

  NSDictionary *options2 = [NSDictionary dictionaryWithObjectsAndKeys:
                           @(YES), kCVPixelBufferCGImageCompatibilityKey,
                           @(YES), kCVPixelBufferCGBitmapContextCompatibilityKey,
                           dimensions, kCVImageBufferDisplayDimensionsKey,
                            nil];
  CFDictionaryRef dictOptionsRef = (__bridge CFDictionaryRef)options2;

  CMFormatDescriptionCreate(kCFAllocatorDefault, kCMMediaType_Video, 'brga', dictOptionsRef, &videoInfo);

我需要将该字典传递给CMFormatDescriptionCreate。

问题是最后一行

dimensions, kCVImageBufferDisplayDimensionsKey,

这不是将dimensions添加到该字典的正确方法。它崩溃了应用程序。

我试图用{：1}}将整个事情包裹起来：

NSValue

它在理论上有效，没有崩溃，但NSValue *miValue = [NSValue value: &dimensions withObjCType:@encode(CMVideoDimensions)];未正确创建（OSStatus -12731）。如果我从字典中删除最后一行，则会创建videoInfo，但没有维度的定义，假定为0x0像素或videoInfo。见下文：

codecType

来自常规<CMVideoFormatDescription 0x17044c270 [0x1b0330bb8]> { mediaType:'vide' mediaSubType:'brga' mediaSpecific: { codecType: 0 dimensions: 0 x 0 <--HERE!!! } extensions: {<CFBasicHash 0x17086dcc0 [0x1b0330bb8]>{type = immutable dict, count = 4, entries => 0 : <CFString 0x1aa9427c8 [0x1b0330bb8]>{contents = "CVImageBufferYCbCrMatrix"} = <CFString 0x1aa942808 [0x1b0330bb8]>{contents = "ITU_R_601_4"} 3 : <CFString 0x1aa942c68 [0x1b0330bb8]>{contents = "CGImageCompatibility"} = <CFBoolean 0x1b0331110 [0x1b0330bb8]>{value = true} 5 : <CFString 0x1aa9428a8 [0x1b0330bb8]>{contents = "CVImageBufferColorPrimaries"} = <CFString 0x1aa9427e8 [0x1b0330bb8]>{contents = "ITU_R_709_2"} 6 : <CFString 0x1aa942c48 [0x1b0330bb8]>{contents = "CGBitmapContextCompatibility"} = <CFBoolean 0x1b0331110 [0x1b0330bb8]>{value = true} } } }的{{1}}将CMVideoFormatDescriptionRef显示为CMSampleBufferRef，并将框架的常规尺寸显示为1920x1080。

我该怎么做？

Answer 1

kCVImageBufferDisplayDimensionsKey标头文件表示密钥的值为

//带有以下两个键的CFDictionary

kCVImageBufferDisplayWidthKey和kCVImageBufferDisplayHeightKey，两者都是CFNumber。

您改为通过CMVideoDimensions，因此请将其更改为

NSDictionary *dimensions = [NSDictionary dictionaryWithObjectsAndKeys:@(width), kCVImageBufferDisplayWidthKey, @(height), kCVImageBufferDisplayHeightKey];

将结构添加到NSDictionary

1 个答案: