意外的输出将CVPixelBuffer转换为MTLTexture

Question

我正在使用AVAssetReader从AVAsset提取SampleBuffers。我使用下面的代码片段将每个CMSampleBuffer转换为MTLTexture。但是，我得到了CVPixelBuffer的期望，但是当我尝试对其进行转换时却得到了。预期输出为 ..

我已经尝试调试准确的宽度和高度，我尝试使用发生相同问题的其他视频，尝试创建不同的textureCache。同样的问题。

    func convertToMTLTexture(sampleBuffer: CMSampleBuffer?) -> MTLTexture? {


        if let textureCache = textureCache,
            let sampleBuffer = sampleBuffer,
            let imageBuffer:CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) {

            let width = CVPixelBufferGetWidth(imageBuffer)
            let height = CVPixelBufferGetHeight(imageBuffer)

            var texture: CVMetalTexture?
            CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, textureCache,
                                                      imageBuffer, nil, .bgra8Unorm, width, height, 0, &texture)

            if let texture = texture {
                return CVMetalTextureGetTexture(texture)
            }

        }
        return nil
    }