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标题: ios - 操作 CVPixelBufferRef 高度和宽度 [打印本页]

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作者: 菜鸟教程小白    时间: 2022-12-11 18:28
标题: ios - 操作 CVPixelBufferRef 高度和宽度

我正在使用 GPUImage 库函数来操作 CVPixelbuffer 的高度和宽度。我正在纵向录制视频，当用户旋转设备时，我的屏幕会自行调整为横向模式。我希望横向框架适合屏幕。

例如:- 我以 320x568 的纵向模式开始视频，当我将设备转为横向时，我的帧是 568x320，我想适应 320x568。为了调整这个东西，我想操纵 CVPixelBuffer。但这会占用大量内存，最后我的应用程序崩溃了。

 - (CVPixelBufferRef) GPUImageCreateResizedSampleBufferWithBufferCVPixelBufferRef)cameraFrame withBufferCGSize)finalSize withSampleBufferCMSampleBufferRef)sampleBuffer
{
   CVPixelBufferRef pixel_buffer = NULL;

// CVPixelBufferCreateWithPlanarBytes for YUV input
@autoreleasepool {

    CGSize originalSize = CGSizeMake(CVPixelBufferGetWidth(cameraFrame), CVPixelBufferGetHeight(cameraFrame));

    CVPixelBufferLockBaseAddress(cameraFrame, 0);
    GLubyte *sourceImageBytes = (GLubyte *)CVPixelBufferGetBaseAddress(cameraFrame);
    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, sourceImageBytes, CVPixelBufferGetBytesPerRow(cameraFrame) * originalSize.height, NULL);
    CGColorSpaceRef genericRGBColorspace = CGColorSpaceCreateDeviceRGB();
    CGImageRef cgImageFromBytes = CGImageCreate((int)originalSize.width, (int)originalSize.height, 8, 32, CVPixelBufferGetBytesPerRow(cameraFrame), genericRGBColorspace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst, dataProvider, NULL, NO, kCGRenderingIntentDefault);

    GLubyte *imageData = (GLubyte *) calloc(1, ((int)finalSize.width * (int)finalSize.height * 4));


    CGContextRef imageContext = CGBitmapContextCreate(imageData, (int)finalSize.width, (int)finalSize.height, 8, (int)finalSize.width * 4, genericRGBColorspace,  kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);

    CGRect scaledRect = AVMakeRectWithAspectRatioInsideRect(originalSize, CGRectMake(0, 0, finalSize.width, finalSize.height));

    CGContextDrawImage(imageContext, scaledRect, cgImageFromBytes);
    CGImageRelease(cgImageFromBytes);
    CGContextRelease(imageContext);
    CGColorSpaceRelease(genericRGBColorspace);
    CGDataProviderRelease(dataProvider);

    CVPixelBufferCreateWithBytes(kCFAllocatorDefault, finalSize.width, finalSize.height, kCVPixelFormatType_32BGRA, imageData, finalSize.width * 4, stillImageDataReleaseCallback, NULL, NULL, &pixel_buffer);
    CMVideoFormatDescriptionRef videoInfo = NULL;
    CMVideoFormatDescriptionCreateForImageBuffer(NULL, pixel_buffer, &videoInfo);

    CMTime frameTime = CMTimeMake(1, 30);
    CMSampleTimingInfo timing = {frameTime, frameTime, kCMTimeInvalid};

    CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault, pixel_buffer, YES, NULL, NULL, videoInfo, &timing, &sampleBuffer);
    CVPixelBufferUnlockBaseAddress(cameraFrame, 0);
    CFRelease(videoInfo);
    //   CVPixelBufferRelease(pixel_buffer);

}
return pixel_buffer;

}

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Best Answer-推荐答案

CG* - CoreGraphics 使用 CPU，对于实时视频来说太慢了，使用 CV* 和 GPU

    // - (void)captureOutputAVCaptureOutput *)captureOutput didOutputSampleBufferCMSampleBufferRef)sampleBuffer fromConnectionAVCaptureConnection *)connection
    CVPixelBufferLockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);

    CIImage *baseImg = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    CIImage *resultImg = [baseImg imageByCroppingToRectutputFrameCropRect];
    resultImg = [resultImg imageByApplyingTransformutputFrameTransform];

    // created once
    // glCtx = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
    // ciContext = [CIContext contextWithEAGLContext:glCtx options{kCIContextWorkingColorSpace:[NSNull null]}];
    // ciContextColorSpace = CGColorSpaceCreateDeviceRGB();
    // CVReturn res = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, VTCompressionSessionGetPixelBufferPool(compressionSession), &finishPixelBuffer);

    [ciContext render:resultImg toCVPixelBuffer:finishPixelBuffer bounds:resultImg.extent colorSpace:ciContextColorSpace];

    CVPixelBufferUnlockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);

关于ios - 操作 CVPixelBufferRef 高度和宽度，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41424549/

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