关于cvpixelbuffer 一些数据的异常

[yaoming04111]

目前我通过 didOutputVideoSampleBuffer 接口获取的 sampleBuffer 数据
将他转换成 nsdata 数据 然后在 把nsdata 数据 转换回 CVPixelBufferRef 的时候。设置的格式 为 960540 底部数据会有部分丢失
设置成 19201080 的时候也会有部分的丢失 但是会比 960*540的时候有所好转
转换代码如下：
`-(NSMutableData *) convertVideoSmapleBufferToYuvData:(CVImageBufferRef) pixelBuffer{

OSType pixeltype = CVPixelBufferGetPixelFormatType(pixelBuffer);
bool isPlanar = CVPixelBufferIsPlanar(pixelBuffer);
size_t planeCount = CVPixelBufferGetPlaneCount(pixelBuffer);
//表示开始操作数据
CVPixelBufferLockBaseAddress(pixelBuffer, 0);

//图像宽度（像素）
size_t pixelWidth = CVPixelBufferGetWidth(pixelBuffer);

// a_width = pixelWidth;
//图像高度（像素）
size_t pixelHeight = CVPixelBufferGetHeight(pixelBuffer);
// a_heigt = pixelHeight;
//yuv中的y所占字节数
size_t y_size = pixelWidth * pixelHeight;
//yuv中的uv所占的字节数
size_t uv_size = y_size / 2;

uint8_t *yuv_frame = (uint8_t *)malloc(uv_size + y_size);

//获取CVImageBufferRef中的y数据
uint8_t *y_frame = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
memmove(yuv_frame, y_frame, y_size);

//获取CMVImageBufferRef中的uv数据
uint8_t *uv_frame = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);
memmove(yuv_frame + y_size, uv_frame, uv_size);

CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

//返回数据
return [NSMutableData dataWithBytesNoCopy:yuv_frame length:y_size + uv_size];

// [NSMutableData dataWithBytesNoCopy:yuv_frame length:y_size + uv_size];
}

-(CVPixelBufferRef)createCVPixelBufferRefFromNV12buffer:(unsigned char )buffer width:(int)w height:(int)h {
NSDictionary pixelAttributes = @{
(NSString)kCVPixelBufferIOSurfacePropertiesKey:@{},
(NSString)kCVPixelBufferOpenGLESCompatibilityKey:@yES
};
CVReturn result = 0;
if(_aaapixelBuffer == NULL){
result = CVPixelBufferCreate(kCFAllocatorDefault,
w,
h,// - 58
kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange,
(__bridge CFDictionaryRef)(pixelAttributes),
&_aaapixelBuffer);//kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange,
}
CVPixelBufferLockBaseAddress(_aaapixelBuffer,0);
unsigned char *yDestPlane = CVPixelBufferGetBaseAddressOfPlane(_aaapixelBuffer, 0);

// Here y_ch0 is Y-Plane of YUV(NV12) data.
unsigned char *y_ch0 = buffer;

memmove(yDestPlane, y_ch0, w * h);
unsigned char *uvDestPlane = CVPixelBufferGetBaseAddressOfPlane(_aaapixelBuffer, 1);

// Here y_ch1 is UV-Plane of YUV(NV12) data.
unsigned char *y_ch1 = buffer + w * h;
memmove(uvDestPlane, y_ch1, w * h/2);
CVPixelBufferUnlockBaseAddress(_aaapixelBuffer, 0);

if (result != kCVReturnSuccess) {
    NSLog(@"Unable to create cvpixelbuffer %d", result);
}
return _aaapixelBuffer;

}`

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