iOS （CVPixelBufferRef）NV12转i420、

首先附上libyuv的下载链接，需要自取，后面会用到：链接:https://pan.baidu.com/s/1DwtD5QdeTDHYqkqMxkpI2Q  密码:ijsj

#pragma mark - NV12转I420

/// NV12转I420

+ (CVPixelBufferRef)I420PixelBufferWithNV12:(CVImageBufferRef)cvpixelBufferRef {

    CVPixelBufferLockBaseAddress(cvpixelBufferRef, 0);

    //图像宽度（像素）

    size_t pixelWidth = CVPixelBufferGetWidth(cvpixelBufferRef);

    //图像高度（像素）

    size_t pixelHeight = CVPixelBufferGetHeight(cvpixelBufferRef);

    //获取CVPixelBufferRef中的y数据

    const uint8* y_frame = (uint8*)CVPixelBufferGetBaseAddressOfPlane(cvpixelBufferRef,0);

    //获取CMVImageBufferRef中的uv数据

    const uint8* uv_frame = (uint8*)CVPixelBufferGetBaseAddressOfPlane(cvpixelBufferRef,1);

    //y stride

    size_t plane1_stride = CVPixelBufferGetBytesPerRowOfPlane (cvpixelBufferRef, 0);

    //uv stride

    size_t plane2_stride = CVPixelBufferGetBytesPerRowOfPlane (cvpixelBufferRef, 1);

     //yuv_size(内存空间)

    size_t frame_size = pixelWidth*pixelHeight*3/2;

    //开辟frame_size大小的内存空间用于存放转换好的i420数据

    uint8* buffer = (unsigned char *)malloc(frame_size);

    //buffer为这段内存的首地址,plane1_size代表这一帧中y数据的长度

    uint8* dst_u = buffer + pixelWidth*pixelHeight;

    //dst_u为u数据的首地,plane1_size/4为u数据的长度

    uint8* dst_v = dst_u + pixelWidth*pixelHeight/4;

    //libyuv转换

    int ret = NV12ToI420(y_frame,

                        (int)plane1_stride,

                        uv_frame,

                        (int)plane2_stride,

                        buffer,

                        (int)pixelWidth,

                        dst_u,

                        (int)pixelWidth/2,

                        dst_v,

                        (int)pixelWidth/2,

                        (int)pixelWidth,

                        (int)pixelHeight

                        );

    if (ret) {

        return NULL;

    }

    NSDictionary *pixelAttributes = @{(id)kCVPixelBufferIOSurfacePropertiesKey : @{}};

    CVPixelBufferRef pixelBuffer = NULL;

    CVReturn result = CVPixelBufferCreate(kCFAllocatorDefault,

                                          pixelWidth,

                                          pixelHeight,

                                          kCVPixelFormatType_420YpCbCr8Planar,

                                          (__bridge CFDictionaryRef)(pixelAttributes),

                                          &pixelBuffer);

    CVPixelBufferLockBaseAddress(pixelBuffer, 0);

    size_t d = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0);

    size_t ud = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 1);

    size_t vd = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 2);

    unsigned char* dsty = (unsigned char *)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);

    unsigned char* dstu = (unsigned char *)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);

    unsigned char* dstv = (unsigned char *)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 2);

    unsigned char* srcy = buffer;

    for (unsigned int rIdx = 0; rIdx < pixelHeight; ++rIdx, srcy += pixelWidth, dsty += d) {

        memcpy(dsty, srcy, pixelWidth);

    }

    unsigned char* srcu = buffer + pixelHeight*pixelWidth;

    for (unsigned int rIdx = 0; rIdx < pixelHeight/2; ++rIdx, srcu += pixelWidth/2, dstu += ud) {

        memcpy(dstu, srcu, pixelWidth/2);

    }

    unsigned char* srcv = buffer + pixelHeight*pixelWidth*5/4;

    for (unsigned int rIdx = 0; rIdx < pixelHeight/2; ++rIdx, srcv += pixelWidth/2, dstv += vd) {

        memcpy(dstv, srcv, pixelWidth/2);

    }

    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

    if (result != kCVReturnSuccess) {

        NSLog(@"Unable to create cvpixelbuffer %d", result);

    }

    free(buffer);

//    CVPixelBufferRelease(cvpixelBufferRef);

    return pixelBuffer;

}

#pragma mark - NV12转BGRA

/// NV12转BGRA

+ (CVPixelBufferRef)RGBAPixelBufferWithNV12:(CVImageBufferRef)pixelBufferNV12{

    CVPixelBufferLockBaseAddress(pixelBufferNV12, 0);

    //图像宽度（像素）

    size_t pixelWidth = CVPixelBufferGetWidth(pixelBufferNV12);

    //图像高度（像素）

    size_t pixelHeight = CVPixelBufferGetHeight(pixelBufferNV12);

    //y_stride

    size_t src_stride_y = CVPixelBufferGetBytesPerRowOfPlane(pixelBufferNV12, 0);

    //uv_stride

    size_t src_stride_uv = CVPixelBufferGetBytesPerRowOfPlane(pixelBufferNV12,1);

    //获取CVImageBufferRef中的y数据

    uint8_t *src_y = (unsigned char *)CVPixelBufferGetBaseAddressOfPlane(pixelBufferNV12, 0);

    //获取CMVImageBufferRef中的uv数据

    uint8_t *src_uv =(unsigned char *) CVPixelBufferGetBaseAddressOfPlane(pixelBufferNV12, 1);

    // 创建一个空的32BGRA格式的CVPixelBufferRef

    NSDictionary *pixelAttributes = @{(id)kCVPixelBufferIOSurfacePropertiesKey : @{}};

    CVPixelBufferRef pixelBufferRGBA = NULL;

    CVReturn result = CVPixelBufferCreate(kCFAllocatorDefault,

                                          pixelWidth,pixelHeight,kCVPixelFormatType_32BGRA,

                                          (__bridge CFDictionaryRef)pixelAttributes,&pixelBufferRGBA);//kCVPixelFormatType_32BGRA

    if (result != kCVReturnSuccess) {

        NSLog(@"Unable to create cvpixelbuffer %d", result);

        return NULL;

    }

    result = CVPixelBufferLockBaseAddress(pixelBufferRGBA, 0);

    if (result != kCVReturnSuccess) {

        CFRelease(pixelBufferRGBA);

        NSLog(@"Failed to lock base address: %d", result);

        return NULL;

    }

    // 得到新创建的CVPixelBufferRef中 rgb数据的首地址

    uint8_t *rgb_data = (uint8*)CVPixelBufferGetBaseAddress(pixelBufferRGBA);

    // 使用libyuv为rgb_data写入数据，将NV12转换为BGRA

    size_t bgraStride = CVPixelBufferGetBytesPerRowOfPlane(pixelBufferRGBA,0);

    int ret = NV12ToARGB(src_y, (int)src_stride_y, src_uv, (int)src_stride_uv, rgb_data,(int)bgraStride, (int)pixelWidth, (int)pixelHeight);

    if (ret) {

        NSLog(@"Error converting NV12 VideoFrame to BGRA: %d", result);

        CFRelease(pixelBufferRGBA);

        return NULL;

    }

    CVPixelBufferUnlockBaseAddress(pixelBufferRGBA, 0);

    CVPixelBufferUnlockBaseAddress(pixelBufferNV12, 0);

    return pixelBufferRGBA;

}