[Solved] Argus Convert YUV420(YcbCr420_888) to RGB

[dtok]

Hallo everyone,

I am looking for a easy way to convert YUV420 to RGB.

I need:

• capture a image, [OK]
• write the image to jpeg, [OK]
• export preview, [NOT OK]

How I do it:

[ARGUS LIB]

…

EGLStream::IImage iImageData = Argus::interface_castEGLStream::IImage(image);
yuv_to_rgb((char)iImageData->mapBuffer(), rgb, width, height); // ! Conversion not work !

…

I take always ‘green’ inexplicably images.

YUV - Wikipedia → also not work

I am looking for: description YUV420 format encoder/decoder or example how to decode or contact to support.

I do not need to display this image on TX1 (only decode this format).

Best regards and thx for help.

[dtok]

Perhaps someone know what I do wrong in this converter.

void yuv2rgb(char *yuv, char *rgb, int width, int height)
{
// Based on:
// YUV - Wikipedia

int pos   = 0;
int posUV = 0;
char *_y  = yuv;
char *_u  = yuv+(width)*(height);
char *_v  = yuv+width*height+((width+1)*(height+1))/4;

for (int py = 0; py < height; py+=1)
{
    if (py%2 == 0 && py != 0)  // next line
    {
        posUV = (py/2)*width;
    }

    for (int x = 0; x < width; x+=2)
    {
        int posY = (py * width + x);

        char y  = _y[posY   ];
        char y2 = _y[posY+1 ];

        char u  = _u[posUV  ];
        char v  = _v[posUV  ];

        float r  = static_cast<float>(y + (1.370705 * (v - 128)));
        float g  = static_cast<float>(y - (0.698001 * (v - 128)) - (0.337633 * (u - 128)));
        float b  = static_cast<float>(y + (1.732446 * (u - 128)));

        float r2 = static_cast<float>(y2 + (1.370705 * (v - 128)));
        float g2 = static_cast<float>(y2 - (0.698001 * (v - 128)) - (0.337633 * (u - 128)));
        float b2 = static_cast<float>(y2 + (1.732446 * (u - 128)));

        rgb[pos  ] = static_cast<char>(clamp(r , 0, 255));
        rgb[pos+1] = static_cast<char>(clamp(g , 0, 255));
        rgb[pos+2] = static_cast<char>(clamp(b , 0, 255));

        rgb[pos+3] = static_cast<char>(clamp(r2, 0, 255));
        rgb[pos+4] = static_cast<char>(clamp(g2, 0, 255));
        rgb[pos+5] = static_cast<char>(clamp(b2, 0, 255));

        pos+=6;
        posUV+=1;
    }
}
return ;

}

[dtok]

Perhaps someone have Pixel Format YcbCr420_888 specification ?

[dtok]

Exist any alternative way to collect Camera Image Buffer Data in Real Time ?

[dtok]

I am looking for a contact to someone who knows the tegra argus library.
Perhaps someone from the moderators knows, how to contact them.

[dtok]

Hi,
only to be sure.

This two line should give me Image in streamPixelFormat [Supported only YUV420_888] and with streamResolution ?

EGLStream::IImage *iImageData = Argus::interface_castEGLStream::IImage(image);
iImageData->mapBuffer();

Now Buffer Counter tells my that I have 3x Buffer with this size:
ie. resolution: 720x560
0-Buffer Size = 524288
1-Buffer Size = 131072
2-Buffer Size = 131072

ie. resolution: 640x480
0-Buffer Size = 393216
1-Buffer Size = 131072
2-Buffer Size = 131072

Why Buffer 0 [y] have this size ?
Why Buffer 1-2 [uv] have still the same size ?

According to YUV420 Specification,
ie. resolution 720x560
0-Buffer should have 720560 = 403200
1-Buffer should have 720560/4 = 100800
2-Buffer should have 720*560/4 = 100800

Am I wrong ?

[dtok]

Result from OpenCV library [cvtColor(…)].

[dtok]

And now it works !
Thanks guys for help and all tips.

[joe_kale]

What was the resolution to this thread? It seems to be missing half of the conversation.

When I use a stream resolution of 692x520, I get only 2 buffers and iimage->getBufferSize(0) returns 524288 which does not seem to align with this plane being a grayscale image at the stream resolution.

[yzcyz96]

Hi dtok,

I ran into the same issue. How did you figure this out?

[yzcyz96]

It seems that these rubbish output arise from the ‘block linear’ returned data type of mapbuffer() so that they cannot be sent directly to glTexImage2D to do texture sampling.

[yzcyz96]

Hi dtok,

I ran into the same issue. How did you figure this out?

[yzcyz96]

Ohh, sorry for the duplicate message because of the poor internet connection.