topic Hello! in Intel® Integrated Performance Primitives

MJPEG decoder - chroma decoding issue

Yaroslav_Korchevsky — Thu, 09 Aug 2012 13:08:01 GMT

Here is the issue with chroma decoding.
I feed to decoder the file:

And get decoded:

The picture is coded as JC_YCBCR with subsampling JS_422
If I decode this picture into JC_GRAY - I get goot quality grayscale picture.
But if I require to decode this picture into the colorspace and subsampling
as it is coded internally: JC_YCBCR with subsampling JS_422
I see wrong image.

How to fix it?

MJPEG decoder - chroma decoding issue

Chao_Y_Intel — Fri, 10 Aug 2012 05:59:06 GMT

Hello,

How do you set the output video format? some samle code may be helpful here:
I see from the MJPEG sample code, it needs to set as YUY2:

if(JS_422 == sampling && JC_YCBCR == color)
{
m_colorFormat = YUY2;
m_frameStep = m_frameDims.width*2;

}

MJPEG decoder - chroma decoding issue

Yaroslav_Korchevsky — Fri, 10 Aug 2012 10:42:39 GMT

[bash]My code is there^

jerr = m_decoder.ReadHeader(&in_width, &in_height, &in_channels, &in_color, &in_sampling, &in_precision);

// Allocate buffer here jerr = m_decoder.SetDestination(p42xP4, n42xStepP4, dim4xxY, in_channels, in_color, in_sampling, 8, scale); jerr = m_decoder.ReadData();[/bash]
In this code colorspace and sampling are exactly as coded in compressed JPEG image.
I do so, to avoid redundant color convertions inside of decoder.
Why should I change it?

In IPP 6.1 everithing worked fine.
Why it has been changed?

Hello!

NSkib — Tue, 07 Oct 2014 11:58:00 GMT

Hello!

Problem still exists with ipp-samples ver. 7.0.7. with JPEG 4:2:2 YCbCr. Is it possible to avoid YUY2 in output and get YUV422?

Possibly i have to change 2928 line in jpegdec.cpp from

status = ippiYCbCr422_8u_P3C2R(pSrc8u,srcStep,pDst8u,dstStep,roi);

to something else, or add some other conversion?