topic Re: Decoding JPEG with RST markers in Intel® Integrated Performance Primitives

Decoding JPEG with RST markers

Maciej_K_ — Thu, 13 Apr 2006 02:00:09 GMT

I don't know what I'm doing wrong:

I call:

ippiDecodeHuffman8x8_JPEG_1u16s_C1( m_inptr, len, &pos, block, &comp->dc_pred, &pMarker, huff_dc, huff_ac, m_huff_state );

It decodes image correctly up to first RST marker. It correctly returns pMarker = 0xd0 and ippStsNoErr. Now I call:

if ( m_restart_interval && n_left_to_restart == 0 )
{
m_comp[0].dc_pred = 0;
m_comp[1].dc_pred = 0;
m_comp[2].dc_pred = 0;
ippiDecodeHuffmanStateInit_JPEG_8u( m_huff_state );
n_left_to_restart = m_restart_interval;
}

But all next calls to ippiDecodeHuffman8x8_JPEG_1u16s_C1 return ippStsJPEGOutOfBufErr. JPEGs with no RST markers are decoded correctly. I'm using IPP4.1.

Am I missing something ?

Please help,
Kamil

Re: Decoding JPEG with RST markers

Vladimir_Dudnik — Thu, 13 Apr 2006 02:41:43 GMT

Hi Kamil,

I can guess that you did not clear variable pointed by pMarker before decoding next restart interval. Note, that is input/output parameter for function ippiDecodeHuffman8x8.

You can refer to IPP JPEGView sample for details how to implement JPEG codec with IPP functions.

Regards,
Vladimir

Re: Decoding JPEG with RST markers

Maciej_K_ — Thu, 13 Apr 2006 21:16:56 GMT

Yes, you are right, I forgot to move the decoding position after the RST marker when restart occured too.

Thank you very much,

Kamil

Message Edited by mac_kal@alnet.pl on 04-13-200607:22 AM