topic Re: DCT in ipp_sample MPEG2 for Linux in Intel® Integrated Performance Primitives

DCT in ipp_sample MPEG2 for Linux

estegano — Fri, 06 May 2005 08:26:14 GMT

Hello,

I want to change the DCT coefficients from the encoder.
When I tray do
ippiQuantIntra_MPEG2_16s_C1I( block, pContext->Video[pContext->cvindex].QScale, 0, count);
for (c=0;c<65;c++) block=((block>>1)<<1)|1;

it's ok, but when I take off |1

for (c=0;c<65;c++) block=((block>>1)<<1);

I have the message
qtplayer: video/seq.c:1818: Macroblock_420_I_frame: Assertion `ret == 0' failed.
Aborted

What's happening? Am I in wrong position form encoder?

Re: DCT in ipp_sample MPEG2 for Linux

Vladimir_Dudnik — Fri, 13 May 2005 22:39:38 GMT

Hi,

could you please specify what version of IPP do you use?

Regards,

Vladimir

Re: DCT in ipp_sample MPEG2 for Linux

Vladimir_Dudnik — Fri, 13 May 2005 23:50:40 GMT

By the way,we cansee you use loop through 65 DCT coefficients, but actually they should be64 (or less).

for (c=0;c<65;c++)

The next, while count represents a number of nonzero coefficients, it should be modified accordingly,

i.e decremented when 1 changed to 0.

Regards,
Vladimir

Re: DCT in ipp_sample MPEG2 for Linux

estegano — Sat, 14 May 2005 12:50:25 GMT

Ops! It was a big mistake. ;-)

Thank you.
I'm using l_ipp_ia32_itanium_p_4_1_2 and making some tests with l_ipp-sample-video_p_4.1.002

I have another question, perhaps an easy question.

I want access the DCT coefficients before quantization but ippiReconstructDCTBlockIntra_MPEG2_32s performs inverse quantization.
I'm testing in MPEG2-decode/video/seq.c

How can I do it?

Thank you in advance.

Regards,
Fbio

Re: DCT in ipp_sample MPEG2 for Linux

Vladimir_Dudnik — Wed, 18 May 2005 01:12:27 GMT

Hi Fabio,

unfortunately we do not provide such function in IPP. It might be considered for implementation in the next versions. If you feel such functionality will be useful - please submit your feature request through technical support channel (premier.intel.com)

Regards,

Vladimir