MPEG-4 decoder can't decode mpeg stream from my DSP board !

MPEG-4 decoder can't decode mpeg stream from my DSP board !

It has some problems with B-VOP's. After decoding a few macroblocks itstops decoding with an error "Error when decode B-VOP macroblock". Macroblock type (code) is 0.

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Dear Customer,
Have you submitted this issue with detailsto Intel Premier Support at where our support staff will look into this issue?

Ying S
Intel IPP Support

Not yet ...

I'v attached an examplempeg-4 stream, maybe there is some simple answer, why it doesn't work... ( Extension shoud be changed to *.cmp )


thank you for the data, we will look on it. Please, submit this issue to the tech support as well.



we discovered that

The first error is in the first B-VOP in bits for macroblock number 3 (starting with 0). The byte sequence for first B-VOP (offset in file - 0x1704) is

00 00 01 B6 90 00 B8 54 8F 4D 07 A1 ...

Header info occupies bytes "00 00 01 B6 90 00 B8 54" and first 3 bits of "8F"

Info for macroblock 3 is started from bit 1 in byte "A1". Bits 1-2 indicates modb and next 1-4 bits indicates mb_type and must be "1", "01", "001", "0001", but next four bits are "0000".

Byte - A1

Bits - 10100001

BitPos - 0......7

modb - 01, mb_type - 0000 (illegal bit sequence)