topic IPP decoding question in Intel® Integrated Performance Primitives

IPP decoding question

dirks — Fri, 09 Mar 2007 13:30:34 GMT

Hello,

I try to decode a G729 audio stream, using the evaluation version of IPP 5.1

After a lot of effort I could hear an "alian like" sound after decoding.

I did the same exercise with voiceage decode function and the sound was very very clear.

my question is, what could be the reason for this? the input raw data (payload) is the same for both the decoders, except the voiceage decoder is returning a short * and the IPP decoder is returning a char *

is there anything I should do with the output stream?

please help me since I want to choose for IPP, but if this thing is only working on voiceage ......

thanks

Dirk

Re: IPP decoding question

Vladimir_Dudnik — Fri, 09 Mar 2007 22:13:37 GMT

Hi Dirk,

I forwarded your question to our experts and still waiting for answer from them. I think if you can attach sample bitstream it can help to speedup investigation

Regards,
Vladimir

Re: IPP decoding question

dirks — Mon, 12 Mar 2007 20:27:13 GMT

Hello Vladimir,

Thanks for the reply. Any idea how I should add the attachment?

We have been looking at this issue already for more then a week. We believe that we still need to do something with the input stream or the output stream.

thanks

dirk

Re: IPP decoding question

dirks — Tue, 13 Mar 2007 19:49:42 GMT

Hello Vladimir,

where should I post the input stream, email address?

thanks

Dirk

Re: IPP decoding question

ligoban — Mon, 19 Mar 2007 14:33:51 GMT

I've used 3different softphones while testing my application that uses IPP, and I've got no problem. Perhaps, if the IPP decoder returns char*, you should try to swap the first and the second bytes of the PCM sample. Have you tried this?

Re: IPP decoding question

Vyacheslav_Baranniko — Fri, 23 Mar 2007 09:54:35 GMT

Hello Dirk

Intel decoder uses char* buffer to return 16bit little-endian PCM data.

So, just cast it to short* on LE machine, that's it.

Vyacheslav

Re: IPP decoding question

dirks — Fri, 23 Mar 2007 15:40:29 GMT

hello,

we're working on an intel machine, so LE is ok.

we just casted char* to short*, but this has no effect

(short *)outputstream

how do we have to this? (just casting is apparently not good enough)

do we have to do something additional with the output stream??

please advise,

thanks

Dirk

Re: IPP decoding question

Vyacheslav_Baranniko — Tue, 27 Mar 2007 10:12:02 GMT

OK, short* cast may not help here.

Main reason,Intel codecdecodesG729(A) RTP payload (RFC3551), while VA_G729 decodes 10*8 packed bitstream, with 10 prm's compacted into 80bits, which differsfrom RTP bits ordering.

Vyacheslav