How to decode GSM-EFR ( GSM 6.60 ) with IntelIPP?

[telefonie]

I am searching for sample code to decode GSM-EFR (GSM6.60) with Intel-IPP.



regards,

telefonie

Message Edited by telefonie on 11-29-2005 02:51 AM

[Ivan_Ryzhachkin__Int]

GSM AMR provides GSM EFR mode

(frame type)7 - 12.2 kbit/s (GSM EFR)

Ivan

[telefonie]

Hello Ivan,



sure you are right, but I am a little bit to lazy to search for a solution of open problems if its already done. Do you have decoded already real GSM-EFR with the Intel-IPP GSMAMR-Decoder or is this only a theoretical answer?



Here the main differences:

a.) The SID frame is another type as for GSMAMR. May I pass the SID frames to the GSMAMR decoder? This may no great problem if i ignore the SID frames and throw them away.

b.) I think RTP-Payloadformat for GSM-EFR is another as GSMAMR (see e.g. rfc 3551 for GSM-EFR and rfc3267 for GSMAMR).



I like to test with real rtp-streams.

Unfortunally I have no testdata for GSM-EFR. Best case if I had a sip-client with GSM-EFR Codec to produce a rtp-stream, but I didnt know one. An Ethereal PCAP-File of a complette RTP-Communication (GSM-EFR) may also help testing the decoding.

Do someone knows how to produce real GSM-EFR data (best as a rtpstream e.g. SIP-Communication).



Regards

Joachim

Message Edited by telefonie on 11-30-2005 08:01 AM

[Ivan_Ryzhachkin__Int]

Hi Joachim,

unfortunately we don't dispose with the "pure" GSM EFR codec at the moment.

))it's not a problem to substitute SID-frames using some"white" noise.

)) The SID-freeGSM EFR data can be produced with the GSM AMR encoder if VAD-mode is switched-off.

ATB

Ivan

[telefonie]

Hello Ivan,

may it work correctly if I throw away all SID-Frames? Ill fill the silence correctly (according to the RTP Timestamp) after decoding with lin16 with value 0. I ignore "Comfort Noise" till now.

I give the decoder only the normal 12.2Kbit frames. It shall works then, or?

How do you Interpret rfc 3551 for GSM-EFR and rfc3267 for GSMAMR.

How it is GSM-EFR transfered with RTP?
My Opinion:
RTP-Payload like GSM-FR(=GSM6.10) (see rfc 3551) but bits of frame sortet like (frame type)7 - 12.2 kbit/s from GSMAMR?

Which SDP-Parameter are possible for GSM-EFR?

Has someone GSM-EFR Data (RTP-Packets) out of a RTP-Communication, or know someone a client to produce a RTP-Stream? I have no client to produce the Data.

Regards,
telefonie

[Igor_B_Intel1]

Hi!

Let me just clarify. You could decode GSM-EFR stream with GSM-AMR only if it contains active frames. CN module in GSM-AMR doesn't substitute CN module in GSM-EFR as it done for active frames. And they have god different length for SID frames. Try tointerpret SID frames from GSM-EFRas lost frames. I think it degrades quality but it can work.

Active frames packs in 248 bits: 4 bit for 0xC and 244 bits for bitstream without reordering.

In SDP message for GSM-EFR you can use any number from 96 till 127 because it hasn't got static payload type.

Igor S. Belyakov

[Thomas_B_1]

Hi

i want to packetize AMR in 12.2, so i mean EFR, i use 5.2_beta samples and its codec amr, i have a 31 bytes packet returned by the Encoder (320 bytes PCM) but i'm not able to packetized it correctly. I supposed this packet is the 244 bits bitstream so i try to add CMR and F FT Q at the beginning but it doesn't work...

[ligoban]

Dear Joachim,

I would like to communicate with you. I hope you've got my letter ( pseudor_lib@yahoo.com ).

Sorry for the offtopic.