Hi All,
I am trying to transmit voice with my GTA02 and Osmocom. Upon looking into code I did not find any code transmitting voice. I have tried to do it myself but without much success. What have I done:
1. Merge branch "jolly/voice" into main.
2. Add handling of L1CTL_VOICE_REQ at l23_api.c
3. Create additional queue for voice requests to be handled within the scheduler
4. Create "loopback" code, issuing L1CTL_VOICE_REQ each time voice is received at layer23
5. At l1s_tch_cmd, add code, sending the frame from voice request queue, similar to code, sending FACCH frame.
6. During tests against OpenBTS, it appears, that the voice frames are being sent, but all of them have "Stolen" bit turned on, e.g. BTS considers them FACCH frames.
My question is how do I transmit TCH frame with "Stolen" indicator turned off. Or even better, is there any other implementation of transmitting voice via TCH?
Code fragment from l1s_tch_cmd, ------------------------------------------------------------------------------------------------ if (facch_tx_now) { uint16_t *info_ptr = dsp_api.ndb->a_fu; struct msgb *msg; const uint8_t *data;
/* Pull FACCH data (if ready) */ if (icnt > 26) { msg = msgb_dequeue(&l1s.tx_queue[L1S_CHAN_MAIN]); if(!msg && (tch_mode == TCH_FS_MODE)) { msg = msgb_dequeue(&l1s.tx_queue[L1S_CHAN_VOICE]); if(msg && msg->l3h) { tx_sent++; printf("rx_frames: %d tx_recv: %d tx_sent: %d\n", rx_frames, tx_recv, tx_sent); printf("l1s_tch_cmd: voice data = %s\n", hexdump(msg->l3h, 33)); } } } else { msg = NULL; } ------------------------------------------------------------------------------------------------
Many thanks Michael
Hi Sylvain
Did you have any success with transmitting voice?
Best Regards Michael
-----Original Message----- From: Sylvain Munaut [mailto:246tnt@gmail.com] Sent: Monday, April 18, 2011 12:29 PM To: Michael Dvoishes Cc: baseband-devel@lists.osmocom.org Subject: Re: Transmitting voice with Osmocom
I am trying to transmit voice with my GTA02 and Osmocom. Upon looking into code I did not find any code transmitting voice. I have tried to do it myself but without much success.
Just wait for next week, I've planned to do this at EasterHegg with jolly.
Did you have any success with transmitting voice?
Yes.
It still needs cleanup and stuff so it's not gonna be in master right away. (I'm probably gonna merge quadband first) but it's public and it works. See in my sylvain/traffic branch. And jolly has the matching mobile application in his jolly/voice branch. So you have to build 'mobile' from jolly's branch and the layer1 firmware from my branch.
Cheers,
Sylvain
Many thanks, working very good
Michael
From: 246tnt@gmail.com [mailto:246tnt@gmail.com] Sent: Wednesday, April 27, 2011 11:08 AM To: Michael Dvoishes; Sylvain Munaut Cc: baseband-devel@lists.osmocom.org Subject: Re: RE: Transmitting voice with Osmocom
Did you have any success with transmitting voice?
Yes.
It still needs cleanup and stuff so it's not gonna be in master right away. (I'm probably gonna merge quadband first) but it's public and it works. See in my sylvain/traffic branch. And jolly has the matching mobile application in his jolly/voice branch. So you have to build 'mobile' from jolly's branch and the layer1 firmware from my branch.
Cheers,
Sylvain
Hi;
With this way is it possible to encrypt the voice data peer to peer with my own encryption algorithm?
Thank in advance.
With this way is it possible to encrypt the voice data peer to peer with my own encryption algorithm?
No, the network will most likely decompress and decompress the voice so if it's not valid voice packets, it will fails.
It's been discussed here before, search the archives.
Cheers,
Sylvain
On 4/27/11 11:41 PM, Huseyin Turan wrote:
Hi;
With this way is it possible to encrypt the voice data peer to peer with my own encryption algorithm?
Thank in advance.
There has been a discussion thread here with some ideas: http://lists.osmocom.org/pipermail/baseband-devel/2011-January/001004.html http://lists.osmocom.org/pipermail/baseband-devel/2011-January/000998.html
Then anybody tried to verify if calls within the same network doesn't get transcoded and so the AMR or GSM-EFR payload into the GSM frame is still intact?
I mean trying to setup the simple XOR of every AMR frame payload between two phones?
IMHO it should work because the network operators are not going to transcode voice flow when it's not needed (if caller and called speak the same audio codec and they are within the same gsm network).
Turan, if you are going to make some testing it would be cool!
-naif
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