| this is a small utility program illustrating the use of the new (2020) |
| TRAU related blocks like I.460 mux, TRAU frame synchronizer, TRAU frame |
| decoder and trau2rtp conversion. |
| |
| The only argument to the progrmam is the input file, which can either be |
| |
| * a DAHDI device like /dev/dahdi/chan/004/002 to use TS2 on span/line 4 |
| * a pre-recorded capture file containing raw binary 64k timeslot data |
| |
| The tool will automatically determine if a regular file or a DAHDI device |
| was passed, and behave accordingly. |
| |
| |
| == reading capture files |
| |
| There are FR and EFR exampel captures included. |
| |
| The input data (*.log.bz2) was generated using strace on an osmo-nitb process |
| while a MO-to-MT call was running on two sub-slots of TS2. |
| |
| The strace log is converted to a binary stream of the raw 64bit E1 slot |
| using strace-write-parse.py |
| |
| You can use the too like this: |
| |
| * start osmo-gapk as a RTP to ALSA sink like |
| osmo-gapk -I 127.0.0.1/9999 -f gsm -g rawpcm-s16le -A default # for FR |
| osmo-gapk -I 127.0.0.1/9999 -f rtp-efr -g rawpcm-s16le -A default # for EFR |
| |
| * run trau2rtp to read the bin file and generate RTP: |
| ./trau2rtp e1_ts2_fr.bin # for FR |
| ./trau2rtp e1_ts2_efr.bin # for EFR |
| |
| |
| == Interfacing a DAHDI device |
| |
| It can be operated in two modes: |
| |
| a) local loop between sub-slots 1+2 (bit-offset 2 + 4), i.e. connecting the first |
| two calls on a 'typical' TRX0 where the first sub-slot (bit-offset 0) is not |
| used, |
| |
| OR |
| |
| b) interface between 64k TRAU slot and RTP. IP addresses + port numbers are |
| compiled-in, you need to modify them accordingly. |
| |
| |
| In mode "a", you can use it to have voice calls for low-level debugging without a media |
| gateway. |
| |
| In mode "b", you can e.g. play back audio from an exterenal RTP source and listen to it |
| over the GSM attached mobile phone. |
| |
| Command line for playing back EFR via RTP: |
| ./osmo-gapk -f amr-efr -i ../tests/ref-files/hhgttg_part1_5.s16.amr-efr -g rtp-efr -O 192.168.11.179/8002 -t -l |
| |
| Command line for playing back FR via RTP: |
| ./osmo-gapk -f gsm -i ../tests/ref-files/hhgttg_part1_5.s16.gsm -g gsm -O 192.168.11.179/8002 -t -l |
| |
| The '-l' option is experimental and requires gapk patch I2d552695dfb4cc96039838e79e0f5ae25a6737c8. If you want |
| to use it with EFR, you need to change pq_file.c to skip the AMR file header when rewinding: |
| |
| - fseek(state->fh, 0, SEEK_SET); |
| + fseek(state->fh, 6, SEEK_SET); |
| |
| The code has been tested against BS-11 and RBS6000/DUG20 in both modes (loop vs. RTP) and for FR and EFR. |