In case we get offered G729 and G711 we might have selected
G729 as the audio codec. The first packet we receive might be
G711 though. In that case we will need to change. But only if
we have a matching alternate codec payload_type. E.g. in the
case of comfort noise we will receive the PT=11 and we don't
want to change.
We might be offered multiple codecs by the remote and need to
switch between them once we receive data. Do this by moving it
to a struct so we can separate between proposed and current
codec. In SDP we can have multiple codecs but a global ptime.
The current code doesn't separate that clearly instead we write
it to the main codec.
Use the rtp_hdr structure. The basic alignment issue remains
and I need to merge/cherry-pick Jacob's getters for the ts,
sequence number and other attributes.
In case the sender didn't send a couple of frames we will have
a time gap that is bigger than the accepted delta. Add a new
testcase for this and update the next_time.
Transcoding from GSM to PCMA can lead to the MGCP MGW sending
two PCMA packages with the same sequence number and timestamp.
Once with the encoded audio and once completely empty.
This is because "state->dst_packet_duration" is 0 in most cases
(unless a ptime is forced) and we attempt to encode audio even
if there are not enough samples. The encode_audio return will
return 0 in that case which is not trated as an error by the
mgcp network code.
Handle rc == 0 specially and document the semantic.
The sequence number was read from the wrong place and then
the wrong byte order conversion routine was used so we ended
up wirting 0x00, 0x00 into the patched sequence number. Add
a testcase for that.
The GSM handle was never released. This was found using valgrind
and the leak check.
==14933== 752 bytes in 1 blocks are definitely lost in loss record 15 of 19
==14933== at 0x4028B4C: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==14933== by 0x4130201: gsm_create (in /usr/lib/i386-linux-gnu/libgsm.so.1.0.12)
==14933== by 0x80517AE: mgcp_transcoding_setup (mgcp_transcode.c:199)
==14933== by 0x8049691: given_configured_endpoint.isra.1 (mgcp_transcoding_test.c:198)
==14933== by 0x8049C11: test_transcode_result (mgcp_transcoding_test.c:328)
==14933== by 0x8049418: main (mgcp_transcoding_test.c:582)
This patch moves the files relevant to transcoding from
src/osmo-bsc_mgcp to src/libmgcp and src/include/openbsc. Makefiles
and include directives are being updated accordingly.
Sponsored-by: On-Waves ehf
Holger Hans Peter Freyther