mgcp: Add transcoding from PCMU as well
Use the existing ulaw encode/decode to support PCMU as well.
The MERA VoIP switch has some severe issues with the GSM codec
and it appears easier to enable transcoding for it.
The mera switch doesn't appear to cope with codec change
between a SIP 180 trying and the 200 ok connection result.
Inserting the codec is touching too many places. Ideally we
should have the transcoding function as pointer in the struct
as well but the arguments differ.. so it is not a direct way
forward.
diff --git a/openbsc/include/openbsc/mgcp_transcode.h b/openbsc/include/openbsc/mgcp_transcode.h
index cb11cb2..147e48b 100644
--- a/openbsc/include/openbsc/mgcp_transcode.h
+++ b/openbsc/include/openbsc/mgcp_transcode.h
@@ -33,7 +33,8 @@
AF_L16,
AF_GSM,
AF_G729,
- AF_PCMA
+ AF_PCMA,
+ AF_PCMU
};
diff --git a/openbsc/src/libmgcp/mgcp_sdp.c b/openbsc/src/libmgcp/mgcp_sdp.c
index aa4ef30..b648944 100644
--- a/openbsc/src/libmgcp/mgcp_sdp.c
+++ b/openbsc/src/libmgcp/mgcp_sdp.c
@@ -54,6 +54,7 @@
if (!audio_name) {
switch (payload_type) {
+ case 0: audio_name = "PCMU/8000/1"; break;
case 3: audio_name = "GSM/8000/1"; break;
case 8: audio_name = "PCMA/8000/1"; break;
case 18: audio_name = "G729/8000/1"; break;
@@ -89,6 +90,8 @@
payload_type = 3;
else if (!strcmp(audio_codec, "PCMA"))
payload_type = 8;
+ else if (!strcmp(audio_codec, "PCMU"))
+ payload_type = 0;
else if (!strcmp(audio_codec, "G729"))
payload_type = 18;
}
@@ -109,6 +112,11 @@
for (i = 0; i < used; ++i) {
switch (codecs[i].payload_type) {
+ case 0:
+ codecs[i].codec_name = "PCMU";
+ codecs[i].rate = 8000;
+ codecs[i].channels = 1;
+ break;
case 3:
codecs[i].codec_name = "GSM";
codecs[i].rate = 8000;
diff --git a/openbsc/src/libmgcp/mgcp_transcode.c b/openbsc/src/libmgcp/mgcp_transcode.c
index 12cce26..c994d32 100644
--- a/openbsc/src/libmgcp/mgcp_transcode.c
+++ b/openbsc/src/libmgcp/mgcp_transcode.c
@@ -52,6 +52,8 @@
return AF_GSM;
if (!strcasecmp("PCMA", codec->subtype_name))
return AF_PCMA;
+ if (!strcasecmp("PCMU", codec->subtype_name))
+ return AF_PCMU;
#ifdef HAVE_BCG729
if (!strcasecmp("G729", codec->subtype_name))
return AF_G729;
@@ -61,6 +63,8 @@
}
switch (codec->payload_type) {
+ case 0 /* PCMU */:
+ return AF_PCMU;
case 3 /* GSM */:
return AF_GSM;
case 8 /* PCMA */:
@@ -102,6 +106,18 @@
*(sample++) = alaw_to_s16(*(buf++));
}
+static void ulaw_encode(short *sample, unsigned char *buf, size_t n)
+{
+ for (; n > 0; --n)
+ *(buf++) = s16_to_ulaw(*(sample++));
+}
+
+static void ulaw_decode(unsigned char *buf, short *sample, size_t n)
+{
+ for (; n > 0; --n)
+ *(sample++) = ulaw_to_s16(*(buf++));
+}
+
static int processing_state_destructor(struct mgcp_process_rtp_state *state)
{
switch (state->src_fmt) {
@@ -226,6 +242,7 @@
}
break;
#endif
+ case AF_PCMU:
case AF_PCMA:
state->src_frame_size = 80;
state->src_samples_per_frame = 80;
@@ -264,6 +281,7 @@
}
break;
#endif
+ case AF_PCMU:
case AF_PCMA:
state->dst_frame_size = 80;
state->dst_samples_per_frame = 80;
@@ -331,6 +349,10 @@
bcg729Decoder(state->src.g729_dec, *src, 0, state->samples + state->sample_cnt);
break;
#endif
+ case AF_PCMU:
+ ulaw_decode(*src, state->samples + state->sample_cnt,
+ state->src_samples_per_frame);
+ break;
case AF_PCMA:
alaw_decode(*src, state->samples + state->sample_cnt,
state->src_samples_per_frame);
@@ -381,6 +403,10 @@
state->samples + state->sample_offs, dst);
break;
#endif
+ case AF_PCMU:
+ ulaw_encode(state->samples + state->sample_offs, dst,
+ state->src_samples_per_frame);
+ break;
case AF_PCMA:
alaw_encode(state->samples + state->sample_offs, dst,
state->src_samples_per_frame);