cellular-infrastructure
/
osmo-mgw
mirror of https://gerrit.osmocom.org/osmo-mgw
10
0
Fork 0
Code Issues Releases Wiki Activity

mgcp_codec: fix oa/bwe comparison in mgcp_codec_pt_translate() 

The function mgcp_codec_pt_translate is very strict when comparing the
codecs to each other to find a matching payload type number to be used
on the egress side.

This poses a problem when one side uses AMR in bandwith-efficient, while
the other side uses AMR in octet-aligned payload type format. To the pt
translate function the difference in the payload format will appear as
if the codec were different and eventually the payload type number
cannot be translated.

since osmo-mgw offers conversion between the payload type format it
would be no problem to ignore the payload type format when making the
translation decision. The only exception here would be if one side would
announce AMR two times, the first time with octet-aligned and the second
time with bandwith-efficient format. Then we would have to use the
payload type number from the exact match. (and skip any formatconversion)

To archive such an optimized decision we will first go through the codec
lists and perform an exact match. If we don't get a match we go through
the codec lists a second time, but this time we ignore the payload
format.

Change-Id: Ifbd201a2749009a4644a29bd77e1d0fc0c124a9d
Related: OS#5461
This commit is contained in:
Philipp Maier 2023-03-22 16:53:30 +01:00
parent ec967d74f7
commit 621e8666ff
3 changed files with 115 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
src/libosmo-mgcp/mgcp_codec.c
View File

@ -376,10 +376,15 @@ bool mgcp_codec_amr_is_octet_aligned(const struct mgcp_rtp_codec *codec)
return codec->param.amr_octet_aligned;
}
/* Compare two codecs, all parameters must match up, except for the payload type
* number. */
/* Compare two codecs, all parameters must match up */
static bool codecs_same(struct mgcp_rtp_codec *codec_a, struct mgcp_rtp_codec *codec_b)
{
/* All codec properties must match up, except the payload type number. Even though standardisd payload numbers
* exist for certain situations, the call agent may still assign them freely. Hence we must not insist on equal
* payload type numbers. Also the audio_name is not checked since it is already parsed into subtype_name, rate,
* and channels, which are checked. */
if (strcmp(codec_a->subtype_name, codec_b->subtype_name))
return false;
if (codec_a->rate != codec_b->rate)
return false;
if (codec_a->channels != codec_b->channels)
@ -388,9 +393,11 @@ static bool codecs_same(struct mgcp_rtp_codec *codec_a, struct mgcp_rtp_codec *c
return false;
if (codec_a->frame_duration_den != codec_b->frame_duration_den)
return false;
if (strcmp(codec_a->subtype_name, codec_b->subtype_name))
return false;
if (!strcmp(codec_a->subtype_name, "AMR")) {
/* AMR payload may be formatted in two different payload formats, it is still the same codec but since the
* formatting of the payload is different, conversation is required, so we must treat it as a different
* codec here. */
if (strcmp(codec_a->subtype_name, "AMR") == 0) {
if (mgcp_codec_amr_is_octet_aligned(codec_a) != mgcp_codec_amr_is_octet_aligned(codec_b))
return false;
}
@ -398,6 +405,26 @@ static bool codecs_same(struct mgcp_rtp_codec *codec_a, struct mgcp_rtp_codec *c
return true;
}
/* Compare two codecs, all parameters must match up, except parameters related to payload formatting (not checked). */
static bool codecs_convertible(struct mgcp_rtp_codec *codec_a, struct mgcp_rtp_codec *codec_b)
{
/* OsmoMGW currently has no ability to transcode from one codec to another. However OsmoMGW is still able to
* translate between different payload formats as long as the encoded voice data itself does not change.
* Therefore we must insist on equal codecs but still allow different payload formatting. */
if (strcmp(codec_a->subtype_name, codec_b->subtype_name))
return false;
if (codec_a->rate != codec_b->rate)
return false;
if (codec_a->channels != codec_b->channels)
return false;
if (codec_a->frame_duration_num != codec_b->frame_duration_num)
return false;
if (codec_a->frame_duration_den != codec_b->frame_duration_den)
return false;
return true;
}
/*! Translate a given payload type number that belongs to the packet of a
* source connection to the equivalent payload type number that matches the
* configuration of a destination connection.
@ -429,8 +456,8 @@ int mgcp_codec_pt_translate(struct mgcp_conn_rtp *conn_src, struct mgcp_conn_rtp
if (!codec_src)
return -EINVAL;
/* Use the codec information from the source and try to find the
* equivalent of it on the destination side */
/* Use the codec information from the source and try to find the equivalent of it on the destination side. In
* the first run we will look for an exact match. */
codecs_assigned = rtp_dst->codecs_assigned;
OSMO_ASSERT(codecs_assigned <= MGCP_MAX_CODECS);
for (i = 0; i < codecs_assigned; i++) {
@ -439,6 +466,18 @@ int mgcp_codec_pt_translate(struct mgcp_conn_rtp *conn_src, struct mgcp_conn_rtp
break;
}
}
/* In case we weren't able to find an exact match, we will try to find a match that is the same codec, but the
* payload format may be different. This alternative will require a frame format conversion (i.e. AMR bwe->oe) */
if (!codec_dst) {
for (i = 0; i < codecs_assigned; i++) {
if (codecs_convertible(codec_src, &rtp_dst->codecs[i])) {
codec_dst = &rtp_dst->codecs[i];
break;
}
}
}
if (!codec_dst)
return -EINVAL;

48
tests/mgcp/mgcp_test.c
View File

@ -1851,6 +1851,7 @@ static const struct testcase_mgcp_codec_pt_translate test_mgcp_codec_pt_translat
{ .payload_type_map = {96, 97}, },
{ .payload_type_map = {97, 96}, },
{ .payload_type_map = {0, 0}, },
{ .payload_type_map = {123, -EINVAL} },
{ .end = true },
},
},
@ -1907,31 +1908,63 @@ static const struct testcase_mgcp_codec_pt_translate test_mgcp_codec_pt_translat
.expect = {
{ .payload_type_map = {111, 121}, },
{ .payload_type_map = {112, 122} },
{ .payload_type_map = {123, -EINVAL} },
{ .end = true },
},
},
{
.descr = "test AMR with missing octet-aligned settings (defaults to 0)",
.descr = "test AMR with missing octet-aligned settings (oa <-> unset)",
.codecs = {
{
{ 111, "AMR/8000", &amr_param_octet_aligned_true, },
{ 112, "AMR/8000", &amr_param_octet_aligned_false, },
},
{
{ 122, "AMR/8000", &amr_param_octet_aligned_unset, },
},
},
.expect = {
{ .payload_type_map = {111, -EINVAL}, },
{ .payload_type_map = {112, 122} },
{ .payload_type_map = {111, 122}, },
{ .payload_type_map = {55, -EINVAL}, },
{ .end = true },
},
},
{
.descr = "test AMR with NULL param (defaults to 0)",
.descr = "test AMR with missing octet-aligned settings (bwe <-> unset)",
.codecs = {
{
{ 111, "AMR/8000", &amr_param_octet_aligned_false, },
},
{
{ 122, "AMR/8000", &amr_param_octet_aligned_unset, },
},
},
.expect = {
{ .payload_type_map = {111, 122}, },
{ .payload_type_map = {55, -EINVAL}, },
{ .end = true },
},
},
{
.descr = "test AMR with NULL param (oa <-> null)",
.codecs = {
{
{ 112, "AMR/8000", &amr_param_octet_aligned_true, },
},
{
{ 122, "AMR/8000", NULL, },
},
},
.expect = {
/* Note: Both 111, anbd 112 will translate to 122. The translation from 112 */
{ .payload_type_map = {112, 122} },
{ .payload_type_map = {55, -EINVAL}, },
{ .end = true },
},
},
{
.descr = "test AMR with NULL param (bwe <-> null)",
.codecs = {
{
{ 111, "AMR/8000", &amr_param_octet_aligned_true, },
{ 112, "AMR/8000", &amr_param_octet_aligned_false, },
},
{
@ -1939,8 +1972,9 @@ static const struct testcase_mgcp_codec_pt_translate test_mgcp_codec_pt_translat
},
},
.expect = {
{ .payload_type_map = {111, -EINVAL}, },
/* Note: Both 111, anbd 112 will translate to 122. The translation from 112 */
{ .payload_type_map = {112, 122} },
{ .payload_type_map = {55, -EINVAL}, },
{ .end = true },
},
},

40
tests/mgcp/mgcp_test.ok
View File

@ -1324,6 +1324,7 @@ Testing mgcp_codec_pt_translate()
- mgcp_codec_pt_translate(conn1, conn0, 96) -> 97
- mgcp_codec_pt_translate(conn0, conn1, 0) -> 0
- mgcp_codec_pt_translate(conn1, conn0, 0) -> 0
- mgcp_codec_pt_translate(conn0, conn1, 123) -> -22
#3: conn0 has no codecs
- add codecs on conn0:
(none)
@ -1355,25 +1356,40 @@ Testing mgcp_codec_pt_translate()
- mgcp_codec_pt_translate(conn1, conn0, 121) -> 111
- mgcp_codec_pt_translate(conn0, conn1, 112) -> 122
- mgcp_codec_pt_translate(conn1, conn0, 122) -> 112
#6: test AMR with missing octet-aligned settings (defaults to 0)
- mgcp_codec_pt_translate(conn0, conn1, 123) -> -22
#6: test AMR with missing octet-aligned settings (oa <-> unset)
- add codecs on conn0:
0: 111 AMR/8000 octet-aligned=1 -> rc=0
1: 112 AMR/8000 octet-aligned=0 -> rc=0
- add codecs on conn1:
0: 122 AMR/8000 octet-aligned=unset -> rc=0
- mgcp_codec_pt_translate(conn0, conn1, 111) -> -22
- mgcp_codec_pt_translate(conn0, conn1, 112) -> 122
- mgcp_codec_pt_translate(conn1, conn0, 122) -> 112
#7: test AMR with NULL param (defaults to 0)
- mgcp_codec_pt_translate(conn0, conn1, 111) -> 122
- mgcp_codec_pt_translate(conn1, conn0, 122) -> 111
- mgcp_codec_pt_translate(conn0, conn1, 55) -> -22
#7: test AMR with missing octet-aligned settings (bwe <-> unset)
- add codecs on conn0:
0: 111 AMR/8000 octet-aligned=1 -> rc=0
1: 112 AMR/8000 octet-aligned=0 -> rc=0
0: 111 AMR/8000 octet-aligned=0 -> rc=0
- add codecs on conn1:
0: 122 AMR/8000 octet-aligned=unset -> rc=0
- mgcp_codec_pt_translate(conn0, conn1, 111) -> 122
- mgcp_codec_pt_translate(conn1, conn0, 122) -> 111
- mgcp_codec_pt_translate(conn0, conn1, 55) -> -22
#8: test AMR with NULL param (oa <-> null)
- add codecs on conn0:
0: 112 AMR/8000 octet-aligned=1 -> rc=0
- add codecs on conn1:
0: 122 AMR/8000 -> rc=0
- mgcp_codec_pt_translate(conn0, conn1, 111) -> -22
- mgcp_codec_pt_translate(conn0, conn1, 112) -> 122
- mgcp_codec_pt_translate(conn1, conn0, 122) -> 112
#8: match FOO/8000/1 and FOO/8000 as identical, single channel is implicit
- mgcp_codec_pt_translate(conn0, conn1, 55) -> -22
#9: test AMR with NULL param (bwe <-> null)
- add codecs on conn0:
0: 112 AMR/8000 octet-aligned=0 -> rc=0
- add codecs on conn1:
0: 122 AMR/8000 -> rc=0
- mgcp_codec_pt_translate(conn0, conn1, 112) -> 122
- mgcp_codec_pt_translate(conn1, conn0, 122) -> 112
- mgcp_codec_pt_translate(conn0, conn1, 55) -> -22
#10: match FOO/8000/1 and FOO/8000 as identical, single channel is implicit
- add codecs on conn0:
0: 0 PCMU/8000/1 -> rc=0
1: 111 GSM-HR-08/8000/1 -> rc=0
@ -1389,7 +1405,7 @@ Testing mgcp_codec_pt_translate()
- mgcp_codec_pt_translate(conn0, conn1, 111) -> 97
- mgcp_codec_pt_translate(conn1, conn0, 97) -> 111
- mgcp_codec_pt_translate(conn0, conn1, 123) -> -22
#9: match FOO/8000/1 and FOO as identical, 8k and single channel are implicit
#11: match FOO/8000/1 and FOO as identical, 8k and single channel are implicit
- add codecs on conn0:
0: 0 PCMU/8000/1 -> rc=0
1: 111 GSM-HR-08/8000/1 -> rc=0
@ -1405,7 +1421,7 @@ Testing mgcp_codec_pt_translate()
- mgcp_codec_pt_translate(conn0, conn1, 111) -> 97
- mgcp_codec_pt_translate(conn1, conn0, 97) -> 111
- mgcp_codec_pt_translate(conn0, conn1, 123) -> -22
#10: test whether channel number matching is waterproof
#12: test whether channel number matching is waterproof
- add codecs on conn0:
0: 111 GSM-HR-08/8000 -> rc=0
1: 112 GSM-HR-08/8000/2 -> rc=-22