AMR: Add function to convert between bw-effient and octet aligned mode
RFC3267 specifies two framing modes for AMR packets. An octet aligned
mode is specified where all fields of the AMR packets are aligned to
octet boundaries. The second framing mode is the bandwith efficient mode
where the fields are directly packed one after another.
- add paring/generation functions for related SDP fmtp parameters
- add conversion function to convert AMR payload
Depends: libosmo-netif I5b5a0fa644d8dbb1f04f9d7e35312683c7b3d196
Change-Id: I622c01874b25f5049d4f59eb8157e0ea3cbe16ba
Related: OS#3807
diff --git a/src/libosmo-mgcp/mgcp_sdp.c b/src/libosmo-mgcp/mgcp_sdp.c
index 3287cd1..02b9695 100644
--- a/src/libosmo-mgcp/mgcp_sdp.c
+++ b/src/libosmo-mgcp/mgcp_sdp.c
@@ -30,9 +30,9 @@
#include <errno.h>
-/* A struct to store intermediate parsing results. The function
- * mgcp_parse_sdp_data() is using it as temporary storage for parsing the SDP
- * codec information. */
+/* Two structs to store intermediate parsing results. The function
+ * mgcp_parse_sdp_data() is using the following two structs as temporary
+ * storage for parsing the SDP codec information. */
struct sdp_rtp_map {
/* the type */
int payload_type;
@@ -44,6 +44,11 @@
int rate;
int channels;
};
+struct sdp_fmtp_param {
+ int payload_type;
+ struct mgcp_codec_param param;
+};
+
/* Helper function to extrapolate missing codec parameters in a codec mao from
* an already filled in payload_type, called from: mgcp_parse_sdp_data() */
@@ -168,6 +173,92 @@
return -EINVAL;
}
+/* Extract fmtp parameters from SDP, called from: mgcp_parse_sdp_data() */
+static int fmtp_from_sdp(void *ctx, struct sdp_fmtp_param *fmtp_param, char *sdp)
+{
+ char *str;
+ char *str_ptr;
+ char *param_str;
+ unsigned int pt;
+ unsigned int count = 0;
+ char delimiter;
+ unsigned int amr_octet_aligned;
+
+ memset(fmtp_param, 0, sizeof(*fmtp_param));
+
+ str = talloc_zero_size(ctx, strlen(sdp) + 1);
+ str_ptr = str;
+ strcpy(str_ptr, sdp);
+
+ /* Check if the input string begins with an fmtp token */
+ str_ptr = strstr(str_ptr, "fmtp:");
+ if (!str_ptr)
+ goto exit;
+ str_ptr += 5;
+
+ /* Extract payload type */
+ if (sscanf(str_ptr, "%u ", &pt) != 1)
+ goto error;
+ fmtp_param->payload_type = pt;
+
+ /* Advance pointer to the beginning of the parameter section and
+ * tokenize string */
+ str_ptr = strstr(str_ptr, " ");
+ if (!str_ptr)
+ goto error;
+ str_ptr++;
+
+ param_str = strtok(str_ptr, " ");
+ if (!param_str)
+ goto exit;
+
+ while (1) {
+ /* Make sure that we don't get trapped in an endless loop */
+ if (count > 256)
+ goto error;
+
+ /* Chop off delimiters ';' at the end */
+ delimiter = str_ptr[strlen(str_ptr) - 1];
+ if (delimiter == ';' || delimiter == ',')
+ str_ptr[strlen(str_ptr) - 1] = '\0';
+
+ /* AMR octet aligned parameter */
+ if (sscanf(param_str, "octet-align=%d", &amr_octet_aligned) == 1) {
+ fmtp_param->param.amr_octet_aligned_present = true;
+ fmtp_param->param.amr_octet_aligned = false;
+ if (amr_octet_aligned == 1)
+ fmtp_param->param.amr_octet_aligned = true;
+
+ }
+
+ param_str = strtok(NULL, " ");
+ if (!param_str)
+ break;
+ count++;
+ }
+
+exit:
+ talloc_free(str);
+ return 0;
+error:
+ talloc_free(str);
+ return -EINVAL;
+}
+
+/* Pick optional fmtp parameters by payload type, if there are no fmtp
+ * parameters, a nullpointer is returned */
+static struct mgcp_codec_param *param_by_pt(int pt, struct sdp_fmtp_param *fmtp_params, unsigned int fmtp_params_len)
+{
+ unsigned int i;
+
+ for (i = 0; i < fmtp_params_len; i++) {
+ if (fmtp_params[i].payload_type == pt)
+ return &fmtp_params[i].param;
+ }
+
+ return NULL;
+}
+
/*! Analyze SDP input string.
* \param[in] endp trunk endpoint.
* \param[out] conn associated rtp connection.
@@ -181,6 +272,9 @@
{
struct sdp_rtp_map codecs[MGCP_MAX_CODECS];
unsigned int codecs_used = 0;
+ struct sdp_fmtp_param fmtp_params[MGCP_MAX_CODECS];
+ unsigned int fmtp_used = 0;
+ struct mgcp_codec_param *codec_param;
char *line;
unsigned int i;
void *tmp_ctx = talloc_new(NULL);
@@ -225,6 +319,14 @@
rtp->maximum_packet_time = ptime2;
break;
}
+
+ if (strncmp("a=fmtp:", line, 6) == 0) {
+ rc = fmtp_from_sdp(conn->conn, &fmtp_params[fmtp_used], line);
+ if (rc >= 0)
+ fmtp_used++;
+ break;
+ }
+
break;
case 'm':
rc = sscanf(line, "m=audio %d RTP/AVP", &port);
@@ -266,7 +368,8 @@
/* Store parsed codec information */
for (i = 0; i < codecs_used; i++) {
- rc = mgcp_codec_add(conn, codecs[i].payload_type, codecs[i].map_line);
+ codec_param = param_by_pt(codecs[i].payload_type, fmtp_params, fmtp_used);
+ rc = mgcp_codec_add(conn, codecs[i].payload_type, codecs[i].map_line, codec_param);
if (rc < 0)
LOGP(DLMGCP, LOGL_NOTICE, "endpoint:0x%x, failed to add codec\n", ENDPOINT_NUMBER(p->endp));
}
@@ -334,6 +437,64 @@
return 0;
}
+/* Add fmtp strings to sdp payload */
+static int add_fmtp(struct msgb *sdp, struct sdp_fmtp_param *fmtp_params, unsigned int fmtp_params_len,
+ const char *fmtp_extra)
+{
+ unsigned int i;
+ int rc;
+ int fmtp_extra_pt = -1;
+ char *fmtp_extra_pars = "";
+
+ /* When no fmtp parameters ara available but an fmtp extra string
+ * is configured, just add the fmtp extra string */
+ if (fmtp_params_len == 0 && fmtp_extra) {
+ return msgb_printf(sdp, "%s\r\n", fmtp_extra);
+ }
+
+ /* When there is fmtp extra configured we dissect it in order to drop
+ * in the configured extra parameters at the right place when
+ * generating the fmtp strings. */
+ if (fmtp_extra) {
+ if (sscanf(fmtp_extra, "a=fmtp:%d ", &fmtp_extra_pt) != 1)
+ fmtp_extra_pt = -1;
+
+ fmtp_extra_pars = strstr(fmtp_extra, " ");
+
+ if (!fmtp_extra_pars)
+ fmtp_extra_pars = "";
+ else
+ fmtp_extra_pars++;
+ }
+
+ for (i = 0; i < fmtp_params_len; i++) {
+ rc = msgb_printf(sdp, "a=fmtp:%u", fmtp_params[i].payload_type);
+
+ /* Add amr octet align parameter */
+ if (fmtp_params[i].param.amr_octet_aligned_present) {
+ if (fmtp_params[i].param.amr_octet_aligned)
+ rc = msgb_printf(sdp, " octet-align=1");
+ else
+ rc = msgb_printf(sdp, " octet-align=0");
+ if (rc < 0)
+ return -EINVAL;
+ }
+
+ /* Append extra parameters from fmtp extra */
+ if (fmtp_params[i].payload_type == fmtp_extra_pt) {
+ rc = msgb_printf(sdp, " %s", fmtp_extra_pars);
+ if (rc < 0)
+ return -EINVAL;
+ }
+
+ rc = msgb_printf(sdp, "\r\n", fmtp_params[i].payload_type);
+ if (rc < 0)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
/*! Generate SDP response string.
* \param[in] endp trunk endpoint.
* \param[in] conn associated rtp connection.
@@ -348,8 +509,11 @@
const char *fmtp_extra;
const char *audio_name;
int payload_type;
+ struct sdp_fmtp_param fmtp_param;
int rc;
int payload_types[1];
+ struct sdp_fmtp_param fmtp_params[1];
+ unsigned int fmtp_params_len = 0;
OSMO_ASSERT(endp);
OSMO_ASSERT(conn);
@@ -387,12 +551,15 @@
goto buffer_too_small;
}
- if (fmtp_extra) {
- rc = msgb_printf(sdp, "%s\r\n", fmtp_extra);
-
- if (rc < 0)
- goto buffer_too_small;
+ if (codec->param_present) {
+ fmtp_param.payload_type = payload_type;
+ fmtp_param.param = codec->param;
+ fmtp_params[0] = fmtp_param;
+ fmtp_params_len = 1;
}
+ rc = add_fmtp(sdp, fmtp_params, fmtp_params_len, fmtp_extra);
+ if (rc < 0)
+ goto buffer_too_small;
}
if (conn->end.packet_duration_ms > 0 && endp->tcfg->audio_send_ptime) {
rc = msgb_printf(sdp, "a=ptime:%u\r\n",