diff --git a/daemon/media_socket.c b/daemon/media_socket.c
index c4cab2c7a..0d69ecb05 100644
--- a/daemon/media_socket.c
+++ b/daemon/media_socket.c
@@ -1696,6 +1696,14 @@ static const char *kernelize_target(kernelize_state *s, struct packet_stream *st
 		u++;
 	}
 
+	for (u = 0; u < RTP_EXT_NUM; u++) {
+		__auto_type ext = media->extmap_id[u];
+		if (!ext)
+			continue;
+		if (ext->handler.kernel)
+			ext->handler.kernel(s, stream->component, media);
+	}
+
 	recording_stream_kernel_info(stream, reti);
 
 	if (!proto_is_rtp(media->protocol))
@@ -2857,11 +2865,51 @@ static ssize_t rtp_ext_mid_print(void *dst, struct rtp_extension *ext, struct ca
 		return -1;
 	return media->extmap_ops->print(dst, ext->id, &media->media_id);
 }
+__attribute__((nonnull(1, 3)))
+static void rtp_ext_mid_kernel(kernelize_state *s, unsigned int component, struct call_media *media) {
+	struct call_media *bundle = media->bundle;
+	if (!bundle)
+		return;
+	if (!bundle->extmap_id[RTP_EXT_MID])
+		return;
+	if (bundle->extmap_id[RTP_EXT_MID]->id != bundle->extmap_id[RTP_EXT_MID]->id)
+		return;
+
+	s->reti.extmap = 1;
+	s->reti.extmap_mid = bundle->extmap_id[RTP_EXT_MID]->id;
+
+	struct call_monologue *ml = bundle->monologue;
+
+	for (unsigned int i = 0; i < ml->medias->len; i++) {
+		media = ml->medias->pdata[i];
+		if (!media)
+			continue;
+		if (media->bundle != bundle)
+			continue;
+		if (!media->media_id.len)
+			continue;
+		unsigned int idx = media->index - 1;
+		if (idx >= RTPE_NUM_OUTPUT_MEDIA)
+			continue; // warn?
+		if (media->media_id.len > 255)
+			continue;
+
+		s->reti.mid_output[idx].len = media->media_id.len;
+		memcpy(s->reti.mid_output[idx].mid, media->media_id.s, media->media_id.len);
+
+		struct packet_stream *bundle_ps = get_media_component(media, component);
+		if (!bundle_ps)
+			continue; // log as error?
+
+		fill_media_sinks(s, idx, bundle_ps);
+	}
+}
 
 static const rtp_ext_handler rtp_ext_mid = {
 	.parse = rtp_ext_mid_parse,
 	.len = rtp_ext_mid_len,
 	.print = rtp_ext_mid_print,
+	.kernel = rtp_ext_mid_kernel,
 	.id = RTP_EXT_MID,
 };
 
diff --git a/include/media_socket.h b/include/media_socket.h
index 6821fbe30..0f4b57a41 100644
--- a/include/media_socket.h
+++ b/include/media_socket.h
@@ -317,6 +317,8 @@ typedef struct {
 	ssize_t (*len)(struct call_media *);
 	ssize_t (*print)(void *dst, struct rtp_extension *, struct call_media *);
 
+	void (*kernel)(kernelize_state *, unsigned int component, struct call_media *);
+
 	enum {
 		RTP_EXT_MID = 0,
 
diff --git a/kernel-module/xt_RTPENGINE.c b/kernel-module/xt_RTPENGINE.c
index bc1b180cf..303544fa7 100644
--- a/kernel-module/xt_RTPENGINE.c
+++ b/kernel-module/xt_RTPENGINE.c
@@ -1765,6 +1765,8 @@ static int proc_list_show(struct seq_file *f, void *v) {
 		seq_printf(f, " forward-RTCP");
 	if (g->target.rtcp_fb_fw)
 		seq_printf(f, " forward-RTCP-FB");
+	if (g->target.extmap)
+		seq_printf(f, " extmap[%u]", g->target.extmap_mid);
 	seq_printf(f, "\n");
 
 	seq_printf(f, "    output groups:");
@@ -1773,11 +1775,22 @@ static int proc_list_show(struct seq_file *f, void *v) {
 				!= g->target.media_output_idxs[i].rtp_end_idx
 				|| g->target.media_output_idxs[i].rtcp_start_idx
 				!= g->target.media_output_idxs[i].rtcp_end_idx)
-			seq_printf(f, " [%u]=(%u->%u/%u->%u)", i,
-					g->target.media_output_idxs[i].rtp_start_idx,
-					g->target.media_output_idxs[i].rtp_end_idx,
-					g->target.media_output_idxs[i].rtcp_start_idx,
-					g->target.media_output_idxs[i].rtcp_end_idx);
+		{
+			if (g->target.mid_output[i].len)
+				seq_printf(f, " [%u/'%.*s']=(%u->%u/%u->%u)", i,
+						(int) g->target.mid_output[i].len,
+						g->target.mid_output[i].mid,
+						g->target.media_output_idxs[i].rtp_start_idx,
+						g->target.media_output_idxs[i].rtp_end_idx,
+						g->target.media_output_idxs[i].rtcp_start_idx,
+						g->target.media_output_idxs[i].rtcp_end_idx);
+			else
+				seq_printf(f, " [%u]=(%u->%u/%u->%u)", i,
+						g->target.media_output_idxs[i].rtp_start_idx,
+						g->target.media_output_idxs[i].rtp_end_idx,
+						g->target.media_output_idxs[i].rtcp_start_idx,
+						g->target.media_output_idxs[i].rtcp_end_idx);
+		}
 	}
 	seq_printf(f, "\n");
 
@@ -6279,6 +6292,74 @@ static void rtp_stats(struct rtpengine_target *g, struct rtp_parsed *rtp, s64 ar
 }
 
 
+static unsigned int rtp_mid_ext_media_find(const char *mid, size_t len,
+		const struct rtpengine_target_info *tg)
+{
+	if (len == 0)
+		return -1u;
+
+	// XXX not an efficient search
+	for (unsigned int i = 0; i < RTPE_NUM_OUTPUT_MEDIA; i++) {
+		if (len != tg->mid_output[i].len)
+			continue;
+		if (!memcmp(tg->mid_output[i].mid, mid, len))
+			return i;
+	}
+
+	return -1u;
+}
+static unsigned int rtp_mid_ext_media_short(const struct rtp_parsed *rtp,
+		const struct rtpengine_target_info *tg)
+{
+	size_t left = rtp->extension_len;
+	unsigned char *r = rtp->extension;
+	// XXX duplicates filter code somewhat
+	while (left >= 1) {
+		if (*r == 0) {
+			r++;
+			left--;
+			continue;
+		}
+
+		uint8_t id = *r >> 4;
+		uint8_t len = (*r & 0xf) + 1;
+		r++;
+		left--;
+		if (len > left)
+			break;
+
+		if (id == tg->extmap_mid)
+			return rtp_mid_ext_media_find(r, len, tg);
+
+		r += len;
+		left -= len;
+	}
+	return -1u;
+}
+static unsigned int rtp_mid_ext_media_long(const struct rtp_parsed *rtp,
+		const struct rtpengine_target_info *tg)
+{
+	return -1u;
+}
+static unsigned int rtp_mid_ext_media(const struct rtp_parsed *rtp,
+		const struct rtpengine_target_info *tg)
+{
+	if (!rtp->ext_hdr)
+		return -1u;
+	if (!tg->extmap)
+		return -1u;
+	if (!tg->extmap_mid)
+		return -1u;
+
+	if (ntohs(rtp->ext_hdr->undefined) == 0xbede)
+		return rtp_mid_ext_media_short(rtp, tg);
+	else if ((ntohs(rtp->ext_hdr->undefined) & 0xfff0) == 0x0100)
+		return rtp_mid_ext_media_long(rtp, tg);
+
+	return -1u;
+}
+
+
 static unsigned int rtpengine46(struct sk_buff *skb, struct sk_buff *oskb,
 		struct rtpengine_table *t, struct re_address *src,
 		struct re_address *dst, uint8_t in_tos, const struct xt_action_param *par)
@@ -6393,6 +6474,8 @@ static unsigned int rtpengine46(struct sk_buff *skb, struct sk_buff *oskb,
 		// RTP ok
 		rtp_pt_idx = rtp_payload_type(rtp.rtp_header, &g->target, &g->last_pt);
 
+		output_group_idx = rtp_mid_ext_media(&rtp, &g->target);
+
 		// Pass to userspace if SSRC has changed.
 		// Look for matching SSRC index if any SSRC were given
 		ssrc_idx = target_find_ssrc(g, rtp.rtp_header->ssrc);
@@ -6413,7 +6496,8 @@ static unsigned int rtpengine46(struct sk_buff *skb, struct sk_buff *oskb,
 				goto out;
 		}
 		else {
-			output_group_idx = g->target.pt_media_idx[rtp_pt_idx];
+			if (output_group_idx == -1u)
+				output_group_idx = g->target.pt_media_idx[rtp_pt_idx];
 
 			if (ssrc_idx >= 0 && g->target.ssrc_stats[ssrc_idx]) {
 				atomic_set(&g->target.ssrc_stats[ssrc_idx]->last_pt,
@@ -6479,6 +6563,8 @@ static unsigned int rtpengine46(struct sk_buff *skb, struct sk_buff *oskb,
 	}
 
 	// output
+	if (output_group_idx == -1u)
+		output_group_idx = 0;
 	output_group = &g->target.media_output_idxs[output_group_idx];
 	start_idx = (is_rtcp != NOT_RTCP) ? output_group->rtcp_start_idx : output_group->rtp_start_idx;
 	end_idx = (is_rtcp != NOT_RTCP) ? output_group->rtcp_end_idx : output_group->rtp_end_idx;
diff --git a/kernel-module/xt_RTPENGINE.h b/kernel-module/xt_RTPENGINE.h
index b7c327cb1..a5e1fff3c 100644
--- a/kernel-module/xt_RTPENGINE.h
+++ b/kernel-module/xt_RTPENGINE.h
@@ -107,10 +107,16 @@ struct rtpengine_target_info {
 	unsigned int			pt_media_idx[RTPE_NUM_PAYLOAD_TYPES]; // same idx as pt_stats
 	unsigned int			num_payload_types;
 
+	uint8_t				extmap_mid;
+	struct {
+		char				mid[255];
+		size_t				len;
+	}				mid_output[RTPE_NUM_OUTPUT_MEDIA];
+
 	struct interface_stats_block	*iface_stats; // for ingress stats
 	struct stream_stats		*stats; // for ingress stats
 
-	unsigned int			__unused1:1,
+	unsigned int			extmap:1,
 					dtls:1,
 					stun:1,
 					rtp:1,