diff --git a/daemon/codec.c b/daemon/codec.c
index 5548d95b8..a7b495683 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -2328,13 +2328,13 @@ static int codec_decoder_event(enum codec_event event, void *ptr, void *data) {
 	switch (event) {
 		case CE_AMR_CMR_RECV:
 			// ignore locking and races for this
-			media->u.amr.cmr.cmr_in = GPOINTER_TO_UINT(ptr);
-			media->u.amr.cmr.cmr_in_ts = rtpe_now;
+			media->encoder_callback.amr.cmr_in = GPOINTER_TO_UINT(ptr);
+			media->encoder_callback.amr.cmr_in_ts = rtpe_now;
 			break;
 		case CE_AMR_SEND_CMR:
 			// ignore locking and races for this
-			media->u.amr.cmr.cmr_out = GPOINTER_TO_UINT(ptr);
-			media->u.amr.cmr.cmr_out_ts = rtpe_now;
+			media->encoder_callback.amr.cmr_out = GPOINTER_TO_UINT(ptr);
+			media->encoder_callback.amr.cmr_out_ts = rtpe_now;
 		default:
 			break;
 	}
@@ -3663,7 +3663,7 @@ static int packet_decoded_common(decoder_t *decoder, AVFrame *frame, void *u1, v
 
 	// locking deliberately ignored
 	if (mp->media_out)
-		ch->encoder->codec_options.amr.cmr = mp->media_out->u.amr.cmr;
+		ch->encoder->callback = mp->media_out->encoder_callback;
 
 	uint32_t ts = frame->pts + ch->first_ts;
 	__buffer_delay_frame(h->input_handler ? h->input_handler->delay_buffer : h->delay_buffer,
diff --git a/include/call.h b/include/call.h
index d869a4be9..74c62f71d 100644
--- a/include/call.h
+++ b/include/call.h
@@ -414,11 +414,7 @@ struct call_media {
 	GQueue			dtmf_send;
 
 #ifdef WITH_TRANSCODING
-	union {
-		struct {
-			struct amr_cmr cmr;
-		} amr;
-	} u;
+	encoder_callback_t	encoder_callback;
 #endif
 
 	int			ptime; // either from SDP or overridden
diff --git a/lib/codeclib.c b/lib/codeclib.c
index 591c1b802..fb905fdbb 100644
--- a/lib/codeclib.c
+++ b/lib/codeclib.c
@@ -2199,13 +2199,13 @@ static unsigned int amr_encoder_find_next_mode(encoder_t *enc) {
 	return next_mode;
 }
 static void amr_encoder_mode_change(encoder_t *enc) {
-	if (!memcmp(&enc->codec_options.amr.cmr.cmr_in_ts,
+	if (!memcmp(&enc->callback.amr.cmr_in_ts,
 				&enc->u.avc.u.amr.cmr_in_ts, sizeof(struct timeval)))
 		return;
 	// mode change requested: check if this is allowed right now
 	if (enc->codec_options.amr.mode_change_period == 2 && (enc->u.avc.u.amr.pkt_seq & 1) != 0)
 		return;
-	unsigned int cmr = enc->codec_options.amr.cmr.cmr_in;
+	unsigned int cmr = enc->callback.amr.cmr_in;
 	if (cmr == 0xffff)
 		cmr = amr_encoder_find_next_mode(enc);
 	if (cmr >= AMR_FT_TYPES)
@@ -2248,7 +2248,7 @@ static void amr_encoder_mode_change(encoder_t *enc) {
 	}
 	enc->u.avc.avcctx->bit_rate = req_br;
 	if (cmr_done)
-		enc->u.avc.u.amr.cmr_in_ts = enc->codec_options.amr.cmr.cmr_in_ts;
+		enc->u.avc.u.amr.cmr_in_ts = enc->callback.amr.cmr_in_ts;
 }
 static void amr_encoder_got_packet(encoder_t *enc) {
 	amr_encoder_mode_change(enc);
@@ -2283,15 +2283,15 @@ static int packetizer_amr(AVPacket *pkt, GString *buf, str *output, encoder_t *e
 
 	// or do we have a CMR?
 	if (!enc->u.avc.u.amr.cmr_out_seq) {
-		if (memcmp(&enc->u.avc.u.amr.cmr_out_ts, &enc->codec_options.amr.cmr.cmr_out_ts,
+		if (memcmp(&enc->u.avc.u.amr.cmr_out_ts, &enc->callback.amr.cmr_out_ts,
 					sizeof(struct timeval))) {
 			enc->u.avc.u.amr.cmr_out_seq += 3; // make this configurable?
-			enc->u.avc.u.amr.cmr_out_ts = enc->codec_options.amr.cmr.cmr_out_ts;
+			enc->u.avc.u.amr.cmr_out_ts = enc->callback.amr.cmr_out_ts;
 		}
 	}
 	if (enc->u.avc.u.amr.cmr_out_seq) {
 		enc->u.avc.u.amr.cmr_out_seq--;
-		unsigned int cmr = enc->codec_options.amr.cmr.cmr_out;
+		unsigned int cmr = enc->callback.amr.cmr_out;
 		if (cmr < AMR_FT_TYPES && enc->codec_options.amr.bitrates[cmr])
 			s[0] = cmr << 4;
 	}
diff --git a/lib/codeclib.h b/lib/codeclib.h
index e2f98614a..ec9d2f055 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -59,6 +59,7 @@ struct resample_s;
 struct seq_packet_s;
 struct rtp_payload_type;
 union codec_options_u;
+struct encoder_callback_s;
 struct dtx_method_s;
 
 typedef struct codec_type_s codec_type_t;
@@ -68,6 +69,7 @@ typedef struct format_s format_t;
 typedef struct resample_s resample_t;
 typedef struct seq_packet_s seq_packet_t;
 typedef union codec_options_u codec_options_t;
+typedef struct encoder_callback_s encoder_callback_t;
 typedef struct dtx_method_s dtx_method_t;
 
 typedef int packetizer_f(AVPacket *, GString *, str *, encoder_t *);
@@ -91,12 +93,14 @@ struct codec_type_s {
 	void (*encoder_close)(encoder_t *);
 };
 
-struct amr_cmr {
-	struct timeval cmr_in_ts;
-	unsigned int cmr_in;
+struct encoder_callback_s {
+	struct {
+		struct timeval cmr_in_ts;
+		unsigned int cmr_in;
 
-	struct timeval cmr_out_ts;
-	unsigned int cmr_out;
+		struct timeval cmr_out_ts;
+		unsigned int cmr_out;
+	} amr;
 };
 
 union codec_options_u {
@@ -113,8 +117,6 @@ union codec_options_u {
 		const unsigned int *bits_per_frame;
 		const unsigned int *bitrates;
 
-		struct amr_cmr cmr; // input from external calling code
-
 		int cmr_interval;
 	} amr;
 };
@@ -247,6 +249,7 @@ struct encoder_s {
 
 	const codec_def_t *def;
 	codec_options_t codec_options;
+	encoder_callback_t callback;
 
 	union {
 		struct {