From f82e0aebda4eb50194c484e84dede59322f09af3 Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Fri, 7 Oct 2022 16:23:38 -0400
Subject: [PATCH] MT#55447 introduce proper a=fmtp parsing

Parsing out the a=fmtp string has been left up to the codec init
function until now, with the values that resulted from the parsing being
stored only within the codec. Convert this to an explicit method to
parse the a=fmtp string, and introduce a dedicated struct to store the
resulting values.

Functionally this change is a no-op.

Change-Id: Ia84e26d632ed5209b4439fd82c1e4e38850fd024
---
 daemon/codec.c             |   6 +-
 lib/codeclib.c             | 194 +++++++++++++++++++++++--------------
 lib/codeclib.h             |  30 +++---
 lib/rtplib.h               |  22 +++++
 recording-daemon/decoder.c |   2 +-
 5 files changed, 165 insertions(+), 89 deletions(-)

diff --git a/daemon/codec.c b/daemon/codec.c
index a7b495683..e6bbe1bd1 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -3402,7 +3402,8 @@ static struct ssrc_entry *__ssrc_handler_transcode_new(void *p) {
 	if (encoder_config_fmtp(ch->encoder, h->dest_pt.codec_def,
 				ch->bitrate,
 				ch->ptime,
-				&enc_format, &ch->encoder_format, &h->dest_pt.format_parameters,
+				&enc_format, &ch->encoder_format, &h->dest_pt.format,
+				&h->dest_pt.format_parameters,
 				&h->dest_pt.codec_opts))
 		goto err;
 
@@ -3418,7 +3419,8 @@ static struct ssrc_entry *__ssrc_handler_transcode_new(void *p) {
 
 	ch->decoder = decoder_new_fmtp(h->source_pt.codec_def, h->source_pt.clock_rate, h->source_pt.channels,
 			h->source_pt.ptime,
-			&ch->encoder_format, &h->source_pt.format_parameters, &h->source_pt.codec_opts);
+			&ch->encoder_format, &h->source_pt.format,
+			&h->source_pt.format_parameters, &h->source_pt.codec_opts);
 	if (!ch->decoder)
 		goto err;
 	if (rtpe_config.dtx_cn_params.len) {
diff --git a/lib/codeclib.c b/lib/codeclib.c
index fb905fdbb..6d40d4551 100644
--- a/lib/codeclib.c
+++ b/lib/codeclib.c
@@ -37,17 +37,19 @@ static packetizer_f packetizer_amr;
 static format_init_f opus_init;
 static set_enc_options_f opus_set_enc_options;
 
+static format_parse_f ilbc_format_parse;
 static set_enc_options_f ilbc_set_enc_options;
 static set_dec_options_f ilbc_set_dec_options;
 
+static format_parse_f amr_format_parse;
 static set_enc_options_f amr_set_enc_options;
 static set_dec_options_f amr_set_dec_options;
 
 static void avc_def_init(codec_def_t *);
-static const char *avc_decoder_init(decoder_t *, const str *, const str *);
+static const char *avc_decoder_init(decoder_t *, const str *);
 static int avc_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 static void avc_decoder_close(decoder_t *);
-static const char *avc_encoder_init(encoder_t *enc, const str *, const str *);
+static const char *avc_encoder_init(encoder_t *enc, const str *);
 static int avc_encoder_input(encoder_t *enc, AVFrame **frame);
 static void avc_encoder_close(encoder_t *enc);
 
@@ -55,10 +57,10 @@ static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 static void amr_encoder_got_packet(encoder_t *enc);
 static int ilbc_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 
-static const char *dtmf_decoder_init(decoder_t *, const str *, const str *);
+static const char *dtmf_decoder_init(decoder_t *, const str *);
 static int dtmf_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 
-static const char *cn_decoder_init(decoder_t *, const str *, const str *);
+static const char *cn_decoder_init(decoder_t *, const str *);
 static int cn_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 
 static int format_cmp_ignore(const struct rtp_payload_type *, const struct rtp_payload_type *);
@@ -131,10 +133,10 @@ static const dtx_method_t dtx_method_amr = {
 static packetizer_f packetizer_g729; // aggregate some frames into packets
 
 static void bcg729_def_init(codec_def_t *);
-static const char *bcg729_decoder_init(decoder_t *, const str *, const str *);
+static const char *bcg729_decoder_init(decoder_t *, const str *);
 static int bcg729_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 static void bcg729_decoder_close(decoder_t *);
-static const char *bcg729_encoder_init(encoder_t *enc, const str *, const str *);
+static const char *bcg729_encoder_init(encoder_t *enc, const str *);
 static int bcg729_encoder_input(encoder_t *enc, AVFrame **frame);
 static void bcg729_encoder_close(encoder_t *enc);
 
@@ -335,6 +337,7 @@ static codec_def_t __codec_defs[] = {
 		.default_channels = 1,
 		.default_ptime = 30,
 		.default_fmtp = "mode=30",
+		.format_parse = ilbc_format_parse,
 		//.default_bitrate = 15200,
 		.packetizer = packetizer_passthrough,
 		.media_type = MT_AUDIO,
@@ -473,6 +476,7 @@ static codec_def_t __codec_defs[] = {
 		.default_channels = 1,
 		.default_bitrate = 6700,
 		.default_ptime = 20,
+		.format_parse = amr_format_parse,
 		.default_fmtp = "octet-align=1;mode-change-capability=2",
 		.packetizer = packetizer_amr,
 		.bits_per_sample = 2, // max is 12200 / 8000 = 1.525 bits per sample, rounded up
@@ -496,6 +500,7 @@ static codec_def_t __codec_defs[] = {
 		.default_channels = 1,
 		.default_bitrate = 14250,
 		.default_ptime = 20,
+		.format_parse = amr_format_parse,
 		.default_fmtp = "octet-align=1;mode-change-capability=2",
 		.packetizer = packetizer_amr,
 		.bits_per_sample = 2, // max is 23850 / 16000 = 1.490625 bits per sample, rounded up
@@ -590,7 +595,7 @@ const codec_def_t *codec_find_by_av(enum AVCodecID id) {
 
 
 
-static const char *avc_decoder_init(decoder_t *dec, const str *fmtp, const str *extra_opts) {
+static const char *avc_decoder_init(decoder_t *dec, const str *extra_opts) {
 	const AVCodec *codec = dec->def->decoder;
 	if (!codec)
 		return "codec not supported";
@@ -605,7 +610,7 @@ static const char *avc_decoder_init(decoder_t *dec, const str *fmtp, const str *
 	dec->u.avc.avcctx->sample_rate = dec->in_format.clockrate;
 
 	if (dec->def->set_dec_options)
-		dec->def->set_dec_options(dec, fmtp, extra_opts);
+		dec->def->set_dec_options(dec, extra_opts);
 
 	int i = avcodec_open2(dec->u.avc.avcctx, codec, NULL);
 	if (i) {
@@ -625,12 +630,44 @@ static const char *avc_decoder_init(decoder_t *dec, const str *fmtp, const str *
 decoder_t *decoder_new_fmt(const codec_def_t *def, int clockrate, int channels, int ptime,
 		const format_t *resample_fmt)
 {
-	return decoder_new_fmtp(def, clockrate, channels, ptime, resample_fmt, NULL, NULL);
+	return decoder_new_fmtp(def, clockrate, channels, ptime, resample_fmt, NULL, NULL, NULL);
+}
+
+int codec_parse_fmtp(const codec_def_t *def, struct rtp_codec_format *fmtp, const str *fmtp_string,
+		union codec_format_options *copy)
+{
+	struct rtp_codec_format fmtp_store;
+
+	if (copy)
+		ZERO(*copy);
+
+	if (!def)
+		return -1;
+	if (!def->format_parse)
+		return 0;
+	if (!fmtp_string)
+		return 0;
+	if (!fmtp) {
+		ZERO(fmtp_store);
+		fmtp = &fmtp_store;
+	}
+	if (fmtp->fmtp_parsed) {
+		if (copy)
+			*copy = fmtp->parsed;
+		return 0;
+	}
+	int ret = def->format_parse(fmtp, fmtp_string);
+	if (!ret) {
+		fmtp->fmtp_parsed = 1;
+		if (copy)
+			*copy = fmtp->parsed;
+	}
+	return ret;
 }
 
 decoder_t *decoder_new_fmtp(const codec_def_t *def, int clockrate, int channels, int ptime,
 		const format_t *resample_fmt,
-		const str *fmtp,
+		struct rtp_codec_format *fmtp, const str *fmtp_string,
 		const str *extra_opts)
 {
 	const char *err;
@@ -667,7 +704,11 @@ decoder_t *decoder_new_fmtp(const codec_def_t *def, int clockrate, int channels,
 		}
 	}
 
-	err = def->codec_type->decoder_init(ret, fmtp, extra_opts);
+	err = "failed to parse \"fmtp\"";
+	if (codec_parse_fmtp(def, fmtp, fmtp_string, &ret->format_options))
+		goto err;
+
+	err = def->codec_type->decoder_init(ret, extra_opts);
 	if (err)
 		goto err;
 
@@ -1245,7 +1286,7 @@ encoder_t *encoder_new(void) {
 	return ret;
 }
 
-static const char *avc_encoder_init(encoder_t *enc, const str *fmtp, const str *extra_opts) {
+static const char *avc_encoder_init(encoder_t *enc, const str *extra_opts) {
 	enc->u.avc.codec = enc->def->encoder;
 	if (!enc->u.avc.codec)
 		return "output codec not found";
@@ -1281,7 +1322,7 @@ static const char *avc_encoder_init(encoder_t *enc, const str *fmtp, const str *
 	enc->samples_per_packet = enc->samples_per_frame;
 
 	if (enc->def->set_enc_options)
-		enc->def->set_enc_options(enc, fmtp, extra_opts);
+		enc->def->set_enc_options(enc, extra_opts);
 
 	int i = avcodec_open2(enc->u.avc.avcctx, enc->u.avc.codec, NULL);
 	if (i) {
@@ -1295,11 +1336,13 @@ static const char *avc_encoder_init(encoder_t *enc, const str *fmtp, const str *
 int encoder_config(encoder_t *enc, const codec_def_t *def, int bitrate, int ptime,
 		const format_t *requested_format, format_t *actual_format)
 {
-	return encoder_config_fmtp(enc, def, bitrate, ptime, requested_format, actual_format, NULL, NULL);
+	return encoder_config_fmtp(enc, def, bitrate, ptime, requested_format, actual_format,
+			NULL, NULL, NULL);
 }
 
 int encoder_config_fmtp(encoder_t *enc, const codec_def_t *def, int bitrate, int ptime,
-		const format_t *requested_format, format_t *actual_format, const str *fmtp,
+		const format_t *requested_format, format_t *actual_format,
+		struct rtp_codec_format *fmtp, const str *fmtp_string,
 		const str *extra_opts)
 {
 	const char *err;
@@ -1322,7 +1365,11 @@ int encoder_config_fmtp(encoder_t *enc, const codec_def_t *def, int bitrate, int
 	enc->ptime = ptime / def->clockrate_mult;
 	enc->bitrate = bitrate;
 
-	err = def->codec_type->encoder_init ? def->codec_type->encoder_init(enc, fmtp, extra_opts) : 0;
+	err = "failed to parse \"fmtp\"";
+	if (codec_parse_fmtp(def, fmtp, fmtp_string, &enc->format_options))
+		goto err;
+
+	err = def->codec_type->encoder_init ? def->codec_type->encoder_init(enc, extra_opts) : 0;
 	if (err)
 		goto err;
 
@@ -1645,7 +1692,7 @@ static void opus_init(struct rtp_payload_type *pt) {
 	ilog(LOG_DEBUG, "Using default bitrate of %i bps for %i-channel Opus", pt->bitrate, pt->channels);
 }
 
-static void opus_set_enc_options(encoder_t *enc, const str *fmtp, const str *codec_opts) {
+static void opus_set_enc_options(encoder_t *enc, const str *codec_opts) {
 	if (enc->ptime > 0)
 		codeclib_set_av_opt_int(enc, "frame_duration", enc->ptime);
 
@@ -1658,19 +1705,21 @@ static void opus_set_enc_options(encoder_t *enc, const str *fmtp, const str *cod
 	free(s);
 }
 
-static int ilbc_mode(int ptime, const str *fmtp, const char *direction) {
-	int mode = 0;
+static int ilbc_format_parse(struct rtp_codec_format *f, const str *fmtp) {
+	if (!str_cmp(fmtp, "mode=20"))
+		f->parsed.ilbc.mode = 20;
+	else if (!str_cmp(fmtp, "mode=30"))
+		f->parsed.ilbc.mode = 30;
+	else
+		return -1;
+	f->fmtp_parsed = 1;
+	return 0;
+}
 
-	if (fmtp) {
-		if (!str_cmp(fmtp, "mode=20")) {
-			mode = 20;
-			ilog(LOG_DEBUG, "Setting iLBC %s mode to 20 ms based on fmtp", direction);
-		}
-		else if (!str_cmp(fmtp, "mode=30")) {
-			mode = 30;
-			ilog(LOG_DEBUG, "Setting iLBC %s mode to 30 ms based on fmtp", direction);
-		}
-	}
+static int ilbc_mode(int ptime, const union codec_format_options *fmtp, const char *direction) {
+	int mode = 0;
+	if (fmtp)
+		mode = fmtp->ilbc.mode;
 
 	if (!mode) {
 		switch (ptime) {
@@ -1701,13 +1750,13 @@ static int ilbc_mode(int ptime, const str *fmtp, const char *direction) {
 	return mode;
 }
 
-static void ilbc_set_enc_options(encoder_t *enc, const str *fmtp, const str *codec_opts) {
-	int mode = ilbc_mode(enc->ptime, fmtp, "encoder");
+static void ilbc_set_enc_options(encoder_t *enc, const str *codec_opts) {
+	int mode = ilbc_mode(enc->ptime, &enc->format_options, "encoder");
 	codeclib_set_av_opt_int(enc, "mode", mode);
 }
 
-static void ilbc_set_dec_options(decoder_t *dec, const str *fmtp, const str *codec_opts) {
-	int mode = ilbc_mode(dec->ptime, fmtp, "decoder");
+static void ilbc_set_dec_options(decoder_t *dec, const str *codec_opts) {
+	int mode = ilbc_mode(dec->ptime, &dec->format_options, "decoder");
 	if (mode == 20)
 		dec->u.avc.avcctx->block_align = 38;
 	else if (mode == 30)
@@ -1718,9 +1767,9 @@ static void ilbc_set_dec_options(decoder_t *dec, const str *fmtp, const str *cod
 
 static int ilbc_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 	int mode = 0, block_align = 0;
-	static const str mode_20 = STR_CONST_INIT("mode=20");
-	static const str mode_30 = STR_CONST_INIT("mode=30");
-	const str *fmtp;
+	static const union codec_format_options mode_20 = { .ilbc = { 20 } };
+	static const union codec_format_options mode_30 = { .ilbc = { 30 } };
+	const union codec_format_options *fmtp;
 
 	if (data->len % 50 == 0) {
 		mode = 30;
@@ -1742,7 +1791,8 @@ static int ilbc_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 				"block mode (%i ms mode)",
 				(int) dec->u.avc.avcctx->block_align, (int) data->len, block_align, mode);
 		avc_decoder_close(dec);
-		avc_decoder_init(dec, fmtp, NULL);
+		dec->format_options = *fmtp;
+		avc_decoder_init(dec, NULL);
 	}
 
 	return avc_decoder_input(dec, data, out);
@@ -1851,8 +1901,8 @@ static const unsigned int amr_wb_bits_per_frame[AMR_FT_TYPES] = {
 	0, // invalid // 12
 	0, // invalid // 13
 };
-static void amr_set_encdec_options_cb(str *key, str *token, void *data) {
-	codec_options_t *opts = data;
+static void amr_parse_format_cb(str *key, str *token, void *data) {
+	union codec_format_options *opts = data;
 
 	if (!str_cmp(key, "octet-align")) {
 		if (token->len == 1 && token->s[0] == '1')
@@ -1890,7 +1940,11 @@ static void amr_set_encdec_options_cb(str *key, str *token, void *data) {
 			opts->amr.mode_change_neighbor = 1;
 	}
 }
-static void amr_set_encdec_options(codec_options_t *opts, const str *fmtp, const codec_def_t *def) {
+static int amr_format_parse(struct rtp_codec_format *f, const str *fmtp) {
+	codeclib_key_value_parse(fmtp, true, amr_parse_format_cb, f);
+	return 0;
+}
+static void amr_set_encdec_options(codec_options_t *opts, const codec_def_t *def) {
 	if (!strcmp(def->rtpname, "AMR")) {
 		opts->amr.bits_per_frame = amr_bits_per_frame;
 		opts->amr.bitrates = amr_bitrates;
@@ -1899,8 +1953,6 @@ static void amr_set_encdec_options(codec_options_t *opts, const str *fmtp, const
 		opts->amr.bits_per_frame = amr_wb_bits_per_frame;
 		opts->amr.bitrates = amr_wb_bitrates;
 	}
-
-	codeclib_key_value_parse(fmtp, true, amr_set_encdec_options_cb, opts);
 }
 static void amr_set_dec_codec_options(str *key, str *value, void *data) {
 	decoder_t *dec = data;
@@ -1925,17 +1977,17 @@ static void amr_set_enc_codec_options(str *key, str *value, void *data) {
 		g_free(s);
 	}
 }
-static void amr_set_enc_options(encoder_t *enc, const str *fmtp, const str *codec_opts) {
-	amr_set_encdec_options(&enc->codec_options, fmtp, enc->def);
+static void amr_set_enc_options(encoder_t *enc, const str *codec_opts) {
+	amr_set_encdec_options(&enc->codec_options, enc->def);
 
 	codeclib_key_value_parse(codec_opts, true, amr_set_enc_codec_options, enc);
 
 	// if a mode-set was given, pick the highest supported bitrate
-	if (enc->codec_options.amr.mode_set) {
+	if (enc->format_options.amr.mode_set) {
 		int max_bitrate = enc->u.avc.avcctx->bit_rate;
 		int use_bitrate = 0;
 		for (int i = 0; i < AMR_FT_TYPES; i++) {
-			if (!(enc->codec_options.amr.mode_set & (1 << i)))
+			if (!(enc->format_options.amr.mode_set & (1 << i)))
 				continue;
 			unsigned int br = enc->codec_options.amr.bitrates[i];
 			// we depend on the list being in ascending order, with
@@ -1956,8 +2008,8 @@ static void amr_set_enc_options(encoder_t *enc, const str *fmtp, const str *code
 		}
 	}
 }
-static void amr_set_dec_options(decoder_t *dec, const str *fmtp, const str *codec_opts) {
-	amr_set_encdec_options(&dec->codec_options, fmtp, dec->def);
+static void amr_set_dec_options(decoder_t *dec, const str *codec_opts) {
+	amr_set_encdec_options(&dec->codec_options, dec->def);
 	codeclib_key_value_parse(codec_opts, true, amr_set_dec_codec_options, dec);
 }
 
@@ -1976,8 +2028,8 @@ static void amr_bitrate_tracker(decoder_t *dec, unsigned int ft) {
 				break; // end of list
 
 			// ignore restricted modes
-			if (dec->codec_options.amr.mode_set) {
-				if (!(dec->codec_options.amr.mode_set & (1 << i)))
+			if (dec->format_options.amr.mode_set) {
+				if (!(dec->format_options.amr.mode_set & (1 << i)))
 					continue;
 			}
 
@@ -2048,11 +2100,11 @@ static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 		}
 	}
 
-	if (dec->codec_options.amr.octet_aligned) {
+	if (dec->format_options.amr.octet_aligned) {
 		if (bitstr_shift(&d, 4))
 			goto err;
 
-		if (dec->codec_options.amr.interleaving) {
+		if (dec->format_options.amr.interleaving) {
 			unsigned char ill_ilp_chr[2];
 			str ill_ilp = STR_CONST_INIT_BUF(ill_ilp_chr);
 			err = "no ILL/ILP";
@@ -2079,7 +2131,7 @@ static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 		if (bitstr_shift_ret(&d, 6, &toc_entry))
 			goto err;
 
-		if (dec->codec_options.amr.octet_aligned)
+		if (dec->format_options.amr.octet_aligned)
 			if (bitstr_shift(&d, 2))
 				goto err;
 
@@ -2100,7 +2152,7 @@ static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 			break;
 	}
 
-	if (dec->codec_options.amr.crc) {
+	if (dec->format_options.amr.crc) {
 		// CRCs is one byte per frame
 		err = "missing CRC entry";
 		if (bitstr_shift(&d, num_crcs * 8))
@@ -2128,7 +2180,7 @@ static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 		str_unshift(&frame, 1);
 		frame.s[0] = toc_byte & 0x7c; // strip F bit, keep FT and Q, zero padding (01111100)
 
-		if (dec->codec_options.amr.octet_aligned && (bits % 8) != 0) {
+		if (dec->format_options.amr.octet_aligned && (bits % 8) != 0) {
 			unsigned int padding_bits = 8 - (bits % 8);
 			if (bitstr_shift(&d, padding_bits))
 				goto err;
@@ -2178,13 +2230,13 @@ static unsigned int amr_encoder_find_next_mode(encoder_t *enc) {
 		return -1;
 	int next_mode = mode + 1;
 	// if modes are restricted, find the next one up
-	if (enc->codec_options.amr.mode_set) {
+	if (enc->format_options.amr.mode_set) {
 		// is there anything?
-		if ((1 << next_mode) > enc->codec_options.amr.mode_set)
+		if ((1 << next_mode) > enc->format_options.amr.mode_set)
 			return -1;
 		int next_up = -1;
 		for (; next_mode < AMR_FT_TYPES; next_mode++) {
-			if (!(enc->codec_options.amr.mode_set & (1 << next_mode)))
+			if (!(enc->format_options.amr.mode_set & (1 << next_mode)))
 				continue;
 			next_up = next_mode;
 			break;
@@ -2203,7 +2255,7 @@ static void amr_encoder_mode_change(encoder_t *enc) {
 				&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)
+	if (enc->format_options.amr.mode_change_period == 2 && (enc->u.avc.u.amr.pkt_seq & 1) != 0)
 		return;
 	unsigned int cmr = enc->callback.amr.cmr_in;
 	if (cmr == 0xffff)
@@ -2211,13 +2263,13 @@ static void amr_encoder_mode_change(encoder_t *enc) {
 	if (cmr >= AMR_FT_TYPES)
 		return;
 	// ignore CMR for invalid modes
-	if (enc->codec_options.amr.mode_set && !(enc->codec_options.amr.mode_set & (1 << cmr)))
+	if (enc->format_options.amr.mode_set && !(enc->format_options.amr.mode_set & (1 << cmr)))
 		return;
 	int req_br = enc->codec_options.amr.bitrates[cmr];
 	if (!req_br)
 		return;
 	int cmr_done = 1;
-	if (enc->codec_options.amr.mode_change_neighbor) {
+	if (enc->format_options.amr.mode_change_neighbor) {
 		// handle non-neighbour mode changes
 		int cur_br = enc->u.avc.avcctx->bit_rate;
 		// step up or down from the requested bitrate towards the current one
@@ -2234,8 +2286,8 @@ static void amr_encoder_mode_change(encoder_t *enc) {
 			if (cmr_br == cur_br)
 				break;
 			// allowed by mode set?
-			if (enc->codec_options.amr.mode_set) {
-				if (!(enc->codec_options.amr.mode_set & (1 << cmr)))
+			if (enc->format_options.amr.mode_set) {
+				if (!(enc->format_options.amr.mode_set & (1 << cmr)))
 					continue; // go to next mode
 			}
 			// valid bitrate - continue stepping
@@ -2296,11 +2348,11 @@ static int packetizer_amr(AVPacket *pkt, GString *buf, str *output, encoder_t *e
 			s[0] = cmr << 4;
 	}
 
-	if (enc->codec_options.amr.octet_aligned) {
+	if (enc->format_options.amr.octet_aligned) {
 		unsigned int offset = 1; // CMR byte
-		if (enc->codec_options.amr.interleaving)
+		if (enc->format_options.amr.interleaving)
 			s[offset++] = 0; // no interleaving
-		if (enc->codec_options.amr.crc)
+		if (enc->format_options.amr.crc)
 			s[offset++] = 0; // not implemented
 		memcpy(s + offset, pkt->data, pkt->size);
 		output->len = pkt->size + offset;
@@ -2414,7 +2466,7 @@ static void bcg729_def_init(codec_def_t *def) {
 	}
 }
 
-static const char *bcg729_decoder_init(decoder_t *dec, const str *fmtp, const str *extra_opts) {
+static const char *bcg729_decoder_init(decoder_t *dec, const str *extra_opts) {
 	dec->u.bcg729 = initBcg729DecoderChannel();
 	if (!dec->u.bcg729)
 		return "failed to initialize bcg729";
@@ -2458,7 +2510,7 @@ static void bcg729_decoder_close(decoder_t *dec) {
 	dec->u.bcg729 = NULL;
 }
 
-static const char *bcg729_encoder_init(encoder_t *enc, const str *fmtp, const str *extra_opts) {
+static const char *bcg729_encoder_init(encoder_t *enc, const str *extra_opts) {
 	enc->u.bcg729 = initBcg729EncoderChannel(0); // no VAD
 	if (!enc->u.bcg729)
 		return "failed to initialize bcg729";
@@ -2550,7 +2602,7 @@ static int packetizer_g729(AVPacket *pkt, GString *buf, str *input_output, encod
 #endif
 
 
-static const char *dtmf_decoder_init(decoder_t *dec, const str *fmtp, const str *extra_opts) {
+static const char *dtmf_decoder_init(decoder_t *dec, const str *extra_opts) {
 	dec->u.dtmf.event = -1;
 	return NULL;
 }
@@ -2630,12 +2682,12 @@ static int format_cmp_ignore(const struct rtp_payload_type *a, const struct rtp_
 
 
 
-static const char *cn_decoder_init(decoder_t *dec, const str *fmtp, const str *opts) {
+static const char *cn_decoder_init(decoder_t *dec, const str *opts) {
 	// the ffmpeg cngdec always runs at 8000
 	dec->in_format.clockrate = 8000;
 	dec->in_format.channels = 1;
 	dec->resampler.no_filter = true;
-	return avc_decoder_init(dec, fmtp, opts);
+	return avc_decoder_init(dec, opts);
 }
 static int cn_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 	// generate one set of ptime worth of samples
diff --git a/lib/codeclib.h b/lib/codeclib.h
index ec9d2f055..d8b781260 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -18,6 +18,7 @@ enum media_type {
 
 
 #include "str.h"
+#include "rtplib.h"
 
 INLINE enum media_type codec_get_type(const str *type) {
 	if (!type || !type->len)
@@ -74,20 +75,21 @@ typedef struct dtx_method_s dtx_method_t;
 
 typedef int packetizer_f(AVPacket *, GString *, str *, encoder_t *);
 typedef void format_init_f(struct rtp_payload_type *);
-typedef void set_enc_options_f(encoder_t *, const str *, const str *);
-typedef void set_dec_options_f(decoder_t *, const str *, const str *);
+typedef void set_enc_options_f(encoder_t *, const str *);
+typedef void set_dec_options_f(decoder_t *, const str *);
 typedef int format_cmp_f(const struct rtp_payload_type *, const struct rtp_payload_type *);
+typedef int format_parse_f(struct rtp_codec_format *, const str *fmtp);
 
 
 
 struct codec_type_s {
 	void (*def_init)(codec_def_t *);
 
-	const char *(*decoder_init)(decoder_t *, const str *, const str *);
+	const char *(*decoder_init)(decoder_t *, const str *);
 	int (*decoder_input)(decoder_t *, const str *data, GQueue *);
 	void (*decoder_close)(decoder_t *);
 
-	const char *(*encoder_init)(encoder_t *, const str *, const str *);
+	const char *(*encoder_init)(encoder_t *, const str *);
 	int (*encoder_input)(encoder_t *, AVFrame **);
 	void (*encoder_got_packet)(encoder_t *);
 	void (*encoder_close)(encoder_t *);
@@ -105,18 +107,10 @@ struct encoder_callback_s {
 
 union codec_options_u {
 	struct {
-		int interleaving;
-		unsigned int mode_set; // bitfield
-		int mode_change_period;
-		int mode_change_interval;
-		unsigned int octet_aligned:1;
-		unsigned int crc:1;
-		unsigned int robust_sorting:1;
-		unsigned int mode_change_neighbor:1;
-
 		const unsigned int *bits_per_frame;
 		const unsigned int *bitrates;
 
+		int mode_change_interval;
 		int cmr_interval;
 	} amr;
 };
@@ -140,6 +134,7 @@ struct codec_def_s {
 	const int default_bitrate;
 	int default_ptime;
 	const char *default_fmtp;
+	format_parse_f * const format_parse;
 	format_cmp_f * const format_cmp;
 	packetizer_f * const packetizer;
 	const int bits_per_sample;
@@ -204,6 +199,7 @@ struct dtx_method_s {
 struct decoder_s {
 	const codec_def_t *def;
 	codec_options_t codec_options;
+	union codec_format_options format_options;
 	dtx_method_t dtx;
 
 	format_t in_format,
@@ -250,6 +246,7 @@ struct encoder_s {
 	const codec_def_t *def;
 	codec_options_t codec_options;
 	encoder_callback_t callback;
+	union codec_format_options format_options;
 
 	union {
 		struct {
@@ -304,12 +301,14 @@ void codeclib_free(void);
 const codec_def_t *codec_find(const str *name, enum media_type);
 const codec_def_t *codec_find_by_av(enum AVCodecID);
 
+int codec_parse_fmtp(const codec_def_t *def, struct rtp_codec_format *fmtp, const str *fmtp_string,
+		union codec_format_options *copy);
 
 decoder_t *decoder_new_fmt(const codec_def_t *def, int clockrate, int channels, int ptime,
 		const format_t *resample_fmt);
 decoder_t *decoder_new_fmtp(const codec_def_t *def, int clockrate, int channels, int ptime,
 		const format_t *resample_fmt,
-		const str *fmtp, const str *codec_opts);
+		struct rtp_codec_format *fmtp, const str *fmtp_string, const str *codec_opts);
 void decoder_close(decoder_t *dec);
 int decoder_input_data(decoder_t *dec, const str *data, unsigned long ts,
 		int (*callback)(decoder_t *, AVFrame *, void *u1, void *u2), void *u1, void *u2);
@@ -326,7 +325,8 @@ encoder_t *encoder_new(void);
 int encoder_config(encoder_t *enc, const codec_def_t *def, int bitrate, int ptime,
 		const format_t *requested_format, format_t *actual_format);
 int encoder_config_fmtp(encoder_t *enc, const codec_def_t *def, int bitrate, int ptime,
-		const format_t *requested_format, format_t *actual_format, const str *fmtp, const str *codec_opts);
+		const format_t *requested_format, format_t *actual_format,
+		struct rtp_codec_format *fmtp, const str *fmtp_string, const str *codec_opts);
 void encoder_close(encoder_t *);
 void encoder_free(encoder_t *);
 int encoder_input_data(encoder_t *enc, AVFrame *frame,
diff --git a/lib/rtplib.h b/lib/rtplib.h
index cb83fff1e..c28710d54 100644
--- a/lib/rtplib.h
+++ b/lib/rtplib.h
@@ -20,6 +20,27 @@ struct rtp_header {
 } __attribute__ ((packed));
 
 
+union codec_format_options {
+	struct {
+		int interleaving;
+		unsigned int mode_set; // bitfield
+		int mode_change_period;
+		unsigned int octet_aligned:1;
+		unsigned int crc:1;
+		unsigned int robust_sorting:1;
+		unsigned int mode_change_neighbor:1;
+	} amr;
+
+	struct {
+		int mode;
+	} ilbc;
+};
+
+struct rtp_codec_format {
+	union codec_format_options parsed;
+	unsigned int fmtp_parsed:1; // set if fmtp string was successfully parsed
+};
+
 struct rtp_payload_type {
 	int payload_type;
 	str encoding_with_params; // "opus/48000/2"
@@ -37,6 +58,7 @@ struct rtp_payload_type {
 
 	const codec_def_t *codec_def;
 	GList *prefs_link; // link in `codec_prefs` list
+	struct rtp_codec_format format; // parsed out fmtp
 
 	unsigned int for_transcoding:1;
 	unsigned int accepted:1;
diff --git a/recording-daemon/decoder.c b/recording-daemon/decoder.c
index 3b1077eca..694b6b608 100644
--- a/recording-daemon/decoder.c
+++ b/recording-daemon/decoder.c
@@ -86,7 +86,7 @@ decode_t *decoder_new(const char *payload_str, const char *format, int ptime, ou
 	str fmtp;
 	str_init(&fmtp, (char *) format);
 
-	decoder_t *dec = decoder_new_fmtp(def, rtp_clockrate, channels, ptime, &out_format, &fmtp, NULL);
+	decoder_t *dec = decoder_new_fmtp(def, rtp_clockrate, channels, ptime, &out_format, NULL, &fmtp, NULL);
 	if (!dec)
 		return NULL;
 	decode_t *deco = g_slice_alloc0(sizeof(decode_t));