From 9f48d53fc7d6dff69a2bc688a5b5d9d7be082659 Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Tue, 26 Mar 2013 08:57:58 +0100
Subject: [PATCH] AMR codec support

---
 gsm.cpp     | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 gsm.h       |  1 +
 gsm_audio.c |  2 +-
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/gsm.cpp b/gsm.cpp
index 7502eed..6a7445d 100644
--- a/gsm.cpp
+++ b/gsm.cpp
@@ -186,6 +186,8 @@ Pgsm::Pgsm(int type, char *portname, struct port_settings *settings, struct inte
 	p_g_hr_encoder = NULL;
 	p_g_amr_decoder = NULL;
 	p_g_amr_encoder = NULL;
+	p_g_amr_cmr = 0;
+	p_g_amr_cmr_valid = 0;
 #ifdef WITH_GSMFR
 	p_g_fr_decoder = gsm_fr_create();
 	p_g_fr_encoder = gsm_fr_create();
@@ -248,7 +250,7 @@ void Pgsm::frame_receive(void *arg)
 {
 	struct gsm_data_frame *frame = (struct gsm_data_frame *)arg;
 	unsigned char data[160];
-	int i;
+	int i, cmr;
 
 	if (!p_g_fr_decoder)
 		return;
@@ -294,6 +296,30 @@ void Pgsm::frame_receive(void *arg)
 		}
 #endif
 		break;
+	case GSM_TCH_FRAME_AMR:
+		if (p_g_media_type != MEDIA_TYPE_AMR) {
+			PERROR("AMR frame, but current media type mismatches.\n");
+			return;
+		}
+		if (!p_g_amr_decoder) {
+			PERROR("AMR frame, but decoder not created.\n");
+			return;
+		}
+		cmr = (frame->data[1] >> 4);
+		if (cmr <= 7) {
+			p_g_amr_cmr = cmr;
+			p_g_amr_cmr_valid = 1;
+		}
+		if (!(frame->data[2] & 0x04))
+			goto bfi;
+#ifdef WITH_GSMAMR
+		/* decode (skip length byte in front) */
+		gsm_amr_decode(p_g_amr_decoder, frame->data + 1, p_g_samples);
+		for (i = 0; i < 160; i++) {
+			data[i] = audio_s16_to_law[p_g_samples[i] & 0xffff];
+		}
+#endif
+		break;
 	case GSM_BAD_FRAME:
 	default:
 bfi:
@@ -341,6 +367,7 @@ int Pgsm::bridge_rx(unsigned char *data, int len)
 int Pgsm::audio_send(unsigned char *data, int len)
 {
 	unsigned char frame[33];
+	int ret;
 
 	/* record data */
 	if (p_record)
@@ -386,6 +413,22 @@ int Pgsm::audio_send(unsigned char *data, int len)
 			frame_send(frame, 31, GSM_TCHF_FRAME_EFR);
 #endif
 			break;
+		case MEDIA_TYPE_AMR:
+			if (!p_g_amr_encoder) {
+				PERROR("AMR frame, but encoder not created.\n");
+				break;
+			}
+			if (!p_g_amr_cmr_valid) {
+				PDEBUG(DEBUG_GSM, "no valid CMR yet.\n");
+				break;
+			}
+#ifdef WITH_GSMAMR
+			/* encode data (prefix a length byte) */
+			ret = gsm_amr_encode(p_g_amr_encoder, p_g_rxdata, frame + 1, p_g_amr_cmr);
+			frame[0] = ret;
+			frame_send(frame, ret + 1, GSM_TCH_FRAME_AMR);
+#endif
+			break;
 		}
 	}
 
diff --git a/gsm.h b/gsm.h
index b39b005..b0b9b89 100644
--- a/gsm.h
+++ b/gsm.h
@@ -51,6 +51,7 @@ class Pgsm : public Port
 	void *p_g_fr_encoder, *p_g_fr_decoder;	/* gsm handle */
 	void *p_g_hr_encoder, *p_g_hr_decoder;	/* gsm handle */
 	void *p_g_amr_encoder, *p_g_amr_decoder;/* gsm handle */
+	int p_g_amr_cmr, p_g_amr_cmr_valid;
 	signed short p_g_rxdata[160]; /* receive audio buffer */
 	int p_g_rxpos; /* position in audio buffer 0..159 */
 	int p_g_tch_connected; /* indicates if audio is connected */
diff --git a/gsm_audio.c b/gsm_audio.c
index eabf2f5..64756c7 100644
--- a/gsm_audio.c
+++ b/gsm_audio.c
@@ -132,7 +132,7 @@ int gsm_amr_encode(void *arg, signed short *samples, unsigned char *frame, int m
 
 	frame[0] = 0xf0; /* no request */
 
-	return rv;
+	return rv + 1;
 }
 
 const unsigned short gsm690_12_2_bitorder[244] = {
-- 
2.13.6