Add support for MS-GSM codec

Originally committed as revision 8039 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 63 insertions, 15 deletions

diff --git a/libavcodec/libgsm.c b/libavcodec/libgsm.c
index 7cf59be7ac..86dfce575c 100644
--- a/libavcodec/libgsm.c
+++ b/libavcodec/libgsm.c
@@ -1,6 +1,7 @@
 /*
  * Interface to libgsm for gsm encoding/decoding
  * Copyright (c) 2005 Alban Bedel <albeu@free.fr>
+ * Copyright (c) 2006, 2007 Michel Bardiaux <mbardiaux@mediaxim.be>
  *
  * This file is part of FFmpeg.
  *
@@ -24,22 +25,35 @@
  * Interface to libgsm for gsm encoding/decoding
  */
 
+// The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
+
 #include "avcodec.h"
 #include <gsm.h>
 
 // gsm.h miss some essential constants
 #define GSM_BLOCK_SIZE 33
+#define GSM_MS_BLOCK_SIZE 65
 #define GSM_FRAME_SIZE 160
 
 static int libgsm_init(AVCodecContext *avctx) {
-    if (avctx->channels > 1 || avctx->sample_rate != 8000)
+    if (avctx->channels > 1 || avctx->sample_rate != 8000 || avctx->bit_rate != 13000)
         return -1;
 
-    avctx->frame_size = GSM_FRAME_SIZE;
-    avctx->block_align = GSM_BLOCK_SIZE;
-
     avctx->priv_data = gsm_create();
 
+    switch(avctx->codec_id) {
+    case CODEC_ID_GSM:
+        avctx->frame_size = GSM_FRAME_SIZE;
+        avctx->block_align = GSM_BLOCK_SIZE;
+        break;
+    case CODEC_ID_GSM_MS: {
+        int one = 1;
+        gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
+        avctx->frame_size = 2*GSM_FRAME_SIZE;
+        avctx->block_align = GSM_MS_BLOCK_SIZE;
+        }
+    }
+
     avctx->coded_frame= avcodec_alloc_frame();
     avctx->coded_frame->key_frame= 1;
 
@@ -55,11 +69,17 @@ static int libgsm_close(AVCodecContext *avctx) {
 static int libgsm_encode_frame(AVCodecContext *avctx,
                                unsigned char *frame, int buf_size, void *data) {
     // we need a full block
-    if(buf_size < GSM_BLOCK_SIZE) return 0;
-
-    gsm_encode(avctx->priv_data,data,frame);
-
-    return GSM_BLOCK_SIZE;
+    if(buf_size < avctx->block_align) return 0;
+
+    switch(avctx->codec_id) {
+    case CODEC_ID_GSM:
+        gsm_encode(avctx->priv_data,data,frame);
+        break;
+    case CODEC_ID_GSM_MS:
+        gsm_encode(avctx->priv_data,data,frame);
+        gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
+    }
+    return avctx->block_align;
 }
 
 
@@ -73,16 +93,33 @@ AVCodec libgsm_encoder = {
     libgsm_close,
 };
 
+AVCodec libgsm_ms_encoder = {
+    "gsm",
+    CODEC_TYPE_AUDIO,
+    CODEC_ID_GSM_MS,
+    0,
+    libgsm_init,
+    libgsm_encode_frame,
+    libgsm_close,
+};
+
 static int libgsm_decode_frame(AVCodecContext *avctx,
                                void *data, int *data_size,
                                uint8_t *buf, int buf_size) {
 
-    if(buf_size < GSM_BLOCK_SIZE) return 0;
-
-    if(gsm_decode(avctx->priv_data,buf,data)) return -1;
-
-    *data_size = GSM_FRAME_SIZE*2;
-    return GSM_BLOCK_SIZE;
+    if(buf_size < avctx->block_align) return 0;
+
+    switch(avctx->codec_id) {
+    case CODEC_ID_GSM:
+        if(gsm_decode(avctx->priv_data,buf,data)) return -1;
+        *data_size = GSM_FRAME_SIZE*sizeof(int16_t);
+        break;
+    case CODEC_ID_GSM_MS:
+        if(gsm_decode(avctx->priv_data,buf,data) ||
+           gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
+        *data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
+    }
+    return avctx->block_align;
 }
 
 AVCodec libgsm_decoder = {
@@ -95,3 +132,14 @@ AVCodec libgsm_decoder = {
     libgsm_close,
     libgsm_decode_frame,
 };
+
+AVCodec libgsm_ms_decoder = {
+    "gsm_ms",
+    CODEC_TYPE_AUDIO,
+    CODEC_ID_GSM_MS,
+    0,
+    libgsm_init,
+    NULL,
+    libgsm_close,
+    libgsm_decode_frame,
+};