diff --git a/libavcodec/libopencore-amr.c b/libavcodec/libopencore-amr.c
index c8b3a2c1bc..cf8bdbbcb8 100644
--- a/libavcodec/libopencore-amr.c
+++ b/libavcodec/libopencore-amr.c
@@ -21,6 +21,7 @@
 
 #include "avcodec.h"
 #include "libavutil/avstring.h"
+#include "libavutil/opt.h"
 
 static void amr_decode_fix_avctx(AVCodecContext *avctx)
 {
@@ -77,13 +78,24 @@ static int get_bitrate_mode(int bitrate, void *log_ctx)
 }
 
 typedef struct AMRContext {
+    AVClass *av_class;
     int   frame_count;
     void *dec_state;
     void *enc_state;
     int   enc_bitrate;
     int   enc_mode;
+    int   enc_dtx;
 } AMRContext;
 
+static const AVOption options[] = {
+    { "dtx", "Allow DTX (generate comfort noise)", offsetof(AMRContext, enc_dtx), FF_OPT_TYPE_INT, 0, 0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
+    { NULL }
+};
+
+static const AVClass class = {
+    "libopencore_amrnb", av_default_item_name, options, LIBAVUTIL_VERSION_INT
+};
+
 static av_cold int amr_nb_decode_init(AVCodecContext *avctx)
 {
     AMRContext *s  = avctx->priv_data;
@@ -176,7 +188,7 @@ static av_cold int amr_nb_encode_init(AVCodecContext *avctx)
     avctx->frame_size  = 160;
     avctx->coded_frame = avcodec_alloc_frame();
 
-    s->enc_state = Encoder_Interface_init(0);
+    s->enc_state = Encoder_Interface_init(s->enc_dtx);
     if (!s->enc_state) {
         av_log(avctx, AV_LOG_ERROR, "Encoder_Interface_init error\n");
         return -1;
@@ -228,6 +240,7 @@ AVCodec ff_libopencore_amrnb_encoder = {
     NULL,
     .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
     .long_name = NULL_IF_CONFIG_SMALL("OpenCORE Adaptive Multi-Rate (AMR) Narrow-Band"),
+    .priv_class = &class,
 };
 
 #endif
diff --git a/libavcodec/libvo-amrwbenc.c b/libavcodec/libvo-amrwbenc.c
index d3db5f847a..d8a6099561 100644
--- a/libavcodec/libvo-amrwbenc.c
+++ b/libavcodec/libvo-amrwbenc.c
@@ -23,14 +23,25 @@
 
 #include "avcodec.h"
 #include "libavutil/avstring.h"
+#include "libavutil/opt.h"
 
 typedef struct AMRWBContext {
+    AVClass *av_class;
     void  *state;
     int    mode;
     int    last_bitrate;
     int    allow_dtx;
 } AMRWBContext;
 
+static const AVOption options[] = {
+    { "dtx", "Allow DTX (generate comfort noise)", offsetof(AMRWBContext, allow_dtx), FF_OPT_TYPE_INT, 0, 0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
+    { NULL }
+};
+
+static const AVClass class = {
+    "libvo_amrwbenc", av_default_item_name, options, LIBAVUTIL_VERSION_INT
+};
+
 static int get_wb_bitrate_mode(int bitrate, void *log_ctx)
 {
     /* make the correspondance between bitrate and mode */
@@ -78,7 +89,6 @@ static av_cold int amr_wb_encode_init(AVCodecContext *avctx)
     avctx->coded_frame = avcodec_alloc_frame();
 
     s->state     = E_IF_init();
-    s->allow_dtx = 0;
 
     return 0;
 }
@@ -119,5 +129,6 @@ AVCodec ff_libvo_amrwbenc_encoder = {
     .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
     .long_name = NULL_IF_CONFIG_SMALL("Android VisualOn Adaptive Multi-Rate "
                                       "(AMR) Wide-Band"),
+    .priv_class = &class,
 };