avcodec: add Gremlin DPCM decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/codec_desc.c

@@ -2249,6 +2249,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("DPCM Squareroot-Delta-Exact"),
         .props     = AV_CODEC_PROP_LOSSY,
     },
+    {
+        .id        = AV_CODEC_ID_GREMLIN_DPCM,
+        .type      = AVMEDIA_TYPE_AUDIO,
+        .name      = "gremlin_dpcm",
+        .long_name = NULL_IF_CONFIG_SMALL("DPCM Gremlin"),
+        .props     = AV_CODEC_PROP_LOSSY,
+    },
 
     /* audio codecs */
     {