av1: Add codec_id and basic demuxing support

Signed-off-by: Diego Biurrun <diego@biurrun.de>

libavcodec/codec_desc.c

@@ -1205,6 +1205,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("Duck TrueMotion 2.0 Real Time"),
         .props     = AV_CODEC_PROP_LOSSY,
     },
+    {
+        .id        = AV_CODEC_ID_AV1,
+        .type      = AVMEDIA_TYPE_VIDEO,
+        .name      = "av1",
+        .long_name = NULL_IF_CONFIG_SMALL("Alliance for Open Media AV1"),
+        .props     = AV_CODEC_PROP_LOSSY,
+    },
 
     /* image codecs */
     {