diff --git a/libavcodec/aasc.c b/libavcodec/aasc.c
index a136360572..1e4264296d 100644
--- a/libavcodec/aasc.c
+++ b/libavcodec/aasc.c
@@ -68,6 +68,12 @@ static int aasc_decode_frame(AVCodecContext *avctx,
     compr = AV_RL32(buf);
     buf += 4;
     buf_size -= 4;
+    switch (avctx->codec_tag) {
+    case MKTAG('A', 'A', 'S', '4'):
+        bytestream2_init(&s->gb, buf - 4, buf_size + 4);
+        ff_msrle_decode(avctx, (AVPicture*)&s->frame, 8, &s->gb);
+        break;
+    case MKTAG('A', 'A', 'S', 'C'):
     switch(compr){
     case 0:
         stride = (avctx->width * 3 + 3) & ~3;
@@ -89,6 +95,11 @@ static int aasc_decode_frame(AVCodecContext *avctx,
         av_log(avctx, AV_LOG_ERROR, "Unknown compression type %d\n", compr);
         return -1;
     }
+        break;
+    default:
+        av_log(avctx, AV_LOG_ERROR, "Unknown FourCC: %X\n", avctx->codec_tag);
+        return -1;
+    }
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = s->frame;
diff --git a/libavformat/riff.c b/libavformat/riff.c
index ad99ebe1c9..fb3e8ac9dd 100644
--- a/libavformat/riff.c
+++ b/libavformat/riff.c
@@ -260,6 +260,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     { CODEC_ID_VC1IMAGE,     MKTAG('W', 'V', 'P', '2') },
     { CODEC_ID_LOCO,         MKTAG('L', 'O', 'C', 'O') },
     { CODEC_ID_WNV1,         MKTAG('W', 'N', 'V', '1') },
+    { CODEC_ID_AASC,         MKTAG('A', 'A', 'S', '4') },
     { CODEC_ID_AASC,         MKTAG('A', 'A', 'S', 'C') },
     { CODEC_ID_INDEO2,       MKTAG('R', 'T', '2', '1') },
     { CODEC_ID_FRAPS,        MKTAG('F', 'P', 'S', '1') },