avcodec/arbc: clear decoder state when seeking

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/arbc.c

@@ -181,6 +181,13 @@ static av_cold int decode_init(AVCodecContext *avctx)
     return 0;
 }
 
+static void decode_flush(AVCodecContext *avctx)
+{
+    ARBCContext *s = avctx->priv_data;
+
+    av_frame_unref(s->prev_frame);
+}
+
 static av_cold int decode_close(AVCodecContext *avctx)
 {
     ARBCContext *s = avctx->priv_data;
@@ -198,6 +205,7 @@ AVCodec ff_arbc_decoder = {
     .priv_data_size = sizeof(ARBCContext),
     .init           = decode_init,
     .decode         = decode_frame,
+    .flush          = decode_flush,
     .close          = decode_close,
     .capabilities   = AV_CODEC_CAP_DR1,
     .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,