aacdec: Fix Sound fragments after seeking

Fixes Ticket420
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/aacdec.c

@@ -262,6 +262,23 @@ static av_cold int output_configure(AACContext *ac,
     return 0;
 }
 
+static void flush(AVCodecContext *avctx)
+{
+    AACContext *ac= avctx->priv_data;
+    int type, i, j;
+
+    for (type = 3; type >= 0; type--) {
+        for (i = 0; i < MAX_ELEM_ID; i++) {
+            ChannelElement *che = ac->che[type][i];
+            if (che) {
+                for (j = 0; j <= 1; j++) {
+                    memset(che->ch[j].saved, 0, sizeof(che->ch[j].saved));
+                }
+            }
+        }
+    }
+}
+
 /**
  * Decode an array of 4 bit element IDs, optionally interleaved with a stereo/mono switching bit.
  *
@@ -2589,4 +2606,5 @@ AVCodec ff_aac_latm_decoder = {
     },
     .capabilities = CODEC_CAP_CHANNEL_CONF,
     .channel_layouts = aac_channel_layout,
+    .flush = flush,
 };