Index: libavformat/swfenc.c
===================================================================
--- libavformat/swfenc.c	(revision 22880)
+++ libavformat/swfenc.c	(working copy)
@@ -478,6 +478,7 @@
     int file_size, i;
 
     video_enc = NULL;
+    enc = NULL;
     for(i=0;i<s->nb_streams;i++) {
         enc = s->streams[i]->codec;
         if (enc->codec_type == AVMEDIA_TYPE_VIDEO)
@@ -491,15 +492,25 @@
 
     put_flush_packet(s->pb);
 
-    /* patch file size and number of frames if not streamed */
-    if (!url_is_streamed(s->pb) && video_enc) {
+    /* patch file size and number of frames if not streamed (ie, we can perform fseek operations) */
+    if (!url_is_streamed(s->pb)) {
+
+        /* Set correct File Size, replacing dummy file size */
         file_size = url_ftell(pb);
         url_fseek(pb, 4, SEEK_SET);
         put_le32(pb, file_size);
+
+        if (video_enc) {
         url_fseek(pb, swf->duration_pos, SEEK_SET);
         put_le16(pb, swf->video_frame_number);
         url_fseek(pb, swf->vframes_pos, SEEK_SET);
         put_le16(pb, swf->video_frame_number);
+        } else if (enc) { /* Audio */
+          url_fseek(pb, swf->duration_pos, SEEK_SET);
+          put_le16(pb, swf->swf_frame_number); /* Frame Count */
+        }
+
+        /* reset seek pointer (FIXME: why?) */
         url_fseek(pb, file_size, SEEK_SET);
     }
     return 0;