libavdevice/audio.c:293: error: Uninitialized Value
  The value read from ret was never initialized.

libavdevice/audio.c:293:21: 
291.         short *p = (short *) pkt->data;
292. 
293.         for (i = 0; i < ret; i += 4) {
                         ^
294.             *p = ~*p;
295.             p += 2;
