ffplay: Separate AVFrame from AVSubtitle

This is more robust and should avoid false positives in coverity
That is if the type is ever mixed up, after this patch that would
just be a null pointer dereference instead of a random possibly
out of array access
Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffplay.c

@@ -546,9 +546,8 @@ static void decoder_init(Decoder *d, AVCodecContext *avctx, PacketQueue *queue,
     d->start_pts = AV_NOPTS_VALUE;
 }
 
-static int decoder_decode_frame(Decoder *d, void *fframe) {
+static int decoder_decode_frame(Decoder *d, AVFrame *frame, AVSubtitle *sub) {
     int got_frame = 0;
-    AVFrame *frame = fframe;
 
     d->flushed = 0;
 
@@ -608,7 +607,7 @@ static int decoder_decode_frame(Decoder *d, void *fframe) {
                 }
                 break;
             case AVMEDIA_TYPE_SUBTITLE:
-                ret = avcodec_decode_subtitle2(d->avctx, fframe, &got_frame, &d->pkt_temp);
+                ret = avcodec_decode_subtitle2(d->avctx, sub, &got_frame, &d->pkt_temp);
                 break;
         }
 
@@ -1863,7 +1862,7 @@ static int get_video_frame(VideoState *is, AVFrame *frame)
 {
     int got_picture;
 
-    if ((got_picture = decoder_decode_frame(&is->viddec, frame)) < 0)
+    if ((got_picture = decoder_decode_frame(&is->viddec, frame, NULL)) < 0)
         return -1;
 
     if (got_picture) {
@@ -2219,7 +2218,7 @@ static int subtitle_thread(void *arg)
         if (!(sp = frame_queue_peek_writable(&is->subpq)))
             return 0;
 
-        if ((got_subtitle = decoder_decode_frame(&is->subdec, &sp->sub)) < 0)
+        if ((got_subtitle = decoder_decode_frame(&is->subdec, NULL, &sp->sub)) < 0)
             break;
 
         pts = 0;
@@ -2483,7 +2482,7 @@ static int audio_decode_frame(VideoState *is)
             return resampled_data_size;
         }
 
-        if ((got_frame = decoder_decode_frame(&is->auddec, is->frame)) < 0)
+        if ((got_frame = decoder_decode_frame(&is->auddec, is->frame, NULL)) < 0)
             return -1;
 
         if (is->auddec.flushed)