xan: make decoder independent of sizeof(AVFrame)

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/xan.c

@@ -52,7 +52,7 @@
 typedef struct XanContext {
 
     AVCodecContext *avctx;
-    AVFrame last_frame;
+    AVFrame *last_frame;
 
     const unsigned char *buf;
     int size;
@@ -71,6 +71,8 @@ typedef struct XanContext {
 
 } XanContext;
 
+static av_cold int xan_decode_end(AVCodecContext *avctx);
+
 static av_cold int xan_decode_init(AVCodecContext *avctx)
 {
     XanContext *s = avctx->priv_data;
@@ -90,7 +92,11 @@ static av_cold int xan_decode_init(AVCodecContext *avctx)
         av_freep(&s->buffer1);
         return AVERROR(ENOMEM);
     }
-    avcodec_get_frame_defaults(&s->last_frame);
+    s->last_frame = av_frame_alloc();
+    if (!s->last_frame) {
+        xan_decode_end(avctx);
+        return AVERROR(ENOMEM);
+    }
 
     return 0;
 }
@@ -234,7 +240,7 @@ static inline void xan_wc3_copy_pixel_run(XanContext *s, AVFrame *frame,
         return;
 
     palette_plane = frame->data[0];
-    prev_palette_plane = s->last_frame.data[0];
+    prev_palette_plane = s->last_frame->data[0];
     if (!prev_palette_plane)
         prev_palette_plane = palette_plane;
     stride = frame->linesize[0];
@@ -602,8 +608,8 @@ static int xan_decode_frame(AVCodecContext *avctx,
     if (xan_wc3_decode_frame(s, frame) < 0)
         return AVERROR_INVALIDDATA;
 
-    av_frame_unref(&s->last_frame);
-    if ((ret = av_frame_ref(&s->last_frame, frame)) < 0)
+    av_frame_unref(s->last_frame);
+    if ((ret = av_frame_ref(s->last_frame, frame)) < 0)
         return ret;
 
     *got_frame = 1;
@@ -616,7 +622,7 @@ static av_cold int xan_decode_end(AVCodecContext *avctx)
 {
     XanContext *s = avctx->priv_data;
 
-    av_frame_unref(&s->last_frame);
+    av_frame_free(&s->last_frame);
 
     av_freep(&s->buffer1);
     av_freep(&s->buffer2);