avcodec/fmvc: Move frame allocation to a later stage

This way more things are checked before allocation
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/fmvc.c

@@ -400,20 +400,17 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
     GetByteContext *gb = &s->gb;
     PutByteContext *pb = &s->pb;
     int ret, y, x;
+    int key_frame;
 
     if (avpkt->size < 8)
         return AVERROR_INVALIDDATA;
 
-    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
-        return ret;
-
     bytestream2_init(gb, avpkt->data, avpkt->size);
     bytestream2_skip(gb, 2);
 
-    frame->key_frame = !!bytestream2_get_le16(gb);
-    frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
+    key_frame = !!bytestream2_get_le16(gb);
 
-    if (frame->key_frame) {
+    if (key_frame) {
         const uint8_t *src;
         unsigned type, size;
         uint8_t *dst;
@@ -433,6 +430,12 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
             return AVERROR_PATCHWELCOME;
         }
 
+        if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+            return ret;
+
+        frame->key_frame = 1;
+        frame->pict_type = AV_PICTURE_TYPE_I;
+
         src = s->buffer;
         dst = frame->data[0] + (avctx->height - 1) * frame->linesize[0];
         for (y = 0; y < avctx->height; y++) {
@@ -513,6 +516,12 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
             dst = &rect[block_h * s->stride];
         }
 
+        if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+            return ret;
+
+        frame->key_frame = 0;
+        frame->pict_type = AV_PICTURE_TYPE_P;
+
         ssrc = s->buffer;
         ddst = frame->data[0] + (avctx->height - 1) * frame->linesize[0];
         for (y = 0; y < avctx->height; y++) {