avcodec/jpeg2000dec: move cdef default check into get_siz()

This way cdef is at its final value earlier

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/jpeg2000dec.c

@@ -271,6 +271,17 @@ static int get_siz(Jpeg2000DecoderContext *s)
         return AVERROR_INVALIDDATA;
     }
 
+    for (i = 0; i < s->ncomponents; i++) {
+        if (s->cdef[i] < 0) {
+            for (i = 0; i < s->ncomponents; i++) {
+                s->cdef[i] = i + 1;
+            }
+            if ((s->ncomponents & 1) == 0)
+                s->cdef[s->ncomponents-1] = 0;
+        }
+    }
+    // after here we no longer have to consider negative cdef
+
     for (i = 0; i < s->ncomponents; i++) { // Ssiz_i XRsiz_i, YRsiz_i
         uint8_t x    = bytestream2_get_byteu(&s->g);
         s->cbps[i]   = (x & 0x7f) + 1;
@@ -2885,17 +2896,6 @@ static int jpeg2000_decode_frame(AVCodecContext *avctx, AVFrame *picture,
     if (ret = jpeg2000_read_bitstream_packets(s))
         goto end;
 
-    for (int x = 0; x < s->ncomponents; x++) {
-        if (s->cdef[x] < 0) {
-            for (x = 0; x < s->ncomponents; x++) {
-                s->cdef[x] = x + 1;
-            }
-            if ((s->ncomponents & 1) == 0)
-                s->cdef[s->ncomponents-1] = 0;
-            break;
-        }
-    }
-
     for (int x = 0; x < s->ncomponents && s->codsty[x].transform == FF_DWT53;)
         if (++x == s->ncomponents)
             picture->flags |= AV_FRAME_FLAG_LOSSLESS;