avcodec/dca: fix sync word search error condition

This didn't actually check if sync word was found and always errored out
with "-err_detect explode" option enabled.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit ce2f9fdb0a)

libavcodec/dca_core.c

@@ -1900,9 +1900,10 @@ static int parse_optional_info(DCACoreDecoder *s)
                 }
             }
 
-            if (s->avctx->err_recognition & AV_EF_EXPLODE) {
+            if (!s->xch_pos) {
                 av_log(s->avctx, AV_LOG_ERROR, "XCH sync word not found\n");
-                return AVERROR_INVALIDDATA;
+                if (s->avctx->err_recognition & AV_EF_EXPLODE)
+                    return AVERROR_INVALIDDATA;
             }
             break;
 
@@ -1922,9 +1923,10 @@ static int parse_optional_info(DCACoreDecoder *s)
                 }
             }
 
-            if (s->avctx->err_recognition & AV_EF_EXPLODE) {
+            if (!s->x96_pos) {
                 av_log(s->avctx, AV_LOG_ERROR, "X96 sync word not found\n");
-                return AVERROR_INVALIDDATA;
+                if (s->avctx->err_recognition & AV_EF_EXPLODE)
+                    return AVERROR_INVALIDDATA;
             }
             break;
 
@@ -1947,9 +1949,10 @@ static int parse_optional_info(DCACoreDecoder *s)
                 }
             }
 
-            if (s->avctx->err_recognition & AV_EF_EXPLODE) {
+            if (!s->xxch_pos) {
                 av_log(s->avctx, AV_LOG_ERROR, "XXCH sync word not found\n");
-                return AVERROR_INVALIDDATA;
+                if (s->avctx->err_recognition & AV_EF_EXPLODE)
+                    return AVERROR_INVALIDDATA;
             }
             break;
         }