avcodec/ffv1enc: Fix explicitly set -slicecrc 2

crcref needs to be set properly iff ec is two, regardless
of whether it has been explicitly set by the user or set
by default based on level/version.

Reviewed-by: Michael Niedermayer <[email protected]>
Signed-off-by: Andreas Rheinhardt <[email protected]>

Author: mkver

libavcodec/ffv1enc.c

@@ -629,7 +629,6 @@ av_cold int ff_ffv1_encode_init(AVCodecContext *avctx)
     if (s->ec < 0) {
         if (s->version >= 4) {
             s->ec = 2;
-            s->crcref = 0x7a8c4079;
         } else if (s->version >= 3) {
             s->ec = 1;
         } else
@@ -639,8 +638,10 @@ av_cold int ff_ffv1_encode_init(AVCodecContext *avctx)
     // CRC requires version 3+
     if (s->ec == 1)
         s->version = FFMAX(s->version, 3);
-    if (s->ec == 2)
+    if (s->ec == 2) {
         s->version = FFMAX(s->version, 4);
+        s->crcref = 0x7a8c4079;
+    }
 
     if ((s->version == 2 || s->version>3) && avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
         av_log(avctx, AV_LOG_ERROR, "Version 2 or 4 needed for requested features but version 2 or 4 is experimental and not enabled\n");