avcodec/ffv1enc: Check that the crc + version combination is supported

The crc flag is only stored since version 3 thus before this crcs do not
work. We increase the version as needed same as we do with pix_fmts
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/ffv1enc.c

@@ -539,6 +539,10 @@ static av_cold int encode_init(AVCodecContext *avctx)
         s->ec = (s->version >= 3);
     }
 
+    // CRC requires version 3+
+    if (s->ec)
+        s->version = FFMAX(s->version, 3);
+
     if ((s->version == 2 || s->version>3) && avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
         av_log(avctx, AV_LOG_ERROR, "Version 2 needed for requested features but version 2 is experimental and not enabled\n");
         return AVERROR_INVALIDDATA;