ffmpeg: copy color properties in case of -c:v copy.

I have no idea why the first hunk uses ost->enc_ctx, because as far as
I understand, that is never used in case of -c:v copy, but this code
block is only entered if encoding_needed=0, which means stream_copy=1.
My point being: review from someone that knows this really well would
be appreciated.

ffmpeg.c

@@ -2678,7 +2678,7 @@ static int init_output_stream(OutputStream *ost, char *error, int error_len)
         ost->st->time_base = av_add_q(ost->enc_ctx->time_base, (AVRational){0, 1});
         ost->st->codec->codec= ost->enc_ctx->codec;
     } else {
-        ret = av_opt_set_dict(ost->enc_ctx, &ost->encoder_opts);
+        ret = av_opt_set_dict(ost->st->codec, &ost->encoder_opts);
         if (ret < 0) {
            av_log(NULL, AV_LOG_FATAL,
                   "Error setting up codec context options.\n");
@@ -3011,6 +3011,10 @@ static int transcode_init(void)
                 break;
             case AVMEDIA_TYPE_VIDEO:
                 enc_ctx->pix_fmt            = dec_ctx->pix_fmt;
+                enc_ctx->colorspace         = dec_ctx->colorspace;
+                enc_ctx->color_range        = dec_ctx->color_range;
+                enc_ctx->color_primaries    = dec_ctx->color_primaries;
+                enc_ctx->color_trc          = dec_ctx->color_trc;
                 enc_ctx->width              = dec_ctx->width;
                 enc_ctx->height             = dec_ctx->height;
                 enc_ctx->has_b_frames       = dec_ctx->has_b_frames;