Merge commit 'dc71f1958846bb1d96de43a4603983dc8450cfcc'

* commit 'dc71f1958846bb1d96de43a4603983dc8450cfcc':
  video4linux2: Avoid a floating point exception

Merged-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg_opt.c

@@ -2166,7 +2166,8 @@ static int opt_target(void *optctx, const char *opt, const char *arg)
             for (j = 0; j < nb_input_files; j++) {
                 for (i = 0; i < input_files[j]->nb_streams; i++) {
                     AVCodecContext *c = input_files[j]->ctx->streams[i]->codec;
-                    if (c->codec_type != AVMEDIA_TYPE_VIDEO)
+                    if (c->codec_type != AVMEDIA_TYPE_VIDEO ||
+                        !c->time_base.num)
                         continue;
                     fr = c->time_base.den * 1000 / c->time_base.num;
                     if (fr == 25000) {