s->avctx->time_base.den *= 2;
av_reduce(&s->avctx->time_base.num, &s->avctx->time_base.den,
s->avctx->time_base.num, s->avctx->time_base.den, 1<<30);
s->avctx->time_base.den *= 2;
av_reduce(&s->avctx->time_base.num, &s->avctx->time_base.den,
s->avctx->time_base.num, s->avctx->time_base.den, 1<<30);