Setting a max-height on a Bootstrap Carousel

Try this CSS and delete max-height from .carousel:

.carousel .item img {
  max-height: 768px;
  min-width: auto;
}

I added code at the bottom to override Bootstrap styles.

JSFIDDLE

if you want to maintain responsive on the width, you can use javascript/jquery.

I used jquery to maintain it's height to 50% of the width

$(function(){
    var SetCarouselHeight = function() {
        $("#myCarousel .item > img").height(function(){
            return $("#myCarousel").width() * 0.5;
        });
    }

    SetCarouselHeight();
    $(window).resize(function(){
        SetCarouselHeight();
    }); 
});