XML tag count in PHP

<videos>
    <video>
        <title1>Title1</title1>
        <title2>Title2</title2>
        <title3>Title3</title3>
        <title4>Title4</title4>
        <desc> desc</desc>
        <img> img</img>
    </video>
    <video>
        <title1>Title1</title1>
        <title2>Title2</title2>
        <title3>Title3</title3>
        <desc> desc</desc>
        <img> img</img>
    </video>

    <video>
        <title1>Title1</title1>
        <title2>Title2</title2>
        <title3>Title3</title3> 
        <title4>Title3</title4> 
        <title5>Title3</title5>
        <desc> desc</desc>
        <img> img</img>
    </video>
</videos>

I have this type of xml. I want to count titles into one video tag.

also want to create text slide show. How can i do it?

Thanks for help.