To reduce the size of a PowerPoint 2013 presentation file that contains media, you can follow these steps:

1. Compress Images: PowerPoint allows you to compress the images in your presentation to reduce their file size. Here’s how to do it:
   • Open your PowerPoint presentation.
   • Select the image you want to compress.
   • Go to the Picture Tools Format tab that appears when you select the image.
   • Click on the Compress Pictures option in the Adjust group.
   • In the Compress Pictures dialog box, choose the options that suit your needs. You can choose to compress all pictures in the presentation or only the selected ones. You can also specify the resolution you want for the compressed images.
   • Click on the OK button to compress the images.

   By compressing the images, you can significantly reduce the file size of your presentation.

2. Remove Unnecessary Media: Review your presentation and remove any media files (images, videos, audio) that are not essential. Sometimes, large media files can greatly increase the file size of your presentation. Consider removing or replacing them with smaller alternatives or using online media hosting services to link to the media instead of embedding it.
3. Optimize Audio and Video Files: If your presentation contains audio or video files, you can optimize them for size. To do this:
   • Select the audio or video file in your presentation.
   • Go to the Playback tab that appears when you select the media file.
   • Click on the Compress Media option in the Video Options or Audio Options group.
   • Choose the quality and resolution options that suit your needs.
   • Click on the OK button to compress the media file.

   Compressing audio and video files can significantly reduce their size without compromising the overall quality too much.

4. Remove Hidden Data: PowerPoint may store unnecessary data and information in your presentation, which increases its file size. To remove hidden data, do the following:
   • Go to the File tab and click on Options.
   • In the Options dialog box, go to the Save category.
   • Under the Preserve fidelity when sharing this presentation section, check the box that says Discard editing data.
   • Click on the OK button to save the changes.

   This will remove any hidden data and reduce the file size of your presentation.

5. Save the Presentation: After implementing the above steps, save your presentation. You should notice a reduction in the file size.

By following these steps, you can effectively reduce the size of your PowerPoint 2013 presentation file while still retaining the essential content and media.