How to Reduce the Size of Video Files

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Large video files can fill your hard drive in a big hurry, especially in today’s age of high-definition content. If you create and edit your own videos, you may have noticed hot large files can become when dealing with certain codecs and settings. With audio, reducing the file size can be a simple manor of selecting a lossy file format and setting a bitrate. Unfortunately, understanding how to reduce the size of video files can be quite a bit more complicated than with audio alone.

There is a large and understandable amount of confusion among amateur video content creators surrounding what the difference is between a codec and a container. Knowing how these work and what advantages different components give you can be a big help towards understanding how to shrink a video file without sacrificing a large amount of quality.

The most obvious part of a video file is the container (otherwise known as a wrapper) which holds the information of both the video and audio components in a single file. You can easily determine what wrapper you’re working with by checking the file type of your video. If the file has a .MOV at the end of it, you’re likely working with a QuickTime Movie wrapper.

Even though it is the most obvious indicator of the file type, it actually has very little bearing on overall video quality. You can have lossless video inside the same container type as an incredibly lossy one. Not all container formats are created equal. Some allow for features such as menus, captions, 3D, streaming, and more while others may not. When deciding which wrapper to use, first make sure it is compatible with everything you want to put in to it.

An audio or video codec, simply put, is a device or software that allows you to compress and/or decompress digital content. The codec you decide to use and the settings you pair it to will have a more direct result on the quality and size of the resulting video file than anything else. A good current video codec to use for compression is H.264, which works well with some of the most popular container formats out there.

Another major factor in video file size is the bitrate. Simply put, overall quality generally improves with higher bitrates. Unfortunately, so does file size. Imagine that each second of video represents a single folder, and contained inside that folder is 24, 30, or even 60 images. Setting a bitrate on your video essentially determines how much data that folder can contain. If you set the bitrate at 1000 kbits/sec, each image in that folder (second of video) gets a portion of that 1000. You may want to do a few experiments to determine which settings work best with your source video and encoding software.

A higher rate of frames per second means your video will require a larger file to maintain the same level of quality as a video with less. Even though 60 frames per second may look great on paper, it can become a nightmare if you have limited storage space for your video files. Typically, digital video is sent out at either 24 or 30 frames per second. One important thing to remember is that any alterations of the frame rates on your source footage can create unreliable results when rendered. This is one setting that is better off left alone, unless you have a very good understanding of how video encoding works.

Digital video is an incredibly complicated subject to master. Thankfully, there are plenty of programs out there that do the bulk of the calculations for you. iMovie on the Mac and Movie Maker on Windows are two steller video editing programs that have solid presets available for export to help save space without sacrificing a large amount of quality. There are also many video converters on the market including Handbrake, Virtual Dub, and Miro Video Converter which can take source video with many different formats and convert them in to smaller, more manageable files.