It wasn't too long ago when MPEG-4 compression was strictly considered a deliverable format, but many camcorders now capture moving images in this format. So what gives? Has MPEG-4 become the super hero of formats?
The format has matured quite a bit over the years with the h.264 codec, producing high quality videos at super low bit rates. That's great progress, but for us editors it can be quite a nightmare working with a processor intense codec.
What is MPEG-4?
MPEG-4 is a set of compression methods for encoding digital video and audio files. Today's most common encoding method in video production is encoding in h.264 for delivering videos on the web, such as on YouTube. The AVCHD format, which is an acquisition format that uses h.264 video encoding, is the most common MPEG-4 recording video format on camcorders. The h.264 encoding is an incredibly efficient recording format.
The Storage Strength
The advantage of working with MPEG-4 as an editor is that you are typically working with much smaller file sizes. Compare uncompressed high-definition video files which can run at gigabytes per minute to that of an AVCHD file average around 172 megabytes per minute. This savings in storage space means you won't need as much hard drive space to do long form projects. Event videographers - (weddings, music festivals, etc.) - greatly benefit from this aspect. However, the h.264 encoder requires a hefty processor to compress and decompress the digital video and audio from these files.
Small file sizes are good, but this means that editing computers will need to have faster processors. Older computers won't handle the format very well (if at all), while newer, faster processors can play back the files with relative ease. Encoding these video files (i.e. compressing the video and audio data into h.264) is always a fairly time consuming task, even for fast, multi-core processors. There's a great tool that Videomaker reviewed - by Elgato called the Turbo.264 HD (Mac only). This device plugs into a USB port and dramatically decreases the amount of time needed to compress h.264 files by taking some of the processing load off your processors. If you compress many h.264 videos for web distribution this tool is definitely worth a closer look.
It's All About Workflow
Regardless of your situation, working with MPEG-4 formats simply requires a smarter editing workflow so you can manage the challenges that come along with the format. We can take a look at some of the common MPEG-4 editing workflows for working with AVCHD intake and exporting h.264. It's important to have a good plan in place before you get started as it could save you some time and frustrations.
Native AVCHD Editing
Some video editing applications can work with AVCHD natively. This is ideal if you want to get to editing quickly. Although, typically this can bog down the performance of your computer if you're editing complex sequences. For example, a 30-second commercial that has multiple layers of videos and effects would not be ideal in a native AVCHD timeline. If you're doing simpler editing work, using a native format won't slow you down. You'll be able to quickly import the AVCHD file and start making edits immediately. Since so many camcorders these days record to hard drives, native AVCHD editing is the simplest, quickest way to get the files onto the timeline. For editors who are in a hurry to get a video edited and delivered, this could be the best workflow. But with the limitations, more creative editors find that transcoding these files provides a better editing experience.
Editors who want to do more complex effects should transcode the AVCHD video files into a more edit-friendly format. Most video editors have a way to log and transfer AVCHD files to another video format that the timeline can handle more easily. Apple's Final Cut Pro uses it's own ProRes file format that dramatically increases the file size. The trade off here is that you'll first need to have plenty of hard drive space and give your computer plenty of time to transcode the files before you can even start editing. Obviously, if you're in a rush to get the video out the door, this won't likely be an ideal workflow. But, for editors who want to make use of many different effects, such as color correction, this workflow is better in the end.
So editors working with MPEG-4, specifically h.264, will need to either simplify the editing style or be patient (and have plenty of hard drive space available). And this is just the beginning. Once you've finished the edit, some editors will also want to export the video in an MPEG-4 format.
MPEG-4 For Delivery
No matter what your previous workflow, exporting MPEG-4 will always take time. There's no magical shortcuts, although we did mention the Turbo.264 HD device which is very impressive in reducing the time needed for h.264 encoding. Of all the MPEG-4 varieties, the h.264 codec is the most difficult and therefore time consuming to compress. It's a good idea to run a quick test if you're not sure what to expect. For example, you may try to export just five minutes of your project to see how long it takes. This can be a useful gauge, however, different parts of your project may take more or less time depending on the nature of the editing, so don't bank on your test to be exact.
The MPEG-4 format is a great technical achievement for video compression. It's one of the most efficient ways to save high quality video and audio into a small file size. With a good idea of what your editing needs are, you can create a workflow plan that makes the most of your resources and time. Happy editing!
Contributing columnist Mark Montgomery is a web content specialist and produces instructional videos for a leading web application developer.