5.1 to Stereo Converter: Downmix Online in Your Browser

Have you ever noticed that when you play a movie file on your computer, the sound it produces is just different: explosions are so loud they rattle your teeth, the dialog between actors is way too quiet, and the mix just sounds too spacious and off. That's because the movie contains a surround sound audio track, for example a 5.1 track. And your laptop or headphones only have two speakers in them: so the video player renders the track down to stereo. And this is where fidelity could get lost.

You see, it's not your speakers letting you down. And this gave us a reason to develop a new tool in our arsenal: an online downmix tool that runs right in your browser, without having to install any software!

A summary about downmixing

Let's take you on a small detour to see what downmixing actually is, and how you can tweak things around to improve sound quality. If you guessed that 5.1 audio is six channels instead of the usual 2 channels for stereo, you would be totally right. However, your video player automatically converts the 6 channels down to 2 channel. This however means that the audio player decides on what channels are louder than other channels. This process is called downmixing.

This process can be done on two sides: either automatically by your video player, or manually by a piece of software. Our Online Downmix tool takes a different approach: instead of having to install software on your computer, this tool runs completely online and inside of your browser. This means that none of your video files get sent to a server, protecting your privacy while you enjoy software that just works!

What matters the most in downmixing

The real issue when you are playing back a downmixed track is that all channels should be properly balanced. A surround track has the usual front left and front right channels which form a stereo track as well, but a six channel surround mix also contains surround left and right channels to represent sound coming from the back. And don't forget the subwoofer channel which is responsible for giving explosions in movies that extra punch. The center channel is the last channel and responsible for dialogs and is in my opinion the most important channel when downmixing.

When using our tool, you get to choose whether you want to keep the original 5.1 sound track, or if you want to remove it. When the stereo track gets created, you as the user can choose what codec and bitrate you want to use.

Now even though we currently (as of writing this article) only support automatic downmixing, we do plan on adding manual control to sound levels in a later stage. Stay tuned for more updates!