Fundamentals

Transmuxing vs. Transcoding – Everything You Need to Know

transmuxing vs. transcoding - everything you want to know

Transmuxing is the process of changing the format of a digital file without altering the actual content. This article reveals the fundamentals of transmuxing, explains how it streamlines video delivery across devices without altering the content itself. 

Videos come in a large array of formats, and what plays flawlessly on your phone might stutter and crash on your smart TV – not to mention your Xbox! This is not a new problem, and ensuring compatibility between different file formats and devices is truly a harrowing experience for anyone!

But don’t worry. There are heroes in the video conversion and processing world: transmuxing and transcoding that can help solve the compatibility problems between devices and formats.

In this article, we will look at the basics of transmuxing, how it works, and the difference between transcoding and transmuxing (since that is a source of a lot of confusion in the streaming industry!)

A good idea of transmuxing can make your life very easy when faced with a dazzling array of file formats and specifications!

Let’s go!

What is Transmuxing?

Before we dive into transmuxing, let us understand the main parts of a video file.

A video file consists of two key parts:

  1. the data itself (video and audio)
  2. and the container format.

The container format is like a digital wrapper around the audio/video, and it instructs devices and players on how to interpret the data within (video, audio, metadata) and how to play back the content.

Now, let’s understand what transmuxing is!

Transmuxing, a portmanteau of ‘transport’ and ‘multiplexing’, is the process of changing the format of a digital file without altering the actual content.

Imagine you have a video file that you want to play on different devices. Each device may require a different container format to play the video correctly. Transmuxing takes the original video and audio streams and repackages them into various containers, such as MP4, MKV, or WebM, ensuring compatibility across different platforms and devices.

Simple, right?!

But why is transmuxing required in the first place?

Why is Transmuxing Important?

Well, the main purpose of transmuxing is to change the container format of a multimedia file to make it compatible with different media players, devices, or applications that may only support specific container formats.

For example, if you have a video player that cannot play MKV files and only supports MP4 files, then you can use a transmuxer or a transmuxing service to convert the MKV file to MP4 (without affecting the audio and video) and use the MP4 file to watch the video!

transmuxing vs. transcoding explained
Transmuxing can solve a lot of interoperability problems!

How does Transmuxing Work?

While seemingly simple, transmuxing involves some technical wizardry. Here’s a simplified breakdown:

  1. Unpacking: The transmuxer first unpacks the video file. It extracts the video and audio streams from their original containers.
  2. Re-packaging: The magic happens here. The transmuxer takes the extracted video and audio streams and places them into the new container format.
  3. Delivery: The newly packaged video file is then delivered to the target device or platform, ready for playback.

So, when someone says that they transmuxed a video from MP4 to the MOV format, it means that they extracted the compressed video, audio, and other metadata from the MP4 container and transferred it into the MOV container format, without re-encoding or transcoding the media streams.

Transmuxing vs. Transcoding: What's the Difference?

People generally get confused with the two words – transcoding and transmuxing because they sound similar, but they are very different!

Transcoding involves a more comprehensive transformation of the media file. It’s not just about changing the container but also converting the video and audio streams to different codecs, bitrates, resolutions, or formats. This process is necessary when the target device does not support the original video codec (what is a video codec?) or when there’s a need to compress the file to a smaller size for delivery over poor networks.

Unlike transmuxing, transcoding is a resource-intensive process.

Transcoding requires significant computational power and time and the use of specialized video codecs (like H.264/AVC, HEVC, AV1, etc.) and audio codecs (like MP3, WAV, AAC, etc.) as it decodes the original streams and re-encodes them into the new format according to the new requirements. The re-encoding process often results in a loss of quality (the extent depends on the configuration), which is why transcoding is only used when necessary.

A simple example of transcoding is when a video must be prepared for delivery over the Internet using ABR streaming. Here, the original video (e.g., a 1920×1080 file at 25 mbps) is transcoded to multiple profiles, such as

  • 1920x1080p at 5mbps using H.264/AVC
  • 1920x1080p at 3mbps using HEVC
  • 1280x720p at 3mbps using H.264/AVC
  • 960x540p at 1.5mbps using H.264/AVC

As you can see, during the transcoding process, we are varying the resolution of the video, its bitrate, and the codec it uses. And, depending on the encoding configuration, this process can take several hours!

We hope its clear that transcoding is completely different from transmuxing (which simply takes the audio and video and places it into a new container format).

Transmuxing vs. Transcoding: When to Use Which?

Transmuxing and transcoding, though sometimes confused, are distinct processes. Here’s how to choose the right tool for the job, and remember, the decision on when to use transmuxing or transcoding depends largely on the requirements of the task at hand.

  • Use transmuxing when you need to deliver a video in a different container format while maintaining compatibility with various devices.
    • Example: You have a video in MP4 format, but your website requires MOV files for playback. Transmuxing can effortlessly convert it.
  • Use transcoding when you need to modify the video or audio data itself. This could involve:
    • Changing the resolution (e.g., from HD to SD for mobile viewing).
    • Reducing the bitrate (file size) for smoother streaming on slower internet connections.
    • Converting the audio codec (e.g., from AAC to Dolby Digital) for compatibility with specific devices.

The beauty of transmuxing lies in its efficiency. Since the content itself isn’t being changed—only the ‘wrapper’ around it—the process is swift and preserves the original quality.

Finally!

Transmuxing is an important process in the world of digital media for the seamless transfer of content across different platforms and devices. It is quicker and less resource-heavy, and by grasping the nuances of transmuxing and its differences from transcoding, content creators and distributors can make informed decisions that optimize their workflows and enhance the end-user experience.

Visionular’s AuroraCloud helps you avoid all the confusions around transcoding and transmuxing by taking on the heavy lifting and giving you a simple and intuitive interface for video transcoding and delivery.

Powered by the fastest and most efficient H.264/AVC, H.265/HEVC, and AV1 encoders (driven by AI), you can rest assured that your transcoding workflow will never be the same again with AuroraCloud.