What Is Video Transcoding?

Video transcoding is the process of converting a video file from one format to another, generally to meet playback requirements across devices, browsers, and network conditions.

In apps, transcoding is generally used to optimize and normalize uploaded video. These files are often large, inconsistent, or poorly optimized. Transcoding produces standardized outputs that are smaller, more compatible, and easier to deliver.

If your app accepts video uploads, transcoding is how you turn unpredictable user input into something browsers or devices can play efficiently.

Transcoding can modify several aspects of a video file:

You don't need to change all of these. Many systems simply convert whatever was uploaded into MP4 with predictable settings.

This is a common source of confusion, let's clear it up.

Encoding creates a video file from raw media, like exporting from a camera or editing software.

Transcoding converts an already encoded video into a different format or configuration.

If you convert an MOV to MP4 for browser playback, that's transcoding.

Transcoding solves four real problems:

Different browsers and OS's support different formats. MP4 + H.264 is still the safest baseline but WebM is now widely supported.

Compressed, smaller, optimized files start faster, buffer less, and cost less to deliver via CDN.

User video uploads vary widely. Transcoding normalizes format, resolution, bitrate, and playback behaviour.

Adaptive formats like HLS and DASH require multiple renditions, created through transcoding.

A user uploads a 3 minute 4K phone video:

After transcoding:

It's the same video. No discernible loss in quality, it can load fast, play everywhere, and scale cheaply.

Here's a typical pipeline:

This process runs asynchronously, because transcoding is CPU intensive and can take minutes to complete.

The pipeline can be built in house using tools like FFmpeg, or handled by a video transcoding service (managed infrastructure) that automates ingestion, format conversion, rendition generation, and storage.

Some teams run their own transcoding servers when video is core to their product and they need fine control. Most teams use a video transcoding API—it abstracts away scaling, failures, and infrastructure complexity.

Which approach makes sense depends on how central video is to your app, and how much operational overhead you're willing to own.

Note: transcoding is not streaming. It's a pre-processing step that prepares video for delivery, whether that's a single MP4 or adaptive formats like HLS.

Video transcoding is a crucial part of building any app with video. Without it, your app will be slow and many videos won't play at all.

With a transcoding pipeline, you turn arbitrary video uploads into predictable, performant video playback across web and mobile.