Videos: Containers, Codecs, and Protocols
Why Video Compression Makes Modern Streaming Possible
Video compression is one of the most impressive achievements in modern computing. It blends advanced mathematics, computer science, and specialized hardware to make it possible for us to watch movies, stream content, and share videos instantly across the internet.
Without compression, storing or transmitting digital video would be almost impossible due to the massive amount of raw data involved. Let’s break down how this essential technology works and why it matters so much in our everyday digital lives.
How Does Video Compression Work?
At its core, a video is simply a rapid sequence of images—usually displayed at around 24 frames per second. Without compression, even a short video would consume an enormous amount of storage and bandwidth.
Video compression algorithms solve this by identifying patterns and redundancies over time.
Imagine a video of someone running:
- The background remains mostly static.
- Only the person changes position frame by frame.
Instead of storing the entire image repeatedly, codecs detect static regions and represent them as three-dimensional blocks that stay unchanged until the scene significantly changes.
This approach dramatically reduces file size while preserving visual quality—though it requires complex mathematical operations and considerable processing power.
Anatomy of a Digital Video File
A modern digital video is not just a single stream—it’s a structured package composed of several elements:
Container
The file format that holds everything together (.mp4,.mkv,.avi,.mov, etc.)Video tracks
Visual data compressed with a specific video codecAudio tracks
Sound compressed using an audio codecSubtitles
Time-synchronized text displayed at specific moments
A single container can include multiple audio languages, subtitle tracks, or even different camera angles—all within the same file.
Codecs: The Heart of Compression
Codecs are specialized algorithms responsible for compressing and decompressing audiovisual data. Generally speaking:
The more compressed a video is, the more computational power is required to decode it in real time.
Common Video Codecs
H.264 (AVC)
The most widely used standard, governed by the MPEG‑LA consortiumH.265 (HEVC)
A more efficient successor, widely adopted on Apple devicesVP9
Developed by Google as an open alternativeAV1
A newer, highly efficient codec designed for the future of streaming
⚠️ Licensing note: H.264 is proprietary and requires licensing fees. In response, Google acquired ON2 and developed VP9, while the open‑source community created x264, a free implementation of the H.264 algorithm.
Audio Compression and Its Evolution
Audio compression follows a similar principle to image compression formats like JPG—removing sounds the human ear cannot perceive.
Common Audio Codecs
AAC
Commonly paired with H.264 in MP4 containersMP3
Universally compatible and still widely usedOpus
A modern, efficient codec optimized for streaming and real-time communication
While audiophiles may detect subtle differences, for most listeners modern high‑quality audio codecs sound virtually identical.
Video Streaming Over the Internet: Specialized Protocols
Streaming video introduces unique challenges—especially when users jump to arbitrary points in a video (e.g., skipping to minute 5 on YouTube).
To solve this, specialized streaming protocols are used:
- HLS (HTTP Live Streaming) – The most widely used today
- MPEG‑DASH – A standardized alternative
- RTMP – A legacy protocol from the Flash era
These protocols split videos into small segments, each with its own header, allowing seamless playback from any point without downloading the entire file.
Quality Adaptation and Bitrate
Modern streaming platforms constantly monitor available bandwidth and dynamically adjust video quality to prevent buffering.
It’s important to understand the difference between:
- Resolution – The number of pixels (e.g., 1080p, 720p)
- Bitrate – The amount of data transmitted per second
Despite common assumptions, resolution and bitrate are not the same thing. A 1080p video can be encoded at different bitrates, resulting in varying levels of visual quality.
Platforms like Netflix and Twitch recompress video streams in real time, adapting quality to each viewer’s network conditions.
Recommended Export Settings for Maximum Compatibility
If you want the broadest device and platform support, use:
- Container: MP4
- Video codec: H.264
- Audio codec: AAC
Subtitles
The most common subtitle formats are:
- SRT
- VTT
These are simple text files with timestamps that indicate when each subtitle line should appear.
Final Thoughts
Video compression is a constantly evolving field that has reshaped how we consume digital content. It’s the reason streaming quality keeps improving—even when our internet connections stay the same.
Have you noticed how much better streaming looks today compared to a decade ago?
Share your experience in the comments.
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