Written by: Techub News

In Lex Fridman's podcast, core developers of FFmpeg and VLC delved into these two open-source projects that essentially support the entire digital video world. This conversation not only unveiled the technical principles behind them but also touched on open-source philosophy, community collaboration, and how they have thoroughly democratized video creation and distribution, reshaping the media ecology from individuals to giants.

The Ubiquitous "Video Language": What is FFmpeg?

FFmpeg is essentially a set of low-level libraries and tools for multimedia processing. Its core functions include encoding and decoding (compression and decompression), multiplexing and demultiplexing (mux/demux), and filter processing. Based on this, it provides a series of command-line tools that allow users to construct "pipes" to process any video file.

Developers emphasize that FFmpeg is embedded in almost every video-related application you can think of: from the VLC player to the Chrome browser, from smart TVs to online streaming platforms. When you watch a YouTube video, both the client and server are likely using FFmpeg. Recording a live stream with OBS? It's also powered by FFmpeg. Many professional-grade large video processing devices may also have FFmpeg running inside.

From a philosophical perspective, this creates a remarkable equal playing field: your grandmother's home video and the streaming content of trillion-dollar companies are using essentially the same technology stack. These large companies may just be running FFmpeg commands that span up to 3000 lines, or calling its API. The command-line tool `ffmpeg` is legendary because it offers an immense number of parameters, allowing users to customize everything. "It is a language, a true programming language," developers describe it. There are even numerous users starting to generate complex FFmpeg command lines with the help of AI because of the rich filters and operations it can achieve.

In contrast to the image processing field, there is a lack of a tool on the command line as comprehensive and widely applicable as FFmpeg (ImageMagick is similar, but not as complex). FFmpeg allows you to achieve complex video effects like Adobe After Effects in the command line, including adding intros and outros, fading between videos (dip to black), audio cross dissolves, hard coding subtitles with custom fonts, conducting various audio and video layer overlays, etc. All of this magically supports almost all codec formats.

Open Source and Community: A "Movement" Empowering Individuals Worldwide

FFmpeg and VLC share a vision: to make technically extremely complex things easy for ordinary people, everyone to use. Users simply drag files into VLC for playback or input anything with complex filters into FFmpeg, and they work "magically," without the user needing to perceive the underlying complexities.

It is these kinds of tools that democratize the podcasting, streaming, and YouTube revolutions. Developers recall that in the 1990s, you needed equipment worth hundreds of thousands of dollars, the size of a car, to compress videos. Today, almost everyone is at the same technological starting line. This has empowered countless people to have a voice, marking a true "movement."

The core of this movement is open source. Developers used a vivid metaphor to explain open source: normally you buy a cheesecake, and the bakery gives you the finished product. Open source gives you the cake, along with the recipe, tells you how to build the oven, and lets you modify the recipe and resell to others. Software is an ultra-long recipe made up of countless small instructions. The open-source software industry gives you all of this.

Since its inception, about 2000 to 3000 people have contributed code to FFmpeg. It is like the Linux kernel, where developers around the world primarily collaborate online to create the best tools in a certain field. When someone finds a codec not working, they go and fix it; someone wanting to support a new file format goes and adds support. All of this is for the "greater good," benefiting everyone.

Open source licenses are the "social contract" of the community. Community members may agree on the license but hold differing opinions on other aspects; however, the license is the foundation of their collaboration. It allows projects to fork and also permits later merging. There are various kinds of licenses, mainly divided into two categories:

• Permissive licenses: such as MIT, BSD, Apache, which require very little, allowing users almost unrestricted use of the code; some require attribution, while others do not.
• Copyleft licenses: which require modifications to be shared back with the community, with varying degrees of restrictions. The weaker ones, like Mozilla Public License (MPL), and the stronger ones, like GNU GPL, and very strong ones like AGPL.

The choice of license depends on the project's goals and the type of community it hopes to build. FFmpeg and VLC mainly use GPL or LGPL. The Linux kernel is GPL, Android is Apache, and many JavaScript frameworks use MIT; the BSD kernel naturally uses the BSD license.

License Transition: Commercial and Ecological Considerations from GPL to LGPL

Licenses can shift from more permissive to more stringent (because you can impose additional restrictions), but the reverse is not true (you cannot place GPL code into an MIT project). The core engine of VLC, libvlc, transitioned from GPL to LGPL mainly for two reasons.

The first is commercial integration. LGPL (Library GPL) allows third-party applications to use libvlc (thus calling FFmpeg) without needing to open-source the entire application. This has spurred consulting and integration businesses around this technology, such as integrating the VLC engine into game engines or other commercial solutions. For game developers wanting to play videos in their games without being forced to open-source the entire game code, LGPL provides the possibility. LGPL requires you to share modifications to the library itself, but the main application can remain closed-source.

The second is app store compliance. The terms of Apple's iOS App Store make it very complicated for GPL applications to be listed, while LGPL applications are relatively easy. Thus, VLC is GPL on Windows, Mac, and Linux, but its core is LGPL; on iOS (for iPhone and Apple TV versions), it uses another license, MPL.

Changing a license is an extremely arduous process because it requires the consent of all contributors. Open source projects are usually "joint works," with every contributor retaining the copyright for their part of the code. Even if subsequent modifications delete someone's contributions, as long as the new code is based on their original work, their copyright still exists. Some projects require copyright assignments, but community projects like FFmpeg/VLC do not.

To transition libvlc from GPL to LGPL, developers needed to contact over 350 contributors. This process can sometimes be very difficult and emotionally charged. Contributors may only be an email address, requiring tracking from various angles. Developers once personally visited a contributor's workplace only to find that the code was written by their deceased son, needing to explain the meaning of open source to this factory worker and ensure they understood this was not the company appropriating the code. Such experiences highlight that the open source community is made up of living people, and it is crucial to respect their contributions and rights. Disrespecting this process and forcibly re-licensing can "destroy the core of the community," as the only thing the community universally recognizes is the license itself.

The Essence of Community: Code Quality Over Identity

The open-source community gathers individuals from diverse backgrounds around the globe: from contributors with intermittent electricity amid the Syrian conflict to people from various professions, ages, and wealth levels. Many contributors are introverts, making it difficult to connect with them and receive email responses.

However, the core principle of the community is only caring about whether the code is excellent and the technology outstanding. "We don’t care who you are. Sorry, we cannot verify. Maybe you're a dog, I don't care. I don’t care where you come from. I need to see your code," developers say frankly. When people have patches rejected, they might be dissatisfied, but the community's standard is code quality, not the identity of the submitter or the size of their company. This pure pursuit of technology defines the community and attracts numerous contributors who are uniquely diverse, perhaps very introverted but highly skilled.

It is this共同追求卓越技术, along with the collaboration and sharing brought by the open-source model, that enables tools like FFmpeg and VLC to continuously evolve, becoming the invisible cornerstone supporting today's video era, truly empowering everyone with powerful multimedia processing capabilities.

免责声明：本文章仅代表作者个人观点，不代表本平台的立场和观点。本文章仅供信息分享，不构成对任何人的任何投资建议。用户与作者之间的任何争议，与本平台无关。如网页中刊载的文章或图片涉及侵权，请提供相关的权利证明和身份证明发送邮件到support@aicoin.com，本平台相关工作人员将会进行核查。