The Vocabulary Nobody Teaches You
Video is now watched as a matter of course across YouTube, TikTok, and Instagram, and running it in performance advertising has become routine. That means more teams commission creative from partner designers and studios, where the format and spec requirements run fussier than they ever did for images, and the terms are not obvious. This piece covers the basics and the things to watch when you use video in advertising.
Start With Codecs and Containers
You meet codec and container in the format requirements for video ads. Both are names for file formats and compression, and both are unavoidable once video is part of the job.
What a codec is
A codec is the technology that compresses, converts, and restores shot video through software. A video is made of picture data and audio data, and the file is large enough that it has to be compressed and converted. Compressing is called encoding, and restoring it to a playable state is decoding. The program that does both is the codec. Picture and audio each need their own, and there are many of each.
- Video codecs: H.263, H.264, MPEG-1, MPEG-2, and more
- Audio codecs: MP3, AC3, AAC, and more
What a container is
Video compressed by a codec becomes a file with an extension, and that file format is the container. The familiar MP4 and MOV are containers.
The Common Container Formats
Because each codec compresses differently and some files will not play in some software, many formats exist. You choose a codec to suit the playback software and export it with encoding software. As playback moved from DVD to Blu-ray and quality climbed, container types multiplied, and there are well over ten in common use. The representative ones:
ContainerMain video codecsNotesMP4H.264 / MPEG-4High quality and compression, broadly convenient. Supported natively on Windows and Mac and on nearly every device, so it is the safe pick when unsureMOVH.263 / H.264A Mac format; playing it on Windows needs extra softwareAVIH.263 / H.264 / MPEG-1A Windows format; playing it on Mac needs extra softwareWMVWMV9A Windows format, also used on Blu-rayMKVH.264 and othersHolds audio and subtitles; native support on Windows 10MPEG2-TSH.264 / MPEG-2Used as the transmission format for terrestrial digital broadcast
Quality is highest at low compression and high resolution, but the file balloons, sometimes hundreds of times larger than a more compressed cut, which makes it impractical. For a versatile file you can use almost anywhere, export at higher compression while keeping the quality reasonable. In performance advertising, MP4 is the format most often recommended.
The Right Format, Situation by Situation
Outside the ad platforms, on social media, YouTube, and video embedded on a site, the suitable format shifts. The picture for the main destinations:
DestinationSupported or recommendedX (formerly Twitter)MP4 and MOV in the app, MP4 only in the browserInstagramMP4FacebookMany formats supported; MP4 or MOV recommendedTikTokMP4, MOV, MPEG, 3GP, AVIYouTubeMany formats, since it converts on uploadEmbedded on a siteMP4, for fast loading and broad support
The pattern is clear enough: MP4 is the safe choice across most destinations. For an embed in particular, low compression slows the start of playback, which makes MP4 the better fit.
Converting Between Formats
Since destinations accept different formats, you will sometimes need to convert. Free tools handle it, though a low-compatibility conversion such as MOV to MPEG-1 can be beyond them. For those, a paid tool like Adobe Media Encoder is the reliable route.
For the common case of converting to MP4, you can also use YouTube. The approach is to upload set to private, then download the file again as MP4. Be careful: getting the visibility wrong on upload can publish a video by accident, so get the client's explicit permission first if you go this way. As a rule, leaving conversion to a studio or partner is the safer call.
When in Doubt, MP4
This piece ran from codecs and containers through the file formats themselves. The conclusion is simple: MP4 is compatible with most current media and broadly versatile. When a format choice is unclear, export to MP4 and you will rarely go wrong. Holding that one point alone makes the back-and-forth of producing video noticeably smoother.
