what is a video file format? and is it any different then a video container format?

Question

hello, i’m trying to understand what a video file format is and if it’s any different then a video container format, for example

mp4

mv4

mkv

.webm

.flv

.ogg

.gif

.avi
.mov

are these all “video file formats” or video container formats? if these are container formats then what is the video file format of each of them and the difference between the video file format and the container format?

thank you

In: 3

Answer 1

Take video, at its core. It’s a rapid slideshow of images, 30 per second or so usually, and also often sound that goes with it.

In computers, we’ve found lots of ways of digitizing images and audio. That applies to video too. Video is ripe for compression- because most of the time there’s not much difference between one frame and the next, most video CODECs (Compressor-Decompressor) work by storing one full image (key frame) and then only the differences from it for the next several frames. There’s lots of variants on that, but it’s the general idea.

Audio is then stored separately in an audio format like WAV, MP3, AAC, OGG, etc.

That means you have a compressed video stream, and an audio stream, and you have to tie them together in one file. That’s what the container does. It packages the video and audio stream, along with metadata like telling the decoder what codec to use for the video and audio, what the title of the video is, etc. The container is usually what determines the file extension.

It gets confusing because often the video codec and the container are part of the same standard, sometimes not.

Take for example MKV- MKV is just a container. MKV’s benefit is that it can hold multiple video and audio sub-streams, like a DVD where you can switch audio tracks. It’s also royalty free.

MP4 is both a container and a codec. An MP4 container will almost always contain MP4-format video and AAC-format audio.

There’s also times when a file will contain raw video data without a container. For example .m4v is mpeg-4-video, aka the raw video bitstream without the container. .m4a is mpeg-4-audio, usually in AAC format. Etc etc.