Explaining the difference between video and audio file formats means understanding the meaning of terms such as codecs, containers and compression. Knowing how to distinguish between formats and containers of video files makes it easier to distinguish the files from each other and understand why one can be played or not by the DVD player, computer or smartphone.
First of all, let 's see what a codec is .
The codec or decoder is an encoding tool that processes the video and stores it in a byte stream.
Codecs use algorithms to effectively reduce and compress the size of the video file and decompress it when necessary.
BitRate is basically the file size for each second of video, expressed in Megabits per second (one mega bit is, more or less, 125KB).
There are dozens of different codecs and each one uses a different compression technology, with or without data loss .
Lossy Compression is the most practicable compression even if you lose something in the quality of the audio, video or both.
Compression is necessary to prevent a single file from taking up the entire memory and to make the video easier to share and download.
On the other hand, lossless compression works like a ZIP or RAR file.
Through the use of intelligent algorithms, the file does not lose quality, even if it is archived inefficiently and with not much reduction in actual size.
Furthermore, it is inefficient for the online transmission of large video files, it uses too much bandwidth (even if the H.265 encoding changes the situation).
Unless you work on editing high-level videos, you won't have to deal with a lossless video format.
Just think that while a Blu-ray movie is less than 50 gigabytes in size (if it should fit on a disc), a 4K quality movie would be a huge 160 gigabyte file, while an uncompressed 1080p video would even be 410 gigabytes.
The problem with codecs is that if a video is encoded with a certain codec, the one itself must be used to decode it.
We have seen, in another article, codecs and software needed to view all kinds of videos and movies on the PC .
The most popular Codecs are:
- XviD / DivX
While DivX is a commercial codec, the XviD codec is open source, created as a free alternative (today the Divx codec, even if commercial, is free).
Both codecs can decode the other's output since both are based on the MPEG-4 format.
- MPEG-4 is the most common streaming format and is made up of various parts, MPEG-4 Part II used for DivX or XviD video encoding and MP3 for audio.
- H.264 is the most popular format today for high definition videos.
The H.264 is up to 2 times more efficient than MPEG-4 compression, so a file of equal quality takes up half the space.
The H.264 is now included in the MPEG-4 part 10 (or AVC) codec and includes multiple encoding methods in a single package.
Other than codecs, they are containers, that is , file formats that include audio, video, codecs and any metadata, menus, subtitles and various information, all together.
Containers, which can be distinguished according to the extension of a file, are like Windows EXE files, a set of files that are executed together to obtain the final result.
The most common video formats refer to the different containers and are:
- AVI, the standard used on Windows PCs, developed by Microsoft.
It is not a sharing format, it has a fairly high quality and not all AVI are the same because it may be that the video is compressed with different codecs.
- Flash Video ( FLV, SWF ), the online video standard, now increasingly in disuse and which will be replaced with the HTML5 standard.
- MKV (Matroska) is the most adaptable format, designed to support almost all audio or video formats, very efficient in terms of quality, compatible with the H.264 codec and excellent for HD movies.
- MP4 is the recommended format for uploading videos on the internet to sites such as VImeo or YOutube which consider it the preferred format.
The MP4 enclosure uses MPEG-4 or H.264 encoding for video and AAC or AC3 for audio.
It is a format widely supported by most commercial media players and is the most common container used for online videos.
- VOB (DVD Video Object) is the DVD container
- MOV is the video format created by Apple for its Quicktime player.
Eventually, a video will be visible on your computer or TV if you use a player that supports the file or container format .
Sometimes, a container file such as AVI or MKV may have a compressed video inside with a codec that is not compatible with the player used and therefore become illegible.
Fortunately, it is always possible to convert a video file from one format to another with some free programs that we have seen in the past.
