Unlike what happens with audio files, the extension of video files says little about the encodings used. Each of them, from RMVB for extremely small files to MKV for extreme quality, has different types of encoding for audio, video and all the other necessary components of movies, so they are known as containers.
Container? Isn’t that a video codec? To understand them, the best example is that of a backpack. To attend a class, we have to bring a notebook, a case, books and other essentials for good use. Within a container we have a similar situation, with video encoding, audio encoding, subtitles and additional information on frame rate, audio channels, etc.
In our example, if we have the best notebook in the world with a bad pencil and a poorly written book, our experience will be drastically reduced, just like video containers. AVI, RMVB, MKV, each of them has different “levels” of quality depending on the coding of each of the components. Below is the list of currently used video encodings:
RMVB (Real Media Variable Bitrate, extension. Rmvb): Developed by Real Networks for RealPlayer, it has a variable bit rate. Although it is capable of generating a smaller file than the original RealMedia, the quality is the same, but it is far from good. Recommended for users who have a low-speed Internet connection or a data franchise.
RMVB
AVI (Audio Video Interleave, extension. Avi): container developed by Microsoft and currently supported by a variety of devices, from DVD players to smartphones. It uses DivX or XviD (High Loss Compression) encoding for video and generally MP3 for audio, which provides a reasonable video experience, but does not have native subtitle support.
Avi
MP4 (MPEG-4 part 14, extension. Mp4): In many ways, very similar to AVI, MP4 has the advantage of having native subtitle support (i.e. no subtitles in separate files), Xvid, DivX and powerful H. 264 for videos and ACC for audio (learn more about ACC). Users who want a balance between quality and compression generally prefer MP4, but it’s still not popular near AVI.
MP4
MKV(. Matroska Video, MKV Extension. MKV., Mks): Relatively new open source format preferred by users who want their movies to be of the highest quality possible regardless of download size. It is possible to encode all the elements in almost any format, from the frame rate per second and the quality of each image to the use of different encoders for video (DivX, XviD, H.264) and audio (ACC, DTS, Dolby Digital ), where Full HD (1080p) movies are rarely less than 10GB and reach up to almost 70GB in Remux quality.
These are not all video formats. MOV (Apple), WMV (Windows) and VOB (used on DVD) were not mentioned as they did not bring significant differences. The performance of each of them depends more on the compression rate itself than on the format itself, and machines that have hardware decoding can handle any format without major problems.
