What’s correlation between container formats like mp4/mkv/avi/rmvb and video coding like mpeg 4/H.264/H.265?
There are multiple video formats available, like MP4, RMVB, MKV, AVI and etc. Well, you might
be curious about the relationship and connection between the video formats and MPEG-4,
H.264 and H.265 these compressed-coding standards. It’s quite complicated, and let’s start with
MPEG is known as Moving Pictures Experts Group, and MPEG-4 is a codec standard for a group
of audio and video coding formats introduced in late 1998. MPEG-4 is widely used in the
compression of audio & visual digital data, CD distribution, telephone, television, broadcast
applications and much more.
H.264 is the part 10 of MPEG-4, also known as the advanced video codec (MPEG-4 AVC). H.264
is used for taking replace of MPEG-4 Part 2, since it offers higher compression rate than MPEG-4
Part 2’s video codec. The most common encoders of MPEG-4 Part 2 are divx and xvid
(open source), and the most common encode of AVC is x264 (open source).
H.265 is a new video codec standard after H.264. It is called as HEVC (High Effective Video Coding)
by MPEG organization. H.265 is not belong to MPEG-4 standard, and it ensures higher and more
effective compression rate than H.264.
Now, we come to discuss the container format.
Popular video formats include MP4, RMVB, MKV, AVI and more. Formally, all of them are extension
name of video files, and then they are packaging formats (container) of the video files as well.
We take MP4 format as an example. MP4 (MPEG-4 Part 14) is a digital multimedia container format
to store audio and video. What is container format? Container is a kind of standard that packages
the multimedia content (video, audio, subtitle, chapter information and etc.) generated by encoder.
It makes very easy to playback different types of multimedia content.
Another important role of container is to provide index for multimedia content. That is to say, without
container, you are not able to fast forward or rewind when you watch a movie. Moreover, this movie
would be no sound if you don’t load or add the audio file manually.
Another example of container is AAC/M4A. M4A is an extension name and audio format developed
by Apple, and it is based on AAC codec. In fact, M4A is packaged in the MPEG-4 Part 14 (MP4)
container, since it has no original AAC data stream of the container.
Different containers have different features. We still take the above mentioned formats: MP4, RMVB,
MKV and AVI as example.
MP4 is the container format designated officially, so it is supported by almost all platforms, systems
and devices. RMVB is a closed standard container used to package realvideo encoded videos. MKV
is an open container that has high compatibility; it can package almost all encoding formats. As for
AVI, its old framework is no longer applicable to those new encoding formats.