关于MPEG-4 、mp4v 和 mp4a

原文链接： https://www.jianshu.com/p/5c4440659fe4

MPEG-4

MPEG-4是个协议簇，包含了多个协议。

 

MPEG-4只是定义了一部分AAC类型，AAC主要包括MPEG-2 AAC和MPEG-4 AAC,详细如下图：

可以看出MPEG-4中只是定义了一部分类型的AAC。

 

MP4V

MP4V stands for MPEG-4 Video.
It was created by Moving Pictures Experts Group (MPEG) as a codec used to compress and decompress video data.
If you see "MP4V" in the context of a video file, it just means that the video was compressed with the MP4V codec.

MP4V是一种编码格式。

MP4V vs AVC

MPEG-4 is the general name for a set of specifications defined by ISO/IEC 14496.
There are several parts to this specification.
These are the relevant parts:
Part 2 - Commonly known as MPEG-4 Video, is a video compression format.
Part 3 - Commonly known as MPEG-4 Audio, is and audio compression format.
Part 10 - Commonly known as H264 or MPEG-4 AVC, is also a video compression format.
Part 14 - Commonly known as MP4, is a container format.
H.264 is typically considered to be the better for video compression.

MP4V在MPEG-4的第2部分MPEG-4 Video中定义。
AVC在MPEG-4的第10部分H264 or MPEG-4 AVC 定义。

另：MP4A在MPEG-4的第3部分MPEG-4 Audio中定义。

The biggest difference you will typically see is file size.
H.264 will typically be able to compress video at a much lower bitrate than the standard MPEG-4 codec.
You should be able to get comparable quality video with much smaller file sizes.

与MP4V相比，AVC具备更高的压缩效率。
 

MP4V vs MP4V-ES

MP4V-ES stands for MPEG-4 Video Elemental Stream.
MP4V differs from MP4V-ES in that the former is raw video data while the latter is RTP (real-time transport protocol) data that's already prepared to be sent over the RTP network protocol.

MP4V是原始视频数据。
MP4V-ES是RTP数据，可通过RTP协议进行传输。
 

References:

https://www.lifewire.com/mp4v-file-2622025
https://superuser.com/questions/118684/what-is-the-relation-between-the-mp4v-codec-and-the-h-264-format
https://en.wikipedia.org/wiki/MPEG-4
https://en.wikipedia.org/wiki/MPEG-4_Part_3