Infoseite // Video Codec understanding question

Frage von aight8:

So there are many implementations of MPEG-2 / 4 Because I have a few questions.

I understand that is not quite what use are these implementations?

Is it work today is remarkable what codec you take? So you see as differences in quality?

MPEG indicated yes even on a standard format. Is it possible to an MPEG-2 file with codec which decodes X was playing with codec Y? If whom no, I do not understand this standardization of MPEG.


Antwort von jwd96:

I think because what you have understood all wrong.
There are container as mp4, mov, avi or mpeg
These containers are usually a
Audio Stream and
Video Stream
Both streams of codecs using "compressed" to be, because otherwise you would indeed still photos only. (There is synonymous uncompressed format)
Video codecs include H.264 (which can be used for example in mov or mp4 container) or JPEG - PHOTO or ProRoes (of Apple)
The film is called the witrd always played in the codec, in which it is stored.
H.264 is such a highly compressed format Date = small + large computing power


Antwort von Axel:

Mpeg wuirde developed:
Mpeg1 - VCD
Mpeg2 - DVD-Video and HDV
MPEG4 - AVC and H.264

And of course you need a certain way en-encoded video on the player page with the de-coder, which is quite like that.

To achieve the same quality required Mpeg4 (Typical for HD are 17 Mbit / s) a smaller data rate than Mpeg2 (25 Mbit / s), for example.


Antwort von TheBubble:

Basically, it's the targeted video codecs quite simple: There is no standardized video codec itself, but only data formats (bit-stream format). Each player must be able to deal with any valid bitstream. Each compressor must generate as output a valid bitstream.

Nevertheless, the differences between the implementations of the codecs in performance, quality, or both, for, as they produce a valid bitstream or wiederdergeben is not set.


Antwort von WoWu:

@ Aight8

Have you seen the quite correct. MPEG is a Normeirungsgremium and not just a container format.

The best known are well-formed MPEG1, MPEG2, MPEG4, and MPEG7 MPEG21.
MPEG is synonymous not strictly an encoding algorithm ... it is merely a bitstream and MPEG is only and exclusively a set s.Kompressionswerkzeugen ..
For these codecs in MPEG compression tools are used.
There are no synonymous algorithms that produce an encoding, it is only the rules can be encoded as synonymous and the only way that we define the decoder.
MPEG4 is more than that this is a framework. Inside of MPEG 4 there are really only two codecs, which currently play a role: VC1 and H.264 (AVC).

The source was to provide manufacturers with the encoding as much freedom as possible in order to develop unique selling points (read: good codecs). Since MPEG defined only through the decoder, so they had to be necessarily compatible in order to be called MPEG allowed.
The idea was to combine the different devices, without limitation, Manufacturer and / or quality loss with each other. Similarly, for the appliance industry (TV, SAT, etc.) to ensure predictability.
Thus, if a codec only "MPEG compliant", they generally do not MPEG's in it, because the signal to decoders that conform to the standard, not necessarily running.
Thus, for example, may not name synonymous AVCHD MPEG4, because parts are included, which actually is not HD and are the MPEG4 specifications correspond at all but rather come from the SD world.

Actually, with the development of MPEG2 MPEG4 synonymous the development of a broader framework started. Only one has the part for the codec at an early stage and in an "intermediate form" is already used for the TV, the format but do consistently developed and as MPEG4 product for standardization.
MPEG2 is so the 15-year-old "rough draft" for a codec with MPEG4 H.264 only became complete.
Similarly, VC1 is formed of Microsoft from an early draft of H.264 and includes not very many quality tools of H.264.
Unlike older codecs, in which the image quality is associated with the data rate, this can be in H.264 no longer directly read it, because the image quality depends almost exclusively on it, which profiles, so what "tools" I use. That it synonymous indirectly, the data rate is concerned, it is clear, but it is synonymous the request s.den Processor and is then sometimes the picture that is being used to a less good image quality, high data rate needs, just because the processor of the device too weak the tools to work with. Since then nachgeholfen with I-frames to make it easier for the processor. Then follow a bad profiles and is thus a bad picture, while still providing high data rate.
You see, the codecs are einwenig complex and the relationships are not what they once were.


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