Help with some video concepts

[GOH]

I have used many programs with many functions, but I dont know how to explain or difference these funtions when I talk about them, I am confused with the concepts or terms used, and the glossary doesnt clarify my doubts, for this reason I do this request to somebody who want/can help me.

First, I want to know the term used for the accion of some programs that edit the video (trim, join) without alter the video and audio?, like the programs videoredo or avidemux (with the "copy" option).

Second, whats the meaning of "encode/decode" and whats the diference of "convert"?

Finally, whats the difference between mux and multiplex?

I will be thankful if somebody could spend its time helping me

[edDV]

I have used many programs with many functions, but I dont know how to explain or difference these funtions when I talk about them, I am confused with the concepts or terms used, and the glossary doesnt clarify my doubts, for this reason I do this request to somebody who want/can help me.

First, I want to know the term used for the accion of some programs that edit the video (trim, join) without alter the video and audio?, like the programs videoredo or avidemux (with the "copy" option).

Second, whats the meaning of "encode/decode" and whats the diference of "convert"?

Finally, whats the difference between mux and multiplex?

I will be thankful if somebody could spend its time helping me

OK start by helping us explain. What are the source formats that you want to edit/join?

Second, what is the destination? How will you be viewing these joined videos?

[edDV]

First, I want to know the term used for the accion of some programs that edit the video (trim, join) without alter the video and audio?, like the programs videoredo or avidemux (with the "copy" option).

MPEG video is GOP based. That means multiple frames are handed as a GOP. If you cut on the GOP, then there is no re-encode with certain programs. If you cut inside the GOP, there must be a re-encode at least for that GOP.

[edDV]

Second, whats the meaning of "encode/decode" and whats the diference of "convert"?

No difference. If you want to "convert" you need to "decode", then do what you need to do, then "re-encode" to the output format. This process has loss.

[GOH]

In this moment I dont have any video or format to edit, actually, I know how to do it; but I feel strange because I really dont know what I am doing, and, if some program fail me I would like to know how to find similar programs using the correct terms

[edDV]

Finally, whats the difference between mux and multiplex?

Same thing. Mux/Multiplex mostly is about the container. The container holds video and audio elementary streams. You can extract the video/audio streams without re-encode. Then repackage them into a different container optimized for your task.

[jagabo]

Uncompressed video is very large. So it's usually compressed for storage. Encoding is the process of compressing the video. Decoding is the process of decompressing compressed video.

There are two basic types of compression: lossless and lossy. Lossless, as the name implies, loses no information. The frames that come out of the decoder are exactly the same as the frames that went into the encoder. That's great -- except lossless codecs can't compress very much. Lossy codecs can give much more compression but they lose some detail. They try to make sure the lost details are things you won't notice while watching the video. But the more you compress the more details are lost and the worse the video looks.

The basic process of editing video consists of first decompressing the frames, making changes to them, then compressing them again. Recompressing with lossy codecs will result in a loss of quality with each re-encode.

Some types of editing can be performed without decompressing and recompressing the video. Simple cut paste operations, for example.

Mux is short for multiplex. In video this refers to the interleaving of video an audio streams within a file. Ie, you have a little video, then a little audio, then a little more video, a little more audio, etc. Streams are multiplexed like this to make it easier for player to play them. The audio for each frame is near the video so the player doesn't have to seek all over the file looking for the data.

Convert can have many meanings. You can convert from one compression scheme (codec) to another, one container to another, etc.

[GOH]

So, how can we call the programs that edit video without re-encode (lossless)?

[edDV]

So, how can we call the programs that edit video without re-encode (lossless)?

We don't. If you cut on GOPs you can just copy the source GOPs to export GOPs and nothing is changed. GOPs can typically be from 1/2 sec (15/12 frames) to several seconds.

"Lossless" is usually used for encoding/decoding. It is an illusion based on psychology that you won't "see" the difference. It is also possible to do a mathematical "lossless" encode but it won't compress much.

If you want a more direct answer you will explain your source and destination goals.

[jagabo]

So, how can we call the programs that edit video without re-encode (lossless)?

You call them i-frame only editors (cut and paste on i frames only) or non-reencoding editors, or smart editors when they only reencode cut GOPs.

[budwzr]

It's great that you want to learn something new, but if you can't grasp the meaning of these simple terms, then it's probably not your forte.

Editing video requires significant brainpower.

[edDV]

to edit fully lossless (e.g. uncompressed) requires enormous disk capacity. Not disk size but multiple disks running parallel in a RAID.

Most newbies think they can edit without loss but soon run into a cost barrier.

Intelligent editing (on a budget) requires creative use of compression. This is 4-8x true for HD video.

Unlike 2001, SD video can now be edited fully lossless on a budget so long as you can can deal with the tech. We are talking very fast disks or SSD to gain speed for lossless SD editing.