Encoding? Encoders? Transcoding? Transcoders? & DVD backup

[kirby7777]

After doing some searches and reading, I am still very confused about the difference between encoding and transcoding.

Can anyone explain them in simple terms and perhaps gives some examples?

Secondly, I am going to back up some DVD-video.

I was told that programs like DVD Shrink and CloneDVD etc are transcoders. They do not do as good a job as encoder such as DVD Rebuilder.
I didn't realise there is such differences with those programs. If I only back up from DVD 9 to DVD 5, does it involves transcoding or encoding or both?

Thanks for enlightening me.

[guns1inger]

At a very basic level, transcoding tried to find data within an existing encode that can be removed to reduce the size. It is constrained by the parameters of the original encoding, and tends to produce artifacts sooner than re-encoding. Encoding looks at the video and re-encodes from scratch. The advantage of transcoding is speed, pure and simple.

Which is better ? It depends on many factors. For some video transcoding is fine, and will porduce results very close to, if not as good as, encoding. For others, even a small amount of transcoding will produce artifacts.

However there are other things to consider. Programs like DVD Shrink can also be used to remove parts of a DVD that you don't need to backup, or to make your DVD just the main movie. By removing items that you don't need you leave more space for the movie. In many cases, you can fit the movie on a disc with little or no transcoding at all.

[edDV]

I'll kick it off with my understanding that an encoder works from an uncompressed source where a transcoder changes one format to another without full decompression. An example might be transcoding DV format to MPeg2. Both are Rec-601 based and share many characteristics as does MPeg4.

Already I can think of exceptions to that definition.

Wiki defines transcoder as conversion of one lossy digital format to another lossy digital format.

Grass Valley's Glossary, in good hardware tradition calls a transcoder "A device that converts one form of encoded video to another, e.g., to convert NTSC video to PAL. Sometimes mistakenly used to mean translator".

The Free Dictionary is even more general
Transcode: "to convert from one format to another."

PS: I didn't see guns1inger's response until I posted.

[guns1inger]

Yours is a little broader than mine anyway. I tried to contain mine to the context of mpeg2 size reduction, but transcoding does cover a wider area than that.

[kirby7777]

Thank you.

Is there an easy way to tell if a program is a transcoder or a encoder?

[guns1inger]

The best way is by asking here or checking out our tools section. I would not trust the marketing blurb of most venders in the DVD-copy space as they seem to be happy cobbling together bits of freeware under an often ugly front-end, charging you through the nose for it, then providing no support when things go pear shaped. They will happily tell you they can copy a DVD9 to a DVD5 with no quality loss at all, which is patently bollocks.

There are very few tools worth seriously considering. The good ones are all pretty much on par for quality, and vary only slightly in features. For transcoding, DVD Shrink is simple, free and does everything you need. It's reauthor mode allows you to take just the main title and remove everything else, and it's Deep Analysis and AEC means quality is as good as any other transcoder out there.

For the harder to squeeze discs, re-encoding with DVD Rebuilder with HCenc is a quality, free solution, while adding CCE or ProCoder ups the quality to as good as you will get.