Transcoding verses Encoding

[kevinswystun]

There are a lot of Transcoding programs (DVD95Copy, DVD2ONE, InstantCopy, ReMPEG-the old timer) out. Transcoding takes 1/20 the time that Encoding dose, but the quality is not as good.

What is the deference’s in the way these two methods work?

I have used CCE and TMPG for about a year and love the quality, but hate the time it takes (20 hours). People using Transcoder’s say that Encoding is a thing of the past. With Transcoding’s speed and ease of use, I’m starting to believe

[jdobbs]

Well, I don't know if the transcoder will be the end of the encoder -- as you can't transcode something that hasn't been encoded already and you can't encode without an encoder.

Some of the programs you listed aren't really transcoders in the true sense. They simply take a previously encoded stream, decode it, and reencode it. That can create a lot of debate -- some may tell you there is no difference and it's all semantics.

Real transcoders reuse much of the information that was collected during the original encoding -- for example the bit allocation that is normally determined during the first pass of a conventional VBR encode can be simply reused and adjusted when transcoding. Other time consuming actions like motion vector computations, scene change detection, and organizing GOP structures can also be copied from the original.

CCE and TMPEGENC are encoders. ReMPEG2 is a true transcoder (albeit a very poor quality one) -- and DVD2one is a shining example of what can be accomplished with transcoding (it's obvious in the speed). My best guess is that DVD95Copy and InstantCopy are decoder/encoder combinations.

BTW: I searched the net and found about 5 different definitions of "transcoding" in the first five references -- so take anyone's definition (even mine) with a grain of salt...

[auenf]

Originally posted by kevinswystun
People using Transcoder’s say that Encoding is a thing of the past.

well, they should be saying "Re-encoding is a thing of the past due to Transcoding", and then they would be mostly right. as jdobbs says, encoding will still have a purpose, but eventually (ie, when quality is the same) Transcoding will make Re-encoding obsolete, but it currently isnt the case ;)

Enf...