Difference between transcoding and re-rendering?

[Bronx]

I have encoded avi files to mpeg2 but I never understooed the difference between transcoding and re-rendering.

Can someone please explain the difference.

Thanks.

[guns1inger]

Re-rendering, or re-encoding, usually means encoding a source using the same codec. Eg. Encoding an mpeg2 file again with mepg2 to make it smaller.

Transcoding is often used in one of two ways. It can either mean to encode and already encoded file using a different codec, eg. Divx to mpeg2. Or, as in the case of software like DVD shrink, to reduce the size of an encoded source by altering the way it was encoded int he first place, without actually re-encoding. This is done by looking at the original encode, finding where there might be extra bitrate, and reducing the source.

[Mister Flonk-Flonk]

Switching formats (e.g., AVI to MPEG2 - transcoding/encoding/re-compressing) vs re-encoding (re-compressing) multiple times and further degrading quality from the source?

[Bronx]

Thanks for the Info.

[celtic_druid]

Transcoding can also refer to reusing data from the original stream rather than re-encoding. DVDShrink for instance is a transcoder. This tends to be faster than re-encoding.

Re-encoding doesn't mean that you have to use the same format. I can re-encode MPEG-2 to MPEG-4.