[opendtv] Re: re-encoding

  • From: "Gary Hughes" <ghughes@xxxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 18 May 2005 10:40:19 -0400

> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx=20
> [mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of John Willkie
> Sent: Tuesday, May 17, 2005 8:43 PM
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: re-encoding
> Martin;
> What's unique about it?  Does it transcode metadata?  Adjust=20
> timestamps? Or, does it reconstruct the transport stream when=20
> no transport stream is available?

In essence it allows all of the information embodied in the MPEG
headers to travel along with the uncompressed frame. If you think
of this information as a record of the decisions made by the encoder
then it should be possible for a suitable encoder to read this data
and re-encode an unmodified frame, making the same decisions and
recreating the same compressed frame (subject to DCT math errors etc).

Or to take a modified frame with the knowledge of what was modified
and how it was previously encoded to optimise the re-encode.

It is a neat idea. I'm surprised it didn't find more applications.


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