[XviD-devel] "Autoselecting" IDCT for SimpleIDCT encodes
ed.gomez at free.fr
Mon Dec 29 16:33:56 CET 2003
Dirk Knop (dknop at stud.uni-goettingen.de) wrote:
> Since there are a few bitstreams out there with the bitstream number
> 009 (I think) we were thinking about adding an automatic pre-selection
> in bitstream.c (switch to simple if bitstream number is 009) - if that
> selection is wrong, the user still can select the idct from dshow.
Your input data is somewhat wrong, bitstream 0009 has been used for many
time in CVS, you built a binary from it using this, but i'm sure there
are 95% encodes with this BS version that is using Walken iDCT.
> Unfortunately this is a hack which only works because we statically link
> xvid core into dshow. It would be more graceful if we'd extend the API
That can be a solution, but only a decoder flag may be added.
> "(@sysKin): a flag in "frame" I guess - if flag is on && bitstream
> version is 009 -> switch"
> Any objections? :)
As i said BS 0009 is covering a too big period of time, automatic
detection is probably not a good solution that way.
But extending the automatic detection scheme, you can do it:
- check if your build used to have wrong VOL headers (signal type
missing) Look at the changelog of xvid 1.0 to have an idea when i
did ccommit a fix for that.
- try to see if other bitstream signatures can help detecting the
faulting version *only*
Btw we should also add automatic detection of edging bug (old BS
versions <-- this one is easy to spot, the bug is there since... the
very early days :-)... which can cause more trouble than an iDCT drift.
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