[Ffmpeg-devel] deinterlace at the decoding stage...

[leon zadorin]

On 4/2/07, M?ns Rullg?rd <mans at mansr.com> wrote:
> "leon zadorin" <leonleon77 at gmail.com> writes:
>
> > Hi all,
> > pardon if the question is rather silly... is it possible (e.g. via
> > setting some option in codec's context) to deinterlace the image
> > during decoding (e.g. for the avcodec_decode_video to produce
> > de-interlaced frame)... or is it a stupid question because interlaced
> > source may affect encoding process to such an extent that decoding of
> > the interlaced image will not produce easily de-interlaceable output?
>
> What you are suggesting is pointless at best.  The decoder needs the
> original frames for motion compensation anyway.  Furthermore, a good
> deinterlacer uses information from previous and following frames.
>
> You should also know that deinterlacing is necessarily a lossy
> process.  The only exception is a telecined progressive source, but
> that's not really interlaced in the true sense

yes of course... I don't know what I was thinking... :-) I was trying
to deal with inetrlaced-recorded image (from DV/HDV firewire camera)
being shown on the screen with an interlaced effect... but then I
realised that the effect was due to rendering the whole frame (both
fields) at once (i.e. in a progressive style) so the interlacing in
itself was not a problem - it is not following it up with the
field-based rendering that was causing the problem... what I need now,
I think, is to render each "field" separately in time (one after
another)... given that my dislpay rate is >=60Hz and video stream's
rate is 25fps... I think I can get there with syncing to VBlank as
well :-) but that is not libavcodec related... :-)