[Ffmpeg-devel] [Ffmpeg-devel-old] Softcut?

[Michael Niedermayer]

Hi

On Tue, Mar 28, 2006 at 11:46:29AM -0500, Rich Felker wrote:
> On Tue, Mar 28, 2006 at 03:52:51PM +0200, Jindrich Makovicka wrote:
> > On 3/28/06, Patrick Fischer <patrick_fischer at gmx.de> wrote:
> > > Hello
> > > Its a long time ago i have postet my last post on this list....
> > >
> > > A friend and me talked about mpeg cutting.
> > > We both heard about a way to cut mpeg not at the I-Frame but without
> > > reencode.
> > > Im not sure which is the rigth name of this method.
> > > We call it "softcut". Maybe you can tell me the rigth name.
> > >
> > > It works like this
> > >
> > > I-----------I-----------I-----------I-----------I.......
> > >
> > > Now I want to cut at this parts
> > > I-------|---I-----------I-----------I---|-------I.......
> > >
> > > To fake the I-Fameless Cut we want to fill the Frames with "Black
> > > Frames" and cut at the I-Frame
> > >
> > > I#######|---I-----------I-----------I---|#######I.......
> > >
> > > I know there are lots of problems by this way(audio, sync,..), but maybe
> > > you can tell me if there is any projekt(maybe ffmpeg) which can do the job.
> > 
> > AFAIK, avidemux can do this - it only reencodes the GOPs which contain
> > a frame refering to a frame being cut out.
> 
> In theory it's possible to reencode only a single frame..

and by reusing motion vectors and MB types which ffmpeg fully supports
this should be almost working, someone just needs to add support to reuse
the per MB qp values, and fix any bugs then ffmpeg could do this
its not going to be as fast as possible but that IMHO doesnt matter as
such specialized reencoding isnt that common
also note that method of reusing stuff works even for mpeg2->mpeg4(with mpeg 
quantization) or msmpeg4->mpeg4, the encoder would reuse what it can and
reencode what it cannot

[...]

-- 
Michael