[Ffmpeg-devel] Re: [Ffmpeg-cvslog] r7570 - trunk/libavutil/fifo.c

Michael Niedermayer michaelni
Wed Jan 24 11:15:57 CET 2007


On Tue, Jan 23, 2007 at 06:58:31PM -0800, Roman Shaposhnik wrote:
> Hi
> On Fri, 2007-01-19 at 12:12 +0100, Michael Niedermayer wrote:
> > i knew you would like my suggestion ;)
>   I always do ;-)
> > >   Now, the only problem I have with your approach is that you're
> > > exposing the guts of a Fifo implementation and that doesn't seem
> > > right to my OO-self. After all, that's what av_fifo_peek()
> > > was introduced for anyway. 
> > 
> > the problem i have (and had) with av_fifo_peek() is that it doesnt
> > solve the fifo-guts dependance it just hides it which IMHO is worse
> > people could use av_fifo_peek() and expect to have no dependance on the
> > fifo guts but they do, at the ABI level
>   Right. That's the price paid for av_fifo_peek()'s performance. Now,
> currently the way DV audio is shuffled we have to 'peek' every time we
> need to get to the next byte in the FIFO. As I pointed out it is
> possible to restructure the code so that we would go over the bytes
> stored in FIFO in a linear fashion and thus eliminate the peeking
> process. But even though that would let us get rid of av_fifo_peek()
> it will introduce a different kind of ugliness where I would have
> to supply a stateful 'thunk' to av_fifo_generic_read.

maybe the whole could be done easier without using a AVFifoBuffer?

>   I guess at this point I am really curious to understand why do you
> consider ABI level dependency to be a big deal ? Do you actually expect
> anybody to use libavutil independently of libavcodec/libavformat ? 

i wouldnt be surprissed if some distribution do actually use shared libavutil

> We don't make a shared library out of libavutil, do we ?

dunno, if --enable-shared doesnt result in a shared libavutil then thats
a bug


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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