[FFmpeg-devel] [PATCH 1/2] doc/examples/demuxing: show how to use the reference counting system.

[Clément Bœsch]

On Thu, Oct 31, 2013 at 11:50:14AM +0100, wm4 wrote:
> On Thu, 31 Oct 2013 11:13:30 +0100
> Clément Bœsch <u at pkh.me> wrote:
> 
> > On Thu, Oct 31, 2013 at 10:53:00AM +0100, wm4 wrote:
> > > On Wed, 30 Oct 2013 16:28:51 +0100
> > > Clément Bœsch <u at pkh.me> wrote:
> > > 
> > > > From: Clément Bœsch <clement at stupeflix.com>
> > > > 
> > > > ---
> > > >  doc/examples/demuxing.c | 44 ++++++++++++++++++++++++++++++++++++++------
> > > >  1 file changed, 38 insertions(+), 6 deletions(-)
> > > > 
> > > > diff --git a/doc/examples/demuxing.c b/doc/examples/demuxing.c
> > > > index 7ae3654..379b1ea 100644
> > > > --- a/doc/examples/demuxing.c
> > > > +++ b/doc/examples/demuxing.c
> > > > @@ -53,6 +53,11 @@ static AVPacket pkt;
> > > >  static int video_frame_count = 0;
> > > >  static int audio_frame_count = 0;
> > > >  
> > > > +/* This flag is used to make decoding using ref counting or not. In practice,
> > > > + * you choose one way or another; ref counting notably allowing you to keep the
> > > > + * data as long as you wish. */
> > > > +static int use_ref_counting = 0;
> > > 
> > > Why confuse people with providing both? That's just confusing. In fact
> > > I'd expect that the API without reference counting would be removed
> > > sooner or later.
> > > 
> > 
> > I'm assuming it could be helpful when moving code from the old to the new
> > API. Also, the new one requires more non-intuitive code (setting an
> > obscure option).
> > 
> > Are you sure the API without ref counting is supposed to be dropped? Where
> > is that mentioned?
> 
> Libav basically said "eventually, probably", so at least there are no
> definitive plans to this, but it might happen.
> 
> In general, whether the API does refcounting or not doesn't matter
> for an API user who is not interested in refcounting. The user can
> just use av_frame_alloc and av_frame_free at start and end of decoding,
> and ignore the fact that they're really reference counted.
> 

And unref the frame manually after each decode (so you actually need to
understand the ref counting system when using it). This is another
addition from the old method.

Or maybe what you mean is that you can also use the new API without
setting the refcount option, in which case you must not unref the frame
after each decode?

-- 
Clément B.
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