[FFmpeg-devel] [PATCH] avformat/options_table: Set the default maximum number of streams to 100

[wm4]

On Thu, 8 Dec 2016 19:36:20 +0100
Michael Niedermayer <michael at niedermayer.cc> wrote:

> On Thu, Dec 08, 2016 at 07:25:59PM +0100, wm4 wrote:
> > On Thu,  8 Dec 2016 18:37:42 +0100
> > Michael Niedermayer <michael at niedermayer.cc> wrote:
> >   
> > > Suggested-by: Andreas Cadhalpun <andreas.cadhalpun at googlemail.com>
> > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > ---
> > >  libavformat/options_table.h | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/libavformat/options_table.h b/libavformat/options_table.h
> > > index d5448e503f..19cb87ae4e 100644
> > > --- a/libavformat/options_table.h
> > > +++ b/libavformat/options_table.h
> > > @@ -105,7 +105,7 @@ static const AVOption avformat_options[] = {
> > >  {"format_whitelist", "List of demuxers that are allowed to be used", OFFSET(format_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
> > >  {"protocol_whitelist", "List of protocols that are allowed to be used", OFFSET(protocol_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
> > >  {"protocol_blacklist", "List of protocols that are not allowed to be used", OFFSET(protocol_blacklist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
> > > -{"max_streams", "maximum number of streams", OFFSET(max_streams), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 0, INT_MAX, D },
> > > +{"max_streams", "maximum number of streams", OFFSET(max_streams), AV_OPT_TYPE_INT, { .i64 = 100 }, 0, INT_MAX, D },
> > >  {NULL},
> > >  };
> > >    
> > 
> > That seems awfully low. Why limit stream count to 100,  
> 
> Is this too little for real world streams ?
> what limit would not interfere with a positive user experience ?
> 
> 
> > while allowing
> > e.g. 2GB large font attachments?  
> 
> theres no limit on attachments currently except the natural int size
> we may want to have a tighter limit there too
> 
> 

This will lead to thousands of options tuning various limits that
1. nobody wants to use, 2. even if they want, will not find, and 3. are
ugly and intrusive.

And then there'll probably still be a way to easily OOM ffmpeg, and
using a sandbox will still be superior over setting these options.