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

[Ronald S. Bultje]

Hi,

On Thu, Dec 8, 2016 at 7:03 PM, Andreas Cadhalpun <
andreas.cadhalpun at googlemail.com> wrote:

> On 08.12.2016 22:59, Carl Eugen Hoyos wrote:
> > 2016-12-08 18:37 GMT+01:00 Michael Niedermayer <michael at niedermayer.cc>:
> >
> >> -{"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 },
> >
> > I wanted to suggest 1000 which is still a magnitude less than the
> provided
> > crashing sample but 255 also sounds ok to me.
>
> Either value is OK. The important thing is that it's several orders of
> magnitude lower than INT_MAX.


On IRC, we discussed at what values OOM start occurring, which seems to be
around 30k-60k, so from there I suggested a value like 10k or 5k. 1000
seems a little low but I think I can live with it (I doubt ATM I can come
up with legit use cases that use 1000 streams).

If people hit the limit (whatever value we choose), I would propose that we
make the error message very specific, something similar to
AVERROR_PATCHWELCOME. This way, people understand this is not a hard
limitation and can be changed easily; fuzzers will obviously ignore this
message.

Ronald