On Tue, Oct 25, 2016 at 2:39 PM, wm4 <nfx...@googlemail.com> wrote: > On Tue, 25 Oct 2016 09:47:29 +0200 > Hendrik Leppkes <h.lepp...@gmail.com> wrote: > >> On Tue, Oct 25, 2016 at 1:50 AM, Andreas Cadhalpun >> <andreas.cadhal...@googlemail.com> wrote: >> > This should reduce the impact of a demuxer (or API user) setting bogus >> > codec parameters. >> > >> > >> >> This seems rather noisy and doesn't really solve anything, does it? >> Decoders still need to validate values instead of blindly trusting >> them, and this just hides some problems in these decoders, instead of >> fixing them there. API users of avcodec would not fill >> AVCodecParameters, they would fill a codec context directly. > > You could also argue that the demuxer shouldn't return invalid > parameters either.
It should not, but this patch does not address this. There is various combinations of component usage that are possible, and in fact are used in the real world: avformat -> avcodec other demuxer -> avcodec avformat -> other decoder This patch only addresses the first case, and only if you actually use this function (which I for example do not, since I have an abstraction layer in between, so I never have AVCodecParameters and AVCodecContext in the same function). So in short, it just doesn't fix much, and you can still get invalid output from avformat, and potentially still undefined behavior in avcodec if its fed those values through other means. > > How about this: always convert the params to a temporary codecpar, and > provide a function to determine the validity of a codecpar. This way > the check could be done in multiple places without duplicating the code > needed for it. That still sounds odd, although slightly better. At the very least it should be a dedicated function that checks the values in a key place, say you want to check params that are fed to a decoder, then call this check in avcodec_open, because thats something everyone has to call to use avcodec. - Hendrik _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
