[FFmpeg-devel] How to handled gzip'd files?

[wm4]

On Sun, 3 Apr 2016 18:33:44 +0200
Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:

> On Sun, Apr 03, 2016 at 09:02:27AM -0400, Ronald S. Bultje wrote:
> > Hi,
> > 
> > On Sat, Apr 2, 2016 at 12:29 PM, Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> > wrote:
> >   
> > > Hello,
> > > I was looking at these:
> > > http://samples.mplayerhq.hu/game-formats/la-snm/grimfandango/
> > > http://samples.mplayerhq.hu/game-formats/la-snm/force-commander-znm/
> > > and realized that they are perfectly supported, if you first
> > > run them through gunzip.
> > > However there are 2 issues here:
> > > 1) They are misdetected as all kinds of nonsense
> > > (http://samples.mplayerhq.hu/game-formats/la-snm/grimfandango/byeruba.snm
> > > as AAC for example)
> > > 2) How should an ordinary user even come up with that idea?
> > >
> > > Do we have a way to transparently decompress?  
> > 
> > 
> > Why would we? It's not like this is commonplace across all formats, it's
> > only present in a handful, and we can deal with it on a case-by-case basis,
> > just as we handle compressed mov. Right?  
> 
> mov is slightly different as it isn't just a file compressed
> wholesale...
> 
> > So probe and read_packet can optionally decompress and we're pretty much
> > done. I don't see the issue, and this is at best a few lines of code... If
> > you want to share unzip between probes, I'm sure you can extend the input
> > packet to have a "gzip-decompressed" buffer also. This stuff isn't hard.  
> 
> I guess I was looking for a more generic solution, and it won't really
> solve the "gzip'd files are misdetected as random stuff" issue.
> There are also some other small things like having to disable seeking
> in the demuxer etc. but you are right this is probably the simplest
> solution to that specific issue.

I think the problem is rather that libavformat misdetects random stuff
as something. Maybe it shouldn't.