[MPlayer-dev-eng] Bluray input with -demuxer lavf

[wm4]

On Sun, 21 Sep 2014 22:33:57 +0100
Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:

> On 21 September 2014 15:29:18 GMT+01:00, wm4 <nfxjfg at googlemail.com> wrote:
> >On Sun, 21 Sep 2014 16:18:49 +0200
> >Grozdan <neutrino8 at gmail.com> wrote:
> >
> >> On Sun, Sep 21, 2014 at 3:51 PM, wm4 <nfxjfg at googlemail.com> wrote:
> >> > On Sun, 21 Sep 2014 10:26:56 +0100
> >> > Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:
> >> >
> >> >> On Thu, Sep 18, 2014 at 02:06:04PM +0100, Andy Furniss wrote:
> >> >> > Reimar Döffinger wrote:
> >> >> > >On 18 September 2014 00:40:14 CEST, Andy Furniss
> ><adf.lists at gmail.com> wrote:
> >> >> >
> >> >> > >>On all 3 of my disks (on HD) lavf now works without cache and
> >seeking
> >> >> > >>works on 2 of them.
> >> >> > >>
> >> >> > >>One just gets EOF when seeking with lavf with or without
> >cache, it
> >> >> > >>works
> >> >> > >>without lavf.
> >> >> > >>
> >> >> > >>There are two differences from the working - it's encrypted
> >and it's
> >> >> > >>also made up of lots of small .m2ts for multilingual reasons I
> >guess
> >> >> > >>whereas the other 2 the main film is just one large .m2ts.
> >> >> > >
> >> >> > >I would bet that if you dumpstream'd the title and tried to
> >seek in ffplay you'd get the same issue.
> >> >> >
> >> >> > Yes, ffplay can't seek properly on a dumpstream.
> >> >>
> >> >> Could you try attached patch (for FFmpeg) on the bluray?
> >> >> I have not tested it at all though.
> >> >
> >> > You don't need this. Bluray works quite well in mpv (as some users
> >> > report), and there I just forbid demux_lavf to do seeks.
> >> 
> >> We're trying to fix mplayer/ffplay issues, not migrate to mpv
> >
> >It was just a technical suggestion how to fix this. Why solve a problem
> >twice?
> 
> It's appreciated and I considered such a solution.
> However I decided it feels more like a hack/workaround for an FFmpeg bug and I'd rather fix FFmpeg to correctly use the APIs it already offers, assuming I manage to.

Well, the bad news is that it's impossible to seek reasonably in files
with timestamp reset issues with the libavformat API, unless you use
byte seeks. In my fork, I actually force byte seeks for SEEK_FACTOR
seeks in mpeg/mpegts files with libavformat for this reason.

(At least the problem sounded like timestamp reset issues - lots of
small m2ts files, which libbluray will basically concatenate.)

I would say there are two possible solutions:
a) hack libbluray, and make them rewrite mpegts timestamps to playback
   time (then libavformat could seek without issues)
b) add a seeking API to libavformat, that can do some form of relative
   seeks (as typically needed by players)

Apologies if I guess the problem wrong.