[Cin] MKV containers

[Andrea paz]

> This does not cause any real problems.  Basically, when you open a file, if a stream has a known duration, there is no message.  It really should have a duration but it often obviously does not.

Yes, we have already discussed this and I know that the message is not
one of error. But every time it appears I have problems; with mp4 and
webm the message never appears and the rendering is always fast.
In addition I can say that with mkv it seems to me that cinGG exploits
a core, with mp4 exploits them all. To be precise with mkv the 8
threads range from 0% to 75%, while with mp4 they range from 40% to
100%. (seen with the KDE system monitor; I don't know how significant
it is).
Note that using ffmpeg from the command line does not show any
slowdowns (but the settings of cfr or other may be different; I don't
know).
Last but not least, it's a stupid consideration, because it shows my
ignorance of these issues:
Adam Williams in the 7.1 introduced corrections regarding mkvs
(although for quicktime and not ffmpeg). Could it not be that Cin (not
only CinGG) has an internal problem, not of the engine it uses, that
can decrease efficiency?