[openbeos] Re: The importance of a FAT32-driver
- From: François Revol <revol@xxxxxxx>
- To: openbeos@xxxxxxxxxxxxx
- Date: Wed, 06 Mar 2002 22:22:58 +0100 (MET)
En réponse à Marcus Overhagen <dos4gw@xxxxxx>:
>
> It is simply a problem of a accuracy when seeking to another point in
> the file.
> I think MPEG files have no seeking information embedded, thats why BeOS
> currently scans the whole file to build such a table in memory. Such
This is also needed to determine the Duration() of the file.
Ever tried to play a .mpg before it is completely downloaded ?
The playack will just stop at end the file had when you started playing it,
because both the Duration() tells it, and it didn't get scanned beyond this
point.
> behaviour
> is needed when editing files, since you need to be exact. However, this
> is
> not needed when only displaying a video in a player, and it would be
> possible
> to just estimate the postition in the file, then start searching the
> mpeg stream until
> you encounter an I frame (a new picture). This will result in a
> inccurate position
> reporting, the time displayed may be a few seconds wrong.
This is exactly the same as what mp3 player does. (mp3 being no more than an
audio mpeg stream)
> Windows seems to do this, thus is has a fast seeking in mpeg files, and
> nobody
> really notices that the time information may be wrong.
> We will probably add another flag to the
> BMediaTrack::SeekTo[Frame|Time]
> call, so that the application can tell to codec to do a fast but
> inaccurate seeking.
I agree (this would also allow progressive download to be handled correctly).
> This would be useful for all media player aplications. Editing
> applications, as well
> as all other (old) applications not using using this flag would get the
> accurate
> seeking, because they would ommit this flag.
François.
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