[openbeos] Re: The importance of a FAT32-driver
- From: "Marcus Overhagen" <dos4gw@xxxxxx>
- To: openbeos@xxxxxxxxxxxxx
- Date: Wed, 6 Mar 2002 20:02:29 +0100
"Gregor Rosenauer" <rosenauer@xxxxxx> wrote:
>
>> The R5 one reads the whole file before starting playback, the beta scans it
>> in the background. The first one results in long startup time, the second
>> one will
>> in conjunction with FAT-32 result in very choppy playback.
>ic - did not know that.
>How do other players on other OSs handle this? I did not notice such behaviour
>on "The Playa" or MediaPlayer in Win, for example...
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 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.
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.
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.
Marcus
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