[mythtv] Question about the nuv seektable and keyframes

Torbjörn Jansson torbjorn.jansson at mbox200.swipnet.se
Sun Aug 10 21:02:46 EDT 2003

The keyframe interval I have seen is 30.

There is two reasons for building the seektable manualy.
It coud be that it doesn't exist or that the file is being streamd over the
network (http for example) and trying to seek to the seek table will force
the whole file to be downloaded (since the seektable is last in the file)
before being able to see anything.

How will this change affect the calcucation of the total length of the file?
Can I still do something like this: (totalkeyframes*keyframedist)/fps to get
the length? Or will that be somewhat incaurate?

Another thing that woud be helpful is to have for example videoblocks member
of rtfileheader filled with something other than -1. because without the
seektable it's a bit hard to know how long the file is.

> -----Original Message-----
> From: mythtv-dev-bounces at mythtv.org 
> [mailto:mythtv-dev-bounces at mythtv.org] On Behalf Of Geoffrey Hausheer
> Sent: Sunday, August 10, 2003 5:11 PM
> To: mythtv-dev at mythtv.org
> Subject: Re: [mythtv] Question about the nuv seektable and keyframes
> On Sun, 10 Aug 2003 15:58:08 +0200, "Torbjörn Jansson
> torbjorn.jansson-at-mbox200.swipnet.se |mythtv/1.0-Allow|"
> <1pu3hibvy20t at sneakemail.com> said:
> > If i'm going to build the seektable manualy i just have to 
> look for video
> > sync frames and then calculate the keyframe number and position?
> Be careful here.  The addition which was added to support
> commecial-cutting means that you won't find a key-frame every 
> 15 frames
> anymore.  Every keyframe contains its frame number, and the 
> list of all
> key frames is stored in the nuv file (except when something 
> went wrong). 
> I would just find the 'Q' frame that corresponds to the 
> key-indexes, and
> use it to build the seek table.
> -- 
>   Geoffrey Hausheer
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