[mythtv-users] New version of windows filters for mythtv

Torbjörn Jansson torbjorn.jansson at mbox200.swipnet.se
Mon Mar 1 12:54:37 EST 2004

mythtv-users-bounces at mythtv.org <> wrote:
> Torbjörn Jansson wrote:
>> Just wanted to tell that I have released a new version of the
>> directshowfilters for mythtv (0.5).
>> Some of the changes:
>> * A new filter that reads from mythbackend directly.
>> This filter uses two urls to play files, myth://host:port/file.nuv
>> (same as used internaly by mythtv) and mythlivetv: Channel changing
>> is not implemented yet.
> I've used the .4 version on my laptop and main computer and saw bad
> interlacing.  Is there some way to deinterlace the video?

There is filters that mythbackend can use when recording. Some of the
filters is used to deinterlace the video.
The filters is applied per channel and can be added from either the channel
enditor in mythweb or the channel editor in the setup program.
I think there was some discussion about documenting how the filters work and
what filters is available on the developer mailing list.

I have setup all my analog channels to use the filter "kerneldeint" ("Video
filters:" in the channel setup).
Adding filters to a channel will make mythbackend use more cpu when

> What are the advantages of reading from the backend as opposed to
> either from an SMB share (which seems rather jittery on my system over
> 11g) or by using the url for each recording from MythWeb (which
> provides a smoother playback on my system, although I have to actually
> copy the url from mythweb into wmp9)?

Without the network filter some data will be read twice and the reads will
not be sequential.
The network filter adds a small cache to avoid seeking, this lowers network
utilization and improves preformance a bit.

The cache is not perfect, for example it doesn't do any read ahead so if you
have a slow network you may not be able to use the network filter (video and
audio will always be too late and get dropped).
Another problem is that the cache is rather smal, so if audio and video gets
too much out of sync, the filter is forced to ask mythbackend to seek at
every read request and this is bad because seeks is timeconsuming.

I have tried to adjust the cache so it works as good as it can.

> Since I'm running the CVS verion of myth, which has a different
> mythbackend-mythfrontend protocol than .14, I assume that the filter
> that connects to the backend won't work on my system?

Probably not.
There is some checks to make sure the filter and mythbackend uses the same
network protocol.
I have to take a look at the mythtv cvs and check what has changed in the
network protocol.

> Thanks for the hard work and the time to answer my questions!
> Bob

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