[pvrusb2] aspect ratio
pakt223 at freemail.gr
Fri Jan 19 04:00:06 CST 2007
> It seems to me that it would be nice if the pvrusb2 device could
> automatically detect the aspect ratio of the incoming signal (whether
> broadcast, composite or s-video) and set the flag accordingly. At
> present, I have to visually decide what the intended aspect ratio is and
> manually set ctl_video_aspect, which is inconvenient.
It would certainly be nice :-) Unfortunately, AFAIK, this is not an easy
For broadcast, you would probably need VBI support (this is how ivtv does
it IIRC). For composite/s-video, if the thing feeding you the signal is a
decoder that is supposed to be talking to a TV and you have verified that
it can set the aspect ratio on a TV properly, then my (uneducated) guess
would be that it does that by sending VBI signals through the
composite/s-video cable as well, so you stumble on the above problem.
Otherwise, it is pretty much impossible (but then impossible is a pretty
strong word in the open source world, impossible things happen every
day here :-).
If the problem is VBI: It is true that once more ivtv has done a very large
and important part of the difficult work (we love you hans :-) and I would
surely like to implement VBI here (since this is the only way for me to
have greek teletext; not even windows can do that ;-), but I cannot (yet)
find how the VBI signal is coming through USB. The problem is that
VBI support in windows works only in USB 2.0 mode and I can 't get
usbsnoop to work in this mode (it only logs the initial handshake,
nothing more :-(
> I am particularly
> interested in having this functionality for composite and s-video.
> (Analog TV broadcasts have stopped here). But, I have to admit that I
> don't even know if composite or s-video contains information about
> aspect ratio. Would someone care to comment?
In any case, I can only assume that this driver is eventually going to have
VBI support, but I wouldn 't hold my breath since this is nobody 's day job.
My advice would be for you to get a DVB card (since analog broadcasts
have stopped there). This will probably solve your problem since this
way the aspect_ratio information will be right in the mpeg stream from the
source (I think).
That 's all I know. Hope this helps,
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