On Saturday 15 July 2006 20:48, Rich Kadel wrote:
> Hans,
>
> To clarify, are you saying that zvbi, by default, is using hardware
> decoding for VBI, and that maybe I can resolve the problem by turning
> off the hardware decoding? If so, does zvbi also provide the
> software decoder, so I can just switch it and maybe get better
> results?
zvbi provides software decoding (that's the main use of zvbi in fact).
Hardware decoding (sliced VBI) depends on the hardware used, and I
suspect that the cx2584x isn't as good at it as the saa7115. I have
some problems myself with certain channels where the first leading
pulse of the last teletext line is half-height for some reason (clearly
visible with osc). The hardware decoder misses that line in about 25%
of the frames. Just to give you an idea of the problems that might be
involved here.
Sliced VBI however is the only way you can reasonably embed CC data into
an MPEG stream. So in that case you would be limited to sliced VBI.
There may be some tweaking that you can do by setting some cx2584x
registers (see the datasheet, VBI registers) but that didn't have any
effect on my teletext problem, so I'm not holding my breath.
Hans
>
> (Wishful thinking?)
>
> Thanks,
> Rich
>
> --
>
> Rich Kadel
> Know'bout, Inc.
> (858) 433-1747
> www.knowbout.com
>
> Do you know about Know'bout?
>
>
> -----Original Message-----
> From: Hans Verkuil [mailto:[EMAIL PROTECTED]
> Sent: Saturday, July 15, 2006 3:41 AM
> To: [email protected]
> Cc: Rich Kadel; 'User discussion about IVTV'
> Subject: Re: [ivtv-devel] VBI errors on NTSC Cable channels 56 and 57
> - ivtv problem?
>
> On Saturday 15 July 2006 04:59, Rich Kadel wrote:
> > OK. I verified that the PVR-500 does NOT have this problem in
> > Windows Media Center.
>
> Under Windows only 'raw VBI' is used. That should work fine under
> Linux too.
>
> > When I use zvbi to extract VBI closed caption and XDS information,
> > I get constant parity errors on channel 56 (NTSC broadcast), making
> > the CC data unusable. (I'm not sure a single character is right).
> > On channel 57, I get frequent Parity errors (about every 10
> > Line-21's or so). Channels 54, 55, 58, and 59 are very clean.
>
> Are you using 'sliced VBI' or 'raw VBI' with zvbi? That's a very
> important difference. In any case, it may be useful to look at the
> raw VBI data with the osc tool included with zvbi: you can use it to
> check if the VBI wave form is somehow different or noisier in the
> problem channels compared to the other channels.
>
> Hans
>
> > When I look at the video on channel 56, it appears OK.
> >
> >
> >
> > I am using ivtv 0.4.6.
> >
> >
> >
> > Is this an IVTV problem? Is it a known problem?
> >
> >
> >
> > It does not appear to be a problem with the card, since the card
> > works in Windows.
> >
> >
> >
> > As mentioned in the thread below, this occurs on multiple Linux
> > machines, in different locations (miles apart) but with the same
> > cable provider.
> >
> >
> >
> > Thanks,
> >
> > Rich
> >
> >
> >
> > --
> >
> >
> >
> > Rich Kadel
> >
> > Know'bout, Inc.
> >
> > (858) 433-1747
> >
> > www.knowbout.com
> >
> >
> >
> > Do you know about Know'bout?
> >
> >
> >
> > _____
> >
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] On Behalf Of Rich Kadel
> > Sent: Friday, July 07, 2006 6:19 PM
> > To: 'User discussion about IVTV'; [email protected]
> > Subject: [ivtv-devel] Problems with PVR-x/IVTV and VBI data on
> > certainchannels
> >
> >
> >
> > Does anyone know why I get parity errors when trying to extract VBI
> > data (e.g., closed captioning) on certain channels?
> >
> >
> >
> > For comparison, on a Windows PC, using a Conexant Falcon-II based
> > card that appears to come from ASUSTEK (it was bundled in the
> > Windows Media Center HP Pavilliion I got), the closed caption comes
> > through Media Center "loud and clear".
> >
> >
> >
> > However, on Linux (Centos 4.3), using IVTV and the ZVBI library, I
> > have not been able to read VBI on Channels 56 and 57. 55 works
> > fine, as do many other channels. I have not tested exhaustively,
> > but I think 70 worked fine too, so it doesn't appear to stop at the
> > frequency for 55.
> >
> >
> >
> > I am seeing this problem with PVR-150, PVR-250, and PVR-500 cards,
> > in two different physical locations (miles apart), but using the
> > same Time Warner cable provider (San Diego). It is consistent. No
> > luck with those channels over the last 4 days.
> >
> >
> >
> > Is it the IVTV driver or the Hauppauge cards? I bought them all in
> > the last 2 months, and there are a variety of tuners (TCL,
> > Phillips, Samsung, and LG) on these cards. I believe I've tested
> > with all of those varieties. The Tuner appears NOT to be the
> > variable. The picture seems to be fine as well, using the
> > Hauppauge cards.
> >
> >
> >
> > I have not yet tried one of the Hauppauge cards in Windows Media
> > Center, so yes I will do that next and let you know.
> >
> >
> >
> > Thanks,
> >
> > Rich
> >
> >
> >
> > --
> >
> >
> >
> > Rich Kadel
> >
> > Know'bout, Inc.
> >
> > (858) 433-1747
> >
> > www.knowbout.com
> >
> >
> >
> > Do you know about Know'bout?
>
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