[mythtv-users] [UK] - What's the best way to capture from a Sky digibox?

[Nick Morrott]

On 23 November 2010 10:42, George Poulson <george.poulson at gmail.com> wrote:

> Prior to me relocating my backend 'out of the way' it too used to live just
> behind the TV, and I have previously fitted a Hauppauge HVR-1300 (combined
> DVB-T, FM Radio and video capture) PCI card into the backend and linked it
> to the digibox, but all I ever managed to capture from it has been a mixture
> of lousy quality black-and-white video and out-of-sync audio.

Black and white video is frequently due to an S-Video/composite
mismatch somewhere in the path between the STB and capture card.
S-Video transmits the colour (chrominance) and brightness (luminance)
as separate channels, and what tends to happen is the capture card
ends up recording only the luminance channel resulting in a black and
white image/video. I my experience this can happen with a faulty
cable/adapter, or if the wrong driver input is chosen when configuring
the capture card.

You might also want to monitor your system log whilst you are
recording with the card to ensure there are no other issues (IRQ
conflicts/DMA issues, for example) that may also be affecting its
operation.

Perhaps you could detail the signal path between the STB and capture
card (i.e. cables, adapters, the sockets you're using, etc) so we can
get a better understanding of what might be going wrong?

With a hardware MPEG-2 card (such as the HVR-1300) you shouldn't see
any AV sync issues as the audio and video is fed directly into the
card's encoding hardware. You should ensure that the audio and video
connections are entering the capture card directly from the STB
though, to keep latency at a minimum.

I've been using the older PVR-150/350 cards since late 2006 and have
never noticed any sync problems that I can recall. I currently capture
the composite output from a non-HD-capable Virgin TV STB (with lack of
S-Video output option) with a PVR-150, and the quality is fine for us.
Back when we had 2 STBs the PVR-350 was also used, and that was also
fine.

> Compared to
> watching the digibox output via the normal SCART connection I have also been
> seeing huge delays.

What type of delays? Changing channel? Starting LiveTV for the first
time? On my ageing PVR-350/VirginTV setup I see small delays (a few
seconds) when starting LiveTV or changing channel. As my STB provides
no feedback to MythTV as to the success or failure of a channel
change, I've modified the channel changing script to return
immediately and background the actual channel changing operation to
another script. I've disabled the STB's own OSD (which occasionally
gets stuck onscreen and would otherwise be recorded), and carry out
the channel change itself 3 times to better handle failed changes.

Cheers,
Nick

-- 
Nick Morrott

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