[mythtv-users] Draft revisions to HowTo section 3.3, second try
Bruce Markey
bjm at lvcm.com
Wed Apr 23 21:57:58 UTC 2003
Ray Olszewski wrote:
> Based on this morning's feedback -- both directly to my first draft and
> on other issues that were discussed in the last day -- I've revised the
> draft update a good bit. Here is the new version, for comments and
> criticisms.
Here are a few suggestions and comments in the spirit of
improving the documentation. You've taken on some touchy
issues and handled them well. I especially like your
explanation of DMA.
...
> 3.3.1 CPU Type and Speed
>
> Selection of CPU type and speed is the trickiest element of hardware
> selection, mainly because there are so many tradeoffs one can make,
> among number of things the MythTV device can do simultaneously, capture
> size, and encoding quality.
>
> MythTV has two modes of operation. It can function as a software video
> encoder, which means that it uses a fairly generic "dumb" video capture
> card to get frames of video, encodes them using the CPU on your
> motherboard and writes them to disk. High-end video capture cards and
> devices like the Tivo and RePlay have dedicated encoder chips which use
ReplayTV
...
> 3.3.3 Hard Disk(s)
>
> Encoded video takes up a lot of hard disk space. The exact amount
> depends on the encoding scheme, the size of the raw images, and the
> frames per second, but a typical value for MythTV is 2 GB/hour. Allow
> enough space.
typical values for MythTV range from 700MB/hour to 2 GB/hour.
[the default mpeg4 parameters are less than a 800MB/hr.]
...
> 3.3.4 Video Capture Card
>
> The system needs one of more video-capture cards for which Linux kernel
> modules exist. We know of no complete list of video-capture cards known
> to work with Linux; the "Cards" file that ships with kernel-bttv
> documentation is one place to check. The most common, inexpensive cards
> available are cards that use the bt848 or bt878 vidcap chip; examples
> are the "Hauppauge WinTV Go" card and the "AverTV Desktop PVR" card.
> They use the bttv kernel module.
>
> After you have installed a suitable card in a pci slot, you can check
> that the kernel sees it with "lspci". Look for an entry labeled
> "Multimedia video controller". To get more detailed information about
> the card, use "lspci -v" or "lspci -vv".
[this paragraph is installation/configuration and probably
belongs in a video troubleshooting section (which would need
to cover more than lspci ;-). The current docs seem to assume
that not only do you have a card installed, the driver is
loaded and you can probe and read video from /dev/video.]
...
> 3.3.5 Sound card
>
> The system needs a sound card, or an onboard equivalent on the
> motherboard, to play back sound and, in most cases, to record sound. Any
> sound card that can be operated by the alsa (Advanced Linux Sound
> Architecture) kernel modules will work with MythTV.
[Is this true? Might there be cards that have ALSA support
that do not handle full duplex properly?]
...
> 3.3.6 Video Display Card
>
> If you want to view television on a computer monitor, then you can use
> any video card for which there is an XFree86 driver that supports xVideo
> (xv) extensions. Check the XFree86 documentation for details if you are
> uncertain about your preferred card.
>
> Most people, though, want to view television on a television set. For
> this, you need either (a) one of the relatively small number of cards
> with TV-out outputs that are supported by Linux and XFree86, or (b) an
> external VGA-to-TV converter.
>
> For choice (a), MythTV users on the mythtv-users mailing list report the
> following experience:
[Replace the following paragraph]
>
> nVidia: recent nVidia cards (such as the GeForce4 MX440) are
> reported to work with the nvtv drivers, available at
> http//sourceforge.net/projects/nv-tv-out/; and with the drivers
> provided by nVidia itself at
> http://www.nvidia.com/content/drivers/drivers.asp .
>
nVidia: all cards with tv-out that are supported by
the current drivers from nVidia should be able to display
on a television. Some cards with certain chip sets support
overscan adjustment.
See: http://www.nvidia.com/content/drivers/drivers.asp
Many older nVidia cards (such as GeForce2 cards with tv-out)
can use <A HREF=http//sourceforge.net/projects/nv-tv-out/>nvtv</a>,
a utility which provides controls for overscan, x,y position
and several other useful controls to fine tune output.
[GeForce4 MX440 is a card that specifically does not work
with nvtv ;-]
...
> ATI: ATI is adament that it does not support use of its cards on
> Linux systems, and official XFree86 offers no support either. Some
> people report making some ATI cards work with the *experimental* version
with the *experimental* "devel" branch
> of the GATOS drivers, available in CVS at
> http//gatos.sourceforge.net/watching_tv.php.
...
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