[MPlayer-users] Linux USB - VGA/DVI adapters?

[Siemen Baader]

On Sun, Jan 18, 2009 at 7:23 PM, Oliver Seitz <info at vtnd.de> wrote:
> Am 18.01.2009, 19:09 Uhr, schrieb Siemen Baader <siemenbaader at gmail.com>:
>
>> Hi List,
>>
>> I am about to set up a video installation with one pc connected to
>> 18(!) screens playing mostly pre-recorded MPEG clips as well as a few
>> IP based streams and custom visualizations. The MPEG is encoded at
>> 1mbps (I think that is fairly good quality, right?)
>
> For 1680x1050 resolution at 25fps in MPEG2, you should calculate 6MBit per
> stream as I recently tested. Quality's terrible with lower bitrates then.
> Depends on the resolution and framerate of your videos.

Yes - my videos are significantly smaller (640*480), so about 1/6th
the pixel size -- I did not mention that, my bad. But thanks a lot for
the info. It confirms that the bitrate should be ok for that
resolution.

For the calculation I used 2mbps as a safety margin -- so this part
theoretically still holds.

>
>
>
>>
>> After doing a few calculations on the volume of the data streams
>> within the machine (pci & usb bus, hdd reading spead), it seems
>> possible to me to connect all 18 screens using mpeg2-decoding external
>> video cards via USB 2.0 (using powered hubs).
>>
>> So my question is: Do you know of any USB-to-VGA (or DVI) adapters
>> that can decode MPEG2 (or any other suitable encoding) in hardware
>> that will work with Linux / mplayer? Other media players would also be
>> fine.
>
> Haven't seen something like that, I only know of a USB to VGA adapter
> which is very cheap but also very dumb. You can hope to play a 640x480
> video on it, but don't think about using two at a time.

Makes sense; if it is all software decoding then this is going to be CPU bound.

>
> I've tried some things in playing multiple videos and my approach for 18
> screens would be 18 players using cheap onboard graphics or 9 players with
> better graphics cards.
>
> But if you have success with 18 streams at once, tell me, I'd like to know
> ;-)

Sure ;)

I still think it should be possible if the entire decoding & rendering
is off-loaded to the video cards. If I can't do it with USB devices
I'll investigate putting several PCI video cards with multiple heads
into one tower alongside with using stand-alone players...

Any breaktroughs I'll post back here just in case anyone is interested.

>
> Greets,
> Kiste
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