[linux-dvb] Re: dec2000-t success

[Holger Waechtler <holger@convergence.de>]

Bruce Janson wrote:
>     From linux-dvb-bounce@linuxtv.org Sun Apr 27 23:54:05 2003
>     ...
>     From: Alex Woods <linux-dvb@giblets.org>
>     To: pdq808@t-online.de (Reiner Klenk),
>      linux-dvb@linuxtv.org
>     ...
>     Date: Sun, 27 Apr 2003 14:52:22 +0100
>     ...
>     On Sunday 27 Apr 2003 10:08 am, Reiner Klenk wrote:
>     > On Sun, 27 Apr 2003, Bruce Janson wrote:
>     > > However, according to
>     > >
>     > >   http://www.linux-usb.org/linux.conf.au.02/talk/html/slide_5.html
>     > >   http://www.usb.org/faq/ans2#q1
>     > >
>     > > the DEC 2000-t's USB 1.1 interface will impose a 12 Mbits/s limit on
>     > > its USB->PC interface.  I do not know the maximum (compressed)
>     > > throughput that can be required by a 7 MHz, DVB-T transport stream
>     > > (23 Mbits/s?), but I suspect that it does exceed 12 Mbits/s.
>     > > If true, this would impose an unfortunate limitation on the DEC 2000-t.
>     > > (USB 2.x at 480 Mbits/s would have avoided this...)
>     >
>     > Yeah, I am a little confused here, too. I just tuned to one of the
>     > stations and mplayer tells me the video stream is:
>     >
>     >  MPEG2 720x576 (aspect 2)  25,00 fps 18750,0 kbps (2343,8 kbyte/s)
>     >
>     > plus the audio stream:
>     >
>     > Layer: 2  BRate: 192 kb/s  Freq: 48.0 kHz
>     >
>     > That would exceed the USB 1.1 data rate. Does this mean that the transport
>     > stream adds another level of compression ?
>     >
>     > Anyone knows whether the dec2000 can also handle ac3 audio streams ? If
>     > so, how can I extract them from the transport stream ?
>     ...
>     
>     Some of the videostream rates I've had reported from the dec, here in the UK, 
>     have been:
>     
>     4MBit/s, 5.3Mbit/s, 6Mbit/s, 10Mbit/s and 15Mbit/s
>     
>     These are from QAM16 and QAM64.  I've seen 15Mbit/s on both of these.  How it 
>     fits these down USB 1.1, I have no idea.  I'm neither a USB expert or a DVB 
>     expert.
>     ...
>
> Interesting.  Perhaps the Hauppauge web page specification is in error
> and it really is a USB 2.x port.  (I am not a USB expert either.)
This box contains the TUSB3200 transceiver from TI, this is a USB 1.1 chip.

Holger




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