Subject: RE: Firewire/1394 for live streaming

From: Bill Nowicki <[email-masked]>
Date: Wed, 14 Jun 2000 13:07:27 -0700

Alas, the $50 FireWire PCI cards (or motherboard interfaces on Sony PCs
etc.) do not have a decoder for the DV, so you get the DV encoded stream.
The Windows 98 and 2000 support is a Windows Driver Model driver, not Video
for Windows. So DirectShow applications can work (like most DV editing
tools), but Windows Media Encoder does NOT. My DV over RTP implementations
use DirectShow and the Windows driver for simple cards.

A few more expensive cards have DV decoder chips on them. They generally
have private drivers that work only with the applications from the vendor
who sells them, mostly editing tools. We are trying to get an Osprey-500DV
which might be able to be used in this way. We (and others) make boxes that
can decode DV and encode MPEG-2, which you could just connect back to back,
but are "Professional Quality" (i.e. expensive!).

Bill Nowicki, Omneon Video

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 14 Jun 2000 16:18:00 -0400

> use DirectShow and the Windows driver for simple cards.

Is this an application that is available free/otherwise (and thus should
be added to the RTP implementation list)?

> but are "Professional Quality" (i.e. expensive!).

Given that DV is apparently DCT-coded, would it be possible to generate
MPEG-1 I frames without hardware support or is the DV format (besides
the packing into 80? byte units) so different that one has to go back to
"raw bits"?

-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs

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From: Kevin Marks <[email-masked]>
Date: Wed, 14 Jun 2000 17:03:42 -0700

>the packing into 80? byte units) so different that one has to go back to

The way DV encodes fields is different from MPEG, as I understand it. 
DV is a fixed size format which does not map well to MPEG1 (which is 
a different size, and doesn't do fields). You could optimise the 
decode-recode path by going to a common YUV format and only decoding 
the coefficients you need.

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From: Kevin Marks <[email-masked]>
Date: Wed, 14 Jun 2000 17:00:04 -0700

>use DirectShow and the Windows driver for simple cards.

QuickTime has a DV decoder, so you could wrap your capture code in a 
QT VDIG, and use QT to capture and recompress from the API level.

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From: Katsushi Kobayashi <[email-masked]>
Date: Thu, 15 Jun 2000 10:57:04 +0900

> be added to the RTP implementation list)?

You can found a DV over RTP implementation on FreeBSD
from http://www.sfc.wide.ad.jp/DVTS (also including FreeBSD
driver information).

-- 

                                                            [email-masked]

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From: Ricardo Balbinot <[email-masked]>
Date: Thu, 15 Jun 2000 10:35:42 -0300 (EST)

> use DirectShow and the Windows driver for simple cards.

Yeah, that is true... And de WDM drivers are suposed to be better than the
old video for windows ones. 
But you see, most of the available drivers are still developed for Video
for Windows, so, in Win98 and, perhaps, in Win2000, the drivers are
implemented following the WDM, but behaves like a normal Video for Windows
driver. Truly, most directshow or directvideo applications use those
drivers just like a normal video for windows applications (the driver
maps a video for windows driver in the WDM architecture). So, I can't see
why Windows Media Encoder does not work at all. In fact, if you see that
the windows media is heavilly based on the directx technology, that's a
strange sentence. Anyway, at the site of the windows media technologies
you can download the new Media Player (and tools) specific for Win98 and
2000(that's the beta release, I believe), that may solve this "problem".

Bets regards,
Ricardo Balbinot.