Hannu Vuolasaho <[EMAIL PROTECTED]> wrote on Thu, 24 May 2007
> 
> This is second hand information because my HDV camera is still in the shop. 
> I'm waiting for 1080p  :) 
> 
> Anyway. there is program called mpegrab or similar which can grab trough 
> firewire the uncompressed video. The need of mpegcompression comes from the 
> DV-media which can't handle the stream without it.
> 
> I've seen this work with my friend when he shot a scene Sony Vaio in his 
> pocket grabbing the scene. He is real gear geek.
> 
> Or am I now giving totally wrong advices? 

Regarding hdv/mpeg2 capture:
As discussed also on this list and i.e listd on this link
http://www.linux1394.org/view_device.php?id=1035
mpg1394grab and test-mpeg2 are mentioned for hdv capture.
I've not found these tools available for openSUSE as I'm using.

Currently it looks for me of more interest to get a running version of
and try dvgrab w/full hdv-patch as announced on this list and here:
http://sourceforge.net/tracker/index.php?func=detail&aid=1703694&group_id=14103&atid=314103
I'm interested to hear possibly update info about dvgrab compiled with
this patch.

Uncompressed video over firewire:
Maybe, maybe not for DV25 I think, dependent of the baud rate capability
of the camcorder's 1394 interface. FX7 has a S100=100Mbps i.LINK
interface (while higher capacity S200 and S400 interfaces do exist).
DV25 compressed 5:1 uses 25Mbps, or about 3,6MB/s included audio.
"Uncompressed DV25" video looks therefore to require about 125-150Mbps

To compare with HDV 1080i video that also use 25Mbps, does uses a much
higher bit rate reduction ratio 20:1 (mpeg2 compression). Uncompressed
HDV 1080i looks therefore to require higher bandwidth than Firewire can
manage.


> The HDMI confuses me a bit.
>> >
>> >The CityDisk (the second link in my inital post above) is also claimed to
>> >be able to record in DV format at the same time as HDV is recorded on
>> >If you are playing a 1080i HDV tape, the 4:2:0 MPEG-2 is decoded and
>> >chroma up-scaled to a 4:2:2. The HDMI chip downscales 1440 to 1280 while
>> >it up-scales 540 to 720. The result is 720p which is output via HDMI."
>> >
> 
> Be sure to check the firmware of Citydisk. Some work, some don't. I believe 
> this information can be digged from various webforums.

Until HDMI capture cards (with driver support for Linux) become
available, HDMI is of most practical use for output monitoring. As a
more intelligent interface, HDMI does automatically sense the capability
of the receiver and does scale the output to HDV 1080i, HDV 720p or DV
480i/576i according to that.


Terje J. Hanssen



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