[mythtv-users] HDMI Capture
list at onnow.net
list at onnow.net
Mon Sep 18 10:42:28 EDT 2006
This is excellent. I for one, would be willing to shell out for 8
drives in a raid and the card. Whats the next step from here?
Quoting Gene Stapp <genestapp at gmail.com>:
> Graeme Wilford wrote:
>> On 12/09/06, Steve Daniels <steve.p.daniels at googlemail.com> wrote:
>>> Just seen this in the register:
>>> Reckon something like that could be used in linux as a capture device for
>>> myth maybe?
>>> Please feel free to ignore if this is a rubbish idea..
>> So presumably, it may be possible to capture off-air HD in the UK?
>> Say, taking the component output of a SkyHD box, converting it to HDMI
>> using something like this:
>> http://www.gefen.com/kvm/product.jsp?prod_id=3569 and then throwing it
>> at the intensity card... ?
>> I'm stuck with SD on NTL and a PVR350 right now but this does sound
> I emailed the blackmagic development team about the intensity card. It
> looks like on the fly compression is doable with a dual core from what
> they are saying. It's just a driver/codec design thing now. Uncompressed
> HD would require us to raid 0 about four 500GB drives to have enough
> storage and transfer speed for 4 hours of 1080i content.
> here is their reply:
> The Intensity card has generated quite a lot of interest with the
> Linux and Open Source community, something which we did not expect.
> 1. In the Windows platform, we allow the user to capture and compress
> on the fly to a JPEG format while on the Mac, to DV, PhotoJPEG as
> well as DVCPRO HD. A fast processor will be necessary and also a
> capture friendly codec. Certain codecs don't fare well with on the
> fly compression, d.g. HDV.
> 2. Uncompressed HD video will require more than 100MB/sec of transfer
> rate. I've attached a small clipping from our PDF manual with some
> typical transfer rates using the Apple or Blackmagic Uncompressed
> 4:2:2 and 4:4:4 codecs for your reference.
> 3. The compression on capture (if chosen) is in real time but this is
> done in software, relying on the processing power of the system. We
> don't have any hardware acceleration built in. Uncompressed capture
> actually requires less processing power.
> A. I'm not sure of the requirements for post capture compression but
> dual cores and quad core machines should be fine. We use dual cores
> PCs and Macs in our labs as well. I guess post processing is simply
> takes up less time with more powerful hardware.
> 4. You're correct. We don't have any Linux drivers. However, the
> response from the Linux community has been good and we've notified
> our engineers about it. Hopefully, this is something that can look into.
> Kristian Lam
> Blackmagic Design
>> I am a user sometimes code contribute of a popular open-source
>> Linux based pvr system - Mythtv. The new Intensity HDMI capture
>> card coming out looks like it may be the perfect hardware input for
>> cable boxes/high def content coming through non-encrypted hdmi. I
>> have some questions about the capability of the hardware that I
>> didn't see listed on the website or spec sheet anywhere.
>> 1. What would it take to compress the video coming in real-time to
>> make the huge amounts of data easier to manage.
>> 2. What kind of storage requirements/read and write speed
>> requirements are we talking here. As you know, uncompressed HD
>> takes up massive amounts of space. Many mythtv users run very large
>> raid 5 arrays above 1TB with transfer rates usually between 60MB
>> and 100MB a second (if not higher)
>> 3. Does this device use any form of hardware compression or is
>> everything software based.
>> A. If it's hardware or software, what kind of processing power are
>> we needing for compression/partial compression with multi-pass
>> compression later say after the recording is finished. Dual-core?
>> Quad-core? A lot of us run dual processors in the 4ghz range with
>> large amounts of ram.
>> 4. I know you currently do not have Linux drivers, but the Linux
>> development community can make those easy enough if the intensity
>> card can be adapted as a HD capture device.
>> Gene Stapp
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