RE: HD Capture Card (HDMI and Component) output raw pixels

Charlie X. Liu
2013-06-20T00:06:48Z

If 1080i60 or 1080p30 as max supported, the bandwidth requirement would be 124.416MB/s (1920*1080*2*30, in YUV422 format). Make sense and it can pass through over a PCIe lane x1.

-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-owner@vger.kernel.org] On Behalf Of Bjørn Mork
Sent: Wednesday, June 19, 2013 7:10 AM
To: James Board
Cc: Daniel ﻿Glöckner; Steve Cookson; linux-media@vger.kernel.org
Subject: Re: HD Capture Card (HDMI and Component) output raw pixels

James Board <jpboard2@yahoo.com> writes:

> You are right. According to your numbers, this card can't work. So
> why would BlackMagic design an HDMI capture card with only one PCIe
> lane if it can't possibly work? It must work somehow. I must be
> missing some crucial piece of information.
>
> The card doesn't support hardware encoding, right? If so, raw pixels
> are the only output. Maybe the card uses more than one PCIe lane?
> What makes you think the card only uses a single lane?

http://www.blackmagicdesign.com/products/intensity/techspecs/ says so.
It also says

HD Format Support: 1080i50, 1080i59.94, 1080i60, 1080p23.98, 1080p24,
1080p25, 1080p29.97, 1080p30, 720p50, 720p59.94 and
720p60.

which makes the 1080p50 calculation a bit irrelevant.

> Are they using lossless compression to get the raw pixels data rate
> under 200-250 MB/sec, which is the PCIe speed?

None of the supported formats need more than ~180 MB/sec.

Bjørn
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