blackmagic capture card
Posted: 27 Nov 2009 22:56
I do. First, some context.
For the last several months I've been appealing to the VLC development
community (even posting several paying bounties, listings on guru.com and
e-lance, etc) and others (such as the DSP and thread-aware Erik who writes
http://www.baudline.com/, a *nix real time FFT and viz tool) to 'clean up'
several oh-so-completely-messed-up things related to working with, handling,
encoding, and transporting HD-sized video. I feel very strongly that
democratizing not only access to content (the current focus of vlc
development), but also CREATION of content (what used to just 'work' well
enough, but now is broken) is a critical element of democracy. Having had a
tool like VLC which supported cheap/free creation of live, HD content, go
from working to completely non-working in the span of one year,
appropriately, drives me absolutely mad.
At the present time, the HD sized frames that the BlackMagic Intensity (i.e.
decklink de-framer/hdmi transceiver receiver chip under the hood) provides
via directshow are UYVY-formatted, yet represent a different chroma subtype
of HDYC. The current 0.9.x version of VLC available doesn't know how to make
sense of this media subtype. There are accepted patches in the 1.0-trunk
which add support, but there are no color space conversion filters available
for dealing with it 100% correctly.
That is to say, you can bring 4:2:2 in as UYVY, but it's in a HDYC color
space. Further, until 1.0 vlc is out, you won't be able to use it. It's
totally serviceable-looking video, but just keep this in mind if you plan to
use video that pushes the edges of HDYC gamut.
On a positive note, in response to one of my appeals to the VLC community, Ed
Gomez kindly added his patches (for HDYC subtype to support black magic
cards) to the 0.8 bug fix branch, dubbed 0.8.7, and put together a tool chain
to crank out a version for testing purposes.
Here's part of an email regarding what he's done with 0.8.7 so far:
---------- Forwarded message ----------
From: Edouard Gomez <ed.gomez@free.fr>
Date: Wed, Jan 7, 2009 at 4:33 PM
Subject: got something to test (was Re: VLC + blackmagic)
To: Anton Kapela <tkapela@gmail.com>
Anton Kapela (tkapela@gmail.com) wrote:
> and to remind you I have some nifty hardware to test with if you don't mind
>:)
No i don't mind of course.
It's time for you to spend a bit of time trying to get a build running:
http://ed.gomez.free.fr/vrac/vlc-0.8.7-win32.exe
I tried to keep as much as i could from complete vlc, i had to drop:
- internationalization
- activex
- mozilla plugin
- cddax
- vcdx
- skins2
---------- End Forwarded message ------
In short, 0.8.7 as available on Ed's site, will *properly* open the 4:2:2
blackmagic input and display it on-screen.
The unfortunate bit is that the ffmpeg/libavcodec version his tool chain uses
is presently un-threadable on win32!
This means that the clean and nice HD video you just brought in from
directshow won't be able to make it through mpeg2/4/h264-ifying, unless you
happen to have a mythical 6 to 7 ghz single core cpu. The dual-quad cores we
have here sit 700% idle, crunching away the single-thread worth of mpeg2
transcoding. I find that scaling by .5 (960x540) shrinks the mpeg2 workload
enough (though without any rate-distortion compensation, trellis, and motion
pre-estimation enabled) to fit comfortably into about 90% a single core of a
2.3ghz core2quad.
Perhaps this email will reach someone at a university somewhere who happens
to be friends with a few CS grads who'd like to take on the challenge of
cleaning up pthreads and win32 threads in libavcodec/ffmpeg. <G>
Here's to hoping!
Best,
For the last several months I've been appealing to the VLC development
community (even posting several paying bounties, listings on guru.com and
e-lance, etc) and others (such as the DSP and thread-aware Erik who writes
http://www.baudline.com/, a *nix real time FFT and viz tool) to 'clean up'
several oh-so-completely-messed-up things related to working with, handling,
encoding, and transporting HD-sized video. I feel very strongly that
democratizing not only access to content (the current focus of vlc
development), but also CREATION of content (what used to just 'work' well
enough, but now is broken) is a critical element of democracy. Having had a
tool like VLC which supported cheap/free creation of live, HD content, go
from working to completely non-working in the span of one year,
appropriately, drives me absolutely mad.
At the present time, the HD sized frames that the BlackMagic Intensity (i.e.
decklink de-framer/hdmi transceiver receiver chip under the hood) provides
via directshow are UYVY-formatted, yet represent a different chroma subtype
of HDYC. The current 0.9.x version of VLC available doesn't know how to make
sense of this media subtype. There are accepted patches in the 1.0-trunk
which add support, but there are no color space conversion filters available
for dealing with it 100% correctly.
That is to say, you can bring 4:2:2 in as UYVY, but it's in a HDYC color
space. Further, until 1.0 vlc is out, you won't be able to use it. It's
totally serviceable-looking video, but just keep this in mind if you plan to
use video that pushes the edges of HDYC gamut.
On a positive note, in response to one of my appeals to the VLC community, Ed
Gomez kindly added his patches (for HDYC subtype to support black magic
cards) to the 0.8 bug fix branch, dubbed 0.8.7, and put together a tool chain
to crank out a version for testing purposes.
Here's part of an email regarding what he's done with 0.8.7 so far:
---------- Forwarded message ----------
From: Edouard Gomez <ed.gomez@free.fr>
Date: Wed, Jan 7, 2009 at 4:33 PM
Subject: got something to test (was Re: VLC + blackmagic)
To: Anton Kapela <tkapela@gmail.com>
Anton Kapela (tkapela@gmail.com) wrote:
> and to remind you I have some nifty hardware to test with if you don't mind
>:)
No i don't mind of course.
It's time for you to spend a bit of time trying to get a build running:
http://ed.gomez.free.fr/vrac/vlc-0.8.7-win32.exe
I tried to keep as much as i could from complete vlc, i had to drop:
- internationalization
- activex
- mozilla plugin
- cddax
- vcdx
- skins2
---------- End Forwarded message ------
In short, 0.8.7 as available on Ed's site, will *properly* open the 4:2:2
blackmagic input and display it on-screen.
The unfortunate bit is that the ffmpeg/libavcodec version his tool chain uses
is presently un-threadable on win32!
This means that the clean and nice HD video you just brought in from
directshow won't be able to make it through mpeg2/4/h264-ifying, unless you
happen to have a mythical 6 to 7 ghz single core cpu. The dual-quad cores we
have here sit 700% idle, crunching away the single-thread worth of mpeg2
transcoding. I find that scaling by .5 (960x540) shrinks the mpeg2 workload
enough (though without any rate-distortion compensation, trellis, and motion
pre-estimation enabled) to fit comfortably into about 90% a single core of a
2.3ghz core2quad.
Perhaps this email will reach someone at a university somewhere who happens
to be friends with a few CS grads who'd like to take on the challenge of
cleaning up pthreads and win32 threads in libavcodec/ffmpeg. <G>
Here's to hoping!
Best,