hi i'm trying to capture an avi file via virtualdub64 on windows x via al black magic intensity pro 4k card and i would appreciate your thoughts on my workflow/roadblocks im experiencing please.
in my blackmagic video setup under the default video standard - i chose 625i50 pal (its from a pal camcorder to pal)and the input connection was set to composite and some reason it also also asked me to chose between two ntsc settings (0 = japan and 7.5 japan) i chose the former for lack of choice since neither appeared to be relevant top pal
then to virtualdub:
firstly it presented me the device options it gives me a choice between the decklink video capture (direct show) or blackmagic wdm capture (direct show)
in the end i tried both and the video capture pin option below is only enabled when decklink video option above is selected so i ran with that
next step was to select video source and it gives me no choice - no idea why? but if i could it would be composite (its from a pal camcorder to pal)
next i selected the video capture pin and the section called video standard was empty (i was hoping i could choose pal)
but it allowed me to select a frame rate and i inserted 25 fps. for colour space compression i chose UYUY and for out put size it just gave me a chose between 720x576 (default) and 720 x 486. i chose pal
i wanted to check capture filter settings but this option was greyed out
finally for compression it only gave me a choice of blackmagic 8bit mjepg or no compression. i chose the latter
the resulting video is a little jerky but maybe because i did not deinterlace?
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The Decklink is the newer and correct device driver to use.
The Blackmagic WDM is a legacy driver, that sometimes works with old capture programs, but only captures video, no audio.
The Input is set from the Blackmagic control panel applet
Blackmagics collection of device drivers, control panel applet and capture application skitter around the Microsoft DirectShow model.
It works different from what most people expect, mostly I think because they created their own way of doing things so it worked similarly on Windows, OSX and Linux.
For Windows they created the Blackmagic WDM device driver "first" because its the oldest device driver type, and was the simplest, so it only captures video.. it hangs around because people hang on to some very old software that will only work with a WDM device driver. In (those WDM days) it was standard practice to partner a video capture card with a sound card, like an m-audio or turtle beach.
VirtualDub was created when VFW (which preceded WDM) was the default capture method.. and when WDM came along it upgraded to that. So it knows what a VFW or WDM device driver is and sees it and offers it up as well as the Decklink "filter" driver.
VirtualDub works "better" with the Decklink filter driver because it also defaults to "searching" for an audio source on the same filter driver regardless of the Windows sound mixer in whatever version of windows your using.. and associates that with the video source for creating interleaved audio and video files.. avi. You don't ever have to tell it or select a menu option in VirtualDub to do it, it just does it by default.. in fact if you try to take manual control and select an audio source for an input it warns you that it will not return to hunting for the audio pin of the filter driver.. there is not an un-control manual selection in the menu options.. you have to close and reopen VirtualDub for it to probe the edge of the video filter driver for an audio source again.
Most video capture programs other than VirtualDub only expose the audio sources found re-exposed by the windows sound mixer and that gets sketchy because from XP to Vista to Windows 7 to Windows 8.1 to Windows 10 they kept re-inventing the mixer class until no one likes using it because its so unstable and unreliable a source. It has literally exploded its guts all over the place multiple times and no one clearly understands how Microsoft will change audio mixer in the future.. its just untouchable because they can't keep their paws off it. Its very messy.
Moral to the story.. "good" video capture programs just ignore the windows sound system and by-pass it entirely. They are either written specifically for one capture card and its sound source or don't even attempt to capture sound. And for the same reason, few programs will capture audio and video from multiple brands or types of video capture cards.. Microsoft made it a big mess for programmers to sort out.. and they keep changing things.. even in security updates for non-security related reasons.. they just never stop.
The Decklink device driver is more a "filter" that fits into the DirectShow way of doing things.. it exposes Input and Output pins in GraphEdit when you load it from the DirectShow filter classes. (But) that's where it stops behaving like other capture cards. Normally a "filter" exposes a properties panel when right clicked which lets you configure it.. capture programs written for Windows normally wire menu options to these properties. Decklink doesn't really have these.. or they do.. but they are non-functional. Instead of making it work like other Windows programs.. that's put into the Blackmagic Control Panel applet.
The Blackmagic control panel applet is the (setup) program for Inputs and Outputs and Card configuration. Normally you go to it "first" before you open your capture program. Because most of the menu options in a (Windows) capture program won't do anything.
The commonality between Windows and OSX and Linux is they all have a Control panel 'like' group of configuration applets.. and Blackmagic works the same way on all of those. Its bad for Windows users.. but familiar for OSX and Linux users.
The unstable jerky blocky dropouts is partially a matter of the very high speed at which uncompressed video is being flung out the card and into your PC. But it can be made stable.
The Docs for Blackmagic products are usually lacking.. I suspect because they think people don't care, or will appreciate their "All inclusive view" of all operating systems with this three part, 1. control panel, 2. device driver, 3. blackmagic capture application -- world view that is the same on all platforms, windows, osx, linux.
But most (real people) only know a tiny corner of the big picture specific to their favorite operating system.. they are not massive all encompassing code writers.
So basically they are a "fend for yourself".. you must be a programmer to use their product.. aren't we great.. kind of use case.
The opposite extreme is a "don't explain anything" here's a Quickstart sample sheet for capturing video with none of the details. Its a Whiplash snap your neck kind of approach, from extreme SDK programming understanding to a dumbed down.. press this and that.. your done.. kind of documentation.. nothing inbetween.. not even a clumsy attempt.
The speed at which the audio and video data uncompressed is fed into the PC is far too great for most single hard drives to handle, you literally have to spool it across multiple drives in an array.. at least a striped hard drive pair called a RAID0 configuration. An SSD may keep up, but its also likely to be overrun.. you need a special setup to consistently keep up with the data rate.. that's why they include a benchmark speed test program with each card.
Capturing direct to high speed computer memory compared to low speed hard drive happens well enough for Preview in their Blackmagic video capture application.. but that is exactly because its not made of spinning rust.. its not a hard drive.. its computer memory.. its displayed and thrown away immediately.
Computer hard drives and SSD hard drives have really not gotten that much faster, they are still limited by the speed of the SATA device controller interface. The only work around is to use multiple SATA interfaces at the same time, thus why multiple striped drives in a RAID configuration.
The Blackmagic hardware is good.. but its very basic.. and does nothing on the input to clear up signals problems, you have to input a perfect signal with no lag or sync problems. And if there are time base errors, that is entirely up to you to fix. Again.. "fend for yourself" we provide nothing beyond the basics. After the data leaves our card.. its up to you to provide a fast enough system to catch all the data and put it on hard drives.. we buffer nothing for you.
The device drivers are "generalized" to fit multiple operating systems.. so they aren't the smoothest user experience on any one platform.. they are "adequate" but will never feel "native" on any one platform. A generalist, but master of none.
Frankly I think Matrox did a better job when they offered similar hardware and software, but they stayed far away from USB3 or Thunderbolt and stuck strictly to PCI and PCI bridge devices.. which made them the odd man out for entirely different reasons.. but I think they were better for Uncompressed, MPEG2 and H.264 capture. But of course they don't make any products like this anymore.
I will say for all my gripes, they have a long long software development tail that extends all the way from Thunderbolt on Windows XP to the present day. If you have a good enough signal source and a fast enough drive system they work very well.
Last edited by jwillis84; 15th Jun 2021 at 13:43.
Try BlackMagic Media Express app, it should work perfectly with your card. It's lightweight it doesn't take CPU resources like vdub does, You can capture with audio preview with no problem.