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Discussion Starter · #1 ·
Hello All,

I'm looking for any pointers to software that I can use to capture video from a video card with a hardware MPEG2 Encoder on it. Specifically it is a ViXS PureTV-U-48B0 (NTSC/ATSC Combo) card. This is in all liklihood going to have to remain a windows Vista based solution-- was hoping to keep linux as an option, but would have to switch to another capture device-- I actually am quite happy with the quality of this one and it seems quite stable under vista so this is the direction I'm looking right now. The price was right on this particular card (free).


I can successfully use Cyberlink PowerDirector to capture via the SVideo input which is what I want to do. But I am looking for a solution that does not require clicking (I want batch driven to 'start now' and then 'end')


I can use RealProducer to see the capture, (and it has a command line interface) but I can't see that you can coerce that one to simply save the incoming MPEG2 stream-- it seems to insist on transcoding it to some sort of real media file. I could have missed an option on that though. I also haven't confirmed if the audio is capturing properly or not. If anyone knows how to do this with realProducer, it would be great!


VirtualVCR seems to use DirectShow (which is the same sort of interface Real is using as far as I can see). However, it doesn't seem to find the audio correctly even though the configuration for the crossbar of the card seems to be there to link the audio. Again, it seems to insist on taking the incoming mpeg2 stream (which is all I want slapped to a file) and trying to transcode it to an avi format (which is worse quality than the original mpg source and far far bigger in file size (10x bigger)).


I'm a software developer by profession (nothing to do with video/drivers, etc though). I think I can probably hack on the virtualVCR code to get it to do what I want (hopefully), but that's a pretty steep learning curve to figure out this DirectShow bit as well as the virtual VCR code, but since it's GPL, I don't see why I couldn't go this route. I'd have to hack on it to get the audio part working with my particular device and then create the commandline interface. This seems my most viable option unless someone can throw me a bone.


What I want is just some sort of a simple command-line driven utility that can start capturing the device to a .mpg file of my choosing-- preferably with some sort of a mechanism to issue a 'stop'.


Any suggestions?


Thanks in advance!
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by Roussi /forum/post/16919476


Videolan VLC.

http://wiki.videolan.org/VLC_command-line_help

Thanks for the pointer. It's got quite a lot of capability, but in looking at the help page you pointed me to, I didn't see what seemed like a pretty basic point-- how do I identify the device I want to capture from?

Code:
Code:
URL syntax:
  [file://]filename              Plain media file
   [URL='http://ip/file']http://ip:port/file[/URL]             HTTP URL
   [URL='ftp://ip/file']ftp://ip:port/file[/URL]              FTP URL
  mms://ip:port/file             MMS URL
  screen://                      Screen capture
  [dvd://][device][@raw_device]  DVD device
  [vcd://][device]               VCD device
  [cdda://][device]              Audio CD device
  udp://[[]@[][:]]
                                 UDP stream sent by a streaming server
  vlc://pause:          Special item to pause the playlist for a certain time
  vlc://quit                     Special item to quit VLC
The only references in the help page about 'capture' are with regards to screen capture rather than hardware device capture. A capture device isn't really a DVD or udp or any of the above (or I'm just to ignorant to recognize that it can fall into one of these). But I press on...


Then I googled videolan for capture and saw folks asking about this and here it seems you can at the very least configure such a capture device via the UI, however, this thread:

http://forum.videolan.org/viewtopic....=61988&start=0


is a bit discouraging that vlc doesn't support capture cards with a built-in audio device. Still, I don't want to do anything special with the output-- I simply want to take the entire input and dump it to .mpg so maybe it can do at least that much so I'll check it out.


Thanks again.
 

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I am sorry I was not of much help. I grabbed the first link that appeared relevant in my search.


I used the GUI version of VLC to capture from my cable box through firewire (video+audio MPG2 stream). It definitely worked with sound when playing directly. I wasn't able to capture to file though.


No idea how to specify the card in the command line version, sorry... Actually, now when I thinkg about it, I believe the GUI version shows the command line string at the bottom of the "Capture device" dialog box. I don't have VLC here.
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by Roussi /forum/post/16922340


I am sorry I was not of much help. I grabbed the first link that appeared relevant in my search.


I used the GUI version of VLC to capture from my cable box through firewire (video+audio MPG2 stream). It definitely worked with sound when playing directly. I wasn't able to capture to file though.


No idea how to specify the card in the command line version, sorry... Actually, now when I thinkg about it, I believe the GUI version shows the command line string at the bottom of the "Capture device" dialog box. I don't have VLC here.

Oh, please, don't feel sorry. This looks to be very close to what I want, even if it may still need a bit of work. It's at the very least open source and probably a much better starting place than virtualVCR. It was a very good pointer.


Yes, I installed the program and saw that dshow:// seems to be the correct URL syntax to use from the commandline and as you say, it pretty much tells you exactly the commandline syntax you need for any sequence you set up from the UI, so that part all worked out once I started playing with it.


Unfortuantely, I can only capture to a file if I transcode it so I thinks somehow the software is decoding the incoming mpg2 file back to raw data and then I can transcode it (losing the audio in the process) into some other format.


I think if I could just configure it properly to *not* decode the incoming mpg2 and rather just slap it to disk I would be in business. I've tried posting over at the vlc forum. We'll see how it goes. I also found this link about a usb card with builtin mpg2 encoder and how they used a 'graph edit' utility (part of directShow SDK I think??) to accomplish what I am trying to do (not sure if graph edit has a command line interface or if I can make my card do what they were able to make the USB interface do). So all in all, your pointer to vlc very likely pushed me in the right direction.


I'd found plenty of lists of video software-- virtualdub, avisynth, virtualvcr, etc. Somehow I had overlooked vlc, but then again-- from most descriptions it isn't obvious it can capture from a capture card-- seems more to be a streaming utility from most descriptions, but I think it ought to do what I want if the driver can be properly configured (possibly the driver code needs a slight upgrade too).
 
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