I have a Sony HDR-HC1 camcorder that I use for shooting video. It’s a great camera with lots of features. The only problem I ever really have with it is trying to get the HD video off it and onto my computer for editing (getting SD video off is easier). It usually boils down to me not adjusting the camera settings correctly, but I can usually figure it out after a couple of minutes (HDV out and i.link conversion off).

But last night, after not having used my camcorder for about 6 months, I needed to transfer some footage onto my computer to edit it and I couldn’t get it to work. The problem was that my computer – a custom-built Windows XP SP3 box running an AMD Athlon 64 X2 4600+ with 2gb of RAM – wouldn’t recognize my camcorder. I had problems getting my editing software to recognize the video in the past (again, this was always a settings issue), but I had never had a problem with Windows recognizing my camera. What would pop up was the “Detected New Hardware” message and then it would install some crappy, temporary driver for an “AV/C Subunit”, whatever the hell that is. The driver indicated it wasn’t working correctly and it couldn’t get Sony Vegas (my editing program) to recognize the camera.

I knew that I could always switch the i.link conversion to standard definition (SD) before and it worked fine. So, I tried that. This time, however, it still didn’t work fine. Windows was simply not recognizing my camcorder connected via firewire (IEEE 1394), something it had done dozens of times in the past. Like an idiot, I overlooked the obvious explanation (which I’ll explain below), and tried all sorts of other avenues to try to fix this problem.

Of course, the first approach is simply to try every combination of settings I could think of and restart Windows a couple dozen times. That didn’t work. Then I turned to the internet, where I eventually found a hint toward the solution. Other people have had similar problems in the past (see here and here, among many others). The initial advice I found came from Sony’s website (though I’m linking to a different one here as I can’t find the site again; the directions are very similar), which suggested that this was a driver issue and that you simply needed to reinstall the driver. To do this you were supposed to turn on your camera, plug it in, then go to: control panel->system->hardware tab->device manager. You should see your camera listed under “imaging devices”. Right click it and select update driver->No, not this time->Next->Install from a list or a specific location (Advanced)->Don’t search. I will choose the driver to install.->Show compatible hardware->Scroll to the first “Sony” device->Select “Sony D-VHS Device”->Click Next->Click YES to warning->Click Finish->Close. I tried this several times, choosing different Sony devices each time. No luck.

Eventually I stumbled on this website, that finally clued me into what the problem was. The second post (the one by Deep G) mentions that some people may be missing some necessary files because they have a stripped down version of Windows XP. This is when I realized what the problem was: I’ve been using a stripped down version of Windows XP. I learned about nLite via Lifehacker.com and decided it would be worth giving it a try. Basically, nLite lets you take your Windows XP install disc and customizes it so you don’t have to sit around and wait for it to install. It lets you incorporate service packs and basic settings so you can set it and forget. But it also lets you remove components of Windows XP you don’t want. I removed a bunch when I customized my install disc, including the component I think was causing the problems with my camera: Windows Movie Maker. Since I have much more powerful video editing software, I figured I could just cut out Windows Movie Maker and not worry about it. I don’t know for certain, but I think that also meant I cut out the requisite driver files that allowed Windows to recognize my camcorder. Ergo, my stripped down version of Windows XP was missing the drivers required to recognize HD camcorders.

The website where I found this suggestion (and this site) suggested all you need is a few files in the right locations and you’d be good to go: put mstape.inf, avcstrm.sys, and mstape.sys in “c:\windows\system32\drivers” and it will work. Well, the first problem is, since I don’t have those files in my drivers folder, how am I supposed to get them? I searched around online and found a place offering them for money. I wasn’t about to pay for these files. So, I set up a virtual PC on my desktop, installed a fresh version of Windows XP, and stole them from there. It was a serious pain in the ass and, it didn’t work for me. I tried putting them in the right folder and then going through the same steps of updating my drivers (as outlined above). No luck. Maybe I didn’t do something I was supposed to or I did something wrong. Just in case this solution does actually work for someone, you’re welcome to use the files I now have (after reinstalling Windows) to try this approach for yourself: three files for av/c subunit problem zipped (In case you’re worried that these files have some hack or other malware, read the blog. I’m a sociology professor and I identify myself readily – you could easily track me down over this. They are the files I’m currently using on my computer and, if they are malicious, then I’m screwed too and you can blame Microsoft, because they are coming from a fresh install on my computer.)

Having ruled that approach out, I realized that I was going to have to bite-the-bullet and start from scratch. This was, in fact, the original problem anyway. About 3 months ago I had to reformat my desktop, where I do all my video editing. I used the stripped down version of Windows to install the operating system. Since I hadn’t needed to edit any HD footage since then. I didn’t realize that my reformat with the stripped down version was going to lead to problems. I spent a couple hours reformatting this morning, but before I installed any new programs, I plugged in my camcorder to see if it would give the same error. NOPE! It recognized the camera and installed the correct drivers. Problem solved. This time around it recognized it just like it had dozens of times before. I was back in business.

So, what’s the solution and what causes this problem? There are a couple of issues here.

  1. Sony doesn’t provide drivers for their HD cameras, they are built into Windows. So, you can’t find the drivers on Sony’s website nor online anywhere.
  2. If you mess around with the files that come with the standard versions of Windows XP, you run the risk of deleting the necessary drivers. You can do that by stripping out parts of Windows you don’t want, like Movie Maker (I think that’s the problem).
  3. Once you’ve deleted the necessary drivers (or failed to install them in the first place), getting them back is difficult. This is why you get the “AV/C Subunit” driver rather than the standard HD Camcorder driver.
  4. You can try installing the three files I posted. I promise they aren’t hacked; I’m not good enough at programming to hack them.
  5. Worst comes to worst, find an unadulterated version of Windows and install it from scratch without stripping anything out. Then try connecting your camcorder. It should install without any problems.

An additional tidbit. I saw some advice on several websites suggesting people try installing various pieces of HD capture software to see if that solves the problem. FYI, that doesn’t work. The software doesn’t come with drivers for the camcorders. If the computer isn’t recognizing your camcorder, it doesn’t matter what software you try to use to do the capturing, it won’t work.

Also, just so you know, I’m not a computer expert, just a novice who likes to fiddle with these types of things. If your question isn’t answered in the above post, you can try emailing me for more details, but keep in mind that I probably can’t answer your question in much more depth than what I provided (I write these things up as much for me as for other people so I don’t forget them in the future). I have had people email in the past and beg me to help them fix their problem. FYI, I have a more-than-full-time job. I really don’t have time to help you fix your computer. If this doesn’t solve your problem, sorry, but I’m not troubleshooting your problems for you. It worked for me, but that doesn’t mean it will work for you.

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19 Replies to “Sony HDV “AV/C Subunit” Error”

  1. Thank you so much for the files!
    I have a slightly “nlited” Windows XP Service Pack 3 which lacks Windows Movie Maker. I would never had thought that that piece of software would be necessary for professional video editing in Windows. And – it isn’t, thanks to you!
    I copied the files linked above to a folder on my harddisk, then on driver reinstall I manually chose the location of the drivers – tada! Works perfectly now 🙂

  2. I’m sorry that the manual installation of the drivers didn’t work for you. It worked perfectly for me (with XP SP3 “Performance Edition”- a barebones version of Windows). Providing the link to download the drivers right here made solving my problem very quick and easy, so thanks a lot. Thanks a lot for the detailed post, and again, sorry it ended up being such a headache for you.

  3. Many Many thanks, man!
    You fixed my computer, without even wanting to do so…

    Have been looking for those files for hours!
    Such a pitty they dindn’t work for you.

    Thanks again for making me a happy editor.
    Greetings from Argentina.

  4. Thank you so much! I was blaming every bit of hardware and software for this problem. Applied a dozen of hot fixes and driver updates. But I could have never thought it was because of the silly Movie Maker that I stripped out.
    Weeks of frustration finally ended.
    Warm greetings from St. Petersburg (Russia)
    You made my day!

  5. Hmmm…i’ve tried to put these files  in two places… c:\windows\ini c:\windows\system32\drivers Matter of fact, they were already there in the ‘ini’ folder but I’m still getting the dreaded AV/C Subunit Window. I’m at a lost.

  6. Hi Gerard,

    It actually didn’t work for me, either.  Are you using an install of Windows that extracted Moviemaker?  If so, I couldn’t get it to work without reformatting and installing Windows again with Moviemaker included.  I hate to recommend that, but that’s what worked for me.



  7. Hey Ryan- I’m use Premiere Pro CS4 to edit. The weird thing is that I can capture standard def footage no problem. Go figure!

  8. I have the same problem  (HC1 with XP Performance Edition). The files you posted solved the problem of HDV capture.
    You win at life.

  9. AV/C subunit – problem solved!(Canon XHA1 HDV) … I thank you on my knees … allthebest from Germany!

  10. You lost this drivers because you delete the ” TAPE DRIVERS” from XP
    original kit, with NLite. Here is the xp 32 and 64 bit driver.

  11. Thanksssssssss. You have solved the problem for me with these 3 files. I can now capture HDV and I am extremely thankful to you for sharing the files.

  12. Oh my god. Man, you has TOTALLY SAVED MY LIFE NOW!!! I needed to capture some data from DVCAM, that I must return to its owner tomorrow, and my nLited Windows refused to communicate with this DVCAM. I have browsed the internet for some solution for couple of hours, and yours was the only one that worked. Without you, I would be TOTALLY SCREWED!! THANKS!!

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