Logitech C920 webcam impressions.... [ Edited ]

[g4pilut]

I've always had good results with Logitech webcams so when they came out with the C920 I had to have one.  It came today and I've made a few video calls with it.  Here are a few early impressions.

CPU load with the 920 is almost non-existent.  I'm running an i7 processor and with a C910 in HD my CPU load was manageable at around 20%, but with the 920 CPU is running between 1% and 3%.

As with the 910, a call starts out in 640x480.  After 1 minute, conditions permitting, it jumps to 1280x720 in 16:9 aspect ratio.  Then, after another minute or 3, conditions permitting, my video jumps to 1920x1080 in 16:9.  I'm told that my picture is amazingly sharp in full screen at the other end, especially with contacts that have a monitor that can display native 1920x1080 or better.

So far, so good.  Here are a couple of issues.

Bandwidth required for 1080p is substantial.  In 1080p mode I'm uploading between 5 and 8 megabits per second.  So to get the best performance, the user with the C920 has to be able to upload at that rate and the contact at the other end has to be able to download it.

Now comes the disappointment and drawback for me.  Let me start by saying with the C910 I always wished for a Skype option to let me stay in 4:3 aspect ratio.  I liked the clarity of HD but many times being in 16:9 widescreen just displayed more of the junk in my office around me.  Well, with the C920 and in 1920x1080 that problem is worse.

Yes, the picture is clearer than ever, but in wide screen I appear to be zoomed out more.  It looks like I'm sitting further from the camera, and a greater area around me is showing.  With the C910 there are numerous zoom settings available.  With the C920 there are two settings...in and out.

This may work well for a video call where you have a bunch of people sitting at a dais, or something like that.  Maybe an entire family sitting around visiting.  But for one person sitting in front of the webcam on a video call, it's counter productive.

Those are my first takes.   I'll be interested in anyone else's experiences.

My setup:

Intel i7 CPU @ 2.8 GHz.

12 GB RAM

nVidia 9800GT display adapter with v285.62 driver

Windows 7 (x64) SP1

Fiber Internet...25 mb/s up/down

Skype version 5.7.0.137 beta

[rookie4002]

Thanks for the impressions! I'm getting the c920 tomorrow, can't wait. Do you know what the framerate was @ 1080p? And did you test the picture quality/framerate when the lighting is suboptimal (by this I mean a room with artificial lights).

About the upload bandwidth being 5-8 mb/s, on the one hand it's good that it's high because it means there is a lot of info being sent, on the other hand it's sucks a bit cause I will use it with my relatives in Argentina which all have crappy internet connections ~ 3-6mb (I have 50/10 here in Germany so I'm fine). How did you check the upload usage? Cause the release notes said something about 2mb/s, maybe that's just the bare minimum.

[g4pilut]

I've seen up to 30 fps at 1080p but it depends not only on the bandwidth available but the power of the PC on the receiving end.

Keep in mind that although the 920 reduces the CPU load substantially on the PC it's plugged in to, 1080p substantially increases the CPU load on the computer receiving it.

I ran some tests to my wife's PC, a well running vintage XP machine, Duo Core CPU @ 2.4 GHz, also running Skype beta 5.7.0.137.  When the Logitech Quickcam Pro 9000 on that machine is turned on, it's CPU runs in near 100% when receiving 1080p from my PC over our LAN.  Frame rate was hovering around 20-24 fps.  If I turned off the webcam on the XP box, my frame rate jumped up to a solid 30 fps with the receiving machine still running at 74% CPU load.  All the while the CPU load on my i7 based machine was running at 1-3%.

I have done a few calls with poor lighting at night but they didn't go to 1080p so I can't make a comparision to a daytime call.

As for measuring up load, you can use Call Technical Info but I mostly rely on DU Meter, which I have running full time.  On the test call to the XP machine upload was rock stead at 645 kB/s.   That's about what I've seen on calls to the outside world too, although those vary more than the LAN connection.

Yesterday, BTW, the second day I had the 920, I couldn't get in to 1080p with any outside contacts.  It was 1280*720 on all calls.  It takes the proper alignment of the stars for a 1080p call to happen.

I'll be curious how your results are from Germany to South America.  I have been able to get 1080p once or twice to other European countries, but not to Germany.  My routing from the New York area to Germany always seems to be less than optimal.

One thing about doing a test to the other side of the same room is I can walk over to the other PC and see the incoming video quality.  The sharpness of the picture is stunning in full screen.

Good luck with your new webcam.  I look forward to reading your impressions.

[rookie4002]

So, finally I got my c920 today and so far managed to test it locally between different computers in the house. Max resolution that I was able to get was 720p, with a bw upload of ~320kbps. The quality at that resolution was quite amazing (this coming from a lifecam cinema hd that works only @ 640x480, might not be such a big change coming from newer 720p cams).  CPU usage was quite low in all cases when sending video, around ~15% on an AMD Phenom 1055t and 17% on a core i3 2100. I also tested receiving video on a CULV laptop (core SU9400 1.4ghz) and to my surprise after initial hicups I was able to receive 720p on the laptop too, with a slightly lower upload rate (around ~250kbps). 

One thing I noticed is that for all cases the call info shows VGA30, VGA_720 under "problems" tab, but this doesn't make much sense, I don't know if it's related to not being able to send 1080p. I will update the impressions once I actually test it on a real call.

I haven't installed any logitech drivers (camera works without them since it runs under standard uvc h264 protocol), I don't know if that would make a difference or not.

[tulloch]

Hi there,

Hoping you can helpt. I've just got the C920 and have had no success with 1080p calls. The best I've had is 720p. I'm sending from an i5 dual core with 8 gig memory over a 100 megabits business line to an i7 laptop on the same internal network. Bandwidth up and down is running at about 3 megabits and we get 30 fps on the call.

Anyone suggest why I might not be seeing 1080p? (logitech drivers in use).

[g4pilut]

Funny you should bring this up.

When I first got the C920 I did go to 1080p under ideal condtions.  Lately though, it just hasn't happened.   I don't know why.

I only know one other user with a C920 and he says he still goes to 1080p but I'm not seeing it these days.

[tulloch]

Thanks for that. What do you regard as "Ideal condtions"?

[g4pilut]

When I say ideal conditions I mean more than enough bandwidth in both directions, low latency, and enough processing power on the other end of the call.

When I was in 1080p I was uploading ~650-700 kB/s.  The contact at the other end has to be able to download that speed.

I have 3 or 4 contacts who meet those criteria.  In addition, I can run a test to myself (I know.  I know.  ) over my gigabit LAN.   In the case of those 3 or 4 contacts, or my own second PC, I was getting 1080p previously but don't any more.

It seems something's changed with Skype but I have no clue what that might be, or why.

[tulloch]

I was intending to test on my own network. Is it the case the that I will get a direct connection bewtween both PC's, and the call will not be routed over my broadband connection (which would not support 1080p) but over my 100 mb lan which would be ample bandwidth for the test.

[g4pilut]

Yes, that should work.

The device (PC, Mac, etc.) that's running Skype does need to be connected to the Internet and Skype's status showing online for a Skype-to-Skype call to work, but once the call is started, the peer-to-peer connection is over the LAN an latency should be zero.