Recording from 2 microsoft lifecams in 720p

[alexanderfitu]

Hi all

I have a car pc setup that is running 2 MS lifecams (one HD and the other 5000) both offer video in 720p. Both using generic USB drivers to enable 30fps recording.

My question is, what is the best codec to allow recording from them both at the same time?

I currently am recording at 1280x720@30fps using Divx single pass at 4000kpbs. The computer is a core 2 duo at 2.3ghz with 4gb ram running windows 7, 500gb 7200rpm HDD.

The problem I have now, is that I am maxing out my CPU trying to record 2 of these at the same time, so I get dropped frames, see example videos:




I am not so bothered about file size, just easiest on the cpu to record, what is the best codec to do so?

Xvid has given me simlair results. Any help would be much appreicated

[aedipuss]

buy a second laptop. unless you are running a superfast laptop with 2 ssd drives it's not likely to keep up with the writing to the drive with 2 cams running.

[alexanderfitu]

Here is a comparison with 720x578@25fps @780kbps

[alexanderfitu]

buy a second laptop. unless you are running a superfast laptop with 2 ssd drives it's not likely to keep up with the writing to the drive with 2 cams running.

Hdd in this pc can write at 60mb/s no problem. Its a desktop HDD in a USFF optiplex.

720P at 4mb/s x 2 is 8mb/s

CPU @ 100%, got to be a cpu limit. Just a matter of finding the right codec for both.

But thanks.

[jagabo]

Use faster settings in Divx or Xvid.

[alexanderfitu]

Use faster settings in Divx or Xvid.

Sorry, I forgot to mention, I am at the maximum fast setting(rather than quality).

[jagabo]

Use faster settings in Divx or Xvid.

Sorry, I forgot to mention, I am at the maximum fast setting(rather than quality).

Are you using the free version? The paid version has a faster setting (0 on the preset slider) which is significantly faster than the fastest setting on the free version (1 on the preset slider). On my i5 2500K compressing a single 1280x720 video I get 150 to 200 fps at the 0 preset, 120 to 150 at the 1 preset. Xvid's fastest settings are only about half as fast as Divx's.

I don't know if they fixed it, but Divx used to have problems compression two videos at the same time.

And Divx's fastest preset is about as fast as any codec gets. So if you can't get smooth caps with that you'll have to get a faster computer.

[alexanderfitu]

I am using the free version yes, I may lookinto buying the paid version to see if its any better. Thanks

[aedipuss]

maybe try a less compressive codec. mjpeg, ut lossless, lagarith, huffyuv.

[Cornucopia]

Those lifecams show a "minimum system requirement" for the 720p setting to be a 3.0 GHz Core2Duo. And that is of course for ONE camera alone. So I would guess you are seriously underpowered with that laptop alone.
Using a codec with less complexity (such as aedipuss suggested) is a good option, but you have to remember that you will be trading CPU load with Bandwidth/Storage load. Even 2x DV streams (at SD resolutions of 720x480) would be 50Mbps - getting awfully close to your HDD limit, so 2x HD streams are BOUND to give even greater load with similar lighter-efficiency (lossless or slightly-lossy) codecs.

Time to upgrade!?

Scott

[aedipuss]

hopefully the op has mixed up mb with MB and the hard drive can write 60MB/s not mb/s. 2 streams at even 100mb/s shouldn't strain a modern hard drive.

[jagabo]

Using a codec with less complexity (such as aedipuss suggested) is a good option

Divx at the fastest preset is all I frame so it's nearly the same as MJPEG (DCT compression + entropy encoding). It's faster than ffdshow's MJPEG encoder and lossless codecs like HuffYUV, Lagarith, UT Video codec, etc.

For the OP: you can squeeze a little more speed out of Divx by changing from single pass bitrate mode to single pass quality mode. I also verified they fixed the problem with running multiple instances. It used to get really slow, like 1/100 the encoding speed with two instances. Now it's closer to the expected 1/2 as fast.

[alexanderfitu]

hopefully the op has mixed up mb with MB and the hard drive can write 60MB/s not mb/s. 2 streams at even 100mb/s shouldn't strain a modern hard drive.

Indeed I have , there is plenty of bandwidth, as you say.

[alexanderfitu]

Using a codec with less complexity (such as aedipuss suggested) is a good option

Divx at the fastest preset is all I frame so it's nearly the same as MJPEG (DCT compression + entropy encoding). It's faster than ffdshow's MJPEG encoder and lossless codecs like HuffYUV, Lagarith, UT Video codec, etc.

For the OP: you can squeeze a little more speed out of Divx by changing from single pass bitrate mode to single pass quality mode. I also verified they fixed the problem with running multiple instances. It used to get really slow, like 1/100 the encoding speed with two instances. Now it's closer to the expected 1/2 as fast.

Many thanks, I will give it a go.

If I am asking too much, then I am, I will drop the res down to 720x578@25fps, this with a higher bit rate should produce usable videos.

[alexanderfitu]

Many thanks, using DIVX paid version, set to ultimate speed and single pass - quality (thanks Jagabo) at 1280x720 @25fps produced some very good videos at about 80% usage. This leaves me enough for the car pc front end! Hapy days, thanks all.

Some test videos:

Front:



Back (need to change the framerate setting on this recording)

[jagabo]

One other thing that may speed things up: capture as YV12 (YUV 4:2:0) if your webcam supports it. That way you will avoid time consuming colorspace conversions.

[alexanderfitu]

One other thing that may speed things up: capture as YV12 (YUV 4:2:0) if your webcam supports it. That way you will avoid time consuming colorspace conversions.

I did wonder about that. I have 2 options for the resolutions, one is YUV and the other is MJPEG. I will make the switch, many thanks!