UVS 8 Capture is choppy in AVI Format

Tristan · Post by **Tristan** » Mon Apr 18, 2005 10:56 pm

Hi guys,
I have a Divco FusionHDTV Tuner Capture card, with a VCR hooked into it, trying to digitize some videos that I have.

I would have thought it would be no problem in UVS 8 cos the video captures fine in the program that came with the card, (just with the sound settings to high and only in MPG format) however, when trying to capture anything in UVS8, if the 'Format' under Capture Settings is set to AVI - the capture preview goes choppy and I end up with a dodgy recording with bad, cut-up sound and choppy video...

I don't know whats going on... Seeing as I will be saving them (eventually - after Ive cut out ads and etc) as *.AVI DivX files, it'd be nice to have them initially capture as an AVI file...

I can set the Format to DVD or MPEG and it will capture fine, but What I have also noticed, is that when it captures to AVI the file size is enormous!! Like 5-6GB for 3 minutes... where as in 'DVD' format it is about 450 MB for 6 minutes.... what the???

Can anyone give me some pointers?? I WAS capturing the video via a camcorder, via firewire (IE plug the VCR into the input on the camcorder and then via firewire to the PC) and it worked fine coming in as DV-AVI(although the camcorder wasn't mine and I had to return it).

I think the issue is that maybe my PC can't cope with the huge amount of data flow coming in when the setting is on AVI... but why is that (seems weird considering my PC specs)??? Is there some way to reduce something to make it not choppy?? I could be totally wrong here, but because the preview screen is somtimes choppy and then every 15-20 secs it comes good for 5-10 secs or so, it seems that for some reason that my PC isn't quite coping.. and capture to DVD format (or MPG) is perfect...

I have an Athlon 64 3000+ 1GB (2x512MB) DDR RAM, ASUS A8V Deluxe (with WiFi), Radeon 9600XT 8xAGP Video, 20GB&60GB PATA Drives, Pioneer 16x DVD Burner, LG 16x CD Burner & a 56K modem. OS is Windwos XP Pro SP2

Any help would be really really appreciated

THoff · Post by **THoff** » Mon Apr 18, 2005 11:08 pm

AVI files are just containers for video and audio, and unless you specify a codec to use to compress the data, it will be stored uncompressed. That's why the files are so huge. An hour of uncompressed DVD-quality data (not even HDTV!) is ~60GB/hour, so the numbers you are reporting seem in line with that.

So in order to capture more than a few minutes worth of video, you'll wind up having to compress the data, and the question is how. You'll have to decide on a codec that is quite fast, because the compression will have to be done in realtime, i.e. at least 25 or 30 fps -- anything slower will fall behind and drop frames, or fill up UVS' capture buffer.

The other thing to worry about is compression quality. You can go lossless (what's the point of HDTV if you are throwing away video data during the capture?), but that produces relatively large files again, and may also be too slow. I would check if the card has a built-in encoder that performs the encoding in hardware -- it probably does. If that's the case, it will mandate the codec to be used.

Tristan · Post by **Tristan** » Tue Apr 19, 2005 3:21 am

Thanks for that THoff,
I do understand about compression and etc, i generally use XviD or DivX or the like, but I still don't understand how capturing it the way I am(via TV Tuner), will cause the video to be choppy and nasty... Ive captured video from a camcorder (via firewire) without compression and without any problems... It was saved as raw DV-AVI data, and it was also alot smaller than when I do it this way... 3-5GB for 10 or so mins... as apposed to 6GB for 3 mins...

Are you saying I should be encoding the video as its recorded??? IE into say DivX or something?? how do I do that??

How do you tell if a codec is fast or slow?? and do you have any examples??? I assume that my manual for the TV Tuner would tell me about the hardware encoder??

THoff · Post by **THoff** » Tue Apr 19, 2005 3:45 am

The choppyness may be a result of the sheer volume of data overwhelming your I/O subsystem or disk drive. Compression which can reduce this bottleneck obviously requires considerable computing resources, so your processor will work overtime trying to compress the video. You'll have to find the balance between spending too much time compressing, and not compressing enough and wasting disk space. Another variable is that the level and quality of compression may not be acceptable to you if sufficient fidelity of the input material isn't maintained in the compressed video.

The only advice as far as evaluating codecs is concerned that I can give you is to try them. I would download the excellent VirtualDub program, and use that to compress a video that is representative of the material you will work with using various codecs. VirtualDub will show you the throughput in terms of frames per second -- you'll have to squeeze at least 30fps out of the codec in order to keep up with the capture feed.

THoff · Post by **THoff** » Tue Apr 19, 2005 3:49 am

One more thing: I just noticed that you have an AMD processor. While those are excellent for playing games, they tend to fall behind Pentium 4 equivalents when it comes to media encoding.

There are numerous benchmarks on the Internet that compare AMD and Intel offerings using DivX, XviD, and the LAME MP3 encoder, and the AMD processors tend to get spanked there.

grant9954 · Post by **grant9954** » Wed Apr 20, 2005 11:55 pm

I have the same problem with a pentium4, would upgrading ram from 512 to 750 or 1024 help.

Tristan · Post by **Tristan** » Thu Apr 21, 2005 7:56 am

grant9954 wrote:I have the same problem with a pentium4, would upgrading ram from 512 to 750 or 1024 help.

Well, ive got a 1024MB in mine, yeh its an AMD64 but, kinda the same concept don't you think???

Ive basically settled to importing the video in as 'DVD' format under the Format options.. Seems to work fine except that I get an annoying little green line down the bottom of every video recording... but I think that may just be my VCR or Tape... when I convert it to a DivX AVI file, its gone tho... go figure....

The 'DVD' setting (im in Australia btw, so thats PAL DVD) brings it in as quite fine quality, without stuttering... but seeing as my question hasn't really been answered, and I can't work it out.... I guess im gonna have to settle for that.... or buy a Video camera...lol

Thanks for all your input anyway guys!

Tristan · Post by **Tristan** » Thu Apr 21, 2005 7:59 am

Just a quick thought... Ive got a 60GB and 20GB HDD... the 60GB is split up into 3 20GB Partitions, and they are all NTFS... Although the 20GB HDD is FAT32... This FAT32 Drive is the one that im importing the video to....

I can't see how this would matter that much (except for the 4GB limit or whatever it is...) but I suppose it could... Haven't tried it on an NTFS drive yet...

Does anyone else know if this would make any difference???

thecoalman · Post by **thecoalman** » Thu Apr 21, 2005 8:30 am

Tristan wrote: Seems to work fine except that I get an annoying little green line down the bottom of every video recording...

If that green line is pencil thin and razor sharp I have seen this before using Windows Media Player occasionally. It can happen on some files and not others, even the same video will or will not have it. It's not part of the video but some kind of display issue.

If the green line is larger and diretly abuts the frame, about 5 or 10 pixels wide it's overscan and normal.

As far as capturing in AVI try using the Huffy codec, it produces a relatively small file and captures nearly lossless. I think it comes in around 25GB per hour..... well it's a small file compared to uncompressed.

Probably everyone I know uses it for capturing with devices like yours.

You can get the codec here for free. www.videohelp.com Look under the tools link to the left.