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**Sciascia** · 13 October 2001, 17:51

OK, here is the quick explanation of the difference between MJPEG and MPEG.

MJPEG- captures each frame as an individual picture. Does not care what came before it or what is after it.

MPEG- produces the first frame as a complete frame, then uses the difference between that frame and the next to produce a stream of information to create the following frames.

That is why MPEG is smaller than MJPEG files of similar quality and resolution.

Now with that said, if you are editing video, until recently you could not edit MPEG video, it was too hard for a processor to have to try to create that video info on the fly where as MJPEG had all the info in each frame. Now CPU's have sped up as well as everything else so it is possible to edit MPEG, even with all SW compression.

The difference between the G450eTV and the G400 TV is that the 400 performs hardware MJPEG compression. This is all done on the video card so that it won't tax your system. The 450 captures using MPEG SW compression. All of the compressing of the video is done by the CPU. With the speed of todays processors it is not as bad as it was a few years ago.

The problem with Win2k and Win98 for the G400 people is that Matrox could not create the drivers to support the HW compression in Win2k. It has something to do with the actual chip that does this (Zoran). So, most people with the G400 that want HW compression have to use Win98 (not all, some have it working in Win2k). If you want to use MJPEG SW compresion, any OS is fine. It is only for the HW compression of the G400.

If you want to try capturing and editing MJPEG, try the PicVideo MJPEG SW codec. You may need to get a different capture program as well. I am not 100% since I have the G400. I would suggest avi_io. It allows you to specify the EXACT framerate and different compressors.

As for speeding up your system, no, but it will make editing a lot smoother in most cases and the quality is probably better.

You will hear a lot of differences in opinion regarding what the best codec for editing is, I personally believe that MJPEG is the way to go. This is why I am sticking with the G400 and I do have it working very well in Win2k. Of course this is the last OS that I will be able to use this card with.

**Dr Mordrid** · 13 October 2001, 17:54

First of all you can use MJPeg with the eTV and Win2K.

All you need is the PICVideo MJPeg codec, which runs about $18, and the AVI_IO capture program. You just select YUY2 as the capture format and PICVideo MJPeg as the compression. Works great.

PICVideo MJPeg: http://www.jpg.com/video/mjpeg.htm

AVI_IO: http://www.nct.ch/multimedia/avi_io/index.html

PICVideo can capture at higher data rates than Matrox's MJPeg as used with the Marvel G200/400/RR-G. They are limited to ~3 mb/s while PICVIdeo can do 5 mb/s at quality 20. It's also a very fast codec and will export to the eTV's vidout using DualHead/DVDMAX.

Stick with Win2K. It's more stable and less likely to go whack on you after using it heavily for a few months.

Dr. Mordrid

**Indiana** · 13 October 2001, 18:45

If you have lots of lots of HD space (and fast HDs, too) the best codec for capturing is of course HuffYUV. It's lossless so you can use any HQ compression afterwards and get optimal results. The downside is that this creates LARGE files (70+GB for a 2 hour capture and requires a fairly fast HD).

When you have less HD space but are still looking into good quality capture MJPEG is the way to go. Esp. PICVideos codec is very configurable, thus letting you set the optimal filesize/quality tradeoff for your system/needs. It's not very CPU hungry either.
However MJPEG still is not a codec to use if you want to just capture a video and use it like that. Like with HuffYUV you need to recompress the video afterwards with another HQ codec to get convenient filesizes.

MPEG software encoding (or, alternatively directly capturing to DivX) is the way to go if you have low HD space or don't want to have to do a timeconsuming recompression on the movie afterwards.
BUT MPEG encoding is
a. too slow to be done on even todays fastest CPUs in realtime in good quality (with full-res captures), so those realtime MPEG software codecs have to take some shortcuts that lower the quality.
b. as implied in the above, MPEG is VERY heavy on the CPU so you might have to lower the resolution or bitrate to be able to do it without framedrops on your system.

**Chmod** · 14 October 2001, 06:33

izzit?

Hi all
Thanks for all the responses.
At the moment I am capturing direct to AVI using the DivX 4.01 codec, but I'm not able to capture at full PAL resolution using this. I tried out the Huffy thing last night and got BIZARRE results. I'm capturing using VirtualDub, and during the capture everything seemed to be working fine - no frames dropped, full resolution, but the playback was AWFUL - really slow and jerky.
Has anyone got any ideas about why this is or how I can fix it?
Once again, thanks for the feedback.

Peas,
David

**traveller** · 14 October 2001, 07:37

Hey, look at the info for this codec.
It is only for recording not for playback.
You gotta encode to other codec to have smooth playback.

**Chmod** · 14 October 2001, 08:35

oh ri-i-i-ght!

Errrr.
I knew that.
I was just ... ummm ... testing to see if you knew that

Seriously, thanks for the tip, that helps a lot. I am now capturing at FULL resolution, and then converting to maximum DivX for editing. Admittedly, the conversion is a little slow, but it's a small price to pay for the increased resolution.

However, the picture I'm getting has very visible interlaced artifacts. Currently I'm removing them during the conversion to DivX with the internal VirtualDub deinterlace filters - does anyone have any sneaky tricks to prevent them being there in the first place?

Thanks for the help,

Peas,

David

**Indiana** · 14 October 2001, 11:21

The interlacing is just how the source is. If you want to view it on a TV I would let it interlaced. Just try yourself and playback one of these files on your TV - you won't notice the interlacing but get both, high resolution and smooth movement.

When you want to view your videos mainly on a computer CRT, you might want to deinterlace it (although the look of interlaced video on computer monitors is something you CAN get used to...). But this always has some problems depending on your source. In scenes with fast movements the two fields differ just too much to be nicely merged into one frame. Up to now I haven't found a better deinterlacing than what VirtualDub does (not the included filter but theres an extra one for VDub called SmartDeinterlace) and it's results are not always that great. Still searching for the optimal settings, though. Anyway even a good deinterlacing algorithm will try to keep the resolution and smooth movement but there'll always be a slight loss in both.

Since my videos are mostly meant for TV playback and luckily HuffYUV, MJPEG and DivX all support interlaced video I let the video interlaced for now. As said above I got used to the interlaced look when I watch them on CRT. Anyone knows a videoplayer program that does deinterlacing on-the-fly during playback - this would IMHO be the best option with a decent CPU: keep the video interlaced for best results on TV and use the deinterlacing on-the-fly when playing back on your computer.

Announcement

MJPEG? wot's that then?

MJPEG? wot's that then?

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