Encoding MPG files to WMV to accomodate large files!

Vasan · Post by **Vasan** » Wed Jul 20, 2005 8:46 pm

Hi

In an attempt to reduce the file size, I recently encoded a mpg file (4GB)
to WMV. The resulting WMV file showed only 500MB. When I dowloaded this WMV file to the share mode the file now show 4GB.

The mpg file at 4GB showed the same.

I am so puzzled to seet the file size as 500MB, but increase to
4.0GB !!

Please help !!!!

Vasasn

THoff · Post by **THoff** » Wed Jul 20, 2005 9:03 pm

I'm not sure what you are getting at.

WMV and MPEG2 (if that is what you mean by Share mode) use different compression techniques and bitrates. A highly compressed file like a WMV file will balloon in size when converted to a less compressed / less efficient format like MPEG2.

Vasan · Post by **Vasan** » Thu Jul 21, 2005 2:06 am

Dear THoff,

I think I have not made myself clear. What I wanted to achieve is to make a DVD with 4 hours of video in a acceptable quality. When I try to make DVD at 1800Kb/sec compression, the resulting quality is very poor. Alternately I wanted to find whether WMV will help to acjhieve this purpose.

What I did was first made a mpg video file from VSP project.

I have VS9 , Movie Factory 4, XP professional, 3.0 GBMHz, 1.0GB RAM, 250GB HD…

NTSC drop frame (29.97 fps)
MPEG files
24 Bits, 720 x 480, 29.97 fps
Lower Field First
(DVD-NTSC), 4:3 8000Kb/sec

The file size for 65 minutes video was 4.0GB. When I placed the file in “Create disc dialogue box”, the indicator at the bottom showed 4.0GB.

Now I encoded this mpg file to WMV using TMPGEnc at 720x480. The file size now showed 500MB. When I placed this file in “Create disc dialogue box”, the indicator at the bottom showed 4.0GB.

What is that I am doing wrong ? Please suggest me the correct procedure to capture a 4hrs video and make it into one DVD with an acceptable quality.

Thanks again for your help !

Vasan

gordon_fan_24 · Post by **gordon_fan_24** » Thu Jul 21, 2005 2:27 am

That might be because WMV isn't DVD compatible, so whatever program you use to create the DVD will convert it back to MPEG-2 format for DVD burning, because it is DVD compatible.

I've heard (have not tried to do this yet) that it is difficult to get 4 hrs on a single DVD unless it is a dual layer DVD, you will have to lower the bitrate to something around 2000kbps, and that will compromise quality

Post by **Ken Berry** » Thu Jul 21, 2005 2:32 am

I think the simple answer is that WMV is not a DVD format, and in effect, what you are trying to do is create a data DVD which happens to have a WMV archived on it. But VS9 is primarily a video editing program which has burning capacity. It is not normally a data-burning program. In other words, by placing a file in WMV format in the VS9 burner module, the latter obviously 'thinks' that you are wanting to produce a fully compliant video DVD i.e. it will then happily convert your WMV (which started life as a 4 GB mpeg-2) back to a DVD-compliant MPEG-2 and this will be (surprise!) 4GB in size. I wouldn't like to guess what the quality would be like though...

The only way you can produce a video DVD is to use one of the DVD-compliant formats, and if you want to fit 4 hours on one, then you will have to play with bit-rates, audio formats and half-frame formats till one combination works.

You might also want to consider a format like DivX which will produce a small file. And you will have noted in MF4 that this program will produce such a disc. The latest DivX 6 bundle has a converter to switch a MPEG-2 file to a DivX one. There are of course such things as DivX DVDs, but so far there are only a handful of players that will accept them -- though you will be able to play them on your computer with the relevant DivX codec(s) installed.