Crunching Videos Using Divx
Crunching videos using Divx will take a DVD and compress the image and video into a file that will fit a CD instead of a
DVD, without much noticeable quality loss. How is this possible? The first thing to consider is how DVD's are made. The DVD format does not
do much in the way of compression on the individual video pictures, and the sound is captured in WAV format, which is not a size economic
format. The easiest way to explain the essence the difference between DIVX and MPEG4 as opposed to DVD formatting is like the difference
between Bitmap Imaging and Jpeg. You can take one large bitmap, convert this to a jpeg and have only a fraction of the file size, and if you
tune your graphic program right you really can't see much difference. There is more to it than simply crunching each frame into Jpeg images,
there are a lot of factors that are taken into account, like parts of a picture that are stationary like buildings or mountains in the
background. Divx isolates the action area's of the screen, and only works on the motion aspect of each from in those area's and uses the same
motionless back ground. Sometimes this causes some area's where pixilation or other inconsistencies might appear. Wav format used for sound
is about the same as what is used for music CD's, and most people are familiar with MP3 formatting, and how many song's can be put on a CD if
you crunch them into MP3 first.
Just like MP3 format, when converting a video to Divx you can adjust the bitrate to increase the quality of the video., there are also
other adjustments that can be made, but to save space I won't get into those here. With the latest Divx release, Divx has automated a lot of
the technical tweaking for improved performance so even the technically challenged can crunch a video and adjust the quality to their
liking.
For most videos, you can set the bit rate between 750 and 850, use Divx's default balance between quality and speed, and unless your
scrutinizing every minute of the video, up close and personal, you really can't see much loss if any. Sitting across a room and watching a
crunched video is just fine. The new release of Divx also has a nice feature, it is a bitrate calculator that makes crunching videos using
Divx much easier. When you open the IFO file in a program like Flask Mpeg, it gives you a total time for the movie. see image:
remember this time for the Divx Calculator. Select your movie track and sound track options, which are normally preselected
for you.
On the flaskMpeg menu bar, select options>output format options:
This will bring up the output choices, for the codex you wish to use to compress this video:
For Divx, you must select the Divx codec in the video codex window, and in the bottom window for avi formatting, (Divx saves
in AVI format), you must select Fraunhofer IIS MPEG Layer-3 codec. When this is selected, in the window on the right you will see a choice of
audio bitrates. If you scroll down to the 48 KBit/sec / 22,050 stereo, you will get a nice rich quality sound without eating up a lot of your
CD space. Most people will not notice a difference between 48 KBitrate and 96 KBitrate, and this will also leave more room for your video
quality. Now click the configure button and this will bring up the Divx Video configuration menu.
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