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Thursday, 8 June, 2000, 11:18 GMT 12:18 UK
Video shrinks with MP4
Saving Private Ryan
You could be saving Private Ryan to your hard drive
By BBC News Online internet reporter Mark Ward

What MP3 has done for music on the internet, MP4 might do for movies.

After the software standard that compresses sound files comes one that shrinks video files into a more manageable size.

Already pirated versions of films prepared with the MPEG4 software, or MP4 as it is becoming known, are turning up on websites.

Film studios have yet to take action against any of the pirates but are known to be watching how the technology develops.

The MP4 standard was developed by the Moving Picture Experts Group, the same folk who developed MP3.

MPEG-4 is used to compress video and is the successor to MPEG-2.

But a version that can turn massive movie files into a handier size has escaped on to the internet thanks to Microsoft.

It developed the software to compress and decompress video, called a codec, to help the Windows Media Player program handle moving pictures sent over the internet.

Mini movies

This streamed video has to be radically compressed to ensure it arrives in a reasonable amount of time.

But hackers have found that when the codec is fed with high quality video from a DVD disc, it produces files that are much smaller than the original but are still watchable.

Typically, it converts multi-gigabyte files into ones that are only a few hundred in size. Each hour of video converts to 350 megabytes.

By contrast, an hour's worth of MP3 music is around 60 megabytes.

Just like MP3, the MP4 standard strips out the information that people will not miss and only encodes the elements that change from frame to frame of video.

Microsoft has now locked the codec software so it can only be used with the Windows Media Player.

But the damage looks like it has been done. Many websites are now offering MP4 versions of popular movies such as The Wizard of Oz, Saving Private Ryan and The Matrix.

On the web, MP4 is going by the name of DivX, the name of a failed DVD technology.

The early versions of the hacked Microsoft codec that are available on the internet are not perfect. When there are a lot of changes from frame to frame - in action packed moments for instance - the picture can go blocky.

It is unlikely that MP4 will prove such an instant success as MP3. Despite being shrunk, the video files are still a few hundred megabytes in size and will take hours to download over all but the fastest net connections.

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See also:

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