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11. MPEG I Video

Video is corrupt

Maybe you play a cd which has similar directories on it:

Yes.Unmount the cdrom and use kmpg video cd support Under Linux you canīt mount video cds. You can do it, but the data you try to play is corrupted. kmpg need _write_ access to /dev/cdrom.

Open the cdi with file->open URL and enter cdi://

 

 

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The mpeg I lib in kmpg is currently (12.99) the most advanced library for linux. (besides mtvp, which is a commercial/non GPL product, and smpeg (which is GPL) but lacks a few other things.(sync,cdi,http,mp3 audio...) At this state the mpeg player is not tightly integrated in the gui, so the synchronisation between audio/video is not exact. For better sync use the command-line tool yaf-mpgplay

On MMX Intel system we have good performance on at least 400 MHZ.

?

Yes, under Linux you need 400 MHZ for decoding standard mpeg I video. Under Windows a 100 MHz cpu is sufficient, but under Linux we need _more_. much more.

why?

Answer:

hardware support. Linux has no Hardware acceleration for video. (At least not in XFree86 3.3.5, but maybe its in 4.0) So Linux must convert for a typical 352x240 mpeg video stream with 30 frames a second 2.5 Million Pixel a second. Each Pixel is coded with three value (YUV) which make 7 Million byte. Each Pixel is converted in RGB (3 byte=24 bit color depth) which make 21 Million byte. Thus linux passes per second 20 MB from your main memory to your cpu and back == 40MB. When the image is stored in main memory we send it (actually the X11 library) these 20 MB to your graphics card. The total sum is: a mpeg I movie produces 60 MB per second of data.

This is the reason why you need a 400 MHz cpu, better 500 .

With optimal Hardware support you only send 7 Million (YUV) byte.

If you have speed problems, which may be a reason you are reading this you can easily increase the throughout of images, with the following actions:

I canīt resize the image!

Yes.

Read the section above about speed and then try to figure out why you donīt have this option.

DVD/MPEG 2- When?

Answer:

possibly never

?

First you need to decrypt the dvd key, which has actually been done. (See MoRe,LiVid) But currenty it is not clear if it is illegal to decrypt your DVD Rom (which you have bought) with a Software (which you have _not_ bought.)

Then, mpeg 2 is patented. mpeg I is patented as well, but the institution which holds the patents allows you to write _decoders_ without paying for licences.Maybe the reason why mpeg I layer 3 (==mp3) has become so popular

In Mpeg 2 this is completly different. A user of an mpeg 2 decoder must have a licence for it. So it seems to be possible to write a GPLed DVD player, but if you use it (for other than educational purpose) this is illegal.(Strange world, but lawyers and patent holders understand this better than I)