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DivX encoding TIPS

A

AC

Senior member
If I needed to make "backups" of my favorite DVDs, how much space would I need to make ones of equal quality?

Is it possible to make ones of equal quality?

Are there any good tutorials/guides on this science?
 
I think you would need about 1GB maybe a little more.

You also need about 15 hours unless you got some dual 1.2Ghz DDR TBirds up your sleeve.

Use FlaskMPEG.

Be sure to download the most recent 'optimized' flask binary for your CPU from the download site. The optimized versions run about 2x faster than the original. Be sure to use the iDCT settings instead of MMX or vector since it has better quality for the same bitrate.

Eric
 
I've experimented with the low-motion DivX codec and FlaskMPEG.

Yeah, it takes about 15 hrs for a 2.5hr long movie and I end up with a 2GB .avi file. That translates to 3+ CDs. Taking into consideration the time and effort wasted on this process (not to mention decreasing my CPU's life), it would be cheaper to buy a second DVD.

I've also been having NTSC decoding problems (the horizontal lines in high-motion scenes). I've tried blending and interpolation, but they didn't help. Any methods around this?

Also, at a high bitrate of 2000 and keyframes set at 1, jerkiness becomes apparent. I had that problem when I forgot to enable DMA on my drives. Any methods around this?

I'll need to look for that "optimized" binary. iDCT and integer really increase the encoding time.
 
You will never get equal quality from DivX. And a 1gb rip will never be as good as the original. I have a 1.5gb rip of braveheart and its good quality but not the same, far from it.

Do not use FlaskMPEG, it doesnt do it right, unnessicery qualityloss and files often play bad in fullscreen. Use something called mpeg2avi (not the old thing, a new program with a gui and everything.
 
I've also been having NTSC decoding problems (the horizontal lines in high-motion scenes). I've tried blending and interpolation, but they didn't help. Any methods around this?

if you use Flask, turn deinterlacing ON
 
Be sure to download the most recent 'optimized' flask binary for your CPU from the download site. The optimized versions run about 2x faster than the original. Be sure to use the iDCT settings instead of MMX or vector since it has better quality for the same bitrate.

I am not 100% sure that it is necessary or even 'better' to use FPU iDCT since MMX can do it much more quickly while giving out the SAME QUALITY.
There are now published MMX, SIMD algorithms since a few years that give the same quality as FPU iDCT.
http://www.tomshardware.com/cpu/00q4/001125/email-01.html
 
I've tried encoding at up to 2000kb/s and the quality is still not dvd. So don't expect something like that, at such a high bitrate your movies are going to take up quite a bit of harddisk space.
 
Can someone explain to me how DivX works? Do you do it straight from the DVD disk or do you have to rip the DVD uncompressed onto the hard drive and then convert to DIVX? I have a P3 800 @ 900 MHz an AOpen 16X DVD-ROM and an ATA100 7200RPM hard drive. You mentioned CPU power being a big factor in encoding time, well doesn't the DVD-ROM and hard drive also play into this? I don't really care about large compression I'm looking for best quality that I can keep in one file. I run winme and I believe it has the same 1GB file limit as all the win9x OS's right? What program would you guys recommend I use?
 
Ripping DVD to HDD usind DeCSS prolly takes about 15 minutes or less depending on speed of your DVD-ROM
seperation of the audio streams also about 15minutes
re-encode the DVD into DivX prolly takes a lot longer, around 3 hours I think
combine the DivX stream and the Audio streams into 1 file

done
encoding part takes most time as you can see, it is most significant
 
3 hours is very ugh short.. if you have quality settings up and your system is like mine.. more like 9+ hours for a 2 hour movie
 
Running flask on my computer on a 2hour movie takes approx. 6 hours... Havn't tried the optimized version of Flask yet...

Anyone running it?
 
yah sory
it takes about 6hours for a 2 hour movie

my comp does about 10-15fps encoding (with the optimised MMX flask)
 
My flask is probably a bit old(.594) I use ieee-1180 reference quality iDCT.. its slow.. but the quality should be better😛 I think tomshardware had a thing on p4 speed encoding that explained the quality😛 I alsouse HQ Bicubic Filtering.
 
I am kinda 'researching' into that MMX iDCT and FPU iDCT quality issue. From what I read, there are conflicting views.

One say that iDCT can be done in MMX just as good as FPU quality wise. There is no difference in the result. So whether using FPU iDCT actually improve the quality is debatable. Anyone got any information on this?
 
well logically it would seem to be a loss of precision when using mmx, and well intel tagged each setting as different having quality😛
 
logically YES

but then in real life, MMX can do just as good as FPU at same precision at iDCT

thatz what i am reading 🙂
 
I'm not familiar with the algorithms, but this might be true. MMX deals with integers and if iDCT traditionally required floating-point numbers, then using integers would involve some drastic approximations resulting in quality loss. That being said, if a totally different algorithm for iDCT has been made then MMX - even using integers - might produce results comparable and/or equivalent to the old iDCT algorithms involving floating point numbers.

I'd say that, at least with MPEG, using MMX and consequently, using integers which yield very gross approximations may not be such a big deal since the codec is a lossy one and the "lossy" part of the quality might be more attributable to another aspect of MPEG than the loss of precision attributed to using integer approximations in doing iDCT.

Anyway, this is pure speculation on my part but given the same algorithms, floating-point approximations should produce better results (at least in theory) because they more precisely approximate real numbers than do integers.

-GL
 
http://www.tomshardware.com/cpu/00q4/001125/email-01.html
read this

There are now published MMX, SIMD algorithms since a few years that give the same quality as FPU iDCT. And we use them at Matrox. Our customers are broadcaster that want top quality. And our competitors use them also. If FlaskMPEG needs to use FPU iDCT - DCT to get top quality then this is because they have not done their homework yet. By no means I what to discard the poor floating point performance of the Pentium 4. I have not enough expertise to comment of the poor floating point performance in this case. What I say is if you need to activate in a video codec it FPU iDCT - DCT to get top quality then you'd better look somewhere else for a video codec. Even customer video codec shouldn't rely on FPU iDCT codec to get top quality.
 
Frankly- Flask isn't coded that well.

A Junior undergrad in ComSci recoded and recompiled it and got 140% improvement (he was using the MS compiler, not Intel's or Compaq's). With a better compiler it might be more.

The author of Flask has said that his MMX algo uses a lot of quality altering truncation and should be expected to have a lower quality than iDCT standard.

The SSE2 and 3DNow tweaks in each of the enhanced versions results in perfect iDCT quality with about a 2.5x speed gain. Good stuff.

Eric
 
so, what would u guys recommend as bitrate and size for a letterbox DVD?

why low-motion vs. high-motion?
 
ac, it depends on what you want. If you want near dvd then its low motion 1800-2000kb/s. High motion is for low bitrate dvds since it averages pretty low.
 
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