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Old 4 Mar 2002, 01:00 AM   #1
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Default How do I encode movies to fit on 1 cd

Hi guys,
hoping you could help me out. I've encoded a movie at 2pass using flask0.6 (divx 4.11) and audio=MP3 128kbps. Now the movie has come out 2.6Gig. Its lovely quality but rather big.

The thing is i want 2 encode a movie at good quality but be able to predict the size so it fits onto 2 cds (ie total=1400 mb).

Now the only way ive found to predict the movie size is to use a bitrate calculator and encode at a constant bit rate (single-pass quality based). But.....this is crap coz i'm encoding the same rate for slow scenes as for fast action sequences, so its not very efficient and the result is blocky action sequences with lovely still scenes.

So my question to my learned friends is:

What is the best way to encode a movie using divx4, bearing in mind i want to predict the size and be able to put it on 2 cds BUT at the same time not lose too much quality........

(ps dont say things like decrease the audio rate or clip off the credits, i want REAL answers.....)

i thank you for yur time and effort.
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Old 4 Mar 2002, 01:13 AM   #2
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Simple. Half the bitrate that you used for the original encoding. That should get your final filesize somewhere near the 1-CD mark. With luck, you won't cross the boundary of 650 or 700MB.

Good luck.
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Old 4 Mar 2002, 01:31 AM   #3
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Default Re: How do I encode movies to fit on 1 cd

Quote:
Originally posted by TixY
Hi guys,
hoping you could help me out. I've encoded a movie at 2pass using flask0.6 (divx 4.11) and audio=MP3 128kbps. Now the movie has come out 2.6Gig. Its lovely quality but rather big.
Strange I usually get resonable filesize prediction in 2 pass mode (usually within 20 MB). Are u sure u calculated the bitrate correctly. And are you sure your audio settings didn't get screwed between the first and second pass.

*edit* Your file is 1.2GB oversized, that sounds like approx. 2 hours of uncompressed audio.

Quote:
Originally posted by TixY
Now the only way ive found to predict the movie size is to use a bitrate calculator and encode at a constant bit rate (single-pass quality based). But.....this is crap coz i'm encoding the same rate for slow scenes as for fast action sequences, so its not very efficient and the result is blocky action sequences with lovely still scenes.
I'am sorry but this makes no sense, you can't use a bitrate calculator to predict filesize when using one pass quality based encoding, because bitrate settings are ignored in that mode.

And BTW one pass quality based encodeing is not constant bitrate, it's constant quality.
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Last edited by khp; 4 Mar 2002 at 01:45 AM
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Old 9 Mar 2002, 09:30 AM   #4
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Thanks guys for some swift and informative replies.

Okay, the first thing is that i have obviously misunderstood what settngs to use in 2 pass mode. I assumed the encoding didnt take into account the bitrate number, and just relied on the quality of the movie. I thought the only way u could determine the size was by messing about with the min/max quantizer settings.
What i'll try is encoding the movie again and, like u said, halve the bitrate and see what happens.

And yeah, i think i misunderstood what 1 pass quality-based did. Thanks for clearing that up!
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Old 9 Mar 2002, 10:47 AM   #5
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I would like to suggest that you use a bitrate calculator, personally I like this one

http://www.divx-digest.com/software/divx4bitrate.html

And make sure u set the max/min quantizers to the default 12/2, the codec will never disregard these setting even if it can't reach the desired filesize, this means that uncorrect quantizers can really f*ckup an encoding.
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Old 14 Mar 2002, 06:44 AM   #6
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Default Good setting to use

I have been using Flask_6 preview or XMPEG with great success using the 2-pass method. I ripped a perfect 512 * 384 850 bit rate 128Kbit MP3 audio rip of "the wedding singer" 97 minutes long. It came out perfect and was 667MB small. I used Flask and the 2-pass Divx 4.12 codec. I kept the Quantisizers set to Min = 2 Max = 12. These are the default values and I get great results with them. Basically I find that if the movie is longer then 100 minutes that it is best to span it over two CD's, and if it is under 100 minutes that you can have GREAT quality and still fit it on a single CD. I would not suggest going below 850 for the bitrate to keep the quality high. For making a two CD set of any movie a good number I use is 1100 for the bit rate and default quantizers ( 2 and 12 ). It makes perfect quality and any move under 160 minutes long will fit perfect onto two 700MB CD's. Hope this information helps.
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Old 14 Mar 2002, 07:24 AM   #7
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Thanx for the swift reply

Actually, i just did a 2-pass encoding of a 2h13min movie. I did sound mp3 128kbps. I wanted to span it over 3 cd's.

I used a bitrate calc to figure it out, answer was 2061 or so.

I encoded the movie (min/max quant=2/18) and it turns out to be less than 2 cd's! 700mb plus about 650mb.

man this doesn't make any sense.

okay, it wasnt an action movie, and the quality is very good, but predicting file size is still a problem.
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Old 14 Mar 2002, 07:43 AM   #8
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To begin with I think that flask doesn't give you as good quality as you could get with any other programs. Gordian Knot with Nandub and DivX 3.11 SBC encoding. GKnot has everything built in: Bitrate calculator that works fine, cropping and resizing, adding keyframes, adding subtitles etc. I've never had any probs with this program. It's a little bit harder to learn but if you want good quality DivX with not so much to learn you should try this out.

//Erci
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Old 14 Mar 2002, 08:01 AM   #9
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Default Not Really

Predicting the file size is really not all that hard once you have done a few. Pretty much I find the rule of thumb to be:

Movie under 100 minutes for 1 CD =

100 min = 850 bitrate Filesize 698 MB or less Res 512- 384
99 min = 860 bitrate Filesize 698 MB or less Res 512-384
98 min = 870 bitrate Filesize 698 MB or less res 512-384
you get the picture...

Basically I get very good quality at anything above 850, so as long as the movie is under 100 mins, I make it to fit on one CD. Anything greater then that I span it over two and use 1100 for my bitrate. It really holds true for all movies that I have encoded, and I have encoded about 20 + in the last couple of months. All of my movies that were under 100 mins I have on one CD, everything else I put on two. Top Gun for example was a good one the I experimented with. Top Gun is 109 Minutes long, and I wanted to put it on one CD, so I had to use something like 765 for my bitrate so that it would fit on one CD. I used the same setting that I always do for the rest.. 128 Kbit MP3, and 512-384 res, 2-pass with default quantizers ( 2 and 12 ). The movie turned out great, but not a top quality rip like the Wedding Singer which is 97 Mins long and encoded at 850 bitrate. I have found that as long as the bitrate is in the mid to upper 800's or more that the quality is TOP NOTCH. I have played around with the Quantizers, but I found best "size to quality" ratio with the default settings, so that is why I keep them at 2 and 12. So after I made the single CD version of Top Gun I decided to make the 2 CD version and since then have found the rule of thumb to be 100 minutes for a single CD, and anything more 2 CD's. Good luck to you in your future encodes.
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Old 14 Mar 2002, 09:58 AM   #10
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It would be a good idea to lower your max quant. to 8-12. Filesize will be more predictable, esp. when you're depending on values from calculators.
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Old 14 Mar 2002, 12:02 PM   #11
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Default Bits and Pixels

When it comes to selecting resolution, I think the general rule of thumb is to stay close to 0.2 bits per pixel.

If your using GKnot this number will be displayed in the lower part of the screen.

But ofcause it can be calculated manually (bitrate in kbits)*1000/(width*height)
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Old 14 Mar 2002, 01:40 PM   #12
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Sure, thanks
In future what i'll do is leave min/max quantizers at 2/12.

The reason I chose max=18 is obviously to encode action scenes more clearly, because it really pees me off when they get blocky.

btw will the new divx 5 give me more predictable file sizes anyone? Is it worth starting to use it?
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Old 14 Mar 2002, 10:09 PM   #13
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Quote:
Originally posted by TixY
btw will the new divx 5 give me more predictable file sizes anyone? Is it worth starting to use it?
Filesize prediction does appear to work better than in 4.12, but I will probably wait for the next release or two, before using it for anything but testing.
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Old 14 Mar 2002, 10:22 PM   #14
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Quote:
The reason I chose max=18 is obviously to encode action scenes more clearly, because it really pees me off when they get blocky.
I believe lowering the max quant. will result in clearer action scenes instead.
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