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Stevoo187
12-31-2003, 09:25 PM
Hey Guys,

I'm new to this ppc encoding stuff (as you can tell if you've read my other posts) and i am overjoyed that i was able to create divx versions of my LOTR TTT and LOTR FOTR. However, they are still a bit too large to fit on my 256 sd card.. Any ideas on how i could compress the movies even more? Would lowering the bitrate and audio compression do the trick? Thx for your advice(especially surgical...lol)

Pat Logsdon
12-31-2003, 09:52 PM
Any ideas on how i could compress the movies even more? Would lowering the bitrate and audio compression do the trick? Thx for your advice(especially surgical...lol)
Yup - there are several things you can do. First, are you decimating your frames by 2? That's the most important thing to do to reduce file size. This is on the Video/Framerate menu. Also, make sure you're using Bicubic filtering on the Video/Filters/Resize window.

Second, a lower bitrate will help - I usually use 230, but I've gone as low as 200 with no real problems.

For audio compression, make sure you're using MP3 mono, not stereo - I usually use 32k, 22,050 Hz. I'd try stepping down the audio compression levels one a time and see what you can live with.

Two Tips:

First, if you're experimenting, it's easier to test with just a small slice of the original movie file. Use the "Set Selection Start" and "Set Selection End" commands in the File menu, then copy the selection and create a New file to paste it into. That way, you can try whatever settings you want on a much smaller file to see what works best for you. Saves quite a bit of time!

Second, did you know that you can save your settings? Since there are quite a few of them, this is a handy feature of VD. I think this option is in the File menu. Usually, I save the basic settings (2 pass, rotate, 230 kb/sec, brightness, volume, audio compression, etc. etc.) and just adjust the width of the movie to fit the aspect ratio of the movie I'm encoding.

For example, for a 16:9 movie, I'll usually use 320x160 - that way the movie doesn't look weirdly stretched. :mrgreen:

jeffmd
01-02-2004, 06:18 AM
actually decimating frames, using mono sound instead of stereo.. and frame sizes have nothing to do with the size of the end file. You set the primary bitrate of the audio and video streams, and they determine exactly how big the avi will be on a per second base. However they DO allow for lower bitrates to be more watchable. Decimating the frame rate by 2 allows for each frame thats left to have double the bandwidth then previously (cleaner frames), not to mention many pocket pc's still cant do a good sound quality and maintain 24-30fps at 320x240. A mono sound track would allow you twice the bandwidth then a stereo track would, so if your bitrate for sound was so low that stereo wasn't worth it, going mono would regain some quality.

my preferable settings atm are 80-96kbit stereo ogg sound, and 250kbit video decimated by 2, using either 320x272 for widescreen, or 280x210 for fullscreen, as the hw sound make even 12-15 fps full screen video a bit tough.

this fits about 24 minutes into 50 megs, now you are trying to fit a 180 minute movie into 256 megs. Your system (video+audio) bitrate would have to be around 189kbits a second. figure 32kbit for a LQ mono sound track, leaves you with 157kbits for video. this thing isn't going to be pretty, if even watchable. To maximize video quality, I recommend 6-8 passes, this however could render your pc unusable for a couple of days.

Pat Logsdon
01-02-2004, 07:02 AM
actually decimating frames, using mono sound instead of stereo.. and frame sizes have nothing to do with the size of the end file.
I agree that frame size doesn't have anything to do with it, but I disagree with you about decimating frames and using mono sound. Decimating frames removes them from the source file. Decimating by two removes every other frame, effectively cutting the size of the encoded movie in half. A stereo track uses more bits than a mono track, simply because you're encoding sound on two channels as opposed to one.

I've used both stereo and mono, and there's really no difference that I can tell. I'm also curious as to why you need to encode in stereo in the first place - a mono track comes out of both headphones just fine... :)

this fits about 24 minutes into 50 megs, now you are trying to fit a 180 minute movie into 256 megs. Your system (video+audio) bitrate would have to be around 189kbits a second. figure 32kbit for a LQ mono sound track, leaves you with 157kbits for video. this thing isn't going to be pretty, if even watchable.

I'm curious - have you tried it? ALL of my movies have been encoded with 2 pass, 230kb/sec bitrate, 32k mono mp3 audio, frames decimated by 2. I've NEVER had a file, even LOTR:TTT go over 230mb. And they're very watchable, with smooth action, little to no artifacting, and great sound.

And a two-pass encoding only takes about 3.5 hours with my XP 3000+ w/1 GB Corsair paired DDR 400 RAM.

Mitchybums
01-03-2004, 09:26 AM
there are easier ways as well.
first, davideo fur pocketpc has a setting for the size of the end file.
it usualy goes over, but if you set it for a 220mb file, it wont go over 250

second: to play around, just get the movie ripped and converted to a decent quality divx file on high bitrate. (maybe 1cd size or something)
then use virtuadub to play around with different settings.

in my case I dont use headphones, so the mono sound is fine, and I get a better picture.
if you do use headphones, the sound might be more important, and you could use stereo sound.
Also, I only have a 128mb memcard, and thus I encode for that size.
usualy video on about 120kbs divx and sound on 4kbs mono (says 24 khz or something like that) and it is sufficient for me to watch it,
these are for 2hr movies.
I do use the full resolution, and I mess around with the panning as well.
you dont believe what the difference is if you shave off 2 pixels on each side and top and bottom on the quality
also I use decimate by 2, what improves the quality significantly.
before I did that, I was on comparable quality with davideo in wmv and divx, and now the divx looks a lot better.

Even if I had a 256 memcard, I'd still prefer carrying 2 movies in a lesser quality then just one in better quality due to watching on a small screen it's hard to tell the difference.
and the crappy speaker doesnt do the high qual sound justice, so why bother.

jeffmd
01-05-2004, 05:21 PM
Surgical, no, decimating frames does remove half the frames (or more, but most dont decimate more then by 2), but you dont effect the bitrate, instead your giving each frame double the data it original had access to. So if a movie was running at 250kbits per second at 30 frames per second, it gets approx 8.3 Kbtits per frame (not entirly accurate, key frames get access to more data and P frames get access to less, but it all works out to 250kbits per 30 frames). Decimating that simply gives each frame 16.6 kbits per second (Very ideal when you want maximum image quality but cant use a high bitrate).

I've used both stereo and mono, and there's really no difference that I can tell. I'm also curious as to why you need to encode in stereo in the first place - a mono track comes out of both headphones just fine...

hmm.. pass that by me again? your saying you can't tell the difference between stereo and mono?

As for if I have tried it, no, I was simply doing it by calculations. I've allways had a 256 meg cf card so I've never been really constrained for space, also I watch anime %90 of the time and so fitting like 4-5 24 minute episodes is easy, with each one coming around 40-50 megs a pop.