Digital camcorder - DIVX

[funky_monkey]

Can anyone help me with a problem ive got with my brand spanking new camcorder! Its a cannon MV400 digital camcorder and i need to capture AND compress the movies from the digital tapes too my Pc. Ive tried using several capture programs and the avi's i make have been HUGE, like 2GB for a minute's film. How can i capture the film AND compress it, to divx standard movies, with out loosing video quality, which is my only option at present with out using several GB's for a 30 minute vacation movie

The camera at present is attached using a firewire card to my pc, which is a P4 1.8A, 256DDR, Geforce3 64mb. Ive used ulead software, premiere and ohers, but the movies are just too big. ANY help from ANYONE would be so very much welcomed, ive been trying for moths and im running out of space on the digital tapes!.. cheers people

James

[joan_fl]

You must be using an indrcedibly high bit rate to have 2gigs/minute. In fact I think that may well be impossible.

ANYWAYS, you can chage the screen size, and bit rate at which it captures your movies somewhere in the the settings of the software your using to capture with. If you tell us exactly what software your using, we may be able to tell you exactly where the settings are.

[Batman]

Use divx compression, I would load the file into virtualdub, and select divx compression, and mp3 audio. The higher the resolution, and bitrate, typically the quality is better, you may have to experiment to get the right balance.

[funky_monkey]

Thanks for the help guys.. i know.. i know.. im a newbie.. so keep it simple, and u never know.. i might just get to grips with this crap!

ok got my hands on a copy of Adobe premiere, and even my degree doesnt make this any easier. the test ive ran so far are a 20 second grab is 80Mb!! so i was a bit off with 2Gb.. but its working about 250Mb/minute, which aint right

ive read up on all sorts of stuff.. but i really need to know the settings of adobe really, or another program, step-by-step, from pluging the firewire into the camcorder to capturing, and then encoding(i canwork the copying to cd!

the point of this is to encode 2hour digital tapes to disk, not a 20 second video tape for grannies birthday, so size and quality is a major factor. Thanks for any help again.

James

[Kordau]

i need to capture AND compress the movies from the digital tapes too my Pc

Sorry, I'm not sure how much experience you have, so I may state the obvious or what you already know at times. I'll just refer to DV, since it all applies to both DV and Mini-DV. I'll also over-simplify a bit to try and avoid confusion.

The video data on your DV tape is already in a digital compressed format, ie: DV format. When you hook the camera up to the firewire and pump the video into the computer, you're "transferring" or "importing" the video data, rather than "capturing". Basically, it's like you're copying a file from the camera to the computer. Since the data was already compressed on the tape, it's still compressed now that it's on your computer. You havn't lost any quality from the transfer... I always associate "capturing" video, with an analog conversion process... so I can't help pointing out the DV transfer difference to people

The compression of DV format is constant rate, so that makes it easy to compare our file sizes. It also makes it easy to predict how much space you need to store x mins of video.

I got a few stats from my current project...

PAL Video project = 25 frames per second = 1500 frames per minute

3,256,476,396 bytes (3.03GB) file = 14m:33s:09f = 21834 frames

149,147 bytes per frame
= 145.7k per frame
= 3641.29k (3.56MB) per second
= 218477k (213.36MB) per minute
= 13108626k (12.5GB) per hour

Also, my sample file is DV format WITH 32kHz uncompressed audio. The audio takes about 3.6% of the file size, so it's not that significant.

So, going back to your experiences so far...

20 second grab is 80Mb!! so i was a bit off with 2Gb.. but its working about 250Mb/minute, which aint right

20 sec x 3.56MB = 71.2MB

Your video is probably NTSC, but that shouldn't make too much difference. 250MB a minute is slightly too much but... sorry man, it's about right.

To give you some idea of how compressed the DV format actually is... absolute RAW video with no audio has a data rate of 1779MB per minute or 104.29GB per hour... so DV is roughly 9.5:1 compression.

the point of this is to encode 2hour digital tapes to disk

Time to spring for that 30GB drive!

But seriously, buying a big drive would be the easiest solution.

You've suggested re-compressing the DV footage into a more compact (DivX) format. There's a few reasons why that'd be bad.

* DV format does NOT use temporal compression and DivX does. That means that in DV format, every frame is stored in its entirety. With DivX, each frame only contains video data for areas that changed since the previous frame. Basically, that means DivX is a bad format for editing.

* Re-compressing into DivX format will mean a significant loss of quality.

* Re-compressing into DivX will take you a LONG time to do... at least a few hours, at a guess.

* Editing in DivX format will take you a VERY VERY LONG time unless your editing is just simple cutting... that's even if Premiere COULD edit with DivX format, which I'm pretty sure it doesn't, as most editing software won't. You'd probably have to use a special DivX/MPEG-4 editor.


Staying in DV format is good because...

* One of the ten commandments of digital video editing is "Avoid re-compression" (actually, I'm just presuming it is ) .

* No quality loss from re-compression. If you export your edited project back out to DV format, the quality should be as good as, if not identical, to the source.

* Exporting into other formats, such as DivX or Cinepak, will compress better. That's because the cleaner the source material is, the more efficient the compression algorithms are.

* Editing in DV format is relatively fast... even on my home Celeron 800, 512MB RAM system... so your system would fly with another 256MB RAM.


If you absolutely cannot get more storage space then I'd suggest one of the following steps before re-compressing the DV source...

* Import and edit small chunks. Say 15-30 mins at a time.

* Import at a lower resolution. 320 x 240 video only needs 25% of the storage space of 640 x 480.

* Import at 15fps. Which halves storage needs.

Of course, I can't take into account how important the varying factors are for you. It actually sounds like you might just be trying to archive this stuff for use later instead of actually working on an editing project. If that's the case, then the easy solution is buy more tapes and wait until DVD burners get cheaper. If you're going to re-compress your DV source for archiving and suffer that quality loss, then the quality of DV is just going to waste.

Well, I hope I was of some help If you still want to re-compress into DivX then good luck! Let me know how it goes, if possible!



Kordau

[funky_monkey]

Thanks for the help.

Thanks for the details Kordau, thats just what ive been looking for, a bit of detial. Yeah, im trying to move the movies from the DV tapes simply to move them really, store them and compress for friends and stuff, not for editing. The whole system is PAL, im in the uk, and so far things have taken a turn for the good. Ive been working Adobe for a good 12 hours and things are going ok. IVe been able to compress a minute file, using good sounds qaulity(32000Hz) and good video quality(640*480) and using the divx4 low motion codec, capture the minutes film in about 20MB.

The HD space isnt a problem. This Unit got 80GB so no worries there, but i was trying to replicate the DIVX standards using in DIVX films, a 2hour good quality divx will fit on a 700MB CD and i was hoping to replicate this from the digital tapes.

If this plan doesnt work then i will just buy a DVD RAM as this is the simplist option, but i want to try to resolve this by other means, due to not everyone owning a DVD drive to read the RAMS(several friends want copies of disk which i hold).

But thanks again and ill keep playing with Premiere and any other points/help would be vrey welcome. Cheers

[Kordau]

i was trying to replicate the DIVX standards using in DIVX films, a 2hour good quality divx will fit on a 700MB CD and i was hoping to replicate this from the digital tapes.

Heh... I guess I got a bit carried away with the editing spiel, when it wasn't even necessary.

I've only ever done one DVD -> DivX conversion... it was a fair while back. My main goal was to get the movie under 670MB and keep quality as close to DVD as possible... the whole process took quite a while, since the tools were fairly immature back then, and the PII-400 was taking 15-20 hours to compress the full 97 mins to DivX

Anyway, in the end I produced a 720 x 576 @ 25fps movie with a 48kHz stereo (20k/s) sound track. It runs for 97 minutes and takes up 627MB... so under 6.5MB per minute. The codec was DivX 3.11 and the encode tool was FlasKMPEG ( v0.57, I think ).

Your DV source (as opposed to DVD) shouldn't be the reason you're getting 20MB/min files... it's probably just a matter of tweaking the settings. The best thing you could do is check out a lot of the "how-to" files on Divx Digest... those guys know what all the best methods and tools are.

When I did the conversion, tweaking settings was what it was all about... some settings gave MUCH bigger files, with hardly any quality increase.

Have fun!