avi conversion

[joecass]

What determines the speed of converting .avi files to DVD ? Is it the CPU, GPU, hardware or conversion software ?
I was using DVD Flick for a few years, started having some problems with the audio output stuttering. Switched
to ConvertX to DVD (older version), that was working well for a while. But I noticed the conversion fps speed is
not the same on different machines ( and operating systems). Recently I upgraded an XP desktop to Vista, the
frame rate really dropped using ConvertX...... what's up with all this ?

[redwudz]

Almost entirely CPU speed, along with how many CPU cores you have and how many cores your codec can use. MPEG encoding speed is mostly from CPU speed as the codec doesn't make good use of multiple cores like Divx/Xvid?H.264 can.

GPU may have some affect, depending on your GPU and your software. Mostly GPU is for display, not encoding. If all those programs use the same codec (MPEG-2) and same settings, they will encode at the same speed.

Hardware, such as hard drives, or RAM, has little affect on encoding speed.

[neomaine]

I'll respectfully disagree with redwudz, or maybe simply clarify...

If I were to put a percentage on what mattered most:

CPU: 65%
HD: 30%
RAM: 5%

So yes, CPU by far has the most affect on the speed of (re)encoding. First is actual clock speed and then multiple cores IF they can be utilized and how efficiently utilized. This pretty much agrees with what redwudz said.

A distant second, but still important in my book, is hard drive configuration. I noticed a significant improvement when giong from a single drive environment to a multiple drive setup. Using one drive strictly as read and the other strictly as write will essentially eliminate disk thrashing (concurrent reads/writes to the same drive). This will eliminate disk i/o from being a bottleneck. (I actually have three drives: OS, video 1, video 2)

I originally had 60/30/10 and changed it to 65/30/5 since the only time RAM becomes an issue is if you're so memory bound that you start swapping. (And, giving RAM 5% gives CPU extra 5%).

EDIT: This assumes that the encoding settings, codecs, filters are the same accross the board.

[bendixG15]

I suspect that many modern machines suffer because of only one hard drive.

So installing a second, or even a third drive gives a performance boost (read from one drive and write to the other) without having to buy a new system.

[redwudz]

I agree using just one HDD for boot and storage can be a bottleneck for encoding speed because of OS operations, though the speed of the drive itself doesn't much matter. Same with using minimal RAM. RAM speed itself doesn't have much affect. Check the RAM usage during encoding and I doubt you will see much usage with most systems. Probably should have clarified that a bit.

EDIT: I don't have any MPEG-2 encodes to do, but I tried a H.264 benchmark. Idle RAM usage was 863MB. H.264 encode with six cores, 100% utilization, RAM usage 1030MB. That's a increase in usage of 167MB, pretty minimal, at least with H.264..

[jagabo]

If I were to put a percentage on what mattered most:

CPU: 65%
HD: 30%
RAM: 5%

For standard definition AVI to MPEG 2 I'd put it at:

CPU: 95%
HD: 3%
RAM: 2%

Unless one is working with uncompressed or losslessly compressed video hard drive speed is immaterial. With hard drive caching the file reads and writes are nearly invisible -- ie the encoder is rarely waiting for drive access.

With modern CPUs and standard definition video almost the entire working set is cached on the CPU in L1/L2/L3 cache.

[redwudz]

jagabo, those seem like creditable numbers. I seem to recall from several years ago that RAM usage during encoding was more like ~300 - 400MB. I was a bit surprised that it was that low with a H.264 encode with the six core CPU, but cache utilization could explain that. Makes you wonder why some people use massive amounts of RAM for encoding purposes, along with ultra fast HDDs.

I do usually use three HDDs with the PCs I put together, Boot, Edit, Archive. Since I still mostly use a 32bit OS, I put in 4GB RAM.

[neomaine]

If I were to put a percentage on what mattered most:

CPU: 65%
HD: 30%
RAM: 5%

For standard definition AVI to MPEG 2 I'd put it at:

CPU: 95%
HD: 3%
RAM: 2%

Unless one is working with uncompressed or losslessly compressed video hard drive speed is immaterial. With hard drive caching the file reads and writes are nearly invisible -- ie the encoder is rarely waiting for drive access.

With modern CPUs and standard definition video almost the entire working set is cached on the CPU in L1/L2/L3 cache.

If/when eliminating hd and ram as bottlenecks, then I'd agree with those numbers. But that means someone had thought of this ahead of time and configured for encoding or editing.

A lot of times we'll see people come here with laptops and wonder why they have such poor FPS numbers compared to others. For them and people with desktops who haven't 'tuned' there PCs for encoding, I'd lean closer to my numbers.

[joecass]

Thanks guys for all the useful info.... I'm using old machines with single-core CPU's and less than 2gb of RAM. I just did a conversion of five 22-minute divX files to DVD, using an old AMD 2.1 Ghz CPU running Vista, couldn't believe how long it took......
like almost 5 hours from start to burn. The first attempt using ConvertX, something went wrong and the audio
was all out of whack, constant skipping every few seconds. Tried again using DVD Flick, audio problem corrected.

The highest frame rate I get is with my 4yr old laptop that has an AMD Turion TL-50 dual core and 1 Gb of RAM. On that
I get between 30 and 40 fps. I've just been too lazy to upgrade my rigs when all my old machines work like a charm.

Next for me to consider:..... have over 100 DVD movies in which I no longer want to keep the discs themselves,
considering converting all of them to .avi and storing everything on an external USB drive. Seems like this will take forever
unless I go out and buy a blazing quad-core machine like a Dell XPS or HP Pavillion Elite. Unfortunately, after looking over
some of these high end machines in retail stores, I'm totally put off by the build quality.....crappy cases, low wattage
power supplies, and really chintzy flip-out DVD trays.

[jagabo]

A fast dual core won't be too bad for DVD to Divx AVI conversions. Divx and Xvid don't really use more than two cores very effectively. If you're planning on using x264 a quad (or more) core will be much better.

[neomaine]

joecass,

Give us a dollar figure to work with. If we know you're putting together a low-end encoding rig I bet we could put something really nice together. Some guys here LOVE to do this sort of thing. Of course, spending someone else's money usually is kind of fun. You may have to filter through an occasional AMD/Intel tiff but otherwise it'll be good.

Ever put a PC together before? These days it's fairly straightforward and still very rewarding. And, there's always the Dells of the world where you can put something together fairly cheap.

General Components:

CPU: 2 - 4 cores
RAM: 2 - 4 gig
HR: 2 x 500gb
Onboard video would be fine.

[joecass]

I don't think I'd wanna build a machine just for encoding..... I have an old Compaq XP desktop that can handle such chores, it's just too damn slow. As for buying a new high-end machine, money wouldn't be an object..... if I knew it would make me happy, but it won't, because Vista and Windows 7 are not backward compatible with my favorite old software and peripherals. I've built about 5 or 6 desktop rigs, and fixed who knows how many older machines myself. When I look at
what's available now, it just makes me cringe how cheaply everything is made. An AMD machine I built in 2002, given to a
cheapskate friend, still works. Doubt if you can say anything I build today will last...... half that long.

I've looked at dozens of motherboards, read an infinite amount of reviews including suggestions right here on videohelp,
nothing strikes my fancy. Spotted a nice ASUS AMD AM+3 board that looked good..... until I read about BIOS problems
right out of the box. No thanks......