The slow burn.

November 23, 2005 11:22 AM

On making DVDs from AVI files: What's transcoding, why does it take so long, and how can I speed it up?

I just bought a 16x DVD burner and have successfully burned data onto DVDs under Windows and Linux (my primary OS). Under Windows, I'm using Nero to make a video DVD from some large AVI files (about 3 fit on a DVD after 'transcoding'). I know that 'transcoding' converts the AVI files into a format that DVD players can read, but what format is that?

The transcoding of each of the AVI files on my fairly speedy machine takes about 1.75 hours. The videos themselves are 45 minutes long. How can I speed that up (under Windows or Linux)?

And generally, is there a smarter way to do this?

posted by Kickstart70 to Technology (14 answers total)

The format is MPEG2. The process is very intensive. Nothing short of a faster processor will speed it up substantially.
posted by deadfather at 11:29 AM on November 23, 2005

Let me apologize ahead of time if I get this wrong.

Generally, I remember burning movies to be a tremendous pain in the ass. It will take a long time, and the best burning apps are the ones that let you walk away from the process and return a few hours later with a result. the worst apps require frequent attention over this period.

avi --> .m2v (video) & .aiff (sound)
posted by phaedon at 11:32 AM on November 23, 2005

I know that 'transcoding' converts the AVI files into a format that DVD players can read, but what format is that?

DVD uses the MPEG 2 video standard. The biggest bottleneck for transcoding video is CPU power, and availability of RAM is a close second. When I transcode DVD's (using DVDShink) it takes around 2 hours per DVD on a Athlon 2800XP with a gig of ram and a Nvidia 6 series GPU.

The transcoding of each of the AVI files on my fairly speedy machine takes about 1.75 hours. The videos themselves are 45 minutes long. How can I speed that up (under Windows or Linux)?

You can buy a video capture card that supports MPEG 2 encoding and decoding in hardware. These Hauppauge cards are nice, and support MPEG decoding on-chip. Other than that, unless you want to spend a bunch of money on the latest dual-64bit CPU machine with two gigs of ram, I think you're doing it the best way you can.
posted by SweetJesus at 11:36 AM on November 23, 2005

Best answer: Transcoding just means you are converting from one digital stream format to another. And it is a very intensive process, especially when you are creating DVD quality MPEG2.

Last time I checked - and it has been a while - Nero's video encoder sucked. Slow, and poor quality.

You should get much faster results and better quality from TMPGEnc, a software MPEG1/MPEG2 encoder (or transcoder, depending on whos glossary you happen to be reading). Coupled with TMPGEnc DVD Author you can create DVD source files that can be burned with Nero.
posted by chuma at 11:37 AM on November 23, 2005

I've been playing with this stuff for a month now, mostly to collect obscure and old music videos (no blockbuster ripping or anything like that). I find that a huge chunk of the work can be circumvented by using WinAVI. However I find that WinAVI just treats each source file as a track (more than 7 and you might get a coaster), and any source file that has a weird/unusual configuration (like 20% of the ones I find off the net) will cause a crash or a bad burn.

Therefore I like to have all my "pending" files sitting around in MPEG1 or MPEG2 format, and in a very standard configuration (like 352 x 240 / 29.97 fps), that way almost nothing can go wrong. To get there, I use either WinAVI (coming from AVI, etc), or if it's a bad/crap MPEG I redo it with TMpgEnc.

From there on, it's easy to get good burns. I've used DVD Shrink for that, but I'm dabbling with TMpgEnc DVD Author since it concatenates source MPGs into flexible tracks & chapters to make them fully compatible. I also notice that TMpgEnc DVD Author examines each source file as you drop them in to make sure it's compatible, and I like that... with a lot of other programs they'll crank out a bad DVD image without batting an eye.

Overall, jack-of-all-trades programs don't seem to cut it for any except the simplest projects, but I find they all have valuable strengths & weaknesses.
posted by rolypolyman at 11:54 AM on November 23, 2005

And to add to what chuma said, I find that Nero sucks, too... a transcode/burn project the other night cranked out a coaster. This nudged me into trying out the TMpgEnc Author.
posted by rolypolyman at 11:56 AM on November 23, 2005

Some of the graphics card manufacturers are looking at ways to offload the transcoding onto the card's GPUs, resulting in around a 5x speedup over fastest CPU times.

The TechReport generally does a good review of current CPUs' transcoding welly (well, encoding, really).

Note that boxes such as ReplayTV, Tivo, or dedicated hardware cards like good MCE ones or the PVR-250 do MPEG-2 encoding using hardware. This is how they can do real-time (or faster) encoding/transcoding using quite slow processors.
posted by meehawl at 11:59 AM on November 23, 2005

Response by poster: Thanks all. I'll come back here to mark some best answers once I've had a little time to play with the suggested softwares.
posted by Kickstart70 at 12:05 PM on November 23, 2005

It doesnt really answer the question but I've found the best solution to the problem is to buy a mulimedia dvd player. I have the Philips DVP642 and found it to work great on a variety of formats. It's pretty inexpensive, can easily be made region free via the remote, and macrovision can be disabled via a firmware downgrade.
posted by whatisish at 12:53 PM on November 23, 2005

It makes sense for transcoding to take longer than playback, if you think about it. First the computer has to decode the original format and render each frame. Then it has to take that rendered frame and encode it in the destination format. Playback requires only the first step. Transcoding requires both.

I also use TMpegEnc. It's okay. Not fantastic but totally serviceable. You're not going to find a magic bullet for this. The times you report are actually not terrible.
posted by scarabic at 1:27 PM on November 23, 2005

If you have the latest version of Nero's authoring program (Vision Express 3, I think), and you've converted the files to MPEG2, you need to go to Video Options and select "Enable Smart Encoding". On older versions without Smart Encoding, Nero will still try to transcode and still take hours and hours. With it, you can make a DVD in minutes, assuming your input files are MPEG2. That was my experience anyway, YMMV.
posted by SuperNova at 2:25 PM on November 23, 2005

I have had good luck with Avi2DVD lately. Just go with the default settings - it will create DVD files ready to burn with Nero. You might need to install XviD, first, in order for the encoder to be able to play your various movies.

Once you have made a few successful ones, you can try playing with the settings to get it to go faster. In general, Less quality = more speed.
posted by SNACKeR at 5:18 PM on November 23, 2005

Other things to consider:

Make sure that the video encoding software is taking full advantage of any special media instructions your CPU has.

Make sure that you aren't encoding into a higher resolution than the souce material merits.

For example if the AVIs are 320x240, it's not worth encoding to full DVD resolution ~720x400, instead pick a DVD-legal resolution that best matches the source resolution,
posted by Good Brain at 12:11 PM on November 24, 2005

Best answer: Good charts here, here, and here comparing transcoding times for different CPUs running Windows. Athlons seem to come out ahead of Pentiums in most cases.
posted by meehawl at 9:38 AM on November 25, 2005