Converted avi to DVD 4 times original size

[phoenixfire]

I have these avi's that I'm converting to DVD. They are about 333 megs, 26 minutes each. I convert them with TMPGEnc, through the wizard so I can batch them, and the resulting file is 1.36GB EACH! I don't get why this is happening! I'm using the same settings as I have for other files I've converted, and none of the others have ever done this. I'm just not getting it, and it's really bugging me. I'd really appreciate it if someone could just explain what is going on.

I searched the archives, and couldn't really find any one with the same problem. Lots of file size smaller, but not bigger.

[schematic2]

Is it possible that your original file had less than 720X480 resolution? When you converted to DVD format it may have been interpolated up to 720X480, thus the increase.....

[garrisonkw]

This doesn't seem too terribly confusing. AVIs and DVD compliant MPEGs use different codecs to compress the video. If I take a 350MB XviD AVI which is approximately 46 minutes and 640x480 resolution with MP3 audio and convert it to a DVD compliant MPEG with MP2 audio, it should be a heck of a lot bigger than 350MB.

How many videos are you trying to put on the DVD? What is the resolution? Codec? Can you take a screenshot from GSpot?

[sanjayk]

AVI container typically have Divx or Xvid as video stream at lesser resolution than DVD but which are highly compressed. Audio may be typically MP3 at 128k or 2 ch AC3.

When you encode to DVD compliant MPEG2, the resolution, video bitrate & audio bitrate will ALL go up. Hence the increase in file size. Its normal.

[ChrissyBoy]

Indeed. The filesize, resolution and the bitrate of your avi files have nothing to do with anything when it comes to encoding them for DVD. The only factor is the duration of the avi video and the bitrate you will encode your mpeg to.

[phoenixfire]

I know all that. But this is the first time that I've converted a 30 minute video, and it's come out the size of a 60-90 minute movie! The last 3 DVDs I did, I was able to get 8 23 minute episodes! Why would these be sooooo different????? There has to be something in the video that makes the difference, right?

[phoenixfire]

How many videos are you trying to put on the DVD? What is the resolution? Codec? Can you take a screenshot from GSpot?

Here the info from GSpot:

Codec: Divx 5.0
Length: 24:30
Frms: 44050
kbps: 1803
Qf: 0.196
Fms/Sec: 29.971
Frame: 640x480
4:3

Audio is mp3, 44100Hz 128/k/b 2 channel

[jimmalenko]

What bitrate are you using in TMPGEnc ?

[Supreme2k]

A 60-90 minute movie usually takes 2.5-3 Gigs, in a "good" dvd quality encode. I have yet to come across a DivX file that didn't substantially increase in size when encoding to DVD specs.

Do the batched files look any different than the other files that came out smaller? Is the quality the same or better?

[phoenixfire]

Jimmalenko: I'm using the bitrate that TMPGEnc comes up with, 7000. It's the same as the files that came out at only 500MB.

Supreme2K: As far as I can tell, the quality is about the same, though the 500MB files were frameserved Anime, and these I'm trying to do now is live Action, so it's hard to compare.

The only difference I've been able to identify in gspot is the Frame Quality (Qf). The original avis are .196. The converted m2v are 3.610, and the 500MB are .772. Is this what's making the difference? And if it is, how can I lower it?

[jimmalenko]

Bitrate is THE ONLY CONTRIBUTING FACTOR to filesize when you know the running time.

By my calculations, a 26 minute clip with a video bitrate of 7000kbps (and assuming an audio bitrate of 192kbps) should have a filesize of 1370MB, or 1.34GB.

... so your experiences sound perfectly normal to me. This is just one reason why I don't use TMPGEnc's wizard - I prefer to know exactly what is going on with my encodes in terms of settings.

[Abond]

I think that the probable difference with your other files is the frame rate. 30 min clip at 23.976 has quite less frames to encode than 30 min at 29.97.

[mats.hogberg]

But again and again and again - as Jimmalenko and others have pointed out: (average) bitrate is the only factor that determines the file size when encoding a fixed length movie. Not frame size. Not frame rate. Not source file codec. Not aspect ratio. Not visual quality. Not air humidity in Upper Volta.

/Mats