Why do some avi files get bigger...

[vcd4me]

Ok I have converted som CAM and some TS avi files to mpg and they get a lot bigger, But last night I downloaded my first dvdrip avi and converted it to mpg and it didn't get bigger. I actually think it got smaller (I Forgot to check). any input would be greatly appreciated. Thanks in advance VCD4ME

[vcd4me]

can anyone answer this ?

I would really like to know what I did wrong.

[Dave B]

AVI files can take on many forms of compression. Uncompressed AVI will produce gigabytes of data for just a couple of minutes worth of film whereas a DivX AVI will typically fit an entire movie in 700MB.

The size of an MPEG file after conversion is almost solely dependant on the bitrates used during encoding. So a standard VCD MPEG-1 stream will produce 10MB per minute of video regardless of the source video.

Therefore an uncompressed AVI is likely to decrease in size when encoded to MPEG and a DivX AVI is likely to increase in size when encoded to MPEG (which is pretty much the opposite of what you claim in your post! )

So.. you haven't done anything wrong you have just misunderstood the nature of AVI files.

[woodie]

What baffles me is not the eventual size of an MPEG file converted from an AVI but the variable time it takes. Equal sized AVIs ~700-800 Mb that convert to a MPEG of 900 to 1300 Mb can take anywhere from 4 to 20 hours. Anyone know why?

[bugster]

There are many variables to consider with respect to encode time, ignoring the raw CPU power of the machine being used. I suppose the main ones are the source audio and video formats and the destination audio and video formats. Remember, to encode your avi (divx?) to mpeg format, it has first to be decoded, a bit at a time, to raw avi format. This is stored in memory then used as the input to the encoding engine (TmpGenc?). If you have audio as well this too has to be decoded and re-encoded (well, most times anyway). It also has to be de-interleaved from the source and interleaved into the destination.
So if your source is raw, uncompressed avi with PCM (uncompressed audio) it will (should!) encode into mpeg format much quicker than if your source is Divx video with mp3 Audio.

Hope that helps.

[vcd4me]

Thanks DAVE,

Ok could you look at these examples and tell me if I'm corectly understanding thisi only have done standard vcd template)

1)zoolander-went from 713,134KB(696.42MB)>910,384KB(889,046MB) so that is was a compressed avi

2)Kpax disc 1- went from 714,816KB(698MB)>614,660KB(596.34B)so this was an uncompressed (I haven't done part 2 yet)

3)If this is so, is the reason some files I download are in 1 file because they are compressed avi.

4) are the two part avi better quality?

The reason I'm asking this is beacause I thought I would try out the 1 disc vcd for zoolander I asked NEWGEN, and gave him the file size of Zoolander and he said just to use the standard vcd template and it should fit.Bu I don't think it wil now .

Any help would be greatly apreciated
Thanks in advance VCD4ME

[bugster]

vcd4me, when encoding using the standard VCD template you get 1min of video for 10Mb of file as it uses CBR. So you can calculate quite accuratley how big the final file will be.

As an attempt to explain what you are seeing tho, when using CBR the size of the output file as compared to the input depends on many factors. Amongst these you can include:-
1) Video compression method
2) Video Bitrate used
3) Resolution
4) Audio compression
5) Audio bitrate

Hope this helps.

[vcd4me]

NOW understand the 1min =10mb

As fo the rest of it could you help me a little more If I give you some examples.

How do I find out about the five things you mentioned?is there a way to tell with my avi files?

I really want to learn about this.

Thanks in advance VCD4ME

[Dave B]

As an attempt to explain what you are seeing tho, when using CBR the size of the output file as compared to the input depends on many factors. Amongst these you can include:-
1) Video compression method
2) Video Bitrate used
3) Resolution
4) Audio compression
5) Audio bitrate

The resolution of the video will have no effect on the final size of the MPEG.

[bugster]

Dave B, Ok, I may be wrong, but if you re-encode a movie to a higher resolution than the original, the file is likley to grow, all other things being equal that is (though I realise quality will not improve!).

vcd4me, to find the details I mentioned, open your avi file in virtualdub, then select file->file properties. This should give you the info you are interested in.

[vcd4me]

BUGSTER can yu help me figure out what I did wrong, I am trying to fit this movie on one cd.

Here is the file info
1) Video compression method
>I have decompressor-Divx 4.12

2) Video Bitrate used
>1066kb

3) Resolution
>640x272

4) Audio compression
> Fraunhofer IIS mpeg 3 codec

5) Audio bitrate
> don't know but Igot an error something about vbr audio rewrite audio with header standard cbr

So now I'll tell you what I did using Virtual dub I ignored the audio error, and extracted the wav anyways.Then I used Tmnpgenc loadd the avi and wav and selected ntsc-vcd standard template 1150 cbr,and finally hit start

Like I said earlier the file is 89 minutes long
bit rate is 1066

THe file started at 713,134KB(696.42MB)>910,384KB(889,046MB)

Also any help on those 4 statements I wrote are those correct or am i wrong?

I really appreciate any help Thanks in advanceVCD4me

[bugster]

Using standard compliant VCD, 1min = 10Mb as I said before, so you can only fit 80mins of video on to an 80min CDR. If you wish to fit more you must use non-standard settings such as a lower bitrate (and therefore lower quality, and your DVD player may then refuse to play it). If your CD burner supports it, you could also try overburning, some CDR brands and burners can support up to 99 mins. Again your DVD player may not be happy with this, all you can do is try it and see, otherwise split the Mpeg onto two CD's

[vcd4me]

THANKS BUGSTER,

ok so I have to lower the bitrate in tmpgenc
I"m trying to do that 1 cd-r using newgens guide and he told me to just use the standard vcd template. I even toldhim how minutes it was> oh well back to the drawing board.Maybe I'll try the over burning thing.

As for my four statements are they correct?

One more question and I'll stop bothering you
Is there a way for me to tell if the file is going to get bigger before I start using tmpgend (using file info like you tole e before or some other way)

Thank you very much for taking the time to help me i really appreciate it

[bugster]

for standard VCD conversions, forget file size, worry about movie length. The size of the original divx depends on the bitrate used, which codec was used and how complex the movie is (divx is is variable bit rate so more motio=more data). For non standard VCD's use a bitrate calculator to find what bitrate you need in order to fit your movie on one CD, there are several in the tools section.

your movie is 89mins long which means 890Mb. You got 889,046 so not far off what is expected

[vcd4me]

THANKS FOR ALL YOUR HELP- VCD4me