File size too big?

[Clicker666]

I made an DivX Avi of some Olympic highlights and it seems a little large, perhaps you fine folks can tell me if it really is too big.

Stats:

320x240
2 mins, 14 secs
1536 kbps
16 bit PCM Audio (48 khz)
29 fps
578 data rate
24 bit video sample size

Its 78 megs in size. The quality seems a bit grainy too.

Any suggestions? I use Virtuadub to capture from my ATI TV Wonder PCI card, cable connection.

[setarip]

The disproportionately large file size is due to "16 bit PCM Audio (48 khz)"

Load the file into VirtualDub

Set "Video" to "Direct Stream Copying"

Set "Audio" to "Full Processing Mode"

Under "Audio", select "Conversion" - select 44,100
Under "Audio", select "Compression" - select any of the available MP3 (MPEG3) 44,100 rates available.

Save with a new filename.

If you don't presently have an MP3 audio codec installed, download and install the Radium MP3 codec.

Let us know of your success ;>}

[Clicker666]

Took me a while to get around to doing it...

Dropped from 78 megs to 54 megs, and I can't tell any difference in audio with it at 128 k MP3.

Thanks.

[Enchanter]

If you can't tell the difference between the audio formats, it's so much the better. You won't be bothered by any obvious differences.

As for your grainy output, I will assume that it's caused by your capture card, not by low video bitrate. You can apply a smoother filter on it. It won't hurt to reencode the video at a lower bitrate as well. The file size is rather too big for the resolution and length of the clip. You can make do with, say, 30MB or less, and your eyes will probably not find any significant difference.

I would advise you to experiment around with the smoother filter settings to find the best thresold to use to remove the grains, while trying not to make the clip noticably blurred. Other filters are available at http://www.virtualdub.org/virtualdub_filters. Have a look around. Perhaps you'll find something better, though I still think the smoother is the right tool to use.

[Clicker666]

Thanks.

Here's a weird one - doing some experimenting this morning and grabbed an infomercial using IU-Vcr. Capture was done at 320x240, using Huffy and straight PCM 44.1. Waited until I had a 502 mb file, about 3 minutes. Then I processed it in VDub, using DivX 4.12, 2 pass 1st pass, everything else default. Set audio for Lame MP3 128 k. Worked beautifully, down to a 3.16 mb file!!! (I was impressed all to hell.)

Weird part - I can play it in VDub, looks fine, but can't play it in ANYTHING else. I ran DivFix on it, no errors, rebuilt the index for fun, still no go.

Any ideas?

[Enchanter]

using DivX 4.12, 2 pass 1st pass

The avi created by the first pass is unplayable. It's specified in the documentation. Do the second pass, making sure you're using the log file generated in the first pass, and save as avi. The final filesize will be determined by the bitrate you use. I can promise you that the filesize will be much bigger than 3.16MB, but still far and considerably smaller than the original.

[Clicker666]

hehe.... too much crack!!! yeah, I realized that afterwards. I have to look up the right way to do a 1-pass 2-pass save. The stuff I've seen so far talks about 2-pass vbr, but I can't seem to figure that one out.

thanks for your help - you're right on the money - I might be able to get some decent stuff out of this today!

[Clicker666]

Two pass seems to work quite well. I converted the 502 megs file to a 56 meg file before audio compression. I can live with that. Whenever I try to convert the audio to MP3 it gets completely hosed. I tried offsetting it, Nicky's tips, the whole nine yards. Nicky's tips and app seem to work best - I have to put a -300 ms delay in the start, but it still seems to wander off about 2 minutes in. Nothing seems to get it back on track after that. It's a shame to leave the file like this - compessed it goes down to 27 megs from the original 502, but 10:1 compression isn't bad overall. (although the near 19:1 is better.)

[Enchanter]

Do keep in mind that the lower the filesize is, the worse the quality will be. For a 320x240 source, I think a bitrate of 500 or more will suffice. You can do with even less if the original source is not too high in quality (There's not much quality to be retained anyway).

[Clicker666]

I set my bit rates to 1000, that should do I imagine.

[benderman]

If you capture from TV/video you should always use a noise-reduction-filter. That gives better quality with lower bitrate.

[Clicker666]

Really? I'll try that. I wish I could get the damned audio into MP3 without all this skewing though - it would reduce the file size so much.