Converting from AVI to MPEG - file gets HUGE!

[imrealdumb]

I have an AVI file that's about 400MB. I've tried converting it to an MPEG file so that I can make a VCD. I've done this with other AVIs without a hitch.

But I'm getting a big problem this time. Using TMPGEnc, it notifies me that that file size will be over 1G, or more than my CD can handle. Further, the process is taking forever - it looks like it could take 12 hours to finish!

I tried using Virtua Dub, but it also noted that finished file size will be huge.

I've never seen something like this before - it's almost like the AVI was super compressed, and converting the file somehow releases files. Is there something I can do to prevent the finished product from being appreciably larger than the original AVI file?

Thanks.

[daamon]

Hi imrealdumb,

Use AVICodec to get a load of info on your AVI and post the results back to this thread. I've seen this before but can't quite remember what the cause was (I have my suspicions, but won't mention them just yet in case I send you on a wild goose chase...). I'm hoping that details of the file will jog my memory...

Failing that, someone else might know the answer from the info provided.

[imrealdumb]

Thanks, daamon.

Here's what the program says about my file:

File : 349 MB (349 MB), duration: 0:42:13, type: AVI, 1 audio stream(s), quality: 50 %

Video : 310 MB, 1029 Kbps, 23.976 fps, 608*336 (16:9), XVID = XVID Mpeg-4, Supported

Audio : 38 MB, 127 Kbps, 48000 Hz, 2 channels, 0x55 = MPEG Layer-3, Supported

I'm trying to create a VCD straight with NERO and letting it do the encoding. It's working so far, but it's taking a long time.

Thanks.

[bugster]

When you open the avi file with virtualdub does it give a warning about it containing VBR audio. If so thats why Tmpgenc doesn't like it. Extract the audio and convert it to uncompressed wav. Then use that as the audio source and the avi as the video source when you encode with TmpGenc.

[daamon]

EDIT: bugster, the mega-fast typer, beat me to it. At least the response was the same...

Aha - MP3! There's a good chance that it's VBR, and (I'm sure I remember this correctly), VBR audio upsets TMPGEnc and causes huge files etc.

To sort the audio:

1. Load the AVI into VirtualDub.
2. Under the "Audio" menu, select "Full Processing Mode".
3. Under the "File" menu, select the "Save as WAV..." option.

This gives you a WAV file that you can then use as your audio input with TMPGEnc. This should (may - disclaimer ) sort the problem.

I mention TMPGEnc coz it's real good at converting to MPEG for VCDs and is free. Give it a go....

Hope that helps.

[imrealdumb]

When you open the avi file with virtualdub does it give a warning about it containing VBR audio. If so thats why Tmpgenc doesn't like it. Extract the audio and convert it to uncompressed wav. Then use that as the audio source and the avi as the video source when you encode with TmpGenc.

Bugster,

You're right. I neglected to mention the error I received with VirtuaDub.

Here's the error I got:

VBR audio stream detected

VirtuaDub has detected an improper VBG audio encoding in the source AVI file and will rewrite the audio header with standard CBR values during processing for better compatibility. This may introduced up to 6726 ms of skew from the video stream. If this is unacceptable, decompress the *entire* audio stream to an uncompressed WAV file and recompress with a constant bitrate encoder. (bitrate: 127.6 * 15.9 kbps)

I'll try stripping out the audio per the suggestions you and Daamon have laid out. Thanks.

[imrealdumb]

Ok, it's working fine with TMPGEnc. Thanks to both of you.

I notice, however, that it's going to take a LONG time (althought the finished product size will be manageable.)

I'm wondering if the video quality is too strong. Is it possible/a good idea to create a different video stream at a lower resolution or something (like how I made a separate audio file)? Would that allow the MPEG creation process to occur quicker?

Thanks.

[bugster]

TmpGenc is slow. There are many threads on optimising the settings for the best compromise between quality and speed. You say you are converting it to VCD. This is probably the quickest format to convert to. Check you settings. Do not use any filters unless you really need to and set motion search precision to normal or motion estimate. Do not use the high setting and definatley not highest.

Or get a faster processor!

[imrealdumb]

Quick question,

I took the advice and used the original file for the video track, and the WAV I had created for the audio. It created an MPEG, and I was able to burn it into a VCD.

Only issue is that the audio track was off by a second or two. Is this normal when you use this technique? Any way of preventing it and/or manually syncing the video and audio tracks?

Thanks.

[mats.hogberg]

You can fix this in TMPGEnc when encoding, setting "audio delay" or something to that effect. I bet the audio comes too soon in your VCD?
Another way to fix it is to add some silence at the start of the wav (if audio is ahead of video) using GoldWave.

/Mats