Splitting & appending an AVI file

[moviebuff2]

Hi everyone:

I received an AVI file which exceeds the capacity of a CD (700MB) so much that I could not overburn the file. So, I used VirtualDubMod to split the file into 2, recorded them onto 2 CDs and discarded the orginal AVI . The AVI files play fine in my DVD player.

Recently, I used VirtualDubMod to append the 2 split AVI files and DivxToDVD to make a DVD. I was surprised to find out that although the files were appended, there is a loud noise at the appended point in the DVD, but the picture is OK.

In the analog age where spliced tapes (R-to-R, for example) were pieced together, that type of noise would be expected. But the 2 AVIs were appended digitally and the picture is fine (no glitches or black screen). Why was there that loud noise?

Thanks

[Abond]

Type of audio?

[moviebuff2]

Hi Abond:

I already discarded the original AVI file. But the 2 AVI files were split by VirtualDubMod, direct stream. So, I think their file information should be the same as the original file's. Here the information:

[mats.hogberg]

My rule is: Never ever split or join video files unless it's absolutely no other way to accomplish what you want to do. And 99.9% of the times there are.

/Mats

[Cornucopia]

Splitting & Combining(Appending) shouldn't be a problem with video in DirectStreamCopy mode as long as you avoid GOP violations (Closed GOP, Edit on the boundary), but you have to remember that audio is SAMPLE-based, not FRAME-based which video is.

If you edit on the frame, depending upon how the file is packed/arranged in multiplexing, you may have duplicate/missing SAMPLES (overlap or hole). Hole is usually worse...

IF the original sample volumes are like this:

• 1_2_3_4_5_6_7_8_9_8_7_6_5_4_3_2_1_0

And you want to edit at the "9", but it take it up til "5" and then has the other segment start at "9", you'll have a combined sample that looks like this:

• 1_2_3_4_5_0_0_0_9_8_7_6_5_4_3_2_1_0

or this:

• 1_2_3_4_5_5_5_5_9_8_7_6_5_4_3_2_1_0

or maybe this:

• 1_2_3_4_5_9_8_7_6_5_4_3_2_1_0

which'll be slightly out of sync (by a portion of 1 video frame).

(See the way those holes would have sharp transient spikes...)

Hopefully, you won't be out of sync, and if you have something like one of those other 2, you could load into an Audio Editor and "re-draw" the waveform to be a nice smooth sinusoid, or use a plugin to do it for you with interpolation, etc.

****In the Future****

If you know you're going to have to split a file:
1. Make a copy of the whole Audio track alone (WAV file)
2. Split the video only (at frame/GOP boundaries of course)

I've been doing this for years with MOV and AVI files (esp. before I had a DVD burner and wanted to archive).

Another thing to try would have been to use a binary file splitter (like HJSplit), or Zip Archive Spanning (though that take a while loading in big files).

Scott

[moviebuff2]

Hi Mats:

It was necessary because the file far exceeded the capacity of a CD and I wanted to watch it on my TV monitor. I could not burn the file as data onto a DVD disc. The computer which received the AVI file does not have enough power (only 566 MHz! ) to burn a DVD, data and video.

Hi Scott aka The Audio Guru

I will have to spend some time to digest your message. All of those numbers are giving me headache!

Thanks to both of you for taking time to help me.

Anyway, for now when I need to split a file, I use MimarSinan to split it into several .pie files and an .exe file. Then I burn them onto a few CDs, transfer them to a more powerful computer which will reunite these files back into one single AVI file, without any problems, video or audio. From there, I can either burn a data DVD or convert it to a video DVD.

p.s.: please don't ask me why I am not using the more powerful computer to receive the AVI in the first place. It's a long story. :P

[moviebuff2]

Hi Scott:

I just got an AVI file which was +900MB. I did exactly your suggestion. It worked.

A big THANK YOU!