Sunday, 30 September 2012

VirtualDub Post Capturing: Deleting Advertisements

There are two things that I do before I start cutting out commercial breaks from my TV captures:

The Problem With VirtualDub

VirtualDub was the first tool that I used for cutting out these ads found in commercial breaks. But AVI capture files that have been resynced (and MP3 artifacts removed) will gradually go out of sync again after cutting out the ads. No matter what I did, I could not cut out ads correctly with VirtualDub.

Avidemux To The Rescue

So, I now use Avidemux to edit out these advertisements from my TV captures.

Avidemux is a multi-platform video editor and it is free and open-source. The version that I have installed on my PC is version 2.5.4 (r7200). I only use 7 keys on the keyboard to locate, mark and cut out advertisements.

  • The Up and Down arrow keys to move (forward and backward, respectively) between I-frames (i.e. key frames) looking for the starts and endings of an commercial breaks;
  • The Left and Right arrow keys to go (backward and forward, respectively) from frame to frame as sometimes the commercial breaks do not start or end on an I-frame;
  • The '[' (Set Marker A) and ']' (Set Marker B) keys to mark the start and end points of a commercial break;
  • And the Delete key to remove the marked advertisement.

Note: New users to Avidemux may find setting Markers A and B a bit confusing at first. You may find the writeup in this document "Simple Cutting" to be helpful.

Confirmation: Index Is Not Up To Date

When loading my AVI file for editing, I always click on "Yes" when the "Confirmation" dialog box informs me that "Index is not up to date".

Avidemux: Video And Audio Set To 'Copy' - Click To Enlarge

I leave the Video and Audio settings at "Copy" (see picture above; circled in red) as I do not want to re-encode my AVI file again when saving after editing. I always append "_NoAds" to the name of my edited file when saving.

I will enable "smart copy" mode when prompted by Avidemux while saving, with the Q factor - the quantizer value - set at 4 (the default). This will ensure that Avidemux will reconstruct back broken frames that I may have introduced while cutting out these ads (see Intra frames and SmartCopy for explanation).


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