How can I edit out commercials from my DVR recordings using a Mac?

November 5, 2004 7:36 AM

I have a DVD video recorder connected to my TV. What software can I use, on my Mac running OS X, to take the contents of these DVDs and do simple editing on them (for example, to cut out adverts), and then burn back to a new DVD? (The burning bit I can probably already do with Toast.)
Cheap is good. Free is better.
posted by Mwongozi to technology (9 comments total)

I do a bit of this, but don't know what'll work for you (due to variations in the way different DVD recorders work, europe/US variations, and the fact you use a mac (there's much more free PC software around for this sort of thing, in my experience)).

That said, all my knowledge came from here.
posted by ascullion at 8:32 AM on November 5, 2004

First, you'll need to extract the MPEG2. For this you can use one of the following:

Mac the Ripper

0SEX

Then, you'll need to bring the .VOB into teh c00l3st MPEG munching tool for the Mac out there, which is free to boot:

MPEG Streamclip

Important to your needs, here's the "What's New in This Version":

• AC3 decoder for playback and conversion of AC3/A52 audio and multichannel extraction
• added a Cut command to remove commercials and other unwanted parts
• also added Undo for both Cut and Trim commands
• new demuxing options to import unsupported MPEGs in Toast and DVD Studio Pro
• changed the size of DV segments to 1.9 GB for compatibility with iMovie 4
• the MPEG audio codec now uses the fast DSP library of Mac OS X
• In point now works for all MPEG streams
• many internal enhancements everywhere

posted by tomierna at 11:30 AM on November 5, 2004

Just so you're aware....

You're recompressing compressed material; it'll take quite a hit. Please understand that I view DVD's as highly compressed and nowhere near in quality the original master.

When you edit the MPEG-2 and then re-encode it back to a DVD you're going to end up recompressing it. It's not additive or multiplicative, but it does get worse.
posted by filmgeek at 12:59 PM on November 5, 2004

Filmgeek - if done correctly with the right software, there should be no need for re-encoding...
posted by ascullion at 3:16 PM on November 5, 2004

filmgeek:

When you edit the MPEG-2 and then re-encode it back to a DVD you're going to end up recompressing it.

This is not necessarily true.

If you've encoded it once, and keep it in MPEG-2, Toast will *not* re-encode it unless you specify a different bitrate than the file is already encoded in.

Also, MPEG Streamclip, despite being able to edit MPEG-2, does not decode/re-encode to do so - it is editing the raw MPEG-2 stream. To do this, it likely has to do all sorts of GOP re-building, but that doesn't require re-encoding, but instead the building of new b-frames and p-frames from the newly-chosen i-frames.

In other words, MPEG-2, while not a great format to edit in, can be edited - it's just harder to do properly.
posted by tomierna at 9:16 PM on November 5, 2004

I was just helping my dear old dad do something like this a couple weeks back. Long story short, there's about 200 apps to do this ... and they almost all suck. IIRC, what we ended up using was Diva to transcode from the DVD into an AVI, and then Divx Doctor to convert the AVI to a MOV that could be used (i.e. had sound) in iMovie. Once you're in iMovie, you're golden; you just edit it until you've got what you want, export to iDVD and burn it.

I don't remember exactly, but we may have also needed one of the rippers, like OSEx, MacTheRipper or DVDBackup, before Diva to remove the copy protection, but I'm not sure about that. Maybe I'll stop by this weekend so he can refresh my memory. All I remember clearly is what an amazing pain in the ass it was testing all those programs to find the few that actually worked as advertised.

PS MPEG Streamclip somehow entirely escaped our notice; looks interesting.
posted by boaz at 10:18 PM on November 5, 2004

Boaz's method, while user-friendly, will definitely involve reencoding. In fact, it involves more than one re-encode. One of the most disappointing things about the iLife applications, particularly iDVD, is that they don't support working with MPEG2 streams.
posted by ascullion at 2:15 AM on November 6, 2004

boaz's way also requires a metric shitload of disk space because DV Streams take up a lot more space than MPEG Streams.

The method I've come upon only requires less than twice the size of the DVD (around 9GB total), depending on how much you edit out of the file you save.

As far as Mac the Ripper/0Sex and MPEG Streamclip, I know they work, 'cos I've used them to do exactly that and with DVD-R content from a consumer DVD Recorder*.

*from which there should be no copy protection, since you're the one making the recordings yourself
posted by tomierna at 6:43 AM on November 6, 2004

Thanks all. MPEG Streamclip is perfect.
posted by Mwongozi at 11:32 AM on November 7, 2004