Performing a Video Extraction
When my trusty VCR finally died, I had tons of old videotape footage lying around the house. While searching for a replacement, I decided to join the DVR revolution. After all, it seems like everyone was replacing traditional VCRs with some kind of digital recorder. Why shouldn’t I do likewise?
After some searching, I settled on a TiVo unit with a built-in DVD burner. I chose this unit because I could connect a borrowed VCR and transfer the content of my videotapes to the unit’s hard drive. That way I could salvage the tapes without having to buy a VCR or dedicated video capture solution.
With my usual dive-right-in attitude, I purchased the TiVo and connected it to our wireless network. With any luck, a Mac version of TiVoToGo would be available before I had time to start transferring the tapes. If not, surely I could burn the files to DVD and bring them to my Mac to edit in iMovie or Final Cut Express. This should be the easiest project I had undertaken in quite a while.
This Is Easy—Not
Fast-forward several months. It’s time to start transferring and editing tape. TiVoToGo still isn’t available for the Mac, so I’ll have to burn the files to DVD to put them on the Mac. It reminds me a little of the “sneaker net” days, but that’s a minor inconvenience. I’ve already spent several hours recording tapes to the TiVo in real time, and half an hour or so later the DVD is burned and I’m ready to pop it into the Mac and start editing.
I insert the DVD into my Mac, and it plays without a hitch, but that’s where the problems start. DVDs capable of being played in set-top DVD players store their video content in a series of DVD Video Object (VOB) files. The important thing to remember is that these files present problems for most consumer-level video editing software—including iMovie and Final Cut Express. Before being imported and edited, VOB files must be converted to a format the iLife suite understands.
Converting VOB files for use in iLife or Final Cut Express presents two problems. First, these files store the video content that we want in a format known as MPEG-2. Even though it creates standard DVD files, iDVD does not import MPEG-formatted video.
The second problem presented by VOB files is that they have been muxed. Muxing, also known as multiplexing, involves combining several streams of digital information into one file. In the case of DVDs, muxed files typically combine video, one or more audio files, and possibly subtitles, in one file. Before we go any further with the project we need a tool that will convert these files into something that iLife can comprehend. Let’s find our tools and get to work.
Gather Your Tools
I looked around for a while before I found a program called MPEG Streamclip 1.5.1. According to the information page, this program is compatible with Mac OS X 10.2 and higher. It works with QuickTime 6 under Jaguar and QuickTime 7 under Panther and Tiger. Although the program itself is free, in order to examine VOB and other MPEG-2 files you will need to purchase and install the QuickTime MPEG-2 Playback Component (currently $20). The current version of MPEG Streamclip can run on Intel processors through Rosetta, and on PowerPC Macs. A Universal version is anticipated at a later date. MPEG Streamclip can be used as a video player, but its file conversion capabilities are what caught my attention.
Since I eventually want to put the edited footage on DVD, I am most interested in the conversion from VOB files to DV format. This is an important consideration, since Apple recommends that for best results movies that are going to be used in iDVD should be in DV format with an audio sample rate of 48KHz. MPEG Streamclip is capable of handling this conversion quite well. Now that we have found the right tool, let’s get down to work.
Getting Down to Work—Loading the Files
After downloading and installing MPEG Streamclip and the QuickTime MPEG-2 Playback Component, it’s time to get to work. Insert the DVD that you want to retrieve footage from and launch MPEG Streamclip. Choose Command-O, navigate to the DVD, and open its VIDEO_TS folder. A basic DVD, one without complex menus or additional data content, will contain three types of files: IFO, BUP, and VOB. IFO files contain information that the DVD player needs in order to understand the disc’s structure such as total running time and the number of chapters. BUP files are essentially backups of the information contained in the IFO files. The VOB files are the ones of interest to us because they contain the video information we are attempting to extract.
There are several VOB files on any given DVD. How do we know which VOB to attempt to extract? Thankfully there is a pattern to the order of these files. The VIDEO_TS.VOB file contains the main background screen for the DVD. The naming pattern for the remainder of the VOB files provide clues to their content. Each title on the DVD has a corresponding series of VOB files. The VOB files for the first title will all have the number 01 in their title. VOB files for the second title will all have the number 02 in the title and so forth.
Let’s assume for a moment that I want to extract the first thirty minutes of the first title on the disc. Double-click the first VOB file that has “VTS_01” in the title. MPEG Streamclip will ask whether you want to open just that file or all of the files for that title. I usually open all of the VOB files for a given title, because I want to extract multiple clips from the same piece of footage. If you have a good idea which file contain the information that you need, it is possible to open just that file.
When I ran tests for this article I used Streamclip’s option to open all VOB files. I wanted to see how well my system would handle such a task. In about a minute, the first video frame appears in the editing window. This window has controls similar to QuickTime Player. From here you can play the video or scroll to the footage that you want to recover and mark editing points. It doesn’t take long to get used to this window.
The Editing Window
On some videos, the first frame appears in the editing window when you open the file. Sometimes I have to use the playback controls to scroll forward a frame or two until a video frame appears in the window. Once you have found the first frame that you want to salvage, go to the Edit menu and choose Select In. Once that is done, you can use the playback controls or the slider to move to the point where you want to stop. Now return to the Edit Menu and choose Select Out. Select In and Select Out mark the beginning and ending respectively of the clip that you want to extract.
Now that you have marked the beginning and end of the clip, it’s time for extraction. Don’t worry; unlike some trips to the dentist, Streamclip makes this about as painless a process as possible.
Extracting the Video
Since we are ready for extraction, let’s take a look at some of our options. A quick trip to Streamclip’s File menu reveals several options for exporting, converting, and demuxing MPEG files into a variety of other file types. Since the goal of this project is to move the files to iMovie or iDVD, we are interested in the Export to DV option. Choosing this option brings up a dialog allowing us to set exporting options. The default compression is set to DV25. The drop down menu labeled Standard is already set for NTSC with a screen size of 720 × 480 and a frame rate of 29.97. These are the standards for DVD in the US. If you need the PAL standard, which is common in Europe and around the world, you can choose that as an option from this menu. If I understand the documentation correctly, inserting a PAL disc would automatically change the settings to those needed for a PAL DVD. Make sure that you know which format you need.
DV Export Options
A variety of other options can be set from this box, including whether to set the screen to the standard 4:3 aspect ratio or the 16:9 ratio needed for widescreen formats. There are a variety of other settings here, including adjustments to color and volume, as well as accounting for progressive video. For my purposes, I am interested in the checkbox that says “Split DV Streams in Segments.” This will divide the resulting file into iMovie-friendly segments that are slightly less than 2 GB.
When you are finished selecting options, choose Make DV to close this dialog. Closing the dialog brings up the standard Save As dialog allowing you to choose where the file will be stored. Extracting video can consume drive space quickly. My test DVD, for example, contained six hours of video footage. I selected a half hour of footage, extracted the video, and saved the resulting files. Four files were created, which consume a total of 6.03 GB of drive space. From the time that I closed the Save As dialog until all files were saved, the process took 13 minutes 37 seconds. Testing was completed on a dual-2GHz G5 with 512 MB of memory. If more than one file needs to be saved, Streamclip saves the files with a .dv extension and three-digit number. This makes it easier to keep the clips in sequence when importing them into iMovie or iDVD. Importing the resulting files into iMovie takes about 1 minute 15 seconds for each file. If you only need to do basic video trimming and editing, you may not even need iMovie. MPEG Streamclip functions well as a basic editor. If you are counting on this program to extract video from encrypted DVDs, you’ll have to look elsewhere. That’s one thing it won’t do.
Believe it or not, once I got started this project was fun. There were some problems along the way. It was testing for this project that convinced me I was having the memory problems I wrote about a few months ago. I tried several pieces of software to complete this project. Perhaps one day when I add a little memory to my system I will write a comparison of the software. Along the way I found a nice piece of free software for my digital toolkit.
Also in This Series
- Give Alert Sounds a Little Personality · March 2012
- Create Your Own iPhone Ringtones · February 2012
- Create Your Own Homemade Audio Book · December 2011
- Upgrade to Lion Painlessly · August 2011
- Make the Most of TextEdit · July 2011
- Using the Free Disk Utility on Your Mac · May 2011
- Making Use of QuickTime X · March 2011
- Making the Most of What’s Already on Your Mac · February 2011
- Making the Most of What’s Already on Your Mac · January 2011
- Complete Archive