Batch Processing Files with Wavelab
By hcadmin |
Speed up conversion and editing time by automatically applying processes to multiple files
By Craig Anderton
There's nothing like batch processing when you need to process a large number of files, as I found out when having to prepare hundreds of samples for my "AdrenaLinn Guitars" sample CD. But you don't have to create sample CDs to need batch processing. Batch processing is a great way to convert libraries of files to MP3 format, or from 24 bit resolution to 16 bits. If you use sample CDs, batch processing can help compensate for problems like inconsistent levels, or differences in loudness maximization. Or consider what happens when you receive a bunch of tracks that all have the same response anomaly, and you need to fix this on all the tracks. Why sit there and do each file by hand when all you need to do is set one up as desired, then have your computer apply those characteristics to all the files?
The concept behind batch processing is pretty simple. Although this article focuses on Wavelab, I've also used batch processing with Syntrillium's Cool Edit and Sonic Foundry's Sound Forge, and while the details are different, the overall process is similar:
- Select the files to batch process.
- Set up the processes you want to apply (normalization, EQ, etc.).
- Set up characteristics of the files to be processed (what directory they go in, whether you want to overwrite existing files or create new ones, etc.).
- Click on "Run," and let the compute do its thing.
Here's a typical example: you have several files open on screen, and want to normalize them. The procedure is...
1. Go Tools > Batch Process.
Clicking on Add All will add all currently open files to the batch processor.
2. Add the files you want to process. Wavelab has a great shortcut: click on the "Add File Already Open In Wavelab" icon (the one to the right of the "Add all Files From Folder" icon; hold your mouse over an icon to see its name). This brings up a list of all currently open files. Select the ones you want, or click on "Add All."
If you want to convert to MP3, a window shows up that lets you set the data compression parameters.
3. The screen now shows the list of files. Click on the Output tab and choose the destination folder, whether to add a prefix or suffix to the processed files, output format (here's where you would convert to MP3 or change bit resolution, etc.
Click here to open up the Processor List window.
4. Set up the batch plug-ins by going to the Input tab, and clicking on the "Edit Batch Plugins" icon.
This window is where you choose the processors you want to apply to the batch of files.
5. Open up the Plug-Ins folder, then drag the plug-ins you want to apply over to the left "Sequence" pane. You can modify the order of plug-ins by drag-and-drop, and check or uncheck plug-ins.
6. Note that there is a Normalizer plug-in in the Plug-Ins folder (not in DirectX, VST, etc.) which is not listed under VST or Wavelab plug-ins but is only accessible from this list of plug-ins. To normalize all the files you've chosen, drag this into the left pane, then click on "OK."
7. When you're back on the Input page, click on "Run," and let your computer do all the work.
There is one caveat: if you want to undo the operation on the open windows, there is no batch undo; you have to select each file and undo individually.
That's the basic idea behind batch processing, but let's drill down one more level with some tips.
- If you save to the folder from which the files originated, as with any other editing process, the new versions aren't saved permanently until you either save them from the file menu, or close the file and click on "yes" when you're asked if you want to save.
- Concerned about overwriting a critical file by mistake? Check the "Create Backups" box under Options (in the Output menu).
- Checking the box "Delete Files After Process" deletes the original files after processing. I strongly recommend you never check this box, because there is no undo if you do something like choose the wrong batch process. Remember, when you batch process, you're affecting a lot of files. If you screw up, you screw up big time.
- If you add a file name suffix or prefix, you don't have to worry about overwriting original files no matter what you do.
- The Presets option can be very handy if you do a task repetitively, like convert to MP3 from WAV, or convert WAV to AIFF. However, using presets isn't very intuitive, so here's how the process works: Type a name for the preset in the field above the Load, Add, Delete, and Update boxes. Click "Add" after entering the process name, which adds the name to the list of presets in the column on the left. If at some point you want to change the preset, adjust your parameters as desired, then click on the preset name from the left-hand column. This does not load the older version of the preset unless you click on Load; instead, click on Update, and the new preset version will overwrite the old one.
- In addition to dragging over individual plug-ins to determine how the batched files will be processed, you can also choose any master section preset and just drag that over. Thus, you have two ways to batch process using presets: choose one from the master section, or create your own preset within the batch process function.
- The "Extra" drop-down menu on the Input page has a number of useful functions, like allowing you to sort the batched files by size, bit resolution, number of channels, etc.
Batch processing may not be the most glamorous signal processing option in the world, but when you need to process a lot of files in an identical way, the amount of time it takes to set up the batch process is negligible compared to how much time you would have to spend applying each process individually. Once you become familiar with the batch processing procedure, you might be surprised by how many times it comes in handy. As they say, "Life's a batch!"
Craig Anderton is Editor Emeritus of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.