ICC 2011 - Sound Forge Workshop Handout

Contents
•	Data compression and file formats 
•	Sound file attributes 
•	Basic editing commands 
•	Processes and effects 
•	Final words 

Data compression and file formats
There are two main ways to minimize the size of stored data, each of which uses different file formats and algorythms based on a common principle: 
•	Lossless compression - the data file is still made considerably smaller than if it were saved without any compression at all but no single piece of information is lost, no distortion is made. Especially programs, documents, web pages, presentations and so on have to be compressed like this rather than using a lossy compression method because nothing can be afforded to be lost for example in a book, of course. Also the so called archives which can contain either a single file, more of them or even one or more folders containing other folders and files, are created using lossless compression. This method of compression is based on the fact that the same piece of information often occurs repeatedly in the same file; the compression algorythm searches for any information that is repeated and then simply counts how many times it repeats in total. The best known formats of archive files are .zip, .rar or .7z, the most popular format of lossless audio compression uses the file extension of .flac which stands for Fast and Lossless Audio Compression. The most widely used format to store uncompressed audio files in CD or higher quality is called Microsoft Wave and has the extension of .wav. People who are not interested in sound designing or editing shouldn't need to work with Wave files. 
•	Lossy compression - this way is prefered for audio, video or pictures because it attempts to remove those details and nuances from the data that the human hearing or sight is most likely to miss anyway. So, these compression algorythms contain rules originating from research that are used to calculate which parts of the data are the least perceivable to an average human, trimming the size much more than lossless compression could, while trying to have the least possible impact on the quality at the same time. The most often found formats of lossy compression and their extensions are .mp3 and nowadays .mp4, .wma (Windows Media Audio) or .ogg for audio, .mpg, .wmv (Windows Media Video) or .avi for video, and .jpg or .gif for pictures. 
Notes
•	Data that was stored using lossless compression can be unpacked or saved in the original format again, resulting in the files with the same larger size as before and with no corruption, distortion or changes made to them; however, lossy compression always removes something from the file. Even if an mp3 file is later saved as a Wave, it will not magically restore the information that was erased during the process of making the original mp3. 
•	To work with any file compression format, there have to be the proper so called codecs for it, either installed in the operating system itself in one way or another or included in a certain program designed to work with files of a specific type (Windows media Player, Winamp, Sound Forge, Winrar or graphics editors). These codecs contain instructions that tell the program how to work with that file format: A compression codec is called an encoder and a decompression codec is a decoder. 
•	Some compression formats such as mp3, zip, rar or jpg are commercial, which means that any developer who wants to use them in their software must pay a fee to the rights owner to gain a license for them, while others like ogg, 7z or gif are free and often opensource, so the programs to read or edit them are completely free. The same is true for codecs, there are even free codecs that can work with commercial formats and vice versa. 

Sound file attributes
Most sound editors and/or encoders give the user the option to specify various parameters of the resulting compressed file. The following attributes are the most important ones you need to know when working with audio files, and in the case of Sound forge you can encounter them mostly in the Open, Save and Save As or Resample dialogs, with the exception of bitrate. 
•	Sample rate - it is measured in kHz (kilohertz) or Hz (hertz) and the most commonly used values are 8000 Hz (poor quality audio such as recordings made with most mobile phones), 16000 Hz (slightly better, used in some other mobiles or MP3 players that can also record audio), 22050 Hz (used to store long human voice recordings like lectures or audiobooks, where the quality doesn't have to be crystal-clear but still easily understandable) and 44100 Hz (most often called CD quality). There are also other seldom used values like 48000 Hz, 96000 Hz or 192000 Hz but there is no point in using these rates unless you are a professional sound engineer with adequate hardware equipment (sound card and microphone, mixer or another similar device). This attribute specifies how many audio samples per second will be captured when recording - how many of the sound waves that are vibrating through the air will be saved. The average human can hear frequencies between 20 Hz up to around 20 or 22 kHz, and it is said that the sample rate of a recording should be about twice this frequency so that if it is saved using lossy compression which removes a lot of the inaudible characteristics of the sound, the result will still be at or slightly above the hearing threshold. So, this means that the optimal sample rate to record Wave files (which can then be further edited and compressed) should be 44 kHz (it's 44100 Hz in most sound editors). 
•	Bit-depth - usually 8 or 16 bits. This adds to the sample rate and determines in how much detail the captured samples will be described, how much disk space they can occupy when saved. So, you don't only have to say how many of the sound waves will be noticed but also how clearly they will be portrayed in the saved file. Again, top sound designers and studios use other values to achieve even better results, such as 24 bits. Like with the sample rate and any other attribute, there is no point in using higher values than your hardware can handle, or combining a bit-depth of 16 bits with a sample rate of 8 kHz, for instance. If you want your files to be of CD quality, use 16 bits. 
•	Number of channels - 1 (mono) or 2 (stereo), but you could also use more if you needed to. Sound Forge supports up to 32 independent audio channels. In this case, you could have one channel for each microphone that you have connected to your mixer. However, you should know that a file in stereo will be twice as large as a mono one, a file with 5 channels would be 5 times as large, etc, because every channel has to be saved in a separate data track; if you have a stereo file recorded with an ordinary mono microphone, both channels will contain the same information independently of the other one, although they are exactly the same. The sound editor canot just know that the left and right channels are not different in any way. If you have recorded a mono file to save space and later decided that you would like to apply some effects to it where the difference in stereo panning would matter, you can simply usethe Channel converter process to convert it to stereo, apply the effects of your choice and then save it again. 
•	bitrate - used for lossy audio compression like mp3 or ogg to specify how much disk space the file will take, more accurately how many kilobites per second (kbps) that will be used. Other parameters also matter in combination with bitrate to determine the resulting quality and sound of such a compressed audio file, but in general it is not advised to use values lower than 192 kbps for mp3's that will be made out of CD quality Waves. Even an mp3 with 320 kbps, which is the highest possible bitrate value for this format, will still be many times smaller than a Wave, with brilliant quality. Most mp3 encoders also let you choose between CBR (constant bitrate) and VBR (variable bitrate). VBR is another feature intended to make lossy compression even more powerful - it attempts to calculate how many kbps will be needed for a certain part of the file, based on its audio characteristics. So, the bitrate of the file will then vary between a specified minimum and maximum value for different places in the file. Be very careful with using this option though, most often it alters the resulting quality of the file in an absolutely disastrous way when it is unwisely used by people who don't have too much practical experience with it and with combining it with the other attributes yet! 
Notes
•	Do not use compressed files if you want to further modify them. If the source file that you want to edit is already saved in a compressed format, I recommend that you save your work as a Wave again for best results and then convert it back to the compressed format using an external encoder such as Winlame, rather than the one built in Sound forge. Winlame is an opensource application as opposed to Sound forge's encoding algorythm called Fraunhoffer, and it is much more thorough and much less neglective in calculating what data should be omited in the resulting file. If you used Sound forge to make an mp3 out of a file that already was an mp3, for example, or even another compressed format, it is very likely that this action would severely damage the resulting quality - remember that the compression process has to be performed all over again when you resave a compressed file. On the other hand, it is always safe to save a Wave as many times as you want because there is no compression. 

Basic editing commands
Below is a list of the most useful and needed keystrokes you will want to use to quickly move through a sound file and mark parts of it to be edited. When you have chosen the part you want, you can just perform the expectable editing tasks on it such as those that you would find in a text editor - copy, paste, cut, delete or even mix. 
Key	Meaning 
Spacebar	Start or stop playback. If you stop the playback of a sound with spacebar and then press it again, the file will be played all the way from the beginning - the cursor position at which the playback was stopped will not be remembered. 
Enter	Pause or unpause playback. Unlike spacebar, this key will just pause the playback, remembering the position at which it was terminated, so it should be used if you want to select a spot to mark. 
Left and right arrows	Scroll through the file by a specified interval. 
Page up and page down	Jump through the file by greater steps. 
Home and end	Move to the beginning or end of the file, respectively. 
J	Revint through the file. You can press the key up to three times to go faster. This command will let you hear the audio at a faster speed so that you will still have a rough idea of where you are in the file at any given moment. 
K	Quickly stop the fast revinding or forwarding. 
L	Fast forward through the file. You can press the key up to three times to go faster. This command will let you hear the audio at a faster speed so that you will still have a rough idea of where you are in the file at any given moment. 
I	Mark in - place the beginning marker for a spot to be edited. If a section of the file is marked, any subsequent movement will only be done inside this part until you place a new marker, which will destroy the present ones, or select another part of the file by other means (control-a to select all or shift plus the arrow keys, page up and page down or home and end). 
O	Mark out - place the end marker for a spot to be edited. If a section of the file is marked, any subsequent movement will only be done inside this part until you place a new marker, which will destroy the present ones, or select another part of the file by other means (control-a to select all or shift plus the arrow keys, page up and page down or home and end). 
Delete	Delete the currently marked junk of audio. 
Control-z	Undo the last operation. 
Control-y	Repeat the last operation. This will just quickly perform the last issued command, preserving the existing markers, the parameters of the effect if relevant, etc. 
control-g	Go to - opens a dialog box with an edit field where you can key in an exact time to jump to, in the following format: Two digits for hours, colon, two digits for minutes, colon, two digits for seconds, period and three digits for miliseconds. 
Tab	Switch between the channels to work with - cycles between both, left and right in the case of a stereo file and has no effect on a mono file. 
Control-F6	Cycle backwards among all the currently opened sound files. 
Notes
•	There are other keystrokes to commands that make it possible to set the interval that the arrow keys or page up and page down move by. If you are curious and motivated enough to work with Sound Forge, you might need them at some point; however, I have never needed them so far and that's why I don't know them yet, so you will have to look for them in the help file if you want to get to know them. :-) 
•	Warning: Never delete source files that you are working with before you save the result! Most of the audio is not loaded directly in the memory, instead Sound forge just creates links to fragments of the original audio and notes the operations you performed on them. So, if you want to get rid of the original file (such as when you are cutting a long interview or something like that), always save the result before deleting the source material, otherwise you could get empty or corrupted sections in your final product! 

Processes and effects
The following is just a list of all the items in the Process and Effects menus that we either talked about during the workshop, as to remind you, or that we didn't have time to mention but that seem the most notable and useful to me, in alphabetical order. 
•	Processes 
o	Auto trim/crop 
o	Bit-depth converter 
o	Channel converter... 
o	Fade 
o	Insert silence... 
o	Mute 
o	Normalize... 
o	Pan/expand... 
o	Resample... 
o	Reverse 
o	Volume... 
•	Effects 
o	Amplitude modulation... 
o	Chorus... 
o	Delay/echo 
o	Distortion... 
o	Flange/wah-wah... 
o	Noise gate... 
o	Pitch 
o	Reverb... 
o	vibrato... 
Notes
•	Note also the Noise reduction plugin in the Tools menu.

Final words
This concludes the handout for the workshop on Sound Forge. 
Of course there is much more that can be learned about Sound Forge, I myself still don't know a lot about it. This is, however, everything that we talked or should have talked about in the workshop, and it should give you enough knowledge to start exploring and gathering your own experience easily. I wrote most information here in greater detail tthan I explained it in the workshop but if something is not entirely clear or you simply have more questions, feel free to contact me. I'll be happy to answer them all; the more curiosity, the better. Hope the workshop met or even exceeded your expectations. The best of luck and lots of fun with your sound-editing endeavors! 
Lukáš