Unit 73: Sounds For Computer Games

Uncompressed format:

CD, WAV, AIFF audio are more or less perfect representations of audio that was recorded, if you want convert one uncompressed format to another it will be a completely perfect copy of the audio. Say if you rip of the audio from a CD and put it into a WAV format on your PC then burn another CD using the WAV that you created, those two CDs will be literally identical, even though you copied them multiple times.

The only bad problem with uncompressed formats are that they are unreasonably big, say all your audio from your 4 gigabyte IPod Nano you would only be able to store around 4 to 5 albums on it that’s how big they can be.

Compressed format:

this type of format is for those who wish to cut corners and try to keep the file as small as possible to keep the file from being corrupted, the most used and most famous is MP3, there are also many others that include WMA and AAC. A program encoding audio into the MP3 audio for an example, it will get rid of some high frequencies, the frequencies are usually too high for the human hearing anyway, it may also perform a lot more complicated calculations, but that is one of the simplest examples there is, the advantage to this type of format is that they hardly take up any of the space on your PC or phone as a Uncompressed format.

How can resolution and bit-depth constrain file size?

In digital audio you can use pulse-code modulation or PCM, Bit-depth is the number of bits of information there is in each sample, and this is directly corresponded to the resolution of each of your samples, the examples of bit-depth include compact disc digital audio, which uses 16 bits of information per sample, and DVD-audio plus the blue-ray disc which can support up to 24 bits of information per sample.

In the form of basic implementations, variations in bit-depth mainly affect the noise level from quantization errors, thus the signal-to-noise ratio or SNR and dynamic range. However techniques such as dithering, noise shaping and oversampling mitigate these effects without changing any of the bit-depth, but the bit-depth affects the bit-rate and the file size as well.

Bit-depth is only good when referencing a PCM digital signal, anything other than a PCM format such as a lossy compression format don’t have any associated bit-depth, for example in the MP3 player quantization is performed on PCM samples that have most likely been transformed into the frequency domain.

What do the following words me?

Sample rate: the meaning of sample rate is the number of samples of audio carried per second and measured in Hz or KHz, for example 44,100 samples per second can be expressed as either 44,100 HZ or as 44.1 KHz.

Mono: the term mono means that you only use one channel for listening to sound because only one channel is open to that sound but it can be sent through many other speakers but the speakers are playing the same signal as the original  

Stereo: stereo means that the sound can be directed through two or more speakers so that is seems to surround the listener and it can also come from more than one source.

Surround: surround means that the sound will be coming from 360 degrees so that the sound is all around you, surround sound systems use up to three or more speakers and channels and place them in front and behind to create a surrounding environment of sound, surround sound can also be analog or digital system. 

Exercise 2

How Can The Following Information Limit The Recording Of Sound?

DSP-Digital Signal Processor: a digital signal processor is used to filter and/or compress analogue sound as it measures it. As the analogue signals are converted into digital the sound files often become compressed in this process before they are converted back to analogue. it is this compression that causes the limit in quality of sound.

RAM-Random Access Memory: RAM is a way of saying something's memory or storage. The more storage available the larger the file size that is usable, leading to greater quality. But if one did not have a decent amount of RAM it limits the size of the file usable meaning that compressed file types may need to be used leading to a lack of audio quality.

File Format: depending on your file format, it can hold so much information. This information is what leads to the general quality of the sound. With file types that compress the information, such as MP3 files, the quality is far inferior to those which don't compress the information.

Audio Output: depending on your audio output, it can be used to give the feeling of sound coming from certain places that when synced up with the audio being played can give a far deeper sense of immersion. Mono is the term used when sound only comes out one way from a source, stereo is used by two sources (left and right) and is used to make a person believe that the sound is coming from one direction or another, surround sound is used by placing many sources around the listener and playing certain sounds from the individual sources giving a far greater effect than that which stereo attempts to accomplish

Audio recording system.

In what types of scenario may you use the following audio recording equipment?

multi-track recording - you would use multi-track recording for when you are use 4 or more music tracks at the same time and want to make the music sound better so you would have 4 or more different parts 1 being guitar 2 being drummer 3 being singer 4 being bass and you want to make them all fit together and make it sound a lot better.

Analogue - you would use analogue when you are using your voice to record you maybe singing or maybe you're just talking to someone either way your using analogue there to begin with you would be singing into a microphone so that it could go onto a computer.

Software sequencer - you would use a sound sequencer if your on your computer because it is a computer software and it lets you create sounds using your keyboard from different musical instruments so that you can create music from home without using a instrument.

DAT - the only time you will be using a .DAT file is when your are saving it into Data on your computer or on your hard drive so that it will be turned into data and that it will be easier to use and see.