You’ve been asked to convert a WAV file to an MP3 file with a rate of 44.1kHz. What does this mean?
A) The MP3 file needs to be exactly 44.1 kilobytes in size.
B) The MP3 file needs to have 44,100 samples every second.
C) The MP3 file bit depth should be 44.1 kHz.
D) The MP3 file should have a compression ratio of 44.1 to 1.
Answer: B) The MP3 file needs to have 44,100 samples every second.
A hertz is a frequency equal to one cycle per second, and you often see it abbreviated as Hz. A kilohertz (kHz) is 1,000 cycles per second. One of the properties of an MP3 file is the number of audio samples per second, so a rate of 44.1 kHz is an MP3 file with 44,100 samples of audio data each second.
The incorrect answers:
A) The MP3 file needs to be exactly 44.1 kilobytes in size.
When converting files, you can usually estimate the converted file size and get close to your estimate, and it’s very impractical to pick an exact file size. Although the total size of the file increases as the kilohertz rate increases, the kHz rate and total file size value is not otherwise related.
C) The MP3 file bit depth should be 44.1 kHz.
The “depth” of an MP3 file refers to the bits of audio data available in each sample of audio. It’s common to see CD quality audio with 16 bits of depth, but you could choose larger or smaller bit depths depending on your requirements. The more bit depth, the higher quality of audio you’ll have (and the larger the file!).
D) The MP3 file should have a compression ratio of 44.1 to 1.
The amount of compression of an MP3 file is based on a compression algorithm, not on a variable set during the conversion process. The sample rate and bit size will determine the audio quality and byte size of the MP3 file.
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Want to know more? Watch “Installing, Configuring, and Upgrading Audio.”The use of audio in personal computers has evolved dramatically through the years, and the current assortment of audio hardware devices and software is varied enough to keep even the most knowledgeable technicians guessing. In this video, we’ll show you common audio input and output methods, discuss the details of sample rates, examine the differences between audio bit depths, and perform some audio configurations in Windows XP. |