PCM stands for Pulse Code Modulation.
PCM converts analog audio to digital audio without any form of compression.
It is a form of digital signal that is used to represent analog audio.
The main purpose of PCM is to duplicate the original analog audio as closely as possible into a digital format.
As the PCM audio format is overall uncompressed, it produces audio of high fidelity.
How Does The Processing Take Place?
A process called sampling is used to convert analog video to digital.
For example, PCM files for DVD Video must employ the sampling rate of 48 kHz. DVD Audio has a sampling rate of 98kHz. The bit depth that must be used is 16-bit (DVD Video) or 24 bit (DVD Audio).
The PCM technology was developed by British Engineer, Alec Reeves, in 1937.
In the 1960s telephone companies used PCM to efficiently transmit long-distance calls between cities.
NHK, also known as Japan Broadcasting Corporation, offered the first public demonstration of the superiority of PCM audio in May 1967. It was undertaken on a 1-inch and 2-head helical scan VTR.
Where is PCM Used?
The PCM audio format is used in applications related to Blu-ray, DVD, CD and Hi-MD, among others.
PCM is also known as linear pulse code modulation (LPCM) when it is used in a surround sound environment.
8mm Video Players
PCM audio is used in 8mm tape decks and camcorders. For example, Digital8 camcorders and tape players are capable of recording PCM 16-bit/12-bit mode digital stereo sound.
PCM is also the mandatory audio format for the PAL, NTSC, and SECAM standards.
Computer Sound Cards
Audio recorded from the microphone jack of a computer sound card is in the PCM format. Compressed audio can also be converted to PCM during playback.
Audio recording software captures sound in the PCM format. It then converts the sound to a compressed format like MP3 or AAC.
TV Sets and AV Equipment
Some TV sets and AV receivers come with ports labeled as PCM. They can be used to transmit uncompressed audio from a playback device like a DVD or Blu-ray player to the television set or AV receiver.
Types of PCM Audio
Among the types of PCM audio are SDII (Sound Designer 2), WAVE, AU, and AIFF, among others.
Advantages of PCM Audio
Here are some advantages of PCM
- Noise immunity is high
- Transmission efficiency is high
- Easy to multiplex
- Good for long-distance communication
- Superior noise performance compared to an analog system
Disadvantages of PCM Audio
Here are among the disadvantages of PCM
- Produces large file sizes
- Uses a larger bandwidth