This holds true for most conversions between files, formats or media containers and especially for VoIP. For instance MP3 audio files are compressed files that lose quite a bit of data from the original. But the resulting clarity is enough for most people thus constituting an acceptable trade-off between saving space and audio quality.
On the other hand, there are other codecs which utilize heavy compression to save bandwidth. This is a primary reason why the discussion of which codec to use becomes important. Many codecs have been developed specifically for certain use cases and using them under the wrong circumstances can be a mistake. Usually when the audio quality is good, organizations rarely have to bother about which codec is being used by the provider.
However if their network is properly optimized and all other aspects of the system are set up properly but quality is still bad, the codec deployed may be the culprit. It is why most businesses rarely have any idea or inquire about the particular codec being used before purchasing services.
A little forethought when researching and comparing vendors can save a lot of trouble down the road. Unfortunately, there is no perfect codec that is acceptable for all enterprises under all circumstances. Some high-quality codecs require licensing fees whereas others are open source, some offer better quality while others use less bandwidth.
All of these aspects will affect the final choice of codec selection by a provider, client or organization. Start a free 30 day trial now, no credit card details are needed! It is the role of a Digital Signal Processor DSP , a dedicated hardware microprocessor, to actually perform the encoding and decoding based on the particular rules of the chosen codec.
Each device that encodes and decodes voice is configured to do so using a particular codec—in other words, to use a specific set of rules for the converting of voice to the necessary format for transmission using VoIP.
In actual fact, there are many different types of codecs and each one has specific uses and parameters. The choice of codec for each voice communication has profound effects on many aspects of that communication including both user experience and network efficiency.
What codec you select to use will affect the quality of the voice heard, as well as the nature of the voice packets placed on the network. As we said before, a voice codec is essentially a set of rules used to encode, digitize, and transfer voice over an IP network. It must be noted that this is something distinct from the SIP protocol. The primary parameters that a codec defines in this procedure are sampling rate, bit depth, and compression.
The primary difference between an analog and a digital signal is the fact that an analog signal is continuous, while a digital signal is discrete. The grey line represents a sound wave as it progresses over time. As you can see it is continuous. The black dots represent the points in time where the samples are taken. Each sample is then stored as a digital number that represents the amplitude, or the intensity of the sound wave at that point in time, which is indicated by the red lines, resulting in a digital representation of that sound.
How often a sound is sampled when digitizing it is called the sampling rate. The more often the sound waveform is sampled, the more accurate the digital representation of that sound becomes. The following diagram shows the same sound wave sampled at twice the rate. This results in a truer digital representation of the original sound but also increases the amount of data needed to represent that sound. You have twice as many data points, and thus, twice as much data to store and transmit. The sampling rate is measured in Hertz Hz , which is a unit of frequency per second.
Telephone quality voice typically uses Hz as the sampling rate, which means that a sample of the voice is taken times a second. This results in the familiar timbre that voice over the telephone possesses. In comparison, CD-quality sound is sampled at a minimum of Hz. A voice codec, therefore, defines the sampling rate that is used to digitize voice. When digitizing voice, each sample of sound must be represented as a series of bits.
The more bits used to represent each sample, the more accurate the representation. Take a look at the following depiction of a sound:. The waveform is continuous, as expected. Now take a look at this same waveform in its digital representation that is sampled using a different number of bits for each sample. The more bits used to represent each sample, the more accurate each sample is represented digitally. Without dedicated bandwidth, you will experience issues such as calls dropping and poor voice quality.
The table below shows the bandwidth that is needed by each codec. As you can see, some codecs require much more bandwidth than others. The G. This could pose an issue if your system is using the G. The bandwidth required above doubles with each concurrent call. For example, if you are using the G. With all the other processes consuming bandwidth in your office, you may struggle with a poor connection such as ADSL. This could be resolved by changing the codec that your system uses or upgrading to a connection with more bandwidth.
Or even if you have a good connection, you might wonder which codec is the best for your system. When deciding between codecs, there are several important considerations. One of the most important considerations is how much bandwidth you have available. On the other hand, if you have plenty of bandwidth, you can go for a bandwidth-hungry codec that guarantees higher voice quality on calls. While there are plenty of free codecs available to use, there are licensed codecs available that improve your call quality.
Some licensed codecs are developed specifically with certain systems and devices in mind. This codec is ideal for use with Polycom devices and will offer a better call quality. So which codec is right for your business?
How can you choose between all the codecs that are available? Hopefully, this brief overview will help you to choose which codec is right for you.
There are a wide selection of VoIP codecs to choose from.
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