G.711 Codec vs G.729 Codec: Everything about VoIP Codecs

What is that robotic voice you sometimes hear on phone calls? The quality of voice calls depends on codecs - the software that converts your voice into data. There are two main codecs used in VoIP calls. G.711 produces higher quality audio than G.729, but G.729 compresses better by making file sizes 8 times smaller. So which should you use? Read on to learn the key differences between these popular codecs and how to choose the right one for your needs. Discover what makes them sound different, their CPU requirements, and more.

How VoIP Codecs Work

Voice over Internet Protocol (VoIP) allows us to make voice calls over the Internet. For this to work, our voice must be converted into a digital format that can be transmitted over the Internet. This is done using codecs. There are many voip solutions providers offering services to enable VoIP capabilities.

A codec is a software program that converts or "codes" analog voice signals into digital signals and vice versa. When we speak into a VoIP phone, the microphone converts our voice into an analog signal. The codec then encodes this analog signal into a compressed digital format. This compression allows the digital voice data to travel faster over networks. 

Popular codecs used in VoIP phones include G.711, G.729, and Opus. G.711 provides good sound quality but does not compress the voice signal much. G.729 compresses the data more, but sound quality is not as good. Opus codec provides excellent sound quality while also compressing data well.

The encoded digital voice data then travels over the Internet. At the other end, the receiving codec decodes the digital data back into analog audio that the call recipient can hear and understand clearly. This encoding and decoding allows natural conversations to happen smoothly over the Internet using VoIP technology.

Narrowband Codecs vs Wideband Codecs vs Ultra-wideband Codecs

Narrowband Codecs

These codecs compress the voice into a narrow range of frequencies - between 300Hz and 3400Hz. This saves a lot of bandwidth but makes the audio quality sound choppy and robotic. Examples include G.729 and G.723.1. They transport voice well but sound unnatural.

Wideband Codecs

These codecs preserve more frequencies up to 7000Hz for better voice quality. They produce clearer and more natural-sounding audio that's easier to understand. They do take up more bandwidth compared to narrowband codecs though. Some examples are G.722 and G.722.2.

Ultra-wideband Codecs

These codecs preserve an even wider range of frequencies up to 12,000Hz to include clearer consonants and more natural voice nuances. They produce very high-quality audio for VoIP calls. But they require a lot of bandwidth. Examples include G.719, G.722.1C, and Opus.

In summary, narrowband codecs use little bandwidth but sound robotic. Wideband codecs sound natural and clearer. Ultra-wideband codecs sound even more natural but use a lot of bandwidth. Companies choose which codec to use based on the voice quality they want to deliver versus the internet bandwidth available. I hope this straightforward explanation helps explain the different VoIP codec types! Let me know if you need any clarification or have additional questions.

Overview of G.711 and G.729

G.711

• One of the oldest and most basic voice compression standards used in telephony. 

• It doesn't compress the voice signal very much

• it just reduces the bandwidth needed while maintaining good voice quality.

• Two main variants: G.711 μ-law (used in North America and Japan) and G.711 a-law (used in Europe and the rest of the world). They work in a very similar way.

• Good voice quality but uses a lot of bandwidth compared to more modern codecs. Each call takes up about 64 kilobits per second.

G.729

• A more modern voice compression standard designed to save bandwidth.

• Uses a complex audio coding system to compress the voice signal to as little as 8 kilobits per second per call. 

• This allows 8 G.729 calls to fit in the same bandwidth as a single G.711 call.

• Voice quality is still good but some background noise can be introduced at very low bitrates. There may also be a little audio delay.

• Overall provides very efficient use of bandwidth while keeping call quality reasonably high.

• Commonly used in Voice over IP (VoIP) and video conferencing solutions where bandwidth needs to be conserved.

In summary, G.711 provides excellent voice quality but is not very efficient. G.729 provides very efficient compression to save bandwidth while still maintaining reasonable call quality. Telecom engineers can choose between them based on their network requirements.

G.711 vs G.729: Which one is best?

Bitrate and Bandwidth

• G.711 operates at 64kbps and provides very high audio quality. It requires more bandwidth compared to G.729.

• G.729 operates at 8kbps, providing reasonably good voice quality at a much lower bitrate. It conserves bandwidth.

Latency

• G.711 has very low algorithmic latency, resulting in more interactivity. 

• G.729 has higher algorithmic latency due to the complexity of its compression techniques. The increased latency may impact interactivity.

Audio Quality  

• G.711 provides superb audio quality as it uses pulse code modulation with very little compress provides on. Voice quality is natural.

• G.729 good voice quality at its lower bitrate by using more complex compression like ACELP. Quality is degraded compared to G.711 but still good.

Recommended Usage

• G.711 is recommended for IP telephony applications where bandwidth is readily available and audio quality is paramount, like office VoIP networks.

• G.729 is best suited for situations where bandwidth conservation is critical, like international VoIP calls or mobile network gateways. The tradeoff in quality is acceptable for the bandwidth savings.

In summary, G.711 delivers the best audio quality while G.729 saves bandwidth at the expense of some voice clarity. Usage depends on which factor is more important for the specific application.

Conclusion

In summary, G.711 and G.729 are both widely used codecs for VoIP calls, but they have key differences. G.711 provides unmatched voice quality and is the preferred choice for landline replacement phone services. However, it requires more bandwidth compared to G.729.

G.729 is specifically designed for low-bandwidth usage, making it popular for mobile VoIP applications. The tradeoff is lower voice quality than G.711, with some robotic-sounding artifacts. G.729 also comes with licensing fees while G.711 is royalty-free.

When choosing between the two, consider factors like sound quality needs, network capacity, and budget. For high voice fidelity regardless of bandwidth, G.711 is better. But if conserving bandwidth is critical and some voice quality degradation is acceptable, then G.729 has advantages. With an understanding of their respective strengths and limitations, both codecs have roles in modern VoIP communications.

For professional VoIP services and solutions tailored to your specific needs, contact Ecosmob at sales@ecosmob.com or visit our contact page