A Jitter Buffer is a piece of software inside a Media Engine taking care of the following network characteristics:

  1. Packet reordering
  2. Jitter

The Jitter Buffer collects and stores incoming media packets and decides when to pass them along to the decoder and playback. It makes that decision based on the packets is has collected, the packets it is still waiting for and the timing required to playback the media.

Working Mechanism

Upon receiving packets, the Jitter Buffer holds them for a predetermined amount of time, known as the buffering delay, before sending them out in a more orderly fashion.

This delay allows the buffer to collect enough packets to smooth out the variations in arrival times.

The challenge here is to strike a balance between reducing jitter and minimizing the buffering delay, as a longer delay can lead to higher latency which is undesirable in real-time communications.

Adaptive Jitter Buffer

In more sophisticated setups, an Adaptive Jitter Buffer is employed. Unlike a static Jitter Buffer, an Adaptive Jitter Buffer can adjust the buffering delay dynamically based on the network conditions.

This flexibility allows for a more optimized performance, ensuring smoother communications even under fluctuating network conditions.

Alternatives to Jitter Buffer

There are alternatives and complementary technologies to Jitter Buffer to handle network inconsistencies and improve the quality of real-time communications. Some of these include:

1. Forward Error Correction (FEC):

Forward Error Correction is a technique used to enhance the reliability of data transmission. In FEC, the sender encodes the message in a redundant way by adding some error-correcting code, which helps the receiver to correct errors without needing a reverse channel to request retransmission of data.

2. Automatic Repeat reQuest (ARQ):

Unlike FEC, Automatic Repeat reQuest requires a feedback path from the receiver to the sender. When the receiver detects an error in the data, it requests the sender to retransmit the erroneous data. ARQ ensures the reliability of data transmission but at the cost of increased latency due to the retransmission process.

3. Packet Loss Concealment (PLC):

Packet Loss Concealment is a technique used to mask the effects of lost or discarded packets. In real-time communications like VoIP, when a packet is lost, PLC algorithms can generate a plausible substitute for the missing data based on the previously received data.

4. Error Resilience:

Error resilience techniques are designed to improve the robustness of the data transmission to packet loss and errors. These techniques can include the use of redundant coding, interleaving, and other methods to make the transmission more robust to network impairments.

5. Quality of Service (QoS) Settings:

Quality of Service settings in network equipment can prioritize real-time communication traffic over less time-sensitive traffic. By doing so, it helps in reducing the jitter and packet loss for real-time communications.

6. Network Improvements:

Improving the overall quality and capacity of the network infrastructure can also help in reducing jitter and improving the quality of real-time communications. This can include upgrading network hardware, increasing bandwidth, or optimizing network configurations.

Each of these alternatives and complementary technologies has its own set of advantages and trade-offs. The choice between them would depend on the specific requirements of the real-time communication system in question, such as the acceptable levels of latency, the importance of data integrity, and the available network resources.

About WebRTC Glossary

The WebRTC Glossary is an ongoing project where users can learn more about WebRTC related terms. It is maintained by Tsahi Levent-Levi of BlogGeek.me.

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