Understand audio buffer

This guide concerns the buffer and latency of Streaming Radio Indeed, although latency is inevitable, the proper management of buffers allows you to optimize your diffusions while minimizing interruptions.

Buffer

The buffer, or buffer memory, is a small memory area that must be filled before the Player starts playing the music of your audio streaming. It corresponds to a sound of a few seconds. It is intended for greater listening comfort, in order to avoid small cuts in the flow being audible, which leads to a brazen and unpleasant sound. The reception and broadcast servers also have buffers.

Radio error diagnostic test (available) on the Manager) displays the amount of memory occupied by buffering each second. If the flow is working properly, the values must be stable. On the other hand, if the flow is unstable and encounters problems of connection, there is a gradual drop in the size of the buffer. The critical area is 20%. If the buffer is empty, the Player performs a microcut - perceptible by a slight click and visible on the graph by a 100% jump. Sometimes the buffer emptys very quickly, sometimes the critical zone is reached after a long time; that is why we offer several test durations.

An unstable buffer is the sign of either poor bond quality or saturation of the line. Be aware of this other guide if you are looking for resolution elements.

This test is also useful to help detect temporary saturations of an Internet line. If the buffer is sometimes stable, sometimes unstable, it may be the sign that some users sharing the Internet line saturate the line from time to time, resulting in disruption of your flow.

To check this hypothesis, launch a long-term buffer test at the full hours of use of your facilities and observe any disturbances.

Understanding and managing latency

Real-time transmission is never instantaneous due to several technical factors:

1. Inevitable latency:
   • The latency of 3 to 4 seconds between the sound generation and its reception is Normal.
   • Players always buffer at least 1 to 2 seconds before starting playback.
2. Tampons (buffers):
   • Icecast uses by default a 64K bytes buffer, equivalent to about 4 seconds of broadcast in 128k mp3.
   • Encoding customers also have buffers to prevent interruptions.
3. Reduction of latency:
   • Decreasing the size of buffers may reduce latency but this practice is risky.
   • Internet connections do not guarantee a constant flow rate, smaller buffers can lead to cuts.
4. Adjustment of buffers:
   • Latency is a challenge but buffers are useful for the stability of diffusion.
   • Adjust the size of the buffers to find an optimal balance between latency and transmission reliability.