What determines streaming sample rates?
Updated
by
Bryan Jones
Scope
This document covers a number of current and legacy Telos and Omnia streaming products and aims to answer questions about what determines the bit rate of a stream.
For purposes of this document, we will only discuss MP3 streams. AAC streams are a much different discussion as there are AAC formats that are designed for different situations.
Description
MP3 output streaming formats are affected by the sample rate of the original content, the number of output channels (stereo or mono) and the bit rate of the MP3 stream.
Stream Bit Rate | Output SR Stereo 48k Input | Output SR Mono 48k Input | Output SR Stereo 44.1 Input | Output SR Mono 44.1 Input |
8 Kbps | NA | 8,000 | NA | 11,025 |
16 Kbps | NA | 16,000 | NA | 11,025 |
20 Kbps | 12,000 | 16,000 | NA | NA |
24 Kbps | 16,000 | 24,000 | 11,025 | 11,025 |
32 Kbps | 16,000 | 24,000 | 11,025 | 22,050 |
48 Kbps | 24,000 | 24,000 | 22,050 | 22,050 |
56 Kbps | 24,000 | 48,000 | 22,050 | 44,100 |
64 Kbps | 24,000 | 48,000 | 22,050 | 44,100 |
96 Kbps | 32,000 | 48,000 | 44,100 | 44,100 |
128 Kbps | 48,000 | 48,000 | 44,100 | 44,100 |
192 Kbps | 48,000 | NA | 44,100 | NA |
256 Kbps | 48,000 | NA | 44,100 | NA |
320 Kbps | 48,000 | NA | 44,100 | NA |
Final thoughts
Sample rate affects the overall frequency response. Often referred to as Nyquist theory or Nyquist frequency, the premise is that the frequency response is roughly half the sample rate. More info on this in Wikipedia
Not all output rates can be achieved by all input rates. For example, note that a 44.1 input sample rate can not produce a 20 Kbps output stream. The sample rates are not evenly divisible in these cases.
Generally, mono output signals can use higher sample rates as there are half as many bits in mono as there are for stereo.
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