Choosing the coding method for your application, Audio coding comparison chart – Telos ZephyrExpress User Manual
Page 89

CODING
5-11
CHOOSING THE CODING METHOD FOR YOUR APPLICATION
This chart describes and compares some of the important characteristics of each
method. Because ZephyrExpress includes all three popular coding methods, it’s possible
to choose the most appropriate one for each application.
Audio Coding Comparison Chart
Layer 3
Layer 2
G.722
Algorithm
Perceptual+Huffman
Perceptual
ADPCM
Audio Freq. Response/mono
7 kHz
24 kHz sample rate, 64 kbps line
15 kHz
8.6 kHz*
32 kHz sample rate, 56 kbps line
15 kHz
7.8 kHz*
48 kHz sample rate, 64 kbps line
20 kHz
9.8 kHz*
48 kHz s/r, 128 kbps line**
20 kHz
Audio Freq. Response/stereo
7 kHZ
at 32 kHz sample rate
15 kHz
at 48 kHz sample rate
20 kHz
20 kHz
Delay at HALF/24 kHz
45 ms
Delay at 32 kHz/mono
275 ms
45 ms-
Delay at 32 kHz/dual mono
275 ms
45 ms-
Delay at 48 kHz/mono
225 ms
160 ms
45 ms-
Delay at 48 kHz/dual mono
225 ms
160 ms
45 ms-
Delay at 48 kHz/mono-128
220 ms
Delay at 32 kHz/stereo/jstereo
390 ms
45 ms-
Delay at 48 kHz/stereo/jstereo
270 ms
220 ms
45 ms-
Joint Stereo
MS Matrix
Intensity Coding
ISO Target Bit Rate
64kbps/channel
128kbps/channel N/A
Coding Power as In/Out Ratio
12:1
6-8:1***
4:1
Frequency Bands
576
32
2
Frequency Resolution (48 kHz)
42 Hz
750 Hz
--
* Layer 2 was not designed for the low bitrates of a single ISDN channel,
so the response is deliberately limited in some Layer 2 conditions
to reduce unpleasant high-frequency artifacts.
** Requires two 64kbps ISDN channels.
*** 12:1 in Intensity Joint Stereo mode
-G.722 delay will vary. Spec is 35 ms +/- 10 msec for 45 ms maximum
Delay times may vary depending upon ISDN line delay and other factors.
Frequency response is given for swept sine test; response with program material
may vary owing to the dynamic nature of the coding process.