Method and apparatus for balanced audio detection and conversion
Systems and processes are provided to detect an balanced audio signal and generation of an unbalanced audio signal including a first audio input for receiving a first audio signal, a second audio input for receiving a second audio signal, a processor for determining a first root mean square value for the first audio signal, a second root mean square value for the second audio signal and a combined root mean square value for a sum of the first audio signal and the second audio signal, the processor being further operative to generate an unbalanced audio signal in response to the first root mean square value exceeding a first threshold value, the second root mean square value exceeding the first threshold value and the combined root mean square value being less than a second threshold value, and an audio decoder operative to decode the unbalanced audio signal.
1. A method comprising:
receiving a first audio signal and a second audio signal at a first audio input;
adding the first audio signal and the second audio signal to generate a combined audio signal;
calculating a first root mean square value for the first audio signal and a second root mean square value for the second audio signal and a combined root mean square value for the combined audio signal;
determining the first audio signal and the second audio signal form a balanced audio signal in response to the first root mean square value exceeding a first threshold value, the second root mean square value exceeding the first threshold value and the combined root mean square being less than a second threshold value; and
generating an unbalanced audio signal in response to the first audio signal and the second audio signal in response to the determination that the first audio signal and the second audio signal form a balanced audio signal.
2. The method of claim 1 where the first threshold is 300 for 16-bit signed integer representation of PCM audio signal.
3. The method of claim 1 wherein the second threshold is 10% of the first root means square value.
4. The method of claim 1 wherein the unbalanced audio signal is a monaural audio signal.
5. The method of claim 1 wherein the unbalanced audio signal is the first audio signal.
6. The method of claim 1 wherein the unbalanced audio signal is a combination of the first audio signal and an inversed polarity second audio signal.
7. The method of claim 1 wherein the first audio signal and the second audio signal are received via an inter IC sound interface.
8. The method of claim 1 further wherein the first audio signal and the second audio signal are pulse width modulated signals.
9. An apparatus comprising:
a first audio input for receiving a first audio signal;
a second audio input for receiving a second audio signal;
a processor for determining a first root mean square value for the first audio signal, a second root mean square value for the second audio signal and a combined root mean square value for a sum of the first audio signal and the second audio signal, the processor being further operative to generate an unbalanced audio signal in response to the first root mean square value exceeding a first threshold value, the second root mean square value exceeding the first threshold value and the combined root mean square value being less than a second threshold value; and
an audio decoder operative to decode the unbalanced audio signal.
10. The apparatus of claim 9 wherein the unbalanced audio signal is generated in response to the first audio signal.
11. The apparatus of claim 9 wherein the unbalanced audio signal is generated from the first audio signal and an inversion of the second audio signal.
12. The apparatus of claim 9 wherein the unbalanced audio signal having a first channel and a second channel and wherein the unbalanced audio signal is generated by coupling the first audio signal to the first channel and the second channel.
13. The apparatus of claim 9 wherein the first audio signal and the second audio signal form a balanced monaural audio signal.
14. The apparatus of claim 9 wherein the first audio signal and the second audio signal form a two-channel audio signal.
15. The apparatus of claim 9 wherein the audio decoder is a pulse code modulated decoder.
16. The apparatus of claim 9 wherein the first audio input is an inter IC sound interface.
17. The apparatus of claim 9 wherein the second threshold value is 10% of the first threshold value.
18. The apparatus of claim 9 wherein the second threshold value is 10% of a peak value of the first root mean square value.
19. An apparatus for decoding an audio signal comprising:
a digital audio input for receiving a digital audio signal;
a decoder for generating a pulse code modulated audio signal having a first channel signal and a second channel signal;
a detector to calculate a first root mean square value for the first channel signal, a second root mean square value for the second channel signal and a combined root mean square value for a sum of the first channel signal and the second channel signal;
a processor to generate an unbalanced audio signal including the first channel signal in response to the first root mean square value exceeding a first threshold, the second root mean square value exceeding the first threshold and the combined root mean square value being less than a second threshold; and
an audio decoder operative to generate a decoded audio signal in response to the unbalanced audio signal.
20. The apparatus for decoding an audio signal of claim 19 wherein the second threshold value is 10% of the first threshold value.