Saturday
Dec152007
InsideDSP discusses BDTi's quality measurements of Avnera's AudioMagic wireless audio link
Saturday, December 15, 2007 at 2:50PM
Over at Audio DesignLine, BDTI's test results of Avnera's AudioMagic system are discussed. Overall, it's a pretty good discussion of our technology.
One point to which I can offer some clarification is in their discussion of the over-the-air bit quality.
AudioMagic is in fact transmitting 16-bits of audio data over-the-air, and thus is actually better than CD-quality - over-the-air - at 16-bits of 48 KHz sampling rate to be exact... for reference CD-quality is 16-bit, 44.1 KHz.
However, the reason they question our CD-quality assertion is that we don't acheive the full 96 dB SNR that would come with 16-bit audio... the Avnera chipset is quoted from digital-in to analog-out, Avnera achieves a ~91 dB signal-to-noise ratio, end-to-end.
Anyways, long story short, Avnera measurements include the analog audio output, which is in fact what limits the SNR to 91 dB. To compare our complete end-products to a CD-system, you would also need to factor in the DAC/headphone amplifier of the CD-based system... it may very well be the same fact that you get less than 96 dB SNR out of a Discman or similar. There is often a quality down-grade during the conversion of the bits stored on the compact disk itself into analog audio. Product makers often use optimization strategies to buy battery-life in portable applications by giving up some fidelity/SNR... many products, like iPod Shuffles, nanos, etc, do this. As does Avnera in the headset chip. It is the headphone amplifier stage, not the over-the-air payload that should have been suspected, as that would have been accurate. Otherwise, good technical discussion of AudioMagic for Avnera.
At the end of the day, the conclusion was fair... for this grade of consumer equipment, >90 dB is plenty good enough. Trust me, it still knocks your socks off.
InsideDSP published the complete report.
One point to which I can offer some clarification is in their discussion of the over-the-air bit quality.
Avnera claims “>90 dB SNR digital-in-to-analog-out.” In an uncompressed digital audio signal, each bit contributes about 6 dB to signal-to-noise ratio, so the Avnera figure of “>90 dB SNR” implies “>15 bits”. Standard CD quality is 16 bits at a sample rate of 44.1 kHz. Thus, the Avnera may not quite reach CD quality.
AudioMagic is in fact transmitting 16-bits of audio data over-the-air, and thus is actually better than CD-quality - over-the-air - at 16-bits of 48 KHz sampling rate to be exact... for reference CD-quality is 16-bit, 44.1 KHz.
However, the reason they question our CD-quality assertion is that we don't acheive the full 96 dB SNR that would come with 16-bit audio... the Avnera chipset is quoted from digital-in to analog-out, Avnera achieves a ~91 dB signal-to-noise ratio, end-to-end.
Anyways, long story short, Avnera measurements include the analog audio output, which is in fact what limits the SNR to 91 dB. To compare our complete end-products to a CD-system, you would also need to factor in the DAC/headphone amplifier of the CD-based system... it may very well be the same fact that you get less than 96 dB SNR out of a Discman or similar. There is often a quality down-grade during the conversion of the bits stored on the compact disk itself into analog audio. Product makers often use optimization strategies to buy battery-life in portable applications by giving up some fidelity/SNR... many products, like iPod Shuffles, nanos, etc, do this. As does Avnera in the headset chip. It is the headphone amplifier stage, not the over-the-air payload that should have been suspected, as that would have been accurate. Otherwise, good technical discussion of AudioMagic for Avnera.
Still, in most consumer settings such as a home-theater-in-a-box in a normal living room, the difference between 15 and 16 bits of precision will probably be imperceptible.
At the end of the day, the conclusion was fair... for this grade of consumer equipment, >90 dB is plenty good enough. Trust me, it still knocks your socks off.
InsideDSP published the complete report.
tagged Audio DesignLine, AudioMagic, Avnera, InsideDSP, iPod in industry
Audio DesignLine, AudioMagic, Avnera, InsideDSP, iPod in industry
Reader Comments (1)
I was curious about InsideDSP's 15 bit estimation when I read that article last week. Thanks for the explanation.
Here is an interesting comparison by CNET of SNR with various .mp3 players (for reference purposes).
http://reviews.cnet.com/4520-11297_7-6510133-2.html?tag=lnav
At regular or even loud listening levels is there a real world distinguishable difference (Can I hear it?) between ~91 SNR and 96 SNR?