- Fri Jul 10, 2015 8:36 am
#22921
As a matter of fact i have
It really boils down to how much sustained throughput the ESP8266 can reliably handle.
The current code examples deal only with compressed MP3 format , which uses little bandwidth but has high latency and is not feasible to encode it real-time economically and with low latency.
To do a wireless speaker link, taking in analog or digital (s/pdif) uncompressed audio, at say 48,000 x 16-bit samples/second, that gives you a net payload throughput of 768 kbit/s. per mono channel - double that for stereo.
Now add to that encoding / packet overhead (you need small packets to maintain low latency, & better handle errors) and you're really talking ~ 1Mbit/s./ch.
Now add some extra bandwidth to leave time to retransmit the occasional dropped packet or 2, and other processing delays, time to receive handshaking/ack messages from the slave device, and you're really talking 1.5Mbit/s./ch, or 3Mbit+ for stereo.
Unfortunately, from what i've read on this forum (netio testing), ESP8266 would not likely be able to handle that.
Now its possible the actual bottleneck is in the ESP8266 firmware, and that some clever hacking in the low level code might release the cork so to speak, but there's no guarantee that will work, i'm not really in a position to do that.
Of course, if Espressif or anyone else figures out and shares how to get at least 3Mbit/s reliably through the ESP8266 , then i'll jump right on that!
In the mean time, i'm focusing on solutions that work well for streaming compressed audio , for example directly from a smartphone / tablet /computer, using bluetooth or WiFi.
Cheers
Frantz
raz123 wrote:Have you considered designing a plug-n-play transparent solution that would include transmitter and receiver audio modules, so as to easily make traditional speakers wireless?
As a matter of fact i have
It really boils down to how much sustained throughput the ESP8266 can reliably handle.
The current code examples deal only with compressed MP3 format , which uses little bandwidth but has high latency and is not feasible to encode it real-time economically and with low latency.
To do a wireless speaker link, taking in analog or digital (s/pdif) uncompressed audio, at say 48,000 x 16-bit samples/second, that gives you a net payload throughput of 768 kbit/s. per mono channel - double that for stereo.
Now add to that encoding / packet overhead (you need small packets to maintain low latency, & better handle errors) and you're really talking ~ 1Mbit/s./ch.
Now add some extra bandwidth to leave time to retransmit the occasional dropped packet or 2, and other processing delays, time to receive handshaking/ack messages from the slave device, and you're really talking 1.5Mbit/s./ch, or 3Mbit+ for stereo.
Unfortunately, from what i've read on this forum (netio testing), ESP8266 would not likely be able to handle that.
Now its possible the actual bottleneck is in the ESP8266 firmware, and that some clever hacking in the low level code might release the cork so to speak, but there's no guarantee that will work, i'm not really in a position to do that.
Of course, if Espressif or anyone else figures out and shares how to get at least 3Mbit/s reliably through the ESP8266 , then i'll jump right on that!
In the mean time, i'm focusing on solutions that work well for streaming compressed audio , for example directly from a smartphone / tablet /computer, using bluetooth or WiFi.
Cheers
Frantz
