Warning: if you are not interested in bluetooth captures or audio hackery, uh, maybe kittenwar is where you want now 🙂
Attached is a bluetooth snoop log (open in Wireshark) of the SmartMic/Mike+ operating natively in Android, so e.g. its high-quality mode. You can see a couple of MPX_CTRL Modem Status Commands that are intriguing, as are the DLC Parameter Negotiation.
Any suggestions on how to put this in highest quality mode in linux?
Answer (partial): it puts it in SPP (serial port) mode, and sends as fast as it can. The packets are about 216 bytes of payload, and about 150/s, giving about 260Kbps of throughput.
So I can't believe I'm doing this on the 15th of September. But it was 3 degrees this am and I'm not getting any younger.
So, let's take a look. Earlier I talked about the heated handlegrips. First we have a problem on the right hand side, the twist throttle is long, and the handlegrip is short. See the image below. Now, I considered removing the throttle, but its a huge safety feature. I don't use it while moving, but it allows me to get away from a stop faster, so I use it a couple of times each commute. So that is out. So I moved the bell to the left side, shifted the shifter and brake over. I'm not super kean on this, I'll try it tomorrow am and see. The right-handlegrip of the heated set is designed for a motorcycle, so its expecting a twist throttle underneath it. So, I did what you would expect, I taped them together 🙂
I mounted the 2nd battery pack in front. I considered wedging it in on top of the main battery, it just fits there, but I couldn't secure it easily. This is out of the way.
I tested the grips out on the bench, the pack can run them for just over 3 hours (the current drops a lot as the voltage sags). I'm a bit nervous, at the 3 hour mark the per cell voltage was 2.4V, it's not clear where the low-voltage cut-off would hit (or if there is even one). So I stopped the test, but, uh, I hope i don't forget and leave them on sometime.
OK, from the previous post about the SmartMic, it appears that if we update the bitpool size (default 51), perhaps by setting sbp_min_bp from https://github.com/EHfive/pulseaudio-modules-bt, that is likely what the app is doing on the phone.
This afternoon, I will try and report back audio fans.
Last fall a device idea appeared on Kickstarter, the Sabinetek SmartMike+. It promised a Bluetooth lavalier microphone with high quality. As most who have used Bluetooth (especially on Linux) know, the microphone support is kind of terrible, you delve into profiles involving phrases like HSP/HFP, and quickly find that you sound .... like a telephone.
Intrigued, but its kind of expensive @ $160, and, I have the Rode Wireless Go which is pretty fantastic (but not Bluetooth). So I let it go.
After some time I start to see SmartMic (not Mike+) appear online, for about $90. It doesn't look quite the same (its round instead of rectangular), but the specs are very similar. So, I hit the buy now button.
And, here we are, photo above, pen for scale. Its light. So, I try it out, the box and extensive user guide (reproduced below) are pretty unabashed. Use the SmartMike+ app. So I do. That my friends, is a terrible application. Its only more terrible since they suggest you have no choice but to use it, that somehow this is not a standard Bluetooth device. It suggests somehow that it streams a bit live and stores the rest for retrieval at higher rate.
I will say, the audio quality was very good for a Bluetooth lavalier. If you used this for a conference call you would be very happy. Maybe even a podcast.
So, lets press on, I'm sure they aren't redoing the Bluetooth stack in Android. So I pair it to the PC. Story checks out, looks like every other Bluetooth headset w/ APT/X, AAC, HSP/HFP profiles. I record some audio in the HSP/HFP profile. Hmm, its ok, not as good as their app. It cuts off at 3500Hz (sharply), so I'm assuming that is the SBC codec.
Let's look at the profiles:
Service Name: Hands-Free unit
Service RecHandle: 0x10000
Service Class ID List:
"Handsfree" (0x111e)
"Generic Audio" (0x1203)
Protocol Descriptor List:
"L2CAP" (0x0100)
"RFCOMM" (0x0003)
Channel: 10
Language Base Attr List:
code_ISO639: 0x656e
encoding: 0x6a
base_offset: 0x100
Profile Descriptor List:
"Handsfree" (0x111e)
Version: 0x0106
Service Name: Headset
Service RecHandle: 0x10001
Service Class ID List:
"Headset" (0x1108)
"" (0x1131)
"Generic Audio" (0x1203)
Protocol Descriptor List:
"L2CAP" (0x0100)
"RFCOMM" (0x0003)
Channel: 11
Language Base Attr List:
code_ISO639: 0x656e
encoding: 0x6a
base_offset: 0x100
Profile Descriptor List:
"Headset" (0x1108)
Version: 0x0102
Service RecHandle: 0x10002
Service Class ID List:
"Audio Sink" (0x110b)
Protocol Descriptor List:
"L2CAP" (0x0100)
PSM: 25
"AVDTP" (0x0019)
uint16: 0x0103
Profile Descriptor List:
"Advanced Audio" (0x110d)
Version: 0x0103
Service RecHandle: 0x10003
Service Class ID List:
"PnP Information" (0x1200)
Service RecHandle: 0x10004
Service Class ID List:
"AV Remote" (0x110e)
"AV Remote Controller" (0x110f)
Protocol Descriptor List:
"L2CAP" (0x0100)
PSM: 23
"AVCTP" (0x0017)
uint16: 0x0104
Profile Descriptor List:
"AV Remote" (0x110e)
Version: 0x0105
Service RecHandle: 0x10005
Service Class ID List:
"AV Remote Target" (0x110c)
Protocol Descriptor List:
"L2CAP" (0x0100)
PSM: 23
"AVCTP" (0x0017)
uint16: 0x0104
Profile Descriptor List:
"AV Remote" (0x110e)
Version: 0x0105
Service Name: M_MIKE_SLV
Service RecHandle: 0x10007
Service Class ID List:
"Serial Port" (0x1101)
Protocol Descriptor List:
"L2CAP" (0x0100)
"RFCOMM" (0x0003)
Channel: 14
Language Base Attr List:
code_ISO639: 0x656e
encoding: 0x6a
base_offset: 0x100
So, I'm not sure what is next. Their app is terrible. The audio and video are wholely unsynced. It has some spinning pink cloud to play back the audio later. No auto sync to Google Drive. Its, ugh.
What I was hoping was a high fidelity Bluetooth microphone, and use w/ Audacity. What I got, well, more hacking will be needed!
Earlier I showed my results for the Covid Tracker (which allows you to log on your phone the hash-key of others who are nearby in case they become infected).
I had some discussion with people about what the ~400 meant. Was that 400 keys I was near? Was it 400/14 for the duration? Interestingly, it then dropped, and is now quite variable.
