665. Dealing with low gain/low volume in Samson XPD2 by boosting the gain in pulseaudio

I've 'solved' this now. See bottom of post.

Old post:

 Got the Samson XPD2 now, and it's ... interesting.

Even if I crank everything up to the max in linux, I can barely hear what I record in audacity (or anywhere -- it's a linux thing).

But if I hook up headphones to the headphone jack on the USB dongle the sound is great.

What figures?

As usual the first port of call is always dmesg:

[Sun Aug 23 05:18:02 2020] usb 2-11: new full-speed USB device number 22 using xhci_hcd
[Sun Aug 23 05:18:02 2020] usb 2-11: New USB device found, idVendor=17a0, idProduct=1616, bcdDevice= 1.00
[Sun Aug 23 05:18:02 2020] usb 2-11: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[Sun Aug 23 05:18:02 2020] usb 2-11: Product: Samson RXD wireless receiver
[Sun Aug 23 05:18:02 2020] usb 2-11: Manufacturer: Samson Technologies
[Sun Aug 23 05:18:02 2020] usb 2-11: Warning! Unlikely big volume range (=496), cval->res is probably wrong.
[Sun Aug 23 05:18:02 2020] usb 2-11: [50] FU [Mic Capture Volume] ch = 1, val = 0/7936/16
[Sun Aug 23 05:18:02 2020] input: Samson Technologies Samson RXD wireless receiver as /devices/pci0000:00/0000:00:14.0/usb2/2-11/2-11:1.2/0003:17A0:1616.0012/input/input58
[Sun Aug 23 05:18:02 2020] hid-generic 0003:17A0:1616.0012: input,hidraw7: USB HID v1.00 Device [Samson Technologies Samson RXD wireless receiver] on usb-0000:00:14.0-11/input2

Linux is normally PnP, but here there seems to be an issue. Time to start reading. Found a similar issue here: https://bugzilla.redhat.com/show_bug.cgi?id=1070706

Will update as/if I fix this.

Also, I got a female 3.5 mm to female XLR connector so that I can use a better lavalier mic. The connector should be mini-XLR -- a full-size XLR is way too big. 

Solution:

What I do now is set the input volume in the terminal using pulseaudio (pacmd/pactl).

By default you can only set the input volume to 150%, but using the command line you can go as crazy as you like.

First identify the card index number: 

pacm list-sources|egrep "name|index"

    index: 26
   name: <alsa_input.usb-Samson_Technologies_Samson_RXD_wireless_receiver-00.analog-mono>
      alsa.name = "USB Audio"
      alsa.subdevice_name = "subdevice #0"
      alsa.card_name = "Samson RXD wireless receiver"
      alsa.long_card_name = "Samson Technologies Samson RXD wireless receiver at usb-0000:00:14.0-2, full sp"
      alsa.driver_name = "snd_usb_audio"
      device.vendor.name = "Samson Technologies Corp."
      device.product.name = "Samson RXD wireless receiver"
      device.profile.name = "analog-mono"
      alsa.mixer_name = "USB Mixer"
      device.icon_name = "audio-card-usb"

Then do (for index 26):

pactl set-source-volume 26 270%

Works great! Of course you can't touch the input slider in the pulseaudio GUI at this point. The next project is to change the pulseaudio source code to allow a higher max volume.

New microphone

I also bought a new microphone to use with the Samson: https://www.amazon.de/-/en/gp/product/B071937RZZ/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

The sound is subjectively a lot better and I feel that it has better dynamic range, than with the stock microphone.

664. Capturing sound when recording/streaming lectures/videos. A few devices.

 I'm interested in capturing sound, either during on-campus lectures, or when recording videos, or when lecturing over zoom.

Here are some of the devices that I own, and what I think:

Logitech C920 webcam with integrated microphone:

The sound is ... fine. Even at a few metres distance, actually.  Nothing like a proper, dedicated microphone, but way beyond e.g. the microphone you'd find in a laptop.

BlueParrot B350-XT bluetootch headset:

It's absolutely bloody awful as a sound source. Absolutely fine for listening to music with, but as a headset for recording sound it stinks. The sound during phone calls is fine, but expectations aren't generally very high. Bloody expensive too.

Logitech G930 wireless gaming headset:

Decent sound, but lacks dynamic range in terms of the microphone. Won't work well during a live lecture since it covers both ears. Great at keeping sound out, so very good as a headset for listening to music.

Samson XPD2 wireless lavalier microphone:

Have ordered, but not yet received. You can use it as a lav mic, but I'm going to experiment with using the Zoom H1n below as the input (via a 2x 3.5 mm cable plus a 3.55 mm female -> XLR converter), so that I can record on the H1n simultaneously as I live-stream. We'll see how it works out.

I also bought what is supposed to be a better Lavalier mic (J-082S 044) and a 3.5 mm/XLR adapter:

Blue Yeti microphone:

This is my default microphone for video conferencing and recording videos. It's a great microphone. Cheaper than the crappy B350-XT above. Has several different pickup patterns. I love it. 

I'm using it together with a boom arm I got off of Amazon ('Neuma Professional Microphone Stand with Pop Protection').

Zom Handy H1n sound recorder:

This is my favoure toy though. It's small, light and have great sound. It's a stereo microphone when use as a sound recorded. You can also hook it up via USB (and have it powered via USB) and use it as a high-quality MONO microphone when recording videos or video conferencing. You can NOT record at the same time as you're using it as a USB microphone. I also got the Zoom APH 1 N/GE Accessories Bundle.

The portability makes it great for a number of uses. You can pass it between lecturers that want to record good-quality sound for lecture videos, and it's easy to take home (the Blue Yeti is a heavy beast).

You can also stick it the podium when giving a lecture and it will capture surprisingly good sound. You can record sound and replace webcam sound in post using e.g. KDENLive. You can attach a lavalier mic and use it to record sound during a live lecture and replace webcam sound in post. And more.

It has a 3.5 mm mic input and a 3.5 mm headphone output. I'm planning on experimenting with recording on the H1n at the same time as I've got the headphone output connected to the Samson (above) so that I can stream the sound to my laptop, and share it via zoo, since wireless technologies can be unstable in a lecture hall with lots of phones with wifi running (anywhere you have students). We'll see how it works out.

----------------
Once the audio is taken care of, I plan on using the following for the visual, and use OBS Studio to tie it all together.

Document camera JOURIST DC80

Webcam Logitech C920

I've also ordered a chromakey set for fancier video production. Will be interesting to see how it turns out.

662. Mini-post: Getting a bluetooth headset to work on linux -- B350-XT

 I have a BlueParrot  B350-XT which is causing issues on linux. It pairs fine, and shows up as a sound device, but it won't actually play sound or record sound.

Looking at dmesg -T, I see

[Tue Aug 18 01:25:33 2020] Bluetooth: hci0: BCM: chip id 63
[Tue Aug 18 01:25:33 2020] Bluetooth: hci0: BCM: features 0x07
[Tue Aug 18 01:25:33 2020] Bluetooth: hci0: BCM20702A
[Tue Aug 18 01:25:33 2020] Bluetooth: hci0: BCM20702A1 (001.002.014) build 0000
[Tue Aug 18 01:25:33 2020] bluetooth hci0: firmware: failed to load brcm/BCM20702A1-050d-065a.hcd (-2)
[Tue Aug 18 01:25:33 2020] bluetooth hci0: Direct firmware load for brcm/BCM20702A1-050d-065a.hcd failed with error -2
[Tue Aug 18 01:25:33 2020] Bluetooth: hci0: BCM: Patch brcm/BCM20702A1-050d-065a.hcd not found

To solve this, unplug/turn off your headset. REMOVE/FORGET the device  so that you can re-pair it.

Next, go to https://github.com/winterheart/broadcom-bt-firmware/blob/master/brcm/BCM20702A1-050d-065a.hcd

Download the hcd file to ~/Downloads, then

me@niobium:/lib$ sudo mkdir /lib/firmware/brcm

me@niobium:/lib$ sudo cp ~/Downloads/BCM20702A1-050d-065a.hcd /lib/firmware/brcm/

Now try again. 

Output from dmesg -T:

[Tue Aug 18 01:33:59 2020] Bluetooth: hci0: BCM: chip id 63

[Tue Aug 18 01:33:59 2020] Bluetooth: hci0: BCM: features 0x07

[Tue Aug 18 01:33:59 2020] Bluetooth: hci0: BCM20702A

[Tue Aug 18 01:33:59 2020] Bluetooth: hci0: BCM20702A1 (001.002.014) build 0000

[Tue Aug 18 01:33:59 2020] bluetooth hci0: firmware: direct-loading firmware brcm/BCM20702A1-050d-065a.hcd

[Tue Aug 18 01:33:59 2020] Bluetooth: hci0: BCM20702A1 (001.002.014) build 1482

[Tue Aug 18 01:33:59 2020] Bluetooth: hci0: Broadcom Bluetooth Device

660. Teaching in the pandemic, part 3: What I'll be doing to capture live lectures. Audio.

I've looked at a few different solutions, but I've basically settled on recording video and audio separately. The downside of this is that I won't stream. The advantage is that I can do post-processing to add clearer pictures of slides etc.

The video part is pretty straight forward. See e.g. http://verahill.blogspot.com/2020/07/659-teaching-during-pandemic-part-2.html

When it comes to audio I've explored a range of solutions:

* Bluetooth headset -- this would've allowed me to stream, but the sound quality is just too poor with bluetooth (I tried Blueparrot B350-XT). For an example of how bad it can be, check out this corporate(!) video:

Advantage: wireless, can stream, only covers one ear
Disadvantage: Sound quality

* 2.4 GHz Wireless headset -- I tested Logitech G930. The sound quality is OK, but it covers both ears, and makes it hard/ uncomfortable to deal with a live audience.
Advantage: sound quality, wireless, can stream
Disadvantage: shuts out the live audience

* 'Normal' microphones -- I have a number of microphones, including Blue Yeti. Many of them are wired (USB), and none of them will work in capturing a moving (i.e. mobile) lecturer.
Advantage: superior audio -- when very close, streaming
Disadvantage: poor audio unless you're right in front of the mic

* Mobile phone lavalier mic -- See here for how to do that: http://verahill.blogspot.com/2020/07/658-teaching-during-pandemic-part-1-how.html.
Advantage: great sound, mobile, can potentially stream
Disadvantage: drains phone battery, can be tricky to set up LAN, if using receiving device (laptop) as hotspot you may not be able to connect to the internet (i.e. can't stream)

My chosen solution:
* Using a portable audio recorder (e.g. dictaphone) --  I've got a Zoom H1n, and a lavalier microphone. I love this microphone. It's lightweight, portable, not too expensive, and the internal XY microphone is great (to my ears). The amplifier for external mics is a bit weak, but it works for my purposes, especially if you post-process in Audacity. But that leaves you having to sync your video and your audio in post. I've already showed you how easy it is to do that here: http://verahill.blogspot.com/2020/07/659-teaching-during-pandemic-part-2.html

Note that you need to invest in a decent lavalier microphone as well. Also note that most these days seem to come with a 3.5 mm TRRS connector (good for mobile phones), and the Zoom needs 3.5 mm TRS (the old standard). Many of the cheap/affordable lavalier mics that you find on e.g. Amazon come with TRS/TRRS adapters, so it's not much of an issue.

Advantage: potentially great sound, great battery life
Disadvantage: you can't stream live, needs a lavalier microphone

So there we are -- I'll set up a single webcam to record video directly to my laptop. I'll capture the sound using it as well, but mostly to help me sync the audio later. I'll record my voice using a dictaphone and a lavalier microphone, post-process the sound in Audacity, then import video and audio in KDENLive, where I'll sync everything. I can then add pictures of my slides as well, and don't have to worry about the image quality during recording.