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doc:appunti:linux:audio:audio_recording [2020/12/28 10:06] – niccolodoc:appunti:linux:audio:audio_recording [2020/12/28 17:21] – [Web References] niccolo
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 Unlike capacitor ones, electret microphones **do not require polarizing voltage**, but generally they contain an integrated preamplifier that **does require power**. In this cases a **TRS jack** can be used, where the ring carries power via a resistor from, normally, a 5 V supply in the computer (often incorrectly called //polarizing power// or //bias//). Generally these microphones built to be plugged into computers and electronic audio devices, have a **TRS 3.5 mm jack**, carrying the mic signal and the required current. Unlike capacitor ones, electret microphones **do not require polarizing voltage**, but generally they contain an integrated preamplifier that **does require power**. In this cases a **TRS jack** can be used, where the ring carries power via a resistor from, normally, a 5 V supply in the computer (often incorrectly called //polarizing power// or //bias//). Generally these microphones built to be plugged into computers and electronic audio devices, have a **TRS 3.5 mm jack**, carrying the mic signal and the required current.
 +
 +====== Problem: silence gaps using a cheap USB dongle ======
 +
 +I was **unable to use the microphone connector** on my Acer TravelMate, so I tried to use an USB dongle, marked **LinQ**. The device was detected by the Linux Kernel 4.9.0:
 +
 +<code>
 +usb 2-1.3: new full-speed USB device number 9 using ehci-pci
 +usb 2-1.3: New USB device found, idVendor=0c76, idProduct=1607
 +usb 2-1.3: New USB device strings: Mfr=0, Product=1, SerialNumber=0
 +usb 2-1.3: Product: USB Headphone Set
 +input: USB Headphone Set as /devices/pci0000:00/0000:00:1d.0
 +    /usb2/2-1/2-1.3/2-1.3:1.3/0003:0C76:1607.0004/input/input92
 +hid-generic 0003:0C76:1607.0004:
 +    input,hidraw2: USB HID v1.00 Device [USB Headphone Set]
 +    on usb-0000:00:1d.0-1.3/input3
 +</code>
 +
 +{{ linq-usb-audio.png?direct&100|LinQ USB audio dongle}}
 +The USB audio adapter worked quite nicely at playing audio, I use it on a QNAP TS-120 NAS, transformed into a media player installing Debian GNU/Linux on it. The Linux kernel and the **ALSA audio subsystem** works well on setting the levels for **playback**.
 +
 +Once started Audacity, I was able to select the microphone line of the USB dongle as a **capture device**:
 +
 +{{audacity-select-usb-audio.png?direct&260|}}
 +
 +Recording a sample track revealed an annoying problem: about **every 0.4 seconds** you can see a **gap of silence** in the audio track of about **two hundredths of a second**. The audio track is unusable!
 +
 +{{audacity-track-gaps.png?direct&400|}}
  
 ====== Wireless UHF microphone ====== ====== Wireless UHF microphone ======
Line 88: Line 115:
 The **2.6 volt** current provided by the USB adapter on th **jack ring** will go nowhere (not connected). The **2.6 volt** current provided on the **jack tip** is probably not required by the UHF receiver, but **it should not harm**. **No infromation** is available about **microphone impedence** expected by the USB adapter, on the other hand no information is available about the **impedence of the mic interface** of the UHF receiver. The **2.6 volt** current provided by the USB adapter on th **jack ring** will go nowhere (not connected). The **2.6 volt** current provided on the **jack tip** is probably not required by the UHF receiver, but **it should not harm**. **No infromation** is available about **microphone impedence** expected by the USB adapter, on the other hand no information is available about the **impedence of the mic interface** of the UHF receiver.
  
-Despite all this empirical approach, the **voice registration is quite satisfying**!+Despite all this empirical approach, the **voice registration is quite satisfying**! See below about connecting the microphone to an Acer TravelMate notebook an to an Android smartphone.
  
-====== External mic on the Acer Travelmate TMB113-E ======+===== Wireless mic on the Acer Travelmate TMB113-E =====
  
 See this article about **[[audio_recording_tmb113_e]]**. See this article about **[[audio_recording_tmb113_e]]**.
  
-====== External mic on Android ======+===== Wireless mic on Android =====
  
 See this article about **[[audio_recording_android]]**. See this article about **[[audio_recording_android]]**.
  
-===== Problem: silence gaps using a cheap USB dongle ===== +===== Wireless mic on Ugreen USB audio adapter =====
- +
-I was **unable to use the microphone connector** on my Acer TravelMate, so I tried to use an USB dongle, marked **LinQ**. The device was detected by the Linux Kernel 4.9.0: +
- +
-<code> +
-usb 2-1.3: new full-speed USB device number 9 using ehci-pci +
-usb 2-1.3: New USB device found, idVendor=0c76, idProduct=1607 +
-usb 2-1.3: New USB device strings: Mfr=0, Product=1, SerialNumber=0 +
-usb 2-1.3: Product: USB Headphone Set +
-input: USB Headphone Set as /devices/pci0000:00/0000:00:1d.0 +
-    /usb2/2-1/2-1.3/2-1.3:1.3/0003:0C76:1607.0004/input/input92 +
-hid-generic 0003:0C76:1607.0004: +
-    input,hidraw2: USB HID v1.00 Device [USB Headphone Set] +
-    on usb-0000:00:1d.0-1.3/input3 +
-</code> +
- +
-{{ linq-usb-audio.png?direct&100|LinQ USB audio dongle}} +
-The USB audio adapter worked quite nicely at playing audio, I use it on a QNAP TS-120 NAS, transformed into a media player installing Debian GNU/Linux on it. The Linux kernel and the **ALSA audio subsystem** works well on setting the levels for **playback**. +
- +
-Once started Audacity, I was able to select the microphone line of the USB dongle as a **capture device**: +
- +
-{{audacity-select-usb-audio.png?direct&260|}} +
- +
-Recording a sample track revealed an annoying problem: about **every 0.4 seconds** you can see a **gap of silence** in the audio track of about **two hundredths of a second**. The audio track is unusable! +
- +
-{{audacity-track-gaps.png?direct&400|}} +
- +
-===== Ugreen USB audio adapter ===== +
- +
-The device is detected by the Linux Kernel 4.9.0 in this way: +
- +
-<code> +
-usb 2-1.3: new full-speed USB device number 5 using ehci-pci +
-usb 2-1.3: New USB device found, idVendor=0d8c, idProduct=0024 +
-usb 2-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0 +
-usb 2-1.3: Product: USB Advanced Audio Device +
-usb 2-1.3: Manufacturer: C-Media Electronics Inc. +
-input: C-Media Electronics Inc. USB Advanced Audio Device as /devices/pci0000:00/0000:00:1d.0 +
-    /usb2/2-1/2-1.3/2-1.3:1.3/0003:0D8C:0024.0004/input/input18 +
-hid-generic 0003:0D8C:0024.0004: +
-    input,hidraw2: USB HID v1.11 Device [C-Media Electronics Inc. USB Advanced Audio Device] +
-    on usb-0000:00:1d.0-1.3/input3 +
-</code> +
- +
-{{ ugreen-usb-audio.jpg?direct&220|Ugreen USB Audio Adapter}} +
- +
-Launching **alsamixer** and hitting F6 you can select the **USB Advanced Audio Device** sound card. Hit F4 to view the only one capture device, i.e. the microphone input line. Press **Space** to enable/disable the **capture** and **Up/Down arrows** to increase/decrease the **gain**. +
- +
-It seems that the best setting for audio recording through the mic, is to keep the **capture mic gain to 100**: +
- +
-{{usb-advanced-audio-device-alsamixer.png?direct&300|USB Advenced Audio Device in Alsamixer}}+
  
-The **microphone socket** is a **3.5 mm TRS type** (three poles), it provides a bias current of **2.6 V** on both the **tip** and the **ring**, so it is advisable, as reported in the device manual, to **NOT use a simple two poles mono jack** (TS type), because it will short-circuit the bias current on the ring with the ground on the sleeve.+See this article about **[[audio_recording_usb_adapter]]**.
  
-===== Web References =====+====== Web References ======
  
   * [[wp>Microphone]]   * [[wp>Microphone]]
doc/appunti/linux/audio/audio_recording.txt · Last modified: 2020/12/28 18:22 by niccolo