doc:appunti:linux:audio:audio_recording
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doc:appunti:linux:audio:audio_recording [2019/04/22 08:27] – [Web References] niccolo | doc:appunti:linux:audio:audio_recording [2020/12/27 08:57] – [Software capabilities and settings] niccolo | ||
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- | ====== Audio Recording With Linux ====== | + | ====== Audio Recording With GNU/Linux ====== |
===== Choosing the right jack ===== | ===== Choosing the right jack ===== | ||
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{{wireless-mic-receiver.jpg? | {{wireless-mic-receiver.jpg? | ||
- | To connect the receiver to the Ugreen | + | To connect the **UHF receiver** to the **Ugreen |
+ | |||
+ | ^ 1/4" TS female jack ^ Signal | ||
+ | | **Tip** | ||
+ | | | Not connected | ||
+ | | **Sleeve** | ||
+ | |||
+ | 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**! | ||
+ | ====== Audio Recording With Android ====== | ||
+ | |||
+ | Recording audio using an **external microphone** connected to an **Android device** can be a real nightmare. We tried the hard way using a Chinese, no-brand, | ||
+ | |||
+ | We can group the problems you can face in three main categories: | ||
+ | |||
+ | * Physical connection | ||
+ | * Electrical compatibility and hardware autodetection | ||
+ | * Software capabilities and settings | ||
+ | |||
+ | ===== Physical connection ===== | ||
+ | |||
+ | Most Android devices have a **3.5 mm jack** accepting a **TRRS connector in CTIA standard** and every brand of mobile phones produces **headsets** with their own standard. The vast majority of solutions uses **electret microphones** requiring a **bias current**, but use **some combinations of impedence** to detect the insertion of the microphone and to **handle the headset button** (or buttons). | ||
+ | |||
+ | So, connecting an external microphone, can be as simple as making a cable that connects the **ring** and the **sleve** of the **CTIA connector** to (respectively) the **ground** and the **microphone line** of the microphone. The hard part is to guess, or empirically try, if the microphone **requires a bias current**, if the Android device is provinding such a current and if the microphone produces a sufficient **output level** (actually a voltage in the order of the millivolts) that can be used by the device. | ||
+ | |||
+ | ===== Electrical compatibility and hardware autodetection ===== | ||
+ | |||
+ | As stated above, the first problem is **powering the microphone** itself, because generally we will use an **electret** one. It is a **common practice** to provide the power on the same line of the microphone signal, so **requiring just two wires** for both power (from the device to the mic) and for signal (from the mic to the device). The power, also called //bias current//, is generally in the range of **2.5** to **5.0 volt**. | ||
+ | |||
+ | On a Xiaomi Mi A1 smartphone, which has a **TRRS | ||
+ | |||
+ | Another parameter which should be considered | ||
+ | |||
+ | ===== Software capabilities and settings ===== | ||
+ | |||
+ | Wishing to connect the **UHF microphone** to an **Android smartphone**, | ||
+ | |||
+ | ^ 1/4" TS female jack ^ Signal | ||
+ | | | Not connected | ||
+ | | | Not connected | ||
+ | | **Sleeve** | ||
+ | | **Tip** | ||
+ | |||
+ | The smartphone **did not sensed the microphone**, | ||
+ | |||
+ | Once completed the electrical connection and acknowledged that **automatic detection of the external microphone does not work**, I decided to use the **[[https:// | ||
+ | |||
+ | To realize the electrical connection explained in the above table, I used a **mic/ | ||
+ | |||
+ | To record audio I used the **[[https:// | ||
+ | |||
+ | The resulting recording is quite good: a **48 kHz 16 bits** file with good sound quality and low noise. | ||
- | ^ Male Jack 3.5 mm TRS ^ Signal | ||
- | | **Tip** | ||
- | | **Ring** | ||
- | | **Sleeve** | ||
===== Web References ===== | ===== Web References ===== | ||
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* [[https:// | * [[https:// | ||
* [[https:// | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// |
doc/appunti/linux/audio/audio_recording.txt · Last modified: 2020/12/28 18:22 by niccolo