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Fix bad naming in simple usecase + expand notice

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laurensmiers 2020-05-27 18:13:55 +02:00
parent d31864be6e
commit 4d8f49b92e
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alsa_info.md
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@ -309,7 +309,10 @@ Here we restrict the device's hardware parameter space
* Play on 6 channels * Play on 6 channels
* Set the samplerate to 96kHz * Set the samplerate to 96kHz
Important: Anything that can be set through the ALSA PCM API can be set in the config file! Important:
* Anything that can be set through the ALSA PCM API can be set in the config file!
* If you put an unsupported setting in this config, you won't get any errors in your program....
* Just some errors about samplerate, ... in dmesg
||| |||
### ALSA mysteries ### ALSA mysteries
@ -411,19 +414,23 @@ Ok, but how do I know what params are actually set?!
||| |||
## Several ways to tackle this ## Several ways to tackle this
* Blocking
* Non-blocking * Synchronous
* Asynchronous * Asynchronous
* Polling * Polling
In each of these, we can chose two modes:
* Blocking API
* Non-blocking API
||| |||
#### Blocking #### Synchronous
* one thread per device * one thread per device
* capture and playback are two separate devices! * capture and playback are two separate devices!
* Results in two threads * Results in two threads
||| |||
#### Blocking #### Synchronous blocking
```c ```c
#define AUDIO_SAMPLERATE 16000 #define AUDIO_SAMPLERATE 16000
@ -498,7 +505,7 @@ int main(int argc, char **argv)
``` ```
||| |||
#### Non-Blocking #### Synchronous non-blocking
* Same as blocking * Same as blocking
* Functions return new error codes * Functions return new error codes
@ -507,7 +514,7 @@ int main(int argc, char **argv)
* -EAGAIN if buffers are full * -EAGAIN if buffers are full
||| |||
#### Non-Blocking #### Synchronous non-blocking
```c ```c
#define AUDIO_SAMPLERATE 16000 #define AUDIO_SAMPLERATE 16000
@ -554,7 +561,7 @@ int main(int argc, char **argv)
``` ```
||| |||
#### Async #### Asynchronous
* 'Microcontroller'-way (patent pending) * 'Microcontroller'-way (patent pending)
* Seems natural/elegant * Seems natural/elegant
* Why let us do the waiting when ALSA can just inform us when it wants samples? * Why let us do the waiting when ALSA can just inform us when it wants samples?
@ -566,14 +573,14 @@ int main(int argc, char **argv)
* Hence, you have to be a wizard to get it working * Hence, you have to be a wizard to get it working
||| |||
#### Async #### Asynchronous
* Not very stable... * Not very stable...
* Seems confirmed by the fact that nobody seems to use it * Seems confirmed by the fact that nobody seems to use it
* Big players (PulseAudio/JACK/PortAudio) don't use it * Big players (PulseAudio/JACK/PortAudio) don't use it
* My official recommendation: don't use it if you want to maintain your sanity... * My official recommendation: don't use it if you want to maintain your sanity...
||| |||
#### Async #### Asynchronous
```c ```c
#define AUDIO_SAMPLERATE 16000 #define AUDIO_SAMPLERATE 16000
@ -752,6 +759,7 @@ int main(int argc, char **argv)
* Sounds logical... * Sounds logical...
* ...However, ALSA will allow to let you define f.e. 48kHz on input and 16kHz on output * ...However, ALSA will allow to let you define f.e. 48kHz on input and 16kHz on output
* Even though this isn't possible due to HW constraints (it's the same device!) * Even though this isn't possible due to HW constraints (it's the same device!)
--- ---
## Complex usecase ## Complex usecase
Several devices Several devices