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SDL Wiki Bot 2021-08-28 18:17:05 +00:00
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include/SDL_audio.h
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@ -462,57 +462,6 @@ extern DECLSPEC int SDLCALL SDL_GetAudioDeviceSpec(int index,
* hostname/IP address for a remote audio server, or a filename in the
* diskaudio driver.
*
* When filling in the desired audio spec structure:
*
* - `desired->freq` should be the frequency in sample-frames-per-second (Hz).
* - `desired->format` should be the audio format (`AUDIO_S16SYS`, etc).
* - `desired->samples` is the desired size of the audio buffer, in _sample
* frames_ (with stereo output, two samples--left and right--would make a
* single sample frame). This number should be a power of two, and may be
* adjusted by the audio driver to a value more suitable for the hardware.
* Good values seem to range between 512 and 8096 inclusive, depending on
* the application and CPU speed. Smaller values reduce latency, but can
* lead to underflow if the application is doing heavy processing and cannot
* fill the audio buffer in time. Note that the number of sample frames is
* directly related to time by the following formula: `ms =
* (sampleframes*1000)/freq`
* - `desired->size` is the size in _bytes_ of the audio buffer, and is
* calculated by SDL_OpenAudioDevice(). You don't initialize this.
* - `desired->silence` is the value used to set the buffer to silence, and is
* calculated by SDL_OpenAudioDevice(). You don't initialize this.
* - `desired->callback` should be set to a function that will be called when
* the audio device is ready for more data. It is passed a pointer to the
* audio buffer, and the length in bytes of the audio buffer. This function
* usually runs in a separate thread, and so you should protect data
* structures that it accesses by calling SDL_LockAudioDevice() and
* SDL_UnlockAudioDevice() in your code. Alternately, you may pass a NULL
* pointer here, and call SDL_QueueAudio() with some frequency, to queue
* more audio samples to be played (or for capture devices, call
* SDL_DequeueAudio() with some frequency, to obtain audio samples).
* - `desired->userdata` is passed as the first parameter to your callback
* function. If you passed a NULL callback, this value is ignored.
*
* `allowed_changes` can have the following flags OR'd together:
*
* - `SDL_AUDIO_ALLOW_FREQUENCY_CHANGE`
* - `SDL_AUDIO_ALLOW_FORMAT_CHANGE`
* - `SDL_AUDIO_ALLOW_CHANNELS_CHANGE`
* - `SDL_AUDIO_ALLOW_ANY_CHANGE`
*
* These flags specify how SDL should behave when a device cannot offer a
* specific feature. If the application requests a feature that the hardware
* doesn't offer, SDL will always try to get the closest equivalent.
*
* For example, if you ask for float32 audio format, but the sound card only
* supports int16, SDL will set the hardware to int16. If you had set
* SDL_AUDIO_ALLOW_FORMAT_CHANGE, SDL will change the format in the `obtained`
* structure. If that flag was *not* set, SDL will prepare to convert your
* callback's float32 audio to int16 before feeding it to the hardware and
* will keep the originally requested format in the `obtained` structure.
*
* If your application can only handle one specific data format, pass a zero
* for `allowed_changes` and let SDL transparently handle any differences.
*
* An opened audio device starts out paused, and should be enabled for playing
* by calling SDL_PauseAudioDevice(devid, 0) when you are ready for your audio
* callback function to be called. Since the audio driver may modify the