libsoundio
1.0.2
|
The size of this struct is not part of the API or ABI. More...
Data Fields | |
struct SoundIoDevice * | device |
Populated automatically when you call soundio_outstream_create. More... | |
enum SoundIoFormat | format |
Defaults to SoundIoFormatFloat32NE, followed by the first one supported. More... | |
int | sample_rate |
Sample rate is the number of frames per second. More... | |
struct SoundIoChannelLayout | layout |
Defaults to Stereo, if available, followed by the first layout supported. More... | |
double | software_latency |
Ignoring hardware latency, this is the number of seconds it takes for the last sample in a full buffer to be played. More... | |
void * | userdata |
Defaults to NULL. Put whatever you want here. More... | |
void(* | write_callback )(struct SoundIoOutStream *, int frame_count_min, int frame_count_max) |
In this callback, you call soundio_outstream_begin_write and soundio_outstream_end_write as many times as necessary to write at minimum frame_count_min frames and at maximum frame_count_max frames. More... | |
void(* | underflow_callback )(struct SoundIoOutStream *) |
This optional callback happens when the sound device runs out of buffered audio data to play. More... | |
void(* | error_callback )(struct SoundIoOutStream *, int err) |
Optional callback. More... | |
const char * | name |
Optional: Name of the stream. More... | |
bool | non_terminal_hint |
Optional: Hint that this output stream is nonterminal. More... | |
int | bytes_per_frame |
computed automatically when you call soundio_outstream_open More... | |
int | bytes_per_sample |
computed automatically when you call soundio_outstream_open More... | |
int | layout_error |
If setting the channel layout fails for some reason, this field is set to an error code. More... | |
The size of this struct is not part of the API or ABI.
int SoundIoOutStream::bytes_per_frame |
computed automatically when you call soundio_outstream_open
int SoundIoOutStream::bytes_per_sample |
computed automatically when you call soundio_outstream_open
struct SoundIoDevice* SoundIoOutStream::device |
Populated automatically when you call soundio_outstream_create.
void(* SoundIoOutStream::error_callback)(struct SoundIoOutStream *, int err) |
Optional callback.
err
is always SoundIoErrorStreaming. SoundIoErrorStreaming is an unrecoverable error. The stream is in an invalid state and must be destroyed. If you do not supply error_callback, the default callback will print a message to stderr and then call abort
. This is called from the SoundIoOutStream::write_callback thread context.
enum SoundIoFormat SoundIoOutStream::format |
Defaults to SoundIoFormatFloat32NE, followed by the first one supported.
struct SoundIoChannelLayout SoundIoOutStream::layout |
Defaults to Stereo, if available, followed by the first layout supported.
int SoundIoOutStream::layout_error |
If setting the channel layout fails for some reason, this field is set to an error code.
Possible error codes are:
const char* SoundIoOutStream::name |
Optional: Name of the stream.
Defaults to "SoundIoOutStream" PulseAudio uses this for the stream name. JACK uses this for the client name of the client that connects when you open the stream. WASAPI uses this for the session display name. Must not contain a colon (":").
bool SoundIoOutStream::non_terminal_hint |
Optional: Hint that this output stream is nonterminal.
This is used by JACK and it means that the output stream data originates from an input stream. Defaults to false
.
int SoundIoOutStream::sample_rate |
Sample rate is the number of frames per second.
Defaults to 48000 (and then clamped into range).
double SoundIoOutStream::software_latency |
Ignoring hardware latency, this is the number of seconds it takes for the last sample in a full buffer to be played.
After you call soundio_outstream_open, this value is replaced with the actual software latency, as near to this value as possible. On systems that support clearing the buffer, this defaults to a large latency, potentially upwards of 2 seconds, with the understanding that you will call soundio_outstream_clear_buffer when you want to reduce the latency to 0. On systems that do not support clearing the buffer, this defaults to a reasonable lower latency value.
On backends with high latencies (such as 2 seconds), frame_count_min
will be 0, meaning you don't have to fill the entire buffer. In this case, the large buffer is there if you want it; you only have to fill as much as you want. On backends like JACK, frame_count_min
will be equal to frame_count_max
and if you don't fill that many frames, you will get glitches.
If the device has unknown software latency min and max values, you may still set this, but you might not get the value you requested. For PulseAudio, if you set this value to non-default, it sets PA_STREAM_ADJUST_LATENCY
and is the value used for maxlength
and tlength
.
For JACK, this value is always equal to SoundIoDevice::software_latency_current of the device.
void(* SoundIoOutStream::underflow_callback)(struct SoundIoOutStream *) |
This optional callback happens when the sound device runs out of buffered audio data to play.
After this occurs, the outstream waits until the buffer is full to resume playback. This is called from the SoundIoOutStream::write_callback thread context.
void* SoundIoOutStream::userdata |
Defaults to NULL. Put whatever you want here.
void(* SoundIoOutStream::write_callback)(struct SoundIoOutStream *, int frame_count_min, int frame_count_max) |
In this callback, you call soundio_outstream_begin_write and soundio_outstream_end_write as many times as necessary to write at minimum frame_count_min
frames and at maximum frame_count_max
frames.
frame_count_max
will always be greater than 0. Note that you should write as many frames as you can; frame_count_min
might be 0 and you can still get a buffer underflow if you always write frame_count_min
frames.
For Dummy, ALSA, and PulseAudio, frame_count_min
will be 0. For JACK and CoreAudio frame_count_min
will be equal to frame_count_max
.
The code in the supplied function must be suitable for real-time execution. That means that it cannot call functions that might block for a long time. This includes all I/O functions (disk, TTY, network), malloc, free, printf, pthread_mutex_lock, sleep, wait, poll, select, pthread_join, pthread_cond_wait, etc.