Espressif ESP32-LyraT, Docs Template Documentation

Page: 40 / 100

Read the Docs Template Documentation, Release
•
el
: The audio element handle
•
buffer
: The buffer pointer
• wanted_size : The wanted size
audio_element_err_t audio_element_output ( audio_element_handle_t el
, char *
buffer
, int
write_size )
Call this function to sendout Element output data.
Return
• > 0 number of bytes written
• <=0 audio_element_err_t
Parameters
•
el
: Depend on setup using ringbuffer or function callback, Element will invokes write t ringbuffer,
or call write callback funtion
• buffer : The buffer pointer
• write_size : The write size
esp_err_t
audio_element_set_read_cb ( audio_element_handle_t el
,
stream_func fn
, void *
context )
This API allows the application to set a read callback for the first audio_element in the pipeline for allowing the
pipeline to interface with other systems. The callback is invoked every time the audio element requires data to
be processed.
Return
• ESP_OK
• ESP_FAIL
Parameters
•
el
: The audio element handle
• fn : Callback read function. The callback function should return number of bytes read or -1 in case
of error in reading. Note that the callback function may decide to block and that may block the entire
pipeline.
•
context
: An optional context which will be passed to callback function on every invocation
esp_err_t
audio_element_set_write_cb (
audio_element_handle_t el , stream_func fn , void * context
)
This API allows the application to set a write callback for the last audio_element in the pipeline for allowing the
pipeline to interface with other systems. The callback is invoked every time the audio element has a processed
data that needs to be passed forward.
Return
• ESP_OK
• ESP_FAIL
Parameters
• el : The audio element
•
fn
: Callback write function. The callback function should return number of bytes written or -1 in
case of error in writing. Note that the callback function may decide to block and that may block the
entire pipeline.
36 Chapter 2. API Reference