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EmmanuelPEmmanuelP
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multiple-acquisition: callback method is not compatible with main thread polling
When the callback is called with ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE, the buffer is already pushed in the output FIFO, and signaled. The buffer could be already pushed back to the input FIFO.
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3 files changed

Lines changed: 135 additions & 31 deletions

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‎02-multiple-acquisition-callback.c‎

Lines changed: 131 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,131 @@
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/* SPDX-License-Identifier:Unlicense */
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/* Aravis header */
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#include <arv.h>
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/* Standard headers */
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#include <stdlib.h>
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#include <stdio.h>
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typedef struct {
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ArvStream *stream;
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int counter;
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gboolean done;
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} ArvStreamCallbackData;
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static void
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stream_callback (void *user_data, ArvStreamCallbackType type, ArvBuffer *buffer)
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{
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ArvStreamCallbackData *callback_data = (ArvStreamCallbackData *) user_data;
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/* This code is called from the stream receiving thread, which means all the time spent there is less time
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* available for the reception of incoming packets */
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switch (type) {
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case ARV_STREAM_CALLBACK_TYPE_INIT:
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/* Stream thread started.
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*
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* Here you may want to change the thread priority arv_make_thread_realtime() or
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* arv_make_thread_high_priority() */
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break;
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case ARV_STREAM_CALLBACK_TYPE_START_BUFFER:
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/* The first packet of a new frame was received */
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break;
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case ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE:
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/* The buffer is received, successfully or not. It is already pushed in the output FIFO.
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*
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* You could here signal the new buffer to another thread than the main one, and pull/push the
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* buffer from this another thread.
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*
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* Or use the buffer here. We need to pull it, process it, then push it back for reuse by the
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* stream receiving thread */
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g_assert (buffer == arv_stream_pop_buffer(callback_data->stream));
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g_assert (buffer != NULL);
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/* Retrieve 10 buffers */
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if (callback_data->counter < 10) {
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if (arv_buffer_get_status(buffer) == ARV_BUFFER_STATUS_SUCCESS)
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printf ("Acquired %d×%d buffer\n",
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arv_buffer_get_image_width (buffer),
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arv_buffer_get_image_height (buffer));
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arv_stream_push_buffer(callback_data->stream, buffer);
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callback_data->counter++;
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} else {
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callback_data->done = TRUE;
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}
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break;
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case ARV_STREAM_CALLBACK_TYPE_EXIT:
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/* Stream thread ended */
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break;
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}
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}
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/*
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* Connect to the first available camera, then acquire 10 buffers.
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*/
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int
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main (int argc, char **argv)
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{
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ArvCamera *camera;
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GError *error = NULL;
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/* Connect to the first available camera */
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camera = arv_camera_new (NULL, &error);
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if (ARV_IS_CAMERA (camera)) {
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ArvStreamCallbackData callback_data;
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printf ("Found camera '%s'\n", arv_camera_get_model_name (camera, NULL));
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/* Create the stream object without callback */
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callback_data.counter = 0;
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callback_data.done = FALSE;
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callback_data.stream = arv_camera_create_stream (camera, stream_callback, &callback_data, &error);
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if (ARV_IS_STREAM (callback_data.stream)) {
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int i;
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size_t payload;
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/* Retrieve the payload size for buffer creation */
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payload = arv_camera_get_payload (camera, &error);
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if (error == NULL) {
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/* Insert some buffers in the stream buffer pool */
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for (i = 0; i < 2; i++)
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arv_stream_push_buffer (callback_data.stream, arv_buffer_new (payload, NULL));
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}
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if (error == NULL)
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/* Start the acquisition */
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arv_camera_start_acquisition (camera, &error);
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if (error == NULL) {
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while (!callback_data.done) {
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usleep (1000);
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}
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}
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if (error == NULL)
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/* Stop the acquisition */
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arv_camera_stop_acquisition (camera, &error);
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/* Destroy the stream object */
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g_clear_object (&callback_data.stream);
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}
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/* Destroy the camera instance */
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g_clear_object (&camera);
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}
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if (error != NULL) {
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/* En error happened, display the correspdonding message */
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printf ("Error: %s\n", error->message);
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}

02-multiple-acquisition.c renamed to 02-multiple-acquisition-main-thread.c

Lines changed: 2 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -9,34 +9,6 @@
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#include <stdlib.h>
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#include <stdio.h>
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static void
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stream_callback (void *user_data, ArvStreamCallbackType type, ArvBuffer *buffer)
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{
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/* This code is called from the stream receiving thread, which means all the time spent there is less time
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* available for the reception of incoming packets */
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switch (type) {
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case ARV_STREAM_CALLBACK_TYPE_INIT:
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/* Stream thread started.
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*
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* Here you may want to change the thread priority arv_make_thread_realtime() or
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* arv_make_thread_high_priority() */
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break;
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case ARV_STREAM_CALLBACK_TYPE_START_BUFFER:
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/* The first packet of a new frame was received */
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break;
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case ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE:
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/* The buffer is received, successfully or not.
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*
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* You could here signal the new buffer to another thread than the main one, and pull/push the
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* buffer from there. */
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break;
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case ARV_STREAM_CALLBACK_TYPE_EXIT:
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/* Stream thread ended */
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break;
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}
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}
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/*
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* Connect to the first available camera, then acquire 10 buffers.
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*/
@@ -56,7 +28,7 @@ main (int argc, char **argv)
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printf ("Found camera '%s'\n", arv_camera_get_model_name (camera, NULL));
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/* Create the stream object without callback */
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stream = arv_camera_create_stream (camera, stream_callback, NULL, &error);
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stream = arv_camera_create_stream (camera, NULL, NULL, &error);
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if (ARV_IS_STREAM (stream)) {
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int i;
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size_t payload;
@@ -65,7 +37,7 @@ main (int argc, char **argv)
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payload = arv_camera_get_payload (camera, &error);
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if (error == NULL) {
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/* Insert some buffers in the stream buffer pool */
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for (i = 0; i < 5; i++)
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for (i = 0; i < 2; i++)
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arv_stream_push_buffer (stream, arv_buffer_new (payload, NULL));
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}
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‎meson.build‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,8 @@ aravis_dep = dependency('aravis-0.8')
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examples = [
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'01-single-acquisition',
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'02-multiple-acquisition',
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'02-multiple-acquisition-main-thread',
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'02-multiple-acquisition-callback',
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'02-multiple-acquisition-signal',
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'03-camera-api',
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'04-camera-features',

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