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webcam: going right direction (EAGAIN)

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This commit is contained in:
Thomas Farstrike
2025-05-13 17:41:54 +02:00
parent d20843c8aa
commit d57aa554d1
1 changed files with 36 additions and 28 deletions
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c_mpos/src/webcam.c
+36 -28
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@@ -6,7 +6,6 @@
#include <linux/videodev2.h>
#include <sys/mman.h>
#include <string.h>
#include <poll.h>
#include "py/obj.h"
#include "py/runtime.h"
@@ -24,7 +23,7 @@
#define CAPTURE_HEIGHT 480
#define OUTPUT_WIDTH 240 // Resize to 240x240
#define OUTPUT_HEIGHT 240
#define NUM_BUFFERS 4 // Use 4 buffers for continuous streaming
#define NUM_BUFFERS 2 // Use 2 buffers, as it worked for two captures
// Webcam object type
typedef struct _webcam_obj_t {
@@ -73,16 +72,42 @@ static void resize_640x480_to_240x240(uint8_t *src, uint8_t *dst) {
static mp_obj_t webcam_capture_grayscale(mp_obj_t self_in) {
webcam_obj_t *self = MP_OBJ_TO_PTR(self_in);
// Poll for available buffer
struct pollfd pfd = { .fd = self->fd, .events = POLLIN };
WEBCAM_DEBUG_PRINT("webcam: Polling for available buffer\n");
if (poll(&pfd, 1, 1000) <= 0) { // 1-second timeout
WEBCAM_DEBUG_PRINT("webcam: Poll timeout or error (errno=%d)\n", errno);
mp_raise_OSError(ETIMEDOUT);
// Try to queue a buffer
struct v4l2_buffer buf = {0};
bool queued = false;
for (size_t i = 0; i < self->num_buffers; i++) {
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
WEBCAM_DEBUG_PRINT("webcam: Attempting to queue buffer (index=%zu)\n", i);
if (ioctl(self->fd, VIDIOC_QBUF, &buf) == 0) {
WEBCAM_DEBUG_PRINT("webcam: Successfully queued buffer (index=%zu)\n", i);
queued = true;
break;
}
WEBCAM_DEBUG_PRINT("webcam: Failed to queue buffer (index=%zu, errno=%d)\n", i, errno);
}
if (!queued) {
WEBCAM_DEBUG_PRINT("webcam: No buffers available for queuing\n");
mp_raise_OSError(EAGAIN); // Try again later
}
// Start streaming if not already started
if (!self->streaming) {
enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
WEBCAM_DEBUG_PRINT("webcam: Starting video streaming\n");
if (ioctl(self->fd, VIDIOC_STREAMON, &type) < 0) {
WEBCAM_DEBUG_PRINT("webcam: Failed to start video streaming (errno=%d)\n", errno);
mp_raise_OSError(errno);
}
self->streaming = true;
}
// Dequeue a buffer (capture frame)
struct v4l2_buffer buf = {0};
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
WEBCAM_DEBUG_PRINT("webcam: Dequeuing buffer\n");
@@ -184,7 +209,7 @@ static mp_obj_t webcam_init(void) {
// Open the webcam device
WEBCAM_DEBUG_PRINT("webcam: Opening device %s\n", VIDEO_DEVICE);
self->fd = open(VIDEO_DEVICE, O_RDWR | O_NONBLOCK); // Non-blocking for polling
self->fd = open(VIDEO_DEVICE, O_RDWR);
if (self->fd < 0) {
WEBCAM_DEBUG_PRINT("webcam: Failed to open device %s (errno=%d)\n", VIDEO_DEVICE, errno);
mp_raise_OSError(errno);
@@ -216,7 +241,7 @@ static mp_obj_t webcam_init(void) {
mp_raise_OSError(errno);
}
self->num_buffers = req.count;
if (self->num_buffers < 2) {
if (self->num_buffers < NUM_BUFFERS) {
WEBCAM_DEBUG_PRINT("webcam: Insufficient buffers allocated (%zu)\n", self->num_buffers);
close(self->fd);
mp_raise_OSError(ENOMEM);
@@ -253,23 +278,6 @@ static mp_obj_t webcam_init(void) {
close(self->fd);
mp_raise_OSError(errno);
}
// Queue the buffer upfront
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
WEBCAM_DEBUG_PRINT("webcam: Initial queuing of buffer %zu\n", i);
if (ioctl(self->fd, VIDIOC_QBUF, &buf) < 0) {
WEBCAM_DEBUG_PRINT("webcam: Failed to queue buffer %zu initially (errno=%d)\n", i, errno);
for (size_t j = 0; j <= i; j++) {
if (self->buffers[j].start != NULL) {
munmap(self->buffers[j].start, self->buffers[j].length);
}
}
close(self->fd);
mp_raise_OSError(errno);
}
}
// Create a tuple to hold the webcam object and method references