Add basic HTTP MJPEG stream server

components/StreamServer/CMakeLists.txt

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+idf_component_register(SRCS "StreamServer/StreamServer.cpp"
+  INCLUDE_DIRS "StreamServer"
+  REQUIRES esp32-camera StateManager ProjectConfig esp_http_server Helpers
+)

components/StreamServer/StreamServer/StreamServer.cpp

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+#include "StreamServer.hpp"
+
+constexpr static const char *STREAM_CONTENT_TYPE = "multipart/x-mixed-replace;boundary=" PART_BOUNDARY;
+constexpr static const char *STREAM_BOUNDARY = "\r\n--" PART_BOUNDARY "\r\n";
+constexpr static const char *STREAM_PART = "Content-Type: image/jpeg\r\nContent-Length: %u\r\nX-Timestamp: %lli.%06li\r\n\r\n";
+
+static const char *STREAM_SERVER_TAG = "[STREAM_SERVER]";
+
+// the stream is super low FPS, find out why
+esp_err_t StreamHelpers::stream(httpd_req_t *req)
+{
+  long last_request_time = 0;
+  camera_fb_t *fb = nullptr;
+  struct timeval _timestamp;
+
+  esp_err_t response = ESP_OK;
+  size_t _jpg_buf_len = 0;
+  uint8_t *_jpg_buf = nullptr;
+
+  char *part_buf[256];
+  static int64_t last_frame = 0;
+  if (!last_frame)
+    last_frame = esp_timer_get_time();
+
+  response = httpd_resp_set_type(req, STREAM_CONTENT_TYPE);
+  if (response != ESP_OK)
+    return response;
+
+  httpd_resp_set_hdr(req, "Access-Control-Allow-Origin", "*");
+  httpd_resp_set_hdr(req, "X-Framerate", "60");
+
+  while (true)
+  {
+    fb = esp_camera_fb_get();
+
+    if (!fb)
+    {
+      ESP_LOGE(STREAM_SERVER_TAG, "Camera capture failed with resposne %s", esp_err_to_name(response));
+      response = ESP_FAIL;
+    }
+    else
+    {
+      _timestamp.tv_sec = fb->timestamp.tv_sec;
+      _timestamp.tv_usec = fb->timestamp.tv_usec;
+      _jpg_buf_len = fb->len;
+      _jpg_buf = fb->buf;
+    }
+    if (response == ESP_OK)
+      response = httpd_resp_send_chunk(req, STREAM_BOUNDARY, strlen(STREAM_BOUNDARY));
+    if (response == ESP_OK)
+    {
+      size_t hlen = snprintf((char *)part_buf, 128, STREAM_PART, _jpg_buf_len, _timestamp.tv_sec, _timestamp.tv_usec);
+      response = httpd_resp_send_chunk(req, (const char *)part_buf, hlen);
+    }
+    if (response == ESP_OK)
+      response = httpd_resp_send_chunk(req, (const char *)_jpg_buf, _jpg_buf_len);
+    if (fb)
+    {
+      esp_camera_fb_return(fb);
+      fb = NULL;
+      _jpg_buf = NULL;
+    }
+    else if (_jpg_buf)
+    {
+      free(_jpg_buf);
+      _jpg_buf = NULL;
+    }
+    if (response != ESP_OK)
+      break;
+    long request_end = Helpers::getTimeInMillis();
+    long latency = (request_end - last_request_time);
+    last_request_time = request_end;
+    ESP_LOGD(STREAM_SERVER_TAG, "Size: %uKB, Time: %lims (%lifps)\n", _jpg_buf_len / 1024, latency, 1000 / latency);
+  }
+  last_frame = 0;
+  return response;
+}
+
+StreamServer::StreamServer(const int STREAM_PORT) : STREAM_SERVER_PORT(STREAM_PORT) {}
+
+esp_err_t StreamServer::startStreamServer()
+{
+  if (cameraStateManager.getCurrentState() != CameraState_e::Camera_Success)
+  {
+    ESP_LOGE(STREAM_SERVER_TAG, "Camera not initialized. Cannot start stream server.");
+    return ESP_FAIL;
+  }
+
+  httpd_config_t config = HTTPD_DEFAULT_CONFIG();
+  config.stack_size = 20480;
+  config.max_uri_handlers = 1;
+  config.server_port = STREAM_SERVER_PORT;
+  config.ctrl_port = STREAM_SERVER_PORT;
+
+  httpd_uri_t stream_page = {
+      .uri = "/",
+      .method = HTTP_GET,
+      .handler = &StreamHelpers::stream,
+      .user_ctx = nullptr,
+  };
+
+  int status = httpd_start(&camera_stream, &config);
+
+  if (status != ESP_OK)
+  {
+    ESP_LOGE(STREAM_SERVER_TAG, "Cannot start stream server.");
+    return status;
+  }
+
+  httpd_register_uri_handler(camera_stream, &stream_page);
+  ESP_LOGI(STREAM_SERVER_TAG, "Stream server started on port %d", STREAM_SERVER_PORT);
+  // todo add printing IP addr here
+
+  return ESP_OK;
+}

components/StreamServer/StreamServer/StreamServer.hpp

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+#pragma once
+#ifndef STREAMSERVER_HPP
+#define STREAMSERVER_HPP
+
+#define PART_BOUNDARY "123456789000000000000987654321"
+
+#include "esp_log.h"
+#include "esp_camera.h"
+#include "esp_http_server.h"
+#include "esp_timer.h"
+#include <StateManager.hpp>
+#include <Helpers.hpp>
+
+namespace StreamHelpers
+{
+  esp_err_t stream(httpd_req_t *req);
+}
+
+class StreamServer
+{
+private:
+  httpd_handle_t camera_stream = nullptr;
+  int STREAM_SERVER_PORT;
+
+public:
+  StreamServer(const int STREAM_PORT = 80);
+  esp_err_t startStreamServer();
+};
+
+#endif