Camera Monitoring API#

It is called within the scope of the oasis::ui namespace.

Header File#

OasisPreview.h

PreviewFrameObserver Interface#

A user-defined observer object derived from PreviewFrameObserver can be specified for a Preview object using the setPreviewFrameObserver function.

The application can obtain video frames displayed on the screen through the onFrame callback function.

class PreviewFrameObserver : public std::enable_shared_from_this<PreviewFrameObserver>
{
public:
    PreviewFrameObserver();
    virtual ~PreviewFrameObserver();
    virtual void onFrame(int32_t camera_id, uint8_t *frame, int32_t stride_width, int32_t width, int32_t height);
    virtual void onNoMediaData(int32_t camera_id);
};

When the video frame format is YUV420, the Y, U, and V channels can be obtained using the formula below:

uint8_t *y = frame;
uint8_t *u = frame + stride_width * height;
uint8_t *v = u + stride_width * height / 4;

Functions#

The key-value map values for each video channel are prefixed with channel<N>- before each key name. <N> starts from 1 and increases by 1.

Example#

Single Camera Monitoring Example#

Below is an example of monitoring video from the camera device ID 0.

Initializes Oasis.

// Does not use the file system.

oasis::key_value_map_t parameters;

parameters["offs-disable"] = "1";

if(oasis::initialize(parameters) < 0) {
    DLOG(DLOG_ERROR, "Oasis init failed\n");
    return -1;
}

Initializes the camera device. Here, a single camera device is used.

parameters.clear();

parameters["source-count"] = "1";

parameters["source1-camera-id"] = "0";
parameters["source1-isp-id"] = "0";
parameters["source1-isp-wdr-mode"] = "0";
parameters["source1-capture-format"] = "YUV420";
parameters["source1-capture-buffers"] = "5";
parameters["source1-fps"] = "30";
parameters["source1-subchannel-rotation"] = "0";
parameters["source1-loc"] = "front";
parameters["source1-capture-resolution"] = "1080p";
parameters["source1-sensor-config"] = "./Resource_tp2863/VIC/0/tp2863_1920x1080_ch0.cfg";
parameters["source1-autoscene-config"] = "./Resource_tp2863/AutoScene/autoscene_conf.cfg";
parameters["source1-resource-dir"] = "./Resource_tp2863/";

configCameras(parameters);  

Initializes the display device.

parameters.clear();

parameters["memory-type"] = "ion"; //cma
parameters["screen-width"] = "480";
parameters["screen-height"] = "320";

display::setup(parameters);

Configures the GUI. In this example, touch is not used.

parameters.clear();

parameters["system-font-size"] = "10";
parameters["system-font-path"] = "/mnt/sd/consola.ttf";
parameters["display-rotation"] = "0";
parameters["enable-touch"] = "0";

err = ui::setup(parameters);
if (err < 0) {
    DLOG(DLOG_ERROR, "Oasis ui::setup failed\n");
    return -1;
}

Initializes the Preview object.

parameters.clear();

// Obtains the default screen object and applies its width and height to the media player.
ui::ScreenRef screen = ui::getDefaultScreen();

int32_t screen_width = ui::screenWidth(screen);
int32_t screen_height = ui::screenHeight(screen);


// Creates a user-defined object derived from ui::PreviewFrameObserver.
std::shared_ptr<MyPreviewFrameObserver> observer = std::make_shared<MyPreviewFrameObserver>();

parameters["channel-count"] = "1";
parameters["primary-channel"] = "1";

parameters["channel1-camera-id"] = std::to_string(camera_id);
parameters["channel1-visible"] = "1";
parameters["channel1-rotation"] = std::to_string(rotation);
// Configures the playback screen to full screen.
parameters["channel1-x"] = "0";
parameters["channel1-y"] = "0";
parameters["channel1-width"] = std::to_string(screen_width);
parameters["channel1-height"] = std::to_string(screen_height);
parameters["channel1-zorder"] = "0";

ui::PreviewRef preview = ui::createPreview(0, parameters);
ui::setPreviewFrameObserver(preview, observer);

Configures the screen layout. A Fixed layout container is used inside the top-level Window object, and the video screen is set to full screen.

ui::WindowRef preview_panel = ui::createWindow("Preview1");

ui::FixedRef fixed_layout = ui::createFixed();
ui::containerAdd(preview_panel, fixed_layout);

ui::setFixedSize(preview, screen_width, screen_height);
ui::fixedPut(fixed_layout, preview, 0, 0);
ui::screenAdd(screen, preview_panel);

ui::setVisible(preview_panel, true);

Starts monitoring.

ui::previewStart(preview);

An example of modifying the screen position during playback:

ui::previewSetPos(preview, 0, 100, 100)

Stops monitoring.

ui::previewStop(preview);

Below is the complete code:

#include "OasisAPI.h"
#include "OasisLog.h"
#include "OasisMedia.h"
#include "OasisUI.h"
#include "OasisFS.h"
#include "OasisUtil.h"
#include "OasisDisplay.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>

#include <signal.h>

#include <thread>
#include <mutex>
#include <memory>
#include <condition_variable>

using namespace oasis;


static bool continue_previewing = true;

void cancel_handler(int signum)
{
    continue_previewing = false;
}

class MyPreviewFrameObserver : public ui::PreviewFrameObserver {
public:
    MyPreviewFrameObserver() {}
    virtual ~MyPreviewFrameObserver() {}

    virtual void onFrame(int32_t camera_id, uint8_t *frame, int32_t stride_width, int32_t width, int32_t height) {
    }
    virtual void onNoMediaData(int32_t camera_id) {
        fprintf(stdout, "no media: camera<%d>\n", camera_id);
    }
};

void printUsage(const char *pgname)
{
    fprintf(stderr, "USAGE: %s [-r <rotation. 90, 270>] <camera id>\n", pgname);
}

int main(int argc, char *argv[])
{
    int32_t err;
    int c;
    int32_t rotation = 0;
    int32_t camera_id = -1;

    opterr = 0;
    while ((c = getopt(argc, argv, "r:h")) != -1) {
        switch (c) {
        case 'r':
            if(optarg == nullptr) {
                fprintf(stderr, "error: bad option argument '%c'\n", optopt);
                return -1;
            }
            rotation = atoi(optarg);
            if(rotation != 0 && rotation != 90 /*&& rotation != 180*/ && rotation != 270) {
                fprintf(stderr, "bad rotation: %d\n", rotation);
                return -1;
            }
            break;
        case 'h':
        default:
            printUsage(argv[0]);
            return -1;
        }
    }

    if(argc-optind < 1) {
        fprintf(stderr, "error: invalid or insufficient arguments (%d, %d)\n", argc, optind);
        printUsage(argv[0]);
        return -1;
    }

    camera_id = atoi(argv[optind]);
    if(camera_id < 0) {
        fprintf(stderr, "invalid camera id: %d\n", camera_id);
        return -1;
    }


    signal(SIGINT, cancel_handler);

    oasis::key_value_map_t parameters;

    ////////////////////////////////////////////////////////////////////////////////////////////
    // init

    parameters["offs-disable"] = "1";

    if(oasis::initialize(parameters) < 0) {
        DLOG(DLOG_ERROR, "Oasis init failed\n");
        return -1;
    }

    ////////////////////////////////////////////////////////////////////////////////////////////
    // camera sources
    parameters.clear();

    parameters["source-count"] = "1";

    parameters["source1-camera-id"] = "0";
    parameters["source1-isp-id"] = "0";
    parameters["source1-isp-wdr-mode"] = "0";
    parameters["source1-capture-format"] = "YUV420";
    parameters["source1-capture-buffers"] = "5";
    parameters["source1-fps"] = "30";
    parameters["source1-subchannel-rotation"] = "0";
    parameters["source1-loc"] = "front";
    parameters["source1-capture-resolution"] = "1080p";
    parameters["source1-sensor-config"] = "./Resource_tp2863/VIC/0/tp2863_1920x1080_ch0.cfg";
    parameters["source1-autoscene-config"] = "./Resource_tp2863/AutoScene/autoscene_conf.cfg";
    parameters["source1-resource-dir"] = "./Resource_tp2863/";

    configCameras(parameters);  

    ////////////////////////////////////////////////////////////////////////////////////////////
    // display setup
    parameters.clear();

    parameters["memory-type"] = "ion"; //cma
    parameters["screen-width"] = "480";
    parameters["screen-height"] = "320";

    display::setup(parameters);


    //////////////////////////////////////////////////////////////////////////////////////////
    // ui setup
    parameters.clear();

    parameters["system-font-size"] = "10";
    parameters["system-font-path"] = "/mnt/sd/consola.ttf";

    parameters["display-rotation"] = "0";
    parameters["enable-touch"] = "0";

    err = ui::setup(parameters);
    if (err < 0) {
        DLOG(DLOG_ERROR, "Oasis ui::setup failed\n");
        return -1;
    }

    /////////////////////////////////////////////////////////////////////////
    // create preview and layout

    ui::ScreenRef screen = ui::getDefaultScreen();

    int32_t screen_width = ui::screenWidth(screen);
    int32_t screen_height = ui::screenHeight(screen);


    parameters.clear();


    //preview_panel
    ui::WindowRef preview_panel = ui::createWindow("Preview1");

    ui::FixedRef fixed_layout = ui::createFixed();
    ui::containerAdd(preview_panel, fixed_layout);

    std::shared_ptr<MyPreviewFrameObserver> observer = std::make_shared<MyPreviewFrameObserver>();

    parameters["channel-count"] = "1";
    parameters["primary-channel"] = "1";

    parameters["channel1-camera-id"] = std::to_string(camera_id);
    parameters["channel1-visible"] = "1";
    parameters["channel1-rotation"] = std::to_string(rotation);
    parameters["channel1-x"] = "0";
    parameters["channel1-y"] = "0";
    parameters["channel1-width"] = std::to_string(screen_width);
    parameters["channel1-height"] = std::to_string(screen_height);
    parameters["channel1-zorder"] = "0";

    ui::PreviewRef preview = ui::createPreview(0, parameters);
    ui::setPreviewFrameObserver(preview, observer);

    ui::setFixedSize(preview, screen_width, screen_height);
    ui::fixedPut(fixed_layout, preview, 0, 0);
    ui::screenAdd(screen, preview_panel);

    ui::setVisible(preview_panel, true);

    ui::previewStart(preview);

    do {
        usleep(100000);
    } while (continue_previewing);

    ui::previewStop(preview);

    err = ui::cleanup();

    oasis::finalize();

    return 0;
}

​

4 Camera Monitoring and Layout Change Example#

Initializes 4 camera devices.

parameters["source-count"] = "4";

parameters["source1-camera-id"] = "0";
parameters["source1-isp-id"] = "0";
parameters["source1-isp-wdr-mode"] = "0";
parameters["source1-capture-format"] = "YUV420";
parameters["source1-capture-buffers"] = "5";
parameters["source1-fps"] = std::to_string(FPS);
parameters["source1-subchannel-rotation"] = "0";
parameters["source1-loc"] = "front";
parameters["source1-capture-resolution"] = "1080p";
parameters["source1-sensor-config"] = "./Resource/VIC/0/tp2855_1920x1080_ch0.cfg";
parameters["source1-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
parameters["source1-resource-dir"] = "./Resource/";

parameters["source2-camera-id"] = "1";
parameters["source2-isp-id"] = "0";
parameters["source2-isp-wdr-mode"] = "0";
parameters["source2-capture-format"] = "YUV420";
parameters["source2-capture-buffers"] = "5";
parameters["source2-fps"] = std::to_string(FPS);
parameters["source2-subchannel-rotation"] = "0";
parameters["source2-loc"] = "front";
parameters["source2-capture-resolution"] = "1080p";
parameters["source2-sensor-config"] = "./Resource/VIC/1/tp2855_1920x1080_ch1.cfg";
parameters["source2-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
parameters["source2-resource-dir"] = "./Resource/";

parameters["source3-camera-id"] = "2";
parameters["source3-isp-id"] = "0";
parameters["source3-isp-wdr-mode"] = "0";
parameters["source3-capture-format"] = "YUV420";
parameters["source3-capture-buffers"] = "5";
parameters["source3-fps"] = std::to_string(FPS);
parameters["source3-subchannel-rotation"] = "0";
parameters["source3-loc"] = "front";
parameters["source3-capture-resolution"] = "1080p";
parameters["source3-sensor-config"] = "./Resource/VIC/2/tp2855_1920x1080_ch2.cfg";
parameters["source3-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
parameters["source3-resource-dir"] = "./Resource/";

parameters["source4-camera-id"] = "3";
parameters["source4-isp-id"] = "0";
parameters["source4-isp-wdr-mode"] = "0";
parameters["source4-capture-format"] = "YUV420";
parameters["source4-capture-buffers"] = "5";
parameters["source4-fps"] = std::to_string(FPS);
parameters["source4-subchannel-rotation"] = "0";
parameters["source4-loc"] = "front";
parameters["source4-capture-resolution"] = "1080p";
parameters["source4-sensor-config"] = "./Resource/VIC/3/tp2860_1920x1080_ch3.cfg";
parameters["source4-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
parameters["source4-resource-dir"] = "./Resource/";

configCameras(parameters);

Creates the Preview object by configuring all 4 cameras to be monitored.

The channel<N>-visible for each channel is set to "0" (hidden) upon Preview creation.

parameters["channel-count"] = "4";
parameters["primary-channel"] = "1";

parameters["channel1-camera-id"] = "0";
parameters["channel1-visible"] = "0";
parameters["channel1-rotation"] = "0";
parameters["channel1-x"] = "0";
parameters["channel1-y"] = "0";
parameters["channel1-width"] = "960";
parameters["channel1-height"] = "360";
parameters["channel1-zorder"] = "0";

parameters["channel2-camera-id"] = "1";
parameters["channel2-visible"] = "0";
parameters["channel2-rotation"] = "0";
parameters["channel2-x"] = "0";
parameters["channel2-y"] = "360";
parameters["channel2-width"] = "960";
parameters["channel2-height"] = "360";
parameters["channel2-zorder"] = "0";

parameters["channel3-camera-id"] = "2";
parameters["channel3-visible"] = "0";
parameters["channel3-rotation"] = "0";
parameters["channel3-x"] = "960";
parameters["channel3-y"] = "0";
parameters["channel3-width"] = "960";
parameters["channel3-height"] = "360";
parameters["channel3-zorder"] = "0";

parameters["channel4-camera-id"] = "3";
parameters["channel4-visible"] = "0";
parameters["channel4-rotation"] = "0";
parameters["channel4-x"] = "960";
parameters["channel4-y"] = "360";
parameters["channel4-width"] = "960";
parameters["channel4-height"] = "360";
parameters["channel4-zorder"] = "0";

ui::PreviewRef preview = ui::createPreview(0, parameters);

On a device with a screen resolution of 1920x720, 4 types of layouts are defined as follows.

struct layout_info {
  int32_t count;
  Rect items[4];
} layouts[4] = {
  [0] = {
    .count = 1,
    .items = {
      [0] = { 0, 0, 1920, 720}
    }
  },
  [1] = {
    .count = 2,
    .items = {
      [0] = { 0, 0, 960, 720},
      [1] = { 960, 0, 960, 720}
    }
  },
  [2] = {
    .count = 3,
    .items = {
      [0] = { 0, 0, 640, 720},
      [1] = { 640, 0, 640, 720},
      [2] = { 1280, 0, 640, 720}
    }
  },
  [3] = {
    .count = 4,
    .items = {
      [0] = { 0, 0, 960, 360},
      [1] = { 0, 360, 960, 360},
      [2] = { 960, 0, 960, 360},
      [3] = { 960, 360, 960, 360}
    }
  },
};

It is a maximum of 4 splits, and a camera ID is assigned to each split region. The relationship between the camera ID to be assigned and the region is defined and managed as a map.

The example below changes the layout using the layout command, and assigns a camera ID to each region using the map command.

The layout 1 command causes a single camera to occupy the entire screen.

map 0 1 2 3 assigns a camera ID to each region. Even if the current layout is 1, camera IDs must also be specified for invisible regions.

The command is executed in the setLayout function.

int32_t layout_to_camera_map[4] = { 0, 1, 2, 3 };
int32_t current_layout_index = 0;

static void setLayout(const ui::PreviewRef &preview, int32_t layout_index)
{
  int32_t i;
  for(i=0; i<layouts[layout_index].count; i++) {
    ui::previewSetRect(preview, layout_to_camera_map[i], layouts[layout_index].items[i].left, layouts[layout_index].items[i].top, layouts[layout_index].items[i].width, layouts[layout_index].items[i].height);
    ui::previewSetVisible(preview, layout_to_camera_map[i], true);
  }
  for(; i<4; i++) {
    ui::previewSetVisible(preview, layout_to_camera_map[i], false);
  }
  current_layout_index = layout_index;
}

When the example is executed, 4 cameras are shown in 4 split regions respectively.

  setLayout(preview, 3);

The show command makes the Preview screen visible, and the hide command makes it invisible.

Below is the complete code.

#include "OasisAPI.h"
#include "OasisLog.h"
#include "OasisMedia.h"
#include "OasisFS.h"
#include "OasisUtil.h"
#include "OasisUI.h"
#include "OasisDisplay.h"

#include "common.h"

#include <thread>
#include <mutex>
#include <memory>
#include <condition_variable>

#include <signal.h>

#include <iostream>
#include <sstream>
#include <cstdio>

#define DLOG_THIS   0x00010000

#undef DLOG_FLAGS
#define  DLOG_FLAGS (DLOG_FLAGS_DEFAULT/*|DLOG_THIS*/)

#undef DLOG_TAG
#define DLOG_TAG "PREVIEW4"

#define FPS 30
#define MAX_LINE 4096

using namespace oasis;

static bool continue_previewing = true;

struct layout_info {
  int32_t count;
  Rect items[4];
} layouts[4] = {
  [0] = {
    .count = 1,
    .items = {
      [0] = { 0, 0, 1920, 720}
    }
  },
  [1] = {
    .count = 2,
    .items = {
      [0] = { 0, 0, 960, 720},
      [1] = { 960, 0, 960, 720}
    }
  },
  [2] = {
    .count = 3,
    .items = {
      [0] = { 0, 0, 640, 720},
      [1] = { 640, 0, 640, 720},
      [2] = { 1280, 0, 640, 720}
    }
  },
  [3] = {
    .count = 4,
    .items = {
      [0] = { 0, 0, 960, 360},
      [1] = { 0, 360, 960, 360},
      [2] = { 960, 0, 960, 360},
      [3] = { 960, 360, 960, 360}
    }
  },
};

int32_t layout_to_camera_map[4] = { 0, 1, 2, 3 };
int32_t current_layout_index = 0;

static void setLayout(const ui::PreviewRef &preview, int32_t layout_index)
{
  int32_t i;
  for(i=0; i<layouts[layout_index].count; i++) {
    ui::previewSetRect(preview, layout_to_camera_map[i], layouts[layout_index].items[i].left, layouts[layout_index].items[i].top, layouts[layout_index].items[i].width, layouts[layout_index].items[i].height);
    ui::previewSetVisible(preview, layout_to_camera_map[i], true);
  }
  for(; i<4; i++) {
    ui::previewSetVisible(preview, layout_to_camera_map[i], false);
  }
  current_layout_index = layout_index;
}

class MyPreviewFrameObserver : public ui::PreviewFrameObserver {
public:
  MyPreviewFrameObserver() {}
  virtual ~MyPreviewFrameObserver() {}

  virtual void onFrame(int32_t camera_id, uint8_t *frame, int32_t stride_width, int32_t width, int32_t height) {
  }
  virtual void onNoMediaData(int32_t camera_id) {
    fprintf(stdout, "no media: camera<%d>\n", camera_id);
  }
};

void print_usage(const char *pname)
{

}

void cancel_handler(int signum)
{
  continue_previewing = false;
}




int main(int argc, char* argv[])
{
  int32_t c, err;
  char input[MAX_LINE];

  oasis::key_value_map_t parameters;

  signal(SIGINT, cancel_handler);

   ////////////////////////////////////////////////////////////////////////////////////////////
  // init

  parameters["offs-disable"] = "1";
  parameters["oasis-log-flags"] = std::to_string(OASIS_LOG_DEBUG/*|OASIS_LOG_ENCODE_BITRATE*/);

  if(oasis::initialize(parameters) < 0) {
    DLOG(DLOG_ERROR, "Oasis init failed\n");
    return -1;
  }


  ////////////////////////////////////////////////////////////////////////////////////////////
  // camera sources
  parameters.clear();

  parameters["source-count"] = "4";

  parameters["source1-camera-id"] = "0";
  parameters["source1-isp-id"] = "0";
  parameters["source1-isp-wdr-mode"] = "0";
  parameters["source1-capture-format"] = "YUV420";
  parameters["source1-capture-buffers"] = "5";
  parameters["source1-fps"] = std::to_string(FPS);
  parameters["source1-subchannel-rotation"] = "0";
  parameters["source1-loc"] = "front";
  parameters["source1-capture-resolution"] = "1080p";
  parameters["source1-sensor-config"] = "./Resource/VIC/0/tp2855_1920x1080_ch0.cfg";
  parameters["source1-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
  parameters["source1-resource-dir"] = "./Resource/";

  parameters["source2-camera-id"] = "1";
  parameters["source2-isp-id"] = "0";
  parameters["source2-isp-wdr-mode"] = "0";
  parameters["source2-capture-format"] = "YUV420";
  parameters["source2-capture-buffers"] = "5";
  parameters["source2-fps"] = std::to_string(FPS);
  parameters["source2-subchannel-rotation"] = "0";
  parameters["source2-loc"] = "front";
  parameters["source2-capture-resolution"] = "1080p";
  parameters["source2-sensor-config"] = "./Resource/VIC/1/tp2855_1920x1080_ch1.cfg";
  parameters["source2-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
  parameters["source2-resource-dir"] = "./Resource/";

  parameters["source3-camera-id"] = "2";
  parameters["source3-isp-id"] = "0";
  parameters["source3-isp-wdr-mode"] = "0";
  parameters["source3-capture-format"] = "YUV420";
  parameters["source3-capture-buffers"] = "5";
  parameters["source3-fps"] = std::to_string(FPS);
  parameters["source3-subchannel-rotation"] = "0";
  parameters["source3-loc"] = "front";
  parameters["source3-capture-resolution"] = "1080p";
  parameters["source3-sensor-config"] = "./Resource/VIC/2/tp2855_1920x1080_ch2.cfg";
  parameters["source3-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
  parameters["source3-resource-dir"] = "./Resource/";

  parameters["source4-camera-id"] = "3";
  parameters["source4-isp-id"] = "0";
  parameters["source4-isp-wdr-mode"] = "0";
  parameters["source4-capture-format"] = "YUV420";
  parameters["source4-capture-buffers"] = "5";
  parameters["source4-fps"] = std::to_string(FPS);
  parameters["source4-subchannel-rotation"] = "0";
  parameters["source4-loc"] = "front";
  parameters["source4-capture-resolution"] = "1080p";
  parameters["source4-sensor-config"] = "./Resource/VIC/3/tp2860_1920x1080_ch3.cfg";
  parameters["source4-autoscene-config"] = "./Resource/AutoScene/autoscene_conf.cfg";
  parameters["source4-resource-dir"] = "./Resource/";

  configCameras(parameters);


  ////////////////////////////////////////////////////////////////////////////////////////////
  // display setup
  parameters.clear();

  parameters["memory-type"] = "ion"; //cma
  parameters["screen-width"] = "720";
  parameters["screen-height"] = "1920";

  display::setup(parameters);

  //////////////////////////////////////////////////////////////////////////////////////////
  // ui setup
  parameters.clear();

  parameters["system-font-size"] = "10";
  parameters["system-font-path"] = "/mnt/flash/leipzig/consola.ttf";

  parameters["display-rotation"] = "270";
  parameters["enable-touch"] = "0";

  parameters["fb0-hlayer"] = "0:1:0";
  parameters["vi0-hlayer"] = "0:0:0";

  err = ui::setup(parameters);
  if (err < 0) {
    DLOG(DLOG_ERROR, "Oasis ui::setup failed\n");
    return -1;
  }


  /////////////////////////////////////////////////////////////////////////
  // create preview and layout

  ui::ScreenRef screen = ui::getDefaultScreen();
  //ASSERT(screen != nullptr);

  int32_t screen_width = ui::screenWidth(screen);
  int32_t screen_height = ui::screenHeight(screen);


  //preview_panel
  ui::WindowRef preview_panel = ui::createWindow("Preview1");
  //ASSERT(preview_panel != nullptr);

  ui::FixedRef fixed_layout = ui::createFixed();
  ui::containerAdd(preview_panel, fixed_layout);

  std::shared_ptr<MyPreviewFrameObserver> observer = std::make_shared<MyPreviewFrameObserver>();

  parameters["channel-count"] = "4";
  parameters["primary-channel"] = "1";

  parameters["channel1-camera-id"] = "0";
  parameters["channel1-visible"] = "0";
  parameters["channel1-rotation"] = "0";
  parameters["channel1-x"] = "0";
  parameters["channel1-y"] = "0";
  parameters["channel1-width"] = "960";
  parameters["channel1-height"] = "360";
  parameters["channel1-zorder"] = "0";

  parameters["channel2-camera-id"] = "1";
  parameters["channel2-visible"] = "0";
  parameters["channel2-rotation"] = "0";
  parameters["channel2-x"] = "0";
  parameters["channel2-y"] = "360";
  parameters["channel2-width"] = "960";
  parameters["channel2-height"] = "360";
  parameters["channel2-zorder"] = "0";

  parameters["channel3-camera-id"] = "2";
  parameters["channel3-visible"] = "0";
  parameters["channel3-rotation"] = "0";
  parameters["channel3-x"] = "960";
  parameters["channel3-y"] = "0";
  parameters["channel3-width"] = "960";
  parameters["channel3-height"] = "360";
  parameters["channel3-zorder"] = "0";

  parameters["channel4-camera-id"] = "3";
  parameters["channel4-visible"] = "0";
  parameters["channel4-rotation"] = "0";
  parameters["channel4-x"] = "960";
  parameters["channel4-y"] = "360";
  parameters["channel4-width"] = "960";
  parameters["channel4-height"] = "360";
  parameters["channel4-zorder"] = "0";

  ui::PreviewRef preview = ui::createPreview(0, parameters);
  ui::setPreviewFrameObserver(preview, observer);

  ui::setFixedSize(preview, screen_width, screen_height);
  ui::fixedPut(fixed_layout, preview, 0, 0);
  ui::screenAdd(screen, preview_panel);

  ui::setVisible(preview_panel, true);

  ui::previewStart(preview);

  setLayout(preview, 3);

  do {
    printf("Enter command (h for help. q for quit): ");
    if(fgets(input, sizeof(input), stdin) == nullptr) {
      break;
    }

    std::stringstream ss(input);
    std::string token;
    std::vector<std::string> args;

    while (ss >> token) {
      args.push_back(token);
    }

    if(args.empty()) {
      continue;
    }

    if(args[0] == "h") {
      printf("\n");
      printf("layout <layout number>: 1, 2, 3, 4. In case of no arguments, the current layout is printed.\n");
      printf("map <camera id for region 0> <camera id for region 1> <camera id for region 2> <camera id for region 3>\n");
      printf("show: show and start previewing.\n");
      printf("hide: stop and hide previewing.\n");
      printf("\n");
    } else if(args[0] == "q") {
      break;
    } else if(args[0] == "layout") {
      if(args.size() == 1) {
        printf("current layout: %d\n", current_layout_index+1);
      } else {
        int32_t layout_index = atoi(args[1].c_str()) - 1;
        if(layout_index < 0 || layout_index > 3) {
          printf("invalid value: %d\n", layout_index+1);
        } else {
          setLayout(preview, layout_index);
        }
      }
    } else if(args[0] == "map") {
      if(args.size() == 1) {
        printf("current map: ");
        for(int32_t i=0; i<4; i++) {
          printf("%d ", layout_to_camera_map[i]);
        }
        printf("\n");
      } else if(args.size() == 5) {
        bool has_error = false;
        int32_t new_map[4] = { -1, -1, -1, -1 };
        auto is_dup_camera_id = [&](int32_t n, int32_t val) {
          for(int32_t i=0; i<n; i++) {
            if(new_map[i] == val) {
              return true;
            }
          }
          return false;
        };
        for(int32_t i=0; i<4; i++) {
          int32_t camera_id = atoi(args[i+1].c_str());
          if(camera_id < 0 || camera_id > 3) {
            printf("invalid value: %d\n", camera_id);
            has_error = false;
            break;
          }
          if(is_dup_camera_id(i, camera_id)) {
            printf("duplicate value: %d\n", camera_id);
            has_error = false;
            break;
          }
          new_map[i] = camera_id;
        }
        if(!has_error) {
          printf("map updated\n");
          memcpy(layout_to_camera_map, new_map, sizeof(layout_to_camera_map));
          setLayout(preview, current_layout_index);
        }
      } else {
        printf("insufficent arguments: %d\n", args.size());
      }
    } else if(args[0] == "show") {
      ui::setVisible(preview_panel, true);
      ui::previewStart(preview);
      setLayout(preview, current_layout_index);
    } else if(args[0] == "hide") {
      ui::previewStop(preview);
      ui::setVisible(preview_panel, false);
    }

  } while (continue_previewing == true);
done:

  ui::previewStop(preview);

  err = ui::cleanup();

  oasis::finalize();


  return 0;
}