raspberry camera sync

/***
 *
 * This example is just a proof of a concept 6by9 gave in the raspi forum:
 * that one could synchronize the raspi cam to an external periodical event just
 * fiddling with the framerates.
 *
 * So if you have an external periodical event like:
 * t_event = start_time + k * period, for k being an integer
 *
 * what we want here is to have the frame taken always at the same controlled t_dist from t_event.
 *
 * One could sync many raspis together using PTP, for instance, and get stereo vision synced.
 * Or sync the raspi to the internal (or external) PWM, like done here.
 *
 * This is not a solution for imaging at the exact external trigger event.
 *
 * and is just a hack. it is not like I am caring for mutexes, return status of mmal calls, polluting globals.
 * It it just to show that the concept works.
 *
 *
***/

#include <iostream>
#include <thread>

#include <time.h>

#include <wiringPi.h>

// if one is compiling this, will need to add a few include directories manually in the gcc comamnd.
// at least this is needed when compiling for a buildroot generated sysroot.
// since inside the include files there are many other includes without paths.
#include "mmal/mmal.h"
#include "mmal/util/mmal_util.h"
#include "mmal/util/mmal_default_components.h"
#include "mmal/util/mmal_connection.h"
#include "mmal/util/mmal_util_params.h"
#include "bcm_host.h"

#define WIDTH 1296
#define HEIGHT 972

#define FRAME_RATE_NUM_DEFAULT (40*256)
#define FRAME_RATE_DEN_DEFAULT 256
#define T_DEAD_ZONE 10
#define FR_CORRECTION 32


#define MMAL_CAMERA_PREVIEW_PORT 0
#define MMAL_CAMERA_VIDEO_PORT 1
#define MMAL_CAMERA_CAPTURE_PORT 2


typedef struct {
    MMAL_POOL_T *camera_video_port_pool;
} PORT_USERDATA;

static PORT_USERDATA userdata;
static MMAL_PORT_T * camera_video_port = nullptr;

uint64_t pwm_counter;
uint64_t pwm_start_time;
double pwm_period;
uint64_t pwm_offset;

static void video_buffer_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
{
    static uint64_t frame_count = 0;
    static struct timespec ts;

    frame_count++;

    // get the offset between the mmal time and linux time. We need this to correct the
    // frames timestamps.

    uint64_t t_mmal = 0;
    mmal_port_parameter_get_uint64(port, MMAL_PARAMETER_SYSTEM_TIME, &t_mmal);

    clock_gettime(CLOCK_MONOTONIC, &ts);
    uint64_t t_linux = (uint64_t)ts.tv_sec*1000000 + ts.tv_nsec / 1000;

    int64_t t_offset = t_linux - t_mmal;

    uint64_t t_frame_mmal = buffer->pts; // this timestamp is referenced to the mmal clock.
    uint64_t t_frame_linux = t_frame_mmal + t_offset; // now we have the frame timestamp referenced to the linux clock
    // std::cout << "t_offset =" << t_offset << std::endl;
    // to see mmal time and linux time drifting apart, uncomment above line


    // we have a periodic event we want to sync to.
    // This event is modeled like:
    // t_event(k) = t_event_start + k * t_period, where k is integer.
    // we wanto to keep t_frame_linux, above, locked at a fixed given distance from t_event.
    // like:
    // t_frame_linux = t_event_start + k * t_period + t_dist
    //
    // of course the locking is nor perfect, so we can define:
    // t_error = t_frame_linux - (t_event_start + k * t_period + t_dist)
    //
    // and we should drive the software PLL to zero t_error.

    // we now should find t_error. Begin first by finding a suitable k.

    uint64_t t_event_start = pwm_start_time; // here will sync to pwm
    uint64_t t_dist = pwm_offset;
    double t_period = pwm_period*1e6; // t_period should be in microsec
    uint32_t t_period_us = t_period;

    uint32_t k = (t_frame_linux - t_event_start - t_dist)/t_period;

    uint32_t t_error = t_frame_linux - (t_event_start + (uint64_t)(k * t_period) + t_dist);
    // by contruction, t_error > 0

    // we should drive it to:
    // 0, if t_error < t_period_us / 2;
    // t_period_us, if t_error > t_period_us/2

    // to decrease t_error, we should decrease t_frame_linux by increasing the fps
    // to increase t_error, descrease fps
    // and near a dead zone, close to the targets, we could set a neutral fps

    //std::cout << "cnt= " << frame_count << " t_error=" << t_error << " t_period=" << t_period_us << " k=" << k << std::endl;


    if (t_error > T_DEAD_ZONE && t_error < t_period_us/2)
    {
        MMAL_PARAMETER_FRAME_RATE_T param = {{MMAL_PARAMETER_VIDEO_FRAME_RATE, sizeof(param)}, {0, 0}};
        param.frame_rate.num = FRAME_RATE_NUM_DEFAULT + FR_CORRECTION;
        param.frame_rate.den = FRAME_RATE_DEN_DEFAULT;
        mmal_port_parameter_set(camera_video_port, &param.hdr);
    }
    else if (t_error < t_period_us - T_DEAD_ZONE && t_error > t_period_us/2)
    {
        MMAL_PARAMETER_FRAME_RATE_T param = {{MMAL_PARAMETER_VIDEO_FRAME_RATE, sizeof(param)}, {0, 0}};
        param.frame_rate.num = FRAME_RATE_NUM_DEFAULT - FR_CORRECTION;
        param.frame_rate.den = FRAME_RATE_DEN_DEFAULT;
        mmal_port_parameter_set(camera_video_port, &param.hdr);
    }
    else
    {
        MMAL_PARAMETER_FRAME_RATE_T param = {{MMAL_PARAMETER_VIDEO_FRAME_RATE, sizeof(param)}, {0, 0}};
        param.frame_rate.num = FRAME_RATE_NUM_DEFAULT;
        param.frame_rate.den = FRAME_RATE_DEN_DEFAULT;
        mmal_port_parameter_set(camera_video_port, &param.hdr);
    }

    MMAL_BUFFER_HEADER_T *new_buffer;
    PORT_USERDATA * p_userdata = (PORT_USERDATA *) port->userdata;
    MMAL_POOL_T *pool = p_userdata->camera_video_port_pool;

    mmal_buffer_header_mem_lock(buffer);

    // do something cool with data

    mmal_buffer_header_mem_unlock(buffer);
    mmal_buffer_header_release(buffer);

    if (port->is_enabled)
    {

        MMAL_STATUS_T status;
        new_buffer = mmal_queue_get(pool->queue);

        if (new_buffer)
        {
            status = mmal_port_send_buffer(port, new_buffer);
        }
        if (!new_buffer || status != MMAL_SUCCESS)
            printf("Unable to return a buffer to the video port\n");
    }
}


int start_camera() {
    MMAL_COMPONENT_T *camera = 0;
    MMAL_COMPONENT_T *preview = 0;
    MMAL_ES_FORMAT_T *format;
    MMAL_STATUS_T status;
    MMAL_PORT_T *camera_preview_port = NULL;
    MMAL_PORT_T *camera_still_port = NULL;
    MMAL_PORT_T *preview_input_port = NULL;
    MMAL_POOL_T *camera_video_port_pool;
    MMAL_CONNECTION_T *camera_preview_connection = 0;

    bcm_host_init();

    status = mmal_component_create(MMAL_COMPONENT_DEFAULT_CAMERA, &camera);
    if (status != MMAL_SUCCESS) {
        printf("Error: create camera %x\n", status);
        return -1;
    }

    camera_preview_port = camera->output[MMAL_CAMERA_PREVIEW_PORT];
    camera_video_port = camera->output[MMAL_CAMERA_VIDEO_PORT];
    camera_still_port = camera->output[MMAL_CAMERA_CAPTURE_PORT];

    {
        MMAL_PARAMETER_CAMERA_CONFIG_T cam_config =
        {
            { MMAL_PARAMETER_CAMERA_CONFIG, sizeof (cam_config)},
            .max_stills_w = WIDTH,
            .max_stills_h = HEIGHT,
            .stills_yuv422 = 0,
            .one_shot_stills = 0,
            .max_preview_video_w = WIDTH/2,
            .max_preview_video_h = HEIGHT/2,
            .num_preview_video_frames = 2,
            .stills_capture_circular_buffer_height = 0,
            .fast_preview_resume = 1,
            .use_stc_timestamp = MMAL_PARAM_TIMESTAMP_MODE_RAW_STC
        };

        mmal_port_parameter_set(camera->control, &cam_config.hdr);
    }

    format = camera_video_port->format;

    format->encoding = MMAL_ENCODING_I420;
    format->encoding_variant = MMAL_ENCODING_I420;

    format->es->video.width = WIDTH/2;
    format->es->video.height = HEIGHT/2;
    format->es->video.crop.x = 0;
    format->es->video.crop.y = 0;
    format->es->video.crop.width = WIDTH/2;
    format->es->video.crop.height = HEIGHT/2;
    format->es->video.frame_rate.num = FRAME_RATE_NUM_DEFAULT;
    format->es->video.frame_rate.den = FRAME_RATE_DEN_DEFAULT;

    camera_video_port->buffer_size = WIDTH * HEIGHT * 2;
    camera_video_port->buffer_num = 5;
    printf("  Camera video buffer_size = %d\n", camera_video_port->buffer_size);

    status = mmal_port_format_commit(camera_video_port);
    printf("  Camera video recommended buffer_size = %d, %d\n", camera_video_port->buffer_size_recommended, camera_video_port->buffer_num_recommended);

    if (status != MMAL_SUCCESS) {
        printf("Error: unable to commit camera video port format (%u)\n", status);
        return -1;
    }

    format = camera_preview_port->format;

    format->encoding = MMAL_ENCODING_OPAQUE;
    format->encoding_variant = MMAL_ENCODING_I420;

    format->es->video.width = WIDTH/2;
    format->es->video.height = HEIGHT/2;
    format->es->video.crop.x = 0;
    format->es->video.crop.y = 0;
    format->es->video.crop.width = WIDTH/2;
    format->es->video.crop.height = HEIGHT/2;

    status = mmal_port_format_commit(camera_preview_port);

    if (status != MMAL_SUCCESS) {
        printf("Error: camera viewfinder format couldn't be set\n");
        return -1;
    }

    // create pool form camera video port
    camera_video_port_pool = (MMAL_POOL_T *) mmal_port_pool_create(camera_video_port, camera_video_port->buffer_num, camera_video_port->buffer_size);

    std::cout << " num buffer headers: " <<  camera_video_port_pool->headers_num << std::endl;

    userdata.camera_video_port_pool = camera_video_port_pool;

    camera_video_port->userdata = (struct MMAL_PORT_USERDATA_T *) &userdata;

    status = mmal_port_enable(camera_video_port, video_buffer_callback);
    if (status != MMAL_SUCCESS) {
        printf("Error: unable to enable camera video port (%u)\n", status);
        return -1;
    }


    status = mmal_component_enable(camera);

    status = mmal_component_create(MMAL_COMPONENT_DEFAULT_VIDEO_RENDERER, &preview);
    if (status != MMAL_SUCCESS) {
        printf("Error: unable to create preview (%u)\n", status);
        return -1;
    }
    preview_input_port = preview->input[0];

    {
        MMAL_DISPLAYREGION_T param;
        param.hdr.id = MMAL_PARAMETER_DISPLAYREGION;
        param.hdr.size = sizeof (MMAL_DISPLAYREGION_T);
        param.set = MMAL_DISPLAY_SET_LAYER;
        param.layer = 0;
        param.set |= MMAL_DISPLAY_SET_FULLSCREEN;
        param.fullscreen = 1;
        status = mmal_port_parameter_set(preview_input_port, &param.hdr);
        if (status != MMAL_SUCCESS && status != MMAL_ENOSYS) {
            printf("Error: unable to set preview port parameters (%u)\n", status);
            return -1;
        }
    }

    status = mmal_connection_create(&camera_preview_connection, camera_preview_port, preview_input_port, MMAL_CONNECTION_FLAG_TUNNELLING | MMAL_CONNECTION_FLAG_ALLOCATION_ON_INPUT);
    if (status != MMAL_SUCCESS) {
        printf("Error: unable to create connection (%u)\n", status);
        return -1;
    }

    status = mmal_connection_enable(camera_preview_connection);
    if (status != MMAL_SUCCESS) {
        printf("Error: unable to enable connection (%u)\n", status);
        return -1;
    }

    if (1) {
        // Send all the buffers to the camera video port
        int num = mmal_queue_length(camera_video_port_pool->queue);
        int q;

        for (q = 0; q < num; q++) {
            MMAL_BUFFER_HEADER_T *buffer = mmal_queue_get(camera_video_port_pool->queue);

            if (!buffer) {
                printf("Unable to get a required buffer %d from pool queue\n", q);
            }

            if (mmal_port_send_buffer(camera_video_port, buffer) != MMAL_SUCCESS) {
                printf("Unable to send a buffer to encoder output port (%d)\n", q);
            }
        }
    }

    if (mmal_port_parameter_set_boolean(camera_video_port, MMAL_PARAMETER_CAPTURE, 1) != MMAL_SUCCESS) {
        printf("%s: Failed to start capture\n", __func__);
    }

    if (mmal_port_parameter_set_int32(camera->control, MMAL_PARAMETER_EXPOSURE_COMP , -24) != MMAL_SUCCESS) {
        printf("Failed to set exp comp\n");
    }
    if (mmal_port_parameter_set_uint32(camera->control, MMAL_PARAMETER_SHUTTER_SPEED, 23800)!= MMAL_SUCCESS) {
        printf("Failed to set exp comp\n");
    }


    {
       MMAL_PARAMETER_AWBMODE_T param = {{MMAL_PARAMETER_AWB_MODE,sizeof(param)}, MMAL_PARAM_AWBMODE_OFF};

       int st = mmal_port_parameter_set(camera->control, &param.hdr);
       printf("awb_mode=%d\n", st);
    }
    {

        MMAL_PARAMETER_AWB_GAINS_T param = {{MMAL_PARAMETER_CUSTOM_AWB_GAINS, sizeof(param)}, {0, 0}, {0, 0}};

       param.r_gain.num = 65536;
       param.b_gain.num = 65536;
       param.r_gain.den = param.b_gain.den = 65536;
       int st = mmal_port_parameter_set(camera->control, &param.hdr);
       printf("awbg=%d\n", st);
    }

    return 0;

}

int main()
{
    if (wiringPiSetup () == -1)
        exit (1) ;

    //wiringPiISR (1, INT_EDGE_RISING, &pwm_int);

    pinMode (1, PWM_OUTPUT) ;
    pwmSetMode  (PWM_MODE_MS);
    int sclock = 19;
    uint32_t range = 19.2e6/sclock/40 - 19;
    pwmSetRange (range);
    pwmWrite (1, 3);
    struct timespec t1, t2;
    uint64_t tdiff = 0;
    int i = 0;
    do
    {
        clock_gettime(CLOCK_MONOTONIC, &t1);
        pwmSetClock (19);
        clock_gettime(CLOCK_MONOTONIC, &t2);
        tdiff = (uint64_t)t2.tv_sec*1000000 + t2.tv_nsec / 1000 - (uint64_t)t1.tv_sec*1000000 - t1.tv_nsec / 1000;
        ++i;
    } while (tdiff > 200);
    std::cout << "tdiff=" << tdiff << "  i=" << i << "\n";

    pwm_start_time = ((uint64_t)t1.tv_sec)*1000000 + t1.tv_nsec / 1000;
    pwm_period = range*sclock/19.2e6;

    std::this_thread::sleep_for(std::chrono::microseconds(10000));
    std::thread mmal_thread (start_camera);


    uint64_t offset;
    while (true)
    {
        std::cout << "enter offset [µs]:";
        std::cin >> pwm_offset;
        std::cout << "o=" << offset << std::endl;
    }
    return 0;
}