/*
Copyright (c) 2013, Broadcom Europe Ltd
Copyright (c) 2013, James Hughes
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the copyright holder nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/*
 * \file RaspiStillYUV.c
 * Command line program to capture a still frame and dump uncompressed it to file.
 * Also optionally display a preview/viewfinder of current camera input.
 *
 * \date 4th March 2013
 * \Author: James Hughes
 *
 * Description
 *
 * 2 components are created; camera and preview.
 * Camera component has three ports, preview, video and stills.
 * Preview is connected using standard mmal connections, the stills output
 * is written straight to the file in YUV 420 format via the requisite buffer
 * callback. video port is not used
 *
 * We use the RaspiCamControl code to handle the specific camera settings.
 * We use the RaspiPreview code to handle the generic preview
 */

// We use some GNU extensions (basename)
#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>

#define VERSION_STRING "v1.3"

#include "bcm_host.h"
#include "interface/vcos/vcos.h"

#include "interface/mmal/mmal.h"
#include "interface/mmal/mmal_logging.h"
#include "interface/mmal/mmal_buffer.h"
#include "interface/mmal/util/mmal_util.h"
#include "interface/mmal/util/mmal_util_params.h"
#include "interface/mmal/util/mmal_default_components.h"
#include "interface/mmal/util/mmal_connection.h"


#include "RaspiCamControl.h"
#include "RaspiPreview.h"
#include "RaspiCLI.h"

#include <semaphore.h>

/// Camera number to use - we only have one camera, indexed from 0.
#define CAMERA_NUMBER 0

// Standard port setting for the camera component
#define MMAL_CAMERA_PREVIEW_PORT 0
#define MMAL_CAMERA_VIDEO_PORT 1
#define MMAL_CAMERA_CAPTURE_PORT 2


// Stills format information
#define STILLS_FRAME_RATE_NUM 3
#define STILLS_FRAME_RATE_DEN 1

/// Video render needs at least 2 buffers.
#define VIDEO_OUTPUT_BUFFERS_NUM 3

int mmal_status_to_int(MMAL_STATUS_T status);

/** Structure containing all state information for the current run
 */
typedef struct
{
   int timeout;                        /// Time taken before frame is grabbed and app then shuts down. Units are milliseconds
   int width;                          /// Requested width of image
   int height;                         /// requested height of image
   char *filename;                     /// filename of output file
   int verbose;                        /// !0 if want detailed run information
   int timelapse;                      /// Delay between each picture in timelapse mode. If 0, disable timelapse
   int useRGB;                         /// Output RGB data rather than YUV

   RASPIPREVIEW_PARAMETERS preview_parameters;    /// Preview setup parameters
   RASPICAM_CAMERA_PARAMETERS camera_parameters; /// Camera setup parameters

   MMAL_COMPONENT_T *camera_component;    /// Pointer to the camera component
   MMAL_COMPONENT_T *null_sink_component;    /// Pointer to the camera component
   MMAL_CONNECTION_T *preview_connection; /// Pointer to the connection from camera to preview
   MMAL_POOL_T *camera_pool;              /// Pointer to the pool of buffers used by camera stills port
} RASPISTILLYUV_STATE;


/** Struct used to pass information in camera still port userdata to callback
 */
typedef struct
{
   FILE *file_handle;                   /// File handle to write buffer data to.
   VCOS_SEMAPHORE_T complete_semaphore; /// semaphore which is posted when we reach end of frame (indicates end of capture or fault)
   RASPISTILLYUV_STATE *pstate;            /// pointer to our state in case required in callback
} PORT_USERDATA;

static void display_valid_parameters(char *app_name);

/// Comamnd ID's and Structure defining our command line options
#define CommandHelp         0
#define CommandWidth        1
#define CommandHeight       2
#define CommandOutput       3
#define CommandVerbose      4
#define CommandTimeout      5
#define CommandTimelapse    6
#define CommandUseRGB       7

static COMMAND_LIST cmdline_commands[] =
{
   { CommandHelp,    "-help",       "?",  "This help information", 0 },
   { CommandWidth,   "-width",      "w",  "Set image width <size>", 1 },
   { CommandHeight,  "-height",     "h",  "Set image height <size>", 1 },
   { CommandOutput,  "-output",     "o",  "Output filename <filename>. If not specifed, no image is saved", 1 },
   { CommandVerbose, "-verbose",    "v",  "Output verbose information during run", 0 },
   { CommandTimeout, "-timeout",    "t",  "Time (in ms) before takes picture and shuts down. If not specified set to 5s", 1 },
   { CommandTimelapse,"-timelapse", "tl", "Timelapse mode. Takes a picture every <t>ms", 1},
   { CommandUseRGB,  "-rgb",        "rgb","Save as RGB data rather than YUV", 0},
};

static int cmdline_commands_size = sizeof(cmdline_commands) / sizeof(cmdline_commands[0]);

/**
 * Assign a default set of parameters to the state passed in
 *
 * @param state Pointer to state structure to assign defaults to
 */
static void default_status(RASPISTILLYUV_STATE *state)
{
   if (!state)
   {
      vcos_assert(0);
      return;
   }

   // Default everything to zero
   memset(state, 0, sizeof(RASPISTILLYUV_STATE));

   // Now set anything non-zero
   state->timeout = 5000; // 5s delay before take image
   state->width = 2592;
   state->height = 1944;
   state->timelapse = 0;

   // Setup preview window defaults
   raspipreview_set_defaults(&state->preview_parameters);

   // Set up the camera_parameters to default
   raspicamcontrol_set_defaults(&state->camera_parameters);
}

/**
 * Dump image state parameters to stderr. Used for debugging
 *
 * @param state Pointer to state structure to assign defaults to
 */
static void dump_status(RASPISTILLYUV_STATE *state)
{
   if (!state)
   {
      vcos_assert(0);
      return;
   }

   fprintf(stderr, "Width %d, Height %d, filename %s\n", state->width, state->height, state->filename);
   fprintf(stderr, "Time delay %d, Timelapse %d\n", state->timeout, state->timelapse);

   raspipreview_dump_parameters(&state->preview_parameters);
   raspicamcontrol_dump_parameters(&state->camera_parameters);
}

/**
 * Parse the incoming command line and put resulting parameters in to the state
 *
 * @param argc Number of arguments in command line
 * @param argv Array of pointers to strings from command line
 * @param state Pointer to state structure to assign any discovered parameters to
 * @return non-0 if failed for some reason, 0 otherwise
 */
static int parse_cmdline(int argc, const char **argv, RASPISTILLYUV_STATE *state)
{
   // Parse the command line arguments.
   // We are looking for --<something> or -<abreviation of something>

   int valid = 1; // set 0 if we have a bad parameter
   int i;

   for (i = 1; i < argc && valid; i++)
   {
      int command_id, num_parameters;

      if (!argv[i])
         continue;

      if (argv[i][0] != '-')
      {
         valid = 0;
         continue;
      }

      // Assume parameter is valid until proven otherwise
      valid = 1;

      command_id = raspicli_get_command_id(cmdline_commands, cmdline_commands_size, &argv[i][1], &num_parameters);

      // If we found a command but are missing a parameter, continue (and we will drop out of the loop)
      if (command_id != -1 && num_parameters > 0 && (i + 1 >= argc) )
         continue;

      //  We are now dealing with a command line option
      switch (command_id)
      {
      case CommandHelp:
         display_valid_parameters(basename(argv[0]));
         return -1;

      case CommandWidth: // Width > 0
         if (sscanf(argv[i + 1], "%u", &state->width) != 1)
            valid = 0;
         else
            i++;
         break;

      case CommandHeight: // Height > 0
         if (sscanf(argv[i + 1], "%u", &state->height) != 1)
            valid = 0;
         else
            i++;
         break;

      case CommandOutput:  // output filename
      {
         int len = strlen(argv[i + 1]);
         if (len)
         {
            state->filename = malloc(len + 1);
            vcos_assert(state->filename);
            if (state->filename)
               strncpy(state->filename, argv[i + 1], len);
            i++;
         }
         else
            valid = 0;
         break;
      }

      case CommandVerbose: // display lots of data during run
         state->verbose = 1;
         break;

      case CommandTimeout: // Time to run viewfinder for before taking picture, in seconds
      {
         if (sscanf(argv[i + 1], "%u", &state->timeout) == 1)
         {
            // TODO : What limits do we need for timeout?
            i++;
         }
         else
            valid = 0;
         break;
      }

      case CommandTimelapse:
         if (sscanf(argv[i + 1], "%u", &state->timelapse) != 1)
            valid = 0;
         else
            i++;
         break;

      case CommandUseRGB: // display lots of data during run
         state->useRGB = 1;
         break;

      default:
      {
         // Try parsing for any image specific parameters
         // result indicates how many parameters were used up, 0,1,2
         // but we adjust by -1 as we have used one already
         const char *second_arg = (i + 1 < argc) ? argv[i + 1] : NULL;

         int parms_used = (raspicamcontrol_parse_cmdline(&state->camera_parameters, &argv[i][1], second_arg));

         // Still unused, try preview options
         if (!parms_used)
            parms_used = raspipreview_parse_cmdline(&state->preview_parameters, &argv[i][1], second_arg);


         // If no parms were used, this must be a bad parameters
         if (!parms_used)
            valid = 0;
         else
            i += parms_used - 1;

         break;
      }
      }
   }

   if (!valid)
   {
      fprintf(stderr, "Invalid command line option (%s)\n", argv[i]);
      return 1;
   }

   return 0;
}

/**
 * Display usage information for the application to stdout
 *
 * @param app_name String to display as the application name
 *
 */
static void display_valid_parameters(char *app_name)
{
   fprintf(stderr, "Runs camera for specific time, and take uncompressed YUV capture at end if requested\n\n");
   fprintf(stderr, "usage: %s [options]\n\n", app_name);

   fprintf(stderr, "Image parameter commands\n\n");

   raspicli_display_help(cmdline_commands, cmdline_commands_size);

   // Help for preview options
   raspipreview_display_help();

   // Now display any help information from the camcontrol code
   raspicamcontrol_display_help();

   fprintf(stderr, "\n");

   return;
}

/**
 *  buffer header callback function for camera control
 *
 * @param port Pointer to port from which callback originated
 * @param buffer mmal buffer header pointer
 */
static void camera_control_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
{
   fprintf(stderr, "Camera control callback  cmd=0x%08x", buffer->cmd);

   if (buffer->cmd == MMAL_EVENT_PARAMETER_CHANGED)
   {
   }
   else
   {
      vcos_log_error("Received unexpected camera control callback event, 0x%08x", buffer->cmd);
   }

   mmal_buffer_header_release(buffer);
}

/**
 *  buffer header callback function for camera output port
 *
 *  Callback will dump buffer data to the specific file
 *
 * @param port Pointer to port from which callback originated
 * @param buffer mmal buffer header pointer
 */
static void camera_buffer_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
{
   int complete = 0;
   // We pass our file handle and other stuff in via the userdata field.


   PORT_USERDATA *pData = (PORT_USERDATA *)port->userdata;

   if (pData)
   {
      int bytes_written = buffer->length;

      if (buffer->length)
      {
         mmal_buffer_header_mem_lock(buffer);

         bytes_written = fwrite(buffer->data, 1, buffer->length, pData->file_handle);

         mmal_buffer_header_mem_unlock(buffer);
      }

      // We need to check we wrote what we wanted - it's possible we have run out of storage.
      if (bytes_written != buffer->length)
      {
         vcos_log_error("Unable to write buffer to file - aborting");
         complete = 1;
      }

      // Check end of frame or error
      if (buffer->flags & (MMAL_BUFFER_HEADER_FLAG_FRAME_END | MMAL_BUFFER_HEADER_FLAG_TRANSMISSION_FAILED))
         complete = 1;
   }
   else
   {
      vcos_log_error("Received a camera still buffer callback with no state");
   }

   // release buffer back to the pool
   mmal_buffer_header_release(buffer);

   // and send one back to the port (if still open)
   if (port->is_enabled)
   {
      MMAL_STATUS_T status;
      MMAL_BUFFER_HEADER_T *new_buffer = mmal_queue_get(pData->pstate->camera_pool->queue);

      // and back to the port from there.
      if (new_buffer)
      {
         status = mmal_port_send_buffer(port, new_buffer);
      }

      if (!new_buffer || status != MMAL_SUCCESS)
         vcos_log_error("Unable to return the buffer to the camera still port");
   }

   if (complete)
   {
      vcos_semaphore_post(&(pData->complete_semaphore));
   }
}


/**
 * Create the camera component, set up its ports
 *
 * @param state Pointer to state control struct
 *
 * @return 0 if failed, pointer to component if successful
 *
 */
static MMAL_STATUS_T create_camera_component(RASPISTILLYUV_STATE *state)
{
   MMAL_COMPONENT_T *camera = 0;
   MMAL_ES_FORMAT_T *format;
   MMAL_PORT_T *preview_port = NULL, *video_port = NULL, *still_port = NULL;
   MMAL_STATUS_T status;
   MMAL_POOL_T *pool;

   /* Create the component */
   status = mmal_component_create(MMAL_COMPONENT_DEFAULT_CAMERA, &camera);

   if (status != MMAL_SUCCESS)
   {
      vcos_log_error("Failed to create camera component");
      goto error;
   }

   if (!camera->output_num)
   {
      vcos_log_error("Camera doesn't have output ports");
      goto error;
   }

   preview_port = camera->output[MMAL_CAMERA_PREVIEW_PORT];
   video_port = camera->output[MMAL_CAMERA_VIDEO_PORT];
   still_port = camera->output[MMAL_CAMERA_CAPTURE_PORT];

   // Enable the camera, and tell it its control callback function
   status = mmal_port_enable(camera->control, camera_control_callback);

   if (status)
   {
      vcos_log_error("Unable to enable control port : error %d", status);
      goto error;
   }

   //  set up the camera configuration
   {
      MMAL_PARAMETER_CAMERA_CONFIG_T cam_config =
      {
         { MMAL_PARAMETER_CAMERA_CONFIG, sizeof(cam_config) },
         .max_stills_w = state->width,
         .max_stills_h = state->height,
         .stills_yuv422 = 0,
         .one_shot_stills = 1,
         .max_preview_video_w = state->preview_parameters.previewWindow.width,
         .max_preview_video_h = state->preview_parameters.previewWindow.height,
         .num_preview_video_frames = 3,
         .stills_capture_circular_buffer_height = 0,
         .fast_preview_resume = 0,
         .use_stc_timestamp = MMAL_PARAM_TIMESTAMP_MODE_RESET_STC
      };
      mmal_port_parameter_set(camera->control, &cam_config.hdr);
   }

   raspicamcontrol_set_all_parameters(camera, &state->camera_parameters);

   // Now set up the port formats

   format = preview_port->format;

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

   format->es->video.width = state->preview_parameters.previewWindow.width;
   format->es->video.height = state->preview_parameters.previewWindow.height;
   format->es->video.crop.x = 0;
   format->es->video.crop.y = 0;
   format->es->video.crop.width = state->preview_parameters.previewWindow.width;
   format->es->video.crop.height = state->preview_parameters.previewWindow.height;
   format->es->video.frame_rate.num = PREVIEW_FRAME_RATE_NUM;
   format->es->video.frame_rate.den = PREVIEW_FRAME_RATE_DEN;

   status = mmal_port_format_commit(preview_port);

   if (status)
   {
      vcos_log_error("camera viewfinder format couldn't be set");
      goto error;
   }

   // Set the same format on the video  port (which we dont use here)
   mmal_format_full_copy(video_port->format, format);
   status = mmal_port_format_commit(video_port);

   if (status)
   {
      vcos_log_error("camera video format couldn't be set");
      goto error;
   }

   // Ensure there are enough buffers to avoid dropping frames
   if (video_port->buffer_num < VIDEO_OUTPUT_BUFFERS_NUM)
      video_port->buffer_num = VIDEO_OUTPUT_BUFFERS_NUM;

   format = still_port->format;

   // Set our stills format on the stills  port
   if (state->useRGB)
   {
      format->encoding = MMAL_ENCODING_BGR24;
      format->encoding_variant = MMAL_ENCODING_BGR24;
   }
   else
   {
      format->encoding = MMAL_ENCODING_I420;
      format->encoding_variant = MMAL_ENCODING_I420;
   }
   format->es->video.width = state->width;
   format->es->video.height = state->height;
   format->es->video.crop.x = 0;
   format->es->video.crop.y = 0;
   format->es->video.crop.width = state->width;
   format->es->video.crop.height = state->height;
   format->es->video.frame_rate.num = STILLS_FRAME_RATE_NUM;
   format->es->video.frame_rate.den = STILLS_FRAME_RATE_DEN;

   if (still_port->buffer_size < still_port->buffer_size_min)
      still_port->buffer_size = still_port->buffer_size_min;

   still_port->buffer_num = still_port->buffer_num_recommended;

   status = mmal_port_format_commit(still_port);

   if (status)
   {
      vcos_log_error("camera still format couldn't be set");
      goto error;
   }

   /* Enable component */
   status = mmal_component_enable(camera);

   if (status)
   {
      vcos_log_error("camera component couldn't be enabled");
      goto error;
   }

   /* Create pool of buffer headers for the output port to consume */
   pool = mmal_port_pool_create(still_port, still_port->buffer_num, still_port->buffer_size);

   if (!pool)
   {
      vcos_log_error("Failed to create buffer header pool for camera still port %s", still_port->name);
   }

   state->camera_pool = pool;
   state->camera_component = camera;

   if (state->verbose)
      fprintf(stderr, "Camera component done\n");

   return status;

error:

   if (camera)
      mmal_component_destroy(camera);

   return status;
}

/**
 * Destroy the camera component
 *
 * @param state Pointer to state control struct
 *
 */
static void destroy_camera_component(RASPISTILLYUV_STATE *state)
{
   if (state->camera_component)
   {
      mmal_component_destroy(state->camera_component);
      state->camera_component = NULL;
   }
}

/**
 * Connect two specific ports together
 *
 * @param output_port Pointer the output port
 * @param input_port Pointer the input port
 * @param Pointer to a mmal connection pointer, reassigned if function successful
 * @return Returns a MMAL_STATUS_T giving result of operation
 *
 */
static MMAL_STATUS_T connect_ports(MMAL_PORT_T *output_port, MMAL_PORT_T *input_port, MMAL_CONNECTION_T **connection)
{
   MMAL_STATUS_T status;

   status =  mmal_connection_create(connection, output_port, input_port, MMAL_CONNECTION_FLAG_TUNNELLING | MMAL_CONNECTION_FLAG_ALLOCATION_ON_INPUT);

   if (status == MMAL_SUCCESS)
   {
      status =  mmal_connection_enable(*connection);
      if (status != MMAL_SUCCESS)
         mmal_connection_destroy(*connection);
   }

   return status;
}

/**
 * Checks if specified port is valid and enabled, then disables it
 *
 * @param port  Pointer the port
 *
 */
static void check_disable_port(MMAL_PORT_T *port)
{
   if (port && port->is_enabled)
      mmal_port_disable(port);
}

/**
 * Handler for sigint signals
 *
 * @param signal_number ID of incoming signal.
 *
 */
static void signal_handler(int signal_number)
{
   // Going to abort on all signals
   vcos_log_error("Aborting program\n");

   // Need to close any open stuff...

   exit(255);
}

/**
 * main
 */
int main(int argc, const char **argv)
{
   // Our main data storage vessel..
   RASPISTILLYUV_STATE state;

   MMAL_STATUS_T status = MMAL_SUCCESS;
   MMAL_PORT_T *camera_preview_port = NULL;
   MMAL_PORT_T *camera_video_port = NULL;
   MMAL_PORT_T *camera_still_port = NULL;
   MMAL_PORT_T *preview_input_port = NULL;
   FILE *output_file = NULL;

   bcm_host_init();

   // Register our application with the logging system
   vcos_log_register("RaspiStill", VCOS_LOG_CATEGORY);

   signal(SIGINT, signal_handler);

   // Do we have any parameters
   if (argc == 1)
   {
      fprintf(stderr, "\n%s Camera App %s\n\n", basename(argv[0]), VERSION_STRING);

      display_valid_parameters(basename(argv[0]));
      exit(0);
   }

   default_status(&state);

   // Parse the command line and put options in to our status structure
   if (parse_cmdline(argc, argv, &state))
   {
      status = -1;
      exit(0);
   }

   if (state.verbose)
   {
      fprintf(stderr, "\n%s Camera App %s\n\n", basename(argv[0]), VERSION_STRING);
      dump_status(&state);
   }

   // OK, we have a nice set of parameters. Now set up our components
   // We have two components. Camera and Preview
   // Camera is different in stills/video, but preview
   // is the same so handed off to a separate module

   if ((status = create_camera_component(&state)) != MMAL_SUCCESS)
   {
      vcos_log_error("%s: Failed to create camera component", __func__);
   }
   else if ((status = raspipreview_create(&state.preview_parameters)) != MMAL_SUCCESS)
   {
      vcos_log_error("%s: Failed to create preview component", __func__);
      destroy_camera_component(&state);
   }
   else
   {
      PORT_USERDATA callback_data;

      if (state.verbose)
         fprintf(stderr, "Starting component connection stage\n");

      camera_preview_port = state.camera_component->output[MMAL_CAMERA_PREVIEW_PORT];
      camera_video_port   = state.camera_component->output[MMAL_CAMERA_VIDEO_PORT];
      camera_still_port   = state.camera_component->output[MMAL_CAMERA_CAPTURE_PORT];

      // Note we are lucky that the preview and null sink components use the same input port
      // so we can simple do this without conditionals
      preview_input_port  = state.preview_parameters.preview_component->input[0];

      // Connect camera to preview (which might be a null_sink if no preview required)
      status = connect_ports(camera_preview_port, preview_input_port, &state.preview_connection);

      if (status == MMAL_SUCCESS)
      {
         VCOS_STATUS_T vcos_status;

         if (state.filename)
         {
            if (state.verbose)
               fprintf(stderr, "Opening output file %s\n", state.filename);

            output_file = fopen(state.filename, "wb");
            if (!output_file)
            {
               // Notify user, carry on but discarding output buffers
               vcos_log_error("%s: Error opening output file: %s\nNo output file will be generated\n", __func__, state.filename);
            }
         }

         // Set up our userdata - this is passed though to the callback where we need the information.
         callback_data.file_handle = output_file;
         callback_data.pstate = &state;

         vcos_status = vcos_semaphore_create(&callback_data.complete_semaphore, "RaspiStill-sem", 0);
         vcos_assert(vcos_status == VCOS_SUCCESS);

         camera_still_port->userdata = (struct MMAL_PORT_USERDATA_T *)&callback_data;

         if (state.verbose)
            fprintf(stderr, "Enabling camera still output port\n");

         // Enable the camera still output port and tell it its callback function
         status = mmal_port_enable(camera_still_port, camera_buffer_callback);

         if (status != MMAL_SUCCESS)
         {
            vcos_log_error("Failed to setup camera output");
            goto error;
         }

         if (state.verbose)
            fprintf(stderr, "Starting video preview\n");

         int num_iterations =  state.timelapse ? state.timeout / state.timelapse : 1;
         int frame;
         FILE *output_file = NULL;

         for (frame = 1;frame<=num_iterations; frame++)
         {
            if (state.timelapse)
               vcos_sleep(state.timelapse);
            else
               vcos_sleep(state.timeout);

            // Open the file
            if (state.filename)
            {
               if (state.filename[0] == '-')
               {
                  output_file = stdout;

                  // Ensure we don't upset the output stream with diagnostics/info
                  state.verbose = 0;
               }
               else
               {
                  char *use_filename = state.filename;

                  if (state.timelapse)
                     asprintf(&use_filename, state.filename, frame);

                  if (state.verbose)
                     fprintf(stderr, "Opening output file %s\n", use_filename);

                  output_file = fopen(use_filename, "wb");

                  if (!output_file)
                  {
                     // Notify user, carry on but discarding encoded output buffers
                     vcos_log_error("%s: Error opening output file: %s\nNo output file will be generated\n", __func__, use_filename);
                  }

                  // asprintf used in timelapse mode allocates its own memory which we need to free
                  if (state.timelapse)
                     free(use_filename);
               }

               callback_data.file_handle = output_file;
            }

            // And only do the capture if we have specified a filename and its opened OK
            if (output_file)
            {
               // Send all the buffers to the camera output port
               {
                  int num = mmal_queue_length(state.camera_pool->queue);
                  int q;

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

                     if (!buffer)
                        vcos_log_error("Unable to get a required buffer %d from pool queue", q);

                     if (mmal_port_send_buffer(camera_still_port, buffer)!= MMAL_SUCCESS)
                        vcos_log_error("Unable to send a buffer to camera output port (%d)", q);
                  }
               }

               if (state.verbose)
                  fprintf(stderr, "Starting capture %d\n", frame);

               // Fire the capture
               if (mmal_port_parameter_set_boolean(camera_still_port, MMAL_PARAMETER_CAPTURE, 1) != MMAL_SUCCESS)
               {
                  vcos_log_error("%s: Failed to start capture", __func__);
               }
               else
               {
                  // Wait for capture to complete
                  // For some reason using vcos_semaphore_wait_timeout sometimes returns immediately with bad parameter error
                  // even though it appears to be all correct, so reverting to untimed one until figure out why its erratic
                  vcos_semaphore_wait(&callback_data.complete_semaphore);

                  if (state.verbose)
                     fprintf(stderr, "Finished capture %d\n", frame);
               }

               // Ensure we don't die if get callback with no open file
               callback_data.file_handle = NULL;

               if (output_file != stdout)
                  fclose(output_file);
            }
         }
         vcos_semaphore_delete(&callback_data.complete_semaphore);
      }
      else
      {
         mmal_status_to_int(status);
         vcos_log_error("%s: Failed to connect camera to preview", __func__);
      }

error:

      mmal_status_to_int(status);

      if (state.verbose)
         fprintf(stderr, "Closing down\n");

      if (output_file)
         fclose(output_file);

      // Disable all our ports that are not handled by connections
      check_disable_port(camera_video_port);

      mmal_connection_destroy(state.preview_connection);

      /* Disable components */
      if (state.preview_parameters.preview_component)
         mmal_component_disable(state.preview_parameters.preview_component);

      if (state.camera_component)
         mmal_component_disable(state.camera_component);

      raspipreview_destroy(&state.preview_parameters);
      destroy_camera_component(&state);

      if (state.verbose)
         fprintf(stderr, "Close down completed, all components disconnected, disabled and destroyed\n\n");
   }

   if (status != MMAL_SUCCESS)
      raspicamcontrol_check_configuration(128);

   return 0;
}