sdl_display.c

unicap provides an uniform access to video capture devices. Currently you can access v4l, v4l2, IIDC

/*
  unicap
  Copyright (C) 2004  Arne Caspari

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

/**
   sdl_display.c

   This example demonstrates how to display a live video stream using libSDL

**/


#include <stdlib.h>
#include <stdio.h>
#include <string.h> // for memset
#include <unicap.h>
#include <unicap_status.h>

#include <SDL.h>

int main( int argc, char **argv )
{
   unicap_handle_t handle;
   unicap_device_t device;
   unicap_format_t format_spec;
   unicap_format_t format;
   unicap_data_buffer_t buffer;
   unicap_data_buffer_t *returned_buffer;
	
   int i;

   SDL_Surface *screen;
   SDL_Overlay *overlay;

   int quit=0;

   /*
     Enumerate available video capture devices
    */
   printf( "select video device\n" );
   for( i = 0; SUCCESS( unicap_enumerate_devices( NULL, &device, i ) ); i++ )
   {
      printf( "%i: %s\n", i, device.identifier );
   }
   if( --i > 0 )
   {
      printf( "Select video capture device: " );
      scanf( "%d", &i );
   }

   if( !SUCCESS( unicap_enumerate_devices( NULL, &device, i ) ) )
   {
      fprintf( stderr, "Failed to get info for device '%s'\n", device.identifier );
      exit( 1 );
   }

   /*
     Acquire a handle to selected device
   */
   if( !SUCCESS( unicap_open( &handle, &device ) ) )
   {
      fprintf( stderr, "Failed to open device: %s\n", device.identifier );
      exit( 1 );
   }

   printf( "Opened video capture device: %s\n", device.identifier );

   unicap_void_format( &format_spec );
	
   /*
     Get the list of video formats
   */
   for( i = 0; SUCCESS( unicap_enumerate_formats( handle, 
						  NULL, 
						  &format, i ) ); 
	i++ )
   {
      printf( "%d: %s\n", 
	      i,
	      format.identifier );
   }
   if( --i > 0 )
   {
      printf( "Select video format: " );
      scanf( "%d", &i );
   }
   if( !SUCCESS( unicap_enumerate_formats( handle, &format_spec, &format, i ) ) )
   {
      fprintf( stderr, "Failed to get video format\n" );
      exit( 1 );
   }
	
   /*
     If a video format has more than one size, ask for which size to use
   */
   if( format.size_count )
   {
      for( i = 0; i < format.size_count; i++ )
      {
	 printf( "%d: %dx%d\n", i, format.sizes[i].width, format.sizes[i].height );
      }
      do
      {
	 printf( "Select video format size: " );
	 scanf( "%d", &i );
      }while( ( i < 0 ) && ( i > format.size_count ) );
      format.size.width = format.sizes[i].width;
      format.size.height = format.sizes[i].height;
   }

   /*
     Set this video format
   */
   if( !SUCCESS( unicap_set_format( handle, &format ) ) )
   {
      fprintf( stderr, "Failed to set video format\n" );
      exit( 1 );
   }

   /*
     Initialize the image buffer
   */
   memset( &buffer, 0x0, sizeof( unicap_data_buffer_t ) );

   /**
      Init SDL & SDL_Overlay
   **/
   if ( SDL_Init(SDL_INIT_VIDEO) < 0 )
   {
      fprintf(stderr, "Failed to initialize SDL:  %s\n", SDL_GetError());
      exit(1);
   }
	
   atexit(SDL_Quit);

   screen = SDL_SetVideoMode( format.size.width, format.size.height, 32, SDL_HWSURFACE);
   if ( screen == NULL ) {
      fprintf(stderr, "Unable to set video mode: %s\n", SDL_GetError());
      exit(1);
   }
   
   

   overlay = SDL_CreateYUVOverlay( format.size.width, 
				   format.size.height, 
				   format.fourcc, 
				   screen );
   if( overlay == NULL )
   {
      fprintf( stderr, "Unable to create overlay: %s\n", SDL_GetError() );
      exit( 1 );
   }

   /*
     Pass the pointer to the overlay to the unicap data buffer. 
   */
   buffer.data = overlay->pixels[0];	
   buffer.buffer_size = format.size.width * format.size.height * format.bpp / 8;

   /*
     Start the capture process on the device
   */
   if( !SUCCESS( unicap_start_capture( handle ) ) )
   {
      fprintf( stderr, "Failed to start capture on device: %s\n", device.identifier );
      exit( 1 );
   }
	

   while( !quit )
   {
      SDL_Rect rect;
      SDL_Event event;

      rect.x = rect.y = 0;
      rect.w = format.size.width;
      rect.h = format.size.height;
      /*
	Queue the buffer
		  
	The buffer now gets filled with image data by the capture device
      */
      if( !SUCCESS( unicap_queue_buffer( handle, &buffer ) ) )
      {
	 fprintf( stderr, "Failed to queue a buffer on device: %s\n", device.identifier );
	 exit( 1 );
      }
		
      /*
	Wait until the image buffer is ready
      */
      if( !SUCCESS( unicap_wait_buffer( handle, &returned_buffer ) ) )
      {
	 fprintf( stderr, "Failed to wait for buffer on device: %s\n", device.identifier );
      }

      /*
	Display the video data
      */
      SDL_UnlockYUVOverlay( overlay );
      SDL_DisplayYUVOverlay( overlay, &rect );
      SDL_LockYUVOverlay(overlay);

      while( SDL_PollEvent( &event ) )
      {
	 if( event.type == SDL_QUIT )
	 {
	    printf( "Quit\n" );
	    quit=1;
	 }
      }
   }
	
   /*
     Stop the device
   */
   if( !SUCCESS( unicap_stop_capture( handle ) ) )
   {
      fprintf( stderr, "Failed to stop capture on device: %s\n", device.identifier );
   }

   /*
     Close the device 

     This invalidates the handle
   */
   if( !SUCCESS( unicap_close( handle ) ) )
   {
      fprintf( stderr, "Failed to close the device: %s\n", device.identifier );
   }

   SDL_Quit();
	
   return 0;
}