gtk 실시간 jpg 처리 문제

LibJpeg API
This library is based on one structure

struct jpeg_compress_struct cinfo;
Of course there are other structs for example the
jpeg_error_mgr
to handle error messages. But they are not part of the core functionality. First the software has to be configured for the compressed mode
jpeg_create_compress(&cinfo);
To write the output to a file we have to link the file handler with the JPEG library
jpeg_stdio_dest(&cinfo, fh); //fh is the file handler
Most settings can be set to default. But it is important to define the real picture size and the pixel resolution to the library
cinfo.image_width = fmt.fmt.pix.width;
cinfo.image_height = fmt.fmt.pix.height;
cinfo.input_components = 3; //rgb only
cinfo.in_color_space = JCS_RGB;

jpeg_set_defaults(&cinfo);
This is the main step to compress the pixels and write them to the file
jpeg_start_compress(&cinfo, TRUE);

row_stride=cinfo.image_width*3;//JSAMPLEs per row in image_buffer

while (cinfo.next_scanline < cinfo.image_height)
{
row_pointer[0] = & data[cinfo.next_scanline * row_stride];
jpeg_write_scanlines(&cinfo, row_pointer, 1);
}
And of course everything has to be cleaned up
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
The prototype is working and proved all the required functions for Polyphemus. We are able to capture a picture, to compress it and to write it to an output device.