SDL Dreamcast Question

[PH3NOM]

Hello everyone!
I am trying to do my own port of libmpeg2 to Dreamcast. (For now, if successful more things will come...)

I am trying to use SDL for the video driver.

For this project, everything compiles fine, but after the video mode select screen
"Press 'Y' for 60Hz"
the app resets on Dreamcast.

Since im relatively new to Dreamcast KOS, I need to find out is if this is due to an incompatible video driver.

Can anyone here tell, by looking at the code, if this driver with work with Dreamcast SDL?
( Its libvo\video_out_sdl.c, I just modified it to use fast doublebuff instead of sdl_resizeable )

Code: Select all

#include "config.h"

#ifdef LIBVO_SDL

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <SDL.h>
#include <SDL_dreamcast.h>
#include <inttypes.h>


#include "video_out.h"
#include "vo_internal.h"

typedef struct {
    vo_instance_t vo;
    int width;
    int height;
    SDL_Surface * surface;
    Uint32 sdlflags;
    Uint8 bpp;
} sdl_instance_t;

static void sdl_setup_fbuf (vo_instance_t * _instance,
			    uint8_t ** buf, void ** id)
{
    sdl_instance_t * instance = (sdl_instance_t *) _instance;
    SDL_Overlay * overlay;

    *id = overlay = SDL_CreateYUVOverlay (instance->width, instance->height,
					  SDL_YV12_OVERLAY, instance->surface);
    buf[0] = overlay->pixels[0];
    buf[1] = overlay->pixels[2];
    buf[2] = overlay->pixels[1];
    if (((long)buf[0] & 15) || ((long)buf[1] & 15) || ((long)buf[2] & 15)) {
	fprintf (stderr, "Unaligned buffers. Anyone know how to fix this ?\n");
	exit (1);
    }
}

static void sdl_start_fbuf (vo_instance_t * instance,
			    uint8_t * const * buf, void * id)
{
    SDL_LockYUVOverlay ((SDL_Overlay *) id);
}

static void sdl_draw_frame (vo_instance_t * _instance,
			    uint8_t * const * buf, void * id)
{
    sdl_instance_t * instance = (sdl_instance_t *) _instance;
    SDL_Overlay * overlay = (SDL_Overlay *) id;
    SDL_Event event;

    while (SDL_PollEvent (&event))
	if (event.type == SDL_VIDEORESIZE)
	    instance->surface =
		SDL_SetVideoMode (event.resize.w, event.resize.h,
				  instance->bpp, instance->sdlflags);
    SDL_DisplayYUVOverlay (overlay, &(instance->surface->clip_rect));
}

static void sdl_discard (vo_instance_t * _instance,
			 uint8_t * const * buf, void * id)
{
    SDL_UnlockYUVOverlay ((SDL_Overlay *) id);
}

#if 0
static void sdl_close (vo_instance_t * _instance)
{
    sdl_instance_t * instance;
    int i;

    instance = (sdl_instance_t *) _instance;
    for (i = 0; i < 3; i++)
	SDL_FreeYUVOverlay (instance->frame[i].overlay);
    SDL_FreeSurface (instance->surface);
    SDL_QuitSubSystem (SDL_INIT_VIDEO);
}
#endif

static int sdl_setup (vo_instance_t * _instance, unsigned int width,
		      unsigned int height, unsigned int chroma_width,
		      unsigned int chroma_height, vo_setup_result_t * result)
{
    sdl_instance_t * instance;

    instance = (sdl_instance_t *) _instance;

    instance->width = width;
    instance->height = height;
    instance->surface = SDL_SetVideoMode (width, height, instance->bpp,
					  instance->sdlflags);		  
  
    if (! (instance->surface)) {
	fprintf (stderr, "sdl could not set the desired video mode\n");
	return 1;
    }

    result->convert = NULL;
    return 0;
}

vo_instance_t * vo_sdl_open (void)
{
    sdl_instance_t * instance;
    const SDL_VideoInfo * vidInfo;

    instance = (sdl_instance_t *) malloc (sizeof (sdl_instance_t));
    if (instance == NULL)
	return NULL;

    instance->vo.setup = sdl_setup;
    instance->vo.setup_fbuf = sdl_setup_fbuf;
    instance->vo.set_fbuf = NULL;
    instance->vo.start_fbuf = sdl_start_fbuf;
    instance->vo.discard = sdl_discard;
    instance->vo.draw = sdl_draw_frame;
    instance->vo.close = NULL; /* sdl_close; */
    instance->sdlflags = SDL_FULLSCREEN|SDL_DOUBLEBUF|SDL_HWSURFACE;

    //putenv((char *)"SDL_VIDEO_YUV_HWACCEL=1");
    //putenv((char *)"SDL_VIDEO_X11_NODIRECTCOLOR=1");

    if (SDL_Init (SDL_INIT_VIDEO)) {
	fprintf (stderr, "sdl video initialization failed.\n");
	return NULL;
    }

    vidInfo = SDL_GetVideoInfo ();
    if (!SDL_ListModes (vidInfo->vfmt, SDL_FULLSCREEN|SDL_DOUBLEBUF|SDL_HWSURFACE)) {
	instance->sdlflags = SDL_FULLSCREEN|SDL_DOUBLEBUF|SDL_HWSURFACE;
	//if (!SDL_ListModes (vidInfo->vfmt, SDL_RESIZABLE)) {
	//    fprintf (stderr, "sdl couldn't get any acceptable video mode\n");
	 //   return NULL;
	//}
    }
    instance->bpp = vidInfo->vfmt->BitsPerPixel;
    if (instance->bpp < 16) {
	fprintf(stderr, "sdl has to emulate a 16 bit surfaces, "
		"that will slow things down.\n");
	instance->bpp = 16;
    }

    return (vo_instance_t *) instance;
}
#endif

Any replies appreciated! Thanks.

[BlueCrab]

I'd really recommend that you don't use SDL for something like that on the Dreamcast. There are much better ways of interacting with things than SDL. SDL on the Dreamcast is extremely buggy and really quite slow.

[PH3NOM]

Thanks BlueCrab.
Too bad, I was under the impression Dreamcast SDL was quite solid...

At any rate, I dont want to spend time writing a custom video driver If there is a major issue elsewhere in the code..

So, do you see anything in the code posted, that will be particularly incompatible?

[BlueCrab]

In all honesty, I'd halfway be willing to blame it on a SDL bug. I haven't worked with SDL in ages, but it hasn't changed all that much either. Granted, I don't see anything in particular in your code there that would cause any issues (then again, I dunno how well the YUV stuff works in SDL, and its assuredly done in software on the Dreamcast anyway).

That said, its pretty easy to work with KallistiOS directly to get a simple framebuffer rendering scheme running, and its not all that hard to move from that to using the PVR to do any rendering. There are ways of making the PVR do YUV conversion, however I don't know that anyone has ever used it for homebrew purposes (I know I haven't seen any code use the YUV stuff), so I don't know of anyone who could help with that kind of stuff...

[OneThirty8]

In all honesty, I'd halfway be willing to blame it on a SDL bug. I haven't worked with SDL in ages, but it hasn't changed all that much either. Granted, I don't see anything in particular in your code there that would cause any issues (then again, I dunno how well the YUV stuff works in SDL, and its assuredly done in software on the Dreamcast anyway).

That said, its pretty easy to work with KallistiOS directly to get a simple framebuffer rendering scheme running, and its not all that hard to move from that to using the PVR to do any rendering. There are ways of making the PVR do YUV conversion, however I don't know that anyone has ever used it for homebrew purposes (I know I haven't seen any code use the YUV stuff), so I don't know of anyone who could help with that kind of stuff...

Libmpeg2 will output uyvy, and you can send that directly to the PVR. It's the same as YUV422. It worked perfectly in VC/DC. Code is available at http://code.google.com/p/vcdc/downloads/list although much of it is very difficult to read. Also, if you can find lvfdc, that was based on libmpeg2 as well, albeit an older version.

[PH3NOM]

Thanks OneThirty8 I know you have the experience with this code.

It sounds like I will need to learn a bit more about working with the pvr hardware to make this work with decent speeds then. I will take a closer look at your video_out_dc.c.

I compiled the vcdc source you linked using dev iso r4 and r3.
Running the app on dc, it will draw a frame then freeze.
Can you confirm the source package you uploaded is working?

Thanks again.