[vlc-devel] porting the SDL+VLC example (and vaapi/dxva and h264 and...)

[Vittorio G.]

Hello all!
I'm trying to port the sdl+vlc example
(http://wiki.videolan.org/LibVLC_SampleCode_SDL) to SDL 1.3 apis
I'm trying to use this code to decode some h264 videos and to do some
compositing operation on it live.

So far i've got this (not sure whether SDL_LockMutex) should be removed or not:

#ifdef __WIN32
#include "SDL.h"
#else
#include "SDL/SDL.h"
#endif

#include "vlc/vlc.h"
#include "assert.h"

struct ctx {
    SDL_mutex *mutex;
    SDL_Texture *tex;
};

static void *lock (void *data, void **p_pixels) {
    struct ctx *ctx = data;

//    SDL_LockMutex(ctx->mutex);
    int pitch = 1920*4;
    SDL_LockTexture(ctx->tex, NULL, p_pixels, &pitch);
    return NULL; /* picture identifier, not needed here */
}

static void unlock (void *data, void *id, void *const *p_pixels) {
    struct ctx *ctx = data;

    SDL_UnlockTexture(ctx->tex);
//    SDL_UnlockMutex(ctx->mutex);
    assert(id == NULL); /* picture identifier, not needed here */
}

// VLC wants to display the video
static void display (void *data, void *id) {
    struct ctx *ctx = data;
    assert(id == NULL);
}

int main(int argc, char** argv) {

    libvlc_instance_t *libvlc;
    libvlc_media_t *m;
    libvlc_media_player_t *mp;
    char const *vlc_argv[] =
    {
        "--no-audio", /* skip any audio track */
        "--no-xlib", /* tell VLC to not use Xlib */
    };
    int vlc_argc = sizeof(vlc_argv) / sizeof(*vlc_argv);

    int pause = 0;
    int action = 0;
    int done = 0;
    int fullscreen = 0;
    SDL_Event event;
    SDL_DisplayMode mode;
    struct ctx ctx;

    if (argc < 2) {
        fprintf (stderr, "Usage: %s <filename>\n", argv[0]);
        return -1;
    }

    // Initialize SDL.
    if (SDL_Init(SDL_INIT_VIDEO) < 0)
        return -1;

    SDL_GetCurrentDisplayMode(0, &mode);
    SDL_Window *window = SDL_CreateWindow("Window",
                SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, mode.w, mode.h,
                SDL_WINDOW_SHOWN | SDL_WINDOW_BORDERLESS );
    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1,
SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);

    ctx.mutex = SDL_CreateMutex();
    ctx.tex = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
SDL_TEXTUREACCESS_STREAMING, 1920, 1080);

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0);
    SDL_RenderClear(renderer);

    // Initialise libVLC
    libvlc = libvlc_new(vlc_argc, vlc_argv);
    m = libvlc_media_new_path(libvlc, argv[1]);
    mp = libvlc_media_player_new_from_media(m);

    libvlc_video_set_callbacks(mp, lock, unlock, display, &ctx);
    libvlc_video_set_format(mp, "RV32", 1920, 1080, 1920*4);
    libvlc_media_player_play(mp);

    while(!done) {
        action = 0;

        /* Keys: enter (fullscreen), space (pause), escape (quit) */
        while( SDL_PollEvent( &event ) ) {
            switch(event.type) {
                case SDL_QUIT:
                    done = 1;
                    break;
                case SDL_KEYDOWN:
                    action = event.key.keysym.sym;
                    break;
            }
        }

        switch(action) {
            case SDLK_ESCAPE:
                done = 1;
                break;
            case SDLK_RETURN:
                fullscreen = !fullscreen;
                SDL_SetWindowFullscreen(window, fullscreen);
                break;
            case ' ':
                pause = !pause;
                libvlc_media_player_set_pause(mp, pause);
                break;
        }
        SDL_RenderCopy(renderer, ctx.tex, NULL, NULL);
        SDL_RenderPresent(renderer);
        SDL_Delay(10);
    }

    libvlc_media_release(m);
    libvlc_media_player_stop(mp);
    libvlc_media_player_release(mp);
    libvlc_release(libvlc);

    SDL_DestroyTexture(ctx.tex);
    SDL_Quit();
    return 0;
}


this works fine on Windows, i can see the video and render with the
new apis; it works using the direct3d and software renderer, with the
opengl renderer i see only a black screen.
However on Linux, using the opengl renderer, it gets a segfault and
crashes at the first frame or so (works fine with software renderer).

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe2da4700 (LWP 2995)]
0x00007ffff57e3629 in glGetError () from /usr/lib/nvidia-current/libGL.so.1
(gdb) bt
#0  0x00007ffff57e3629 in glGetError () from /usr/lib/nvidia-current/libGL.so.1
#1  0x00007ffff7b50533 in GL_UpdateTexture (renderer=<value optimized
out>, texture=0x88bda0, rect=0x8abfc4, pixels=0x7ffff2c29010,
pitch=7680) at src/render/opengl/SDL_render_gl.c:546
#2  0x00007ffff7b4c197 in SDL_UnlockTexture (texture=0x88bda0) at
src/render/SDL_render.c:732
#3  0x00000000004010d3 in unlock (data=0x7fffffffe0d0, id=0x0,
p_pixels=0x7fffe2da3bf0) at sdl13+vlc.c:26
#4  0x00007fffe2aa0c66 in Unlock (picture=<value optimized out>) at vmem.c:353
#5  0x00007ffff6c48532 in vout_display_Display (vout=0xa94f50,
now=<value optimized out>, deadline=<value optimized out>) at
../include/vlc_vout_wrapper.h:58
#6  ThreadDisplayRenderPicture (vout=0xa94f50, now=<value optimized
out>, deadline=<value optimized out>) at
video_output/video_output.c:1040
#7  ThreadDisplayPicture (vout=0xa94f50, now=<value optimized out>,
deadline=<value optimized out>) at video_output/video_output.c:1113
#8  0x00007ffff6c48ffd in ThreadManage (object=<value optimized out>)
at video_output/video_output.c:1125
#9  Thread (object=<value optimized out>) at video_output/video_output.c:1559
#10 0x00007ffff6ed4971 in start_thread (arg=<value optimized out>) at
pthread_create.c:304
#11 0x00007ffff765792d in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()


Am I using the libraries wrong? Is there some logic flaw (besides
hardcoding video width and height)?
Also if i add "--ffmpeg-hw" to the vlc parameters, in Windows works
fine, in linux i get [0xfce650] avcodec decoder warning: Ignoring VA
API
Is this standard behaviour? Is it normal that (under windows) when i
use vlc directly and hw acceleration i see that the cpu is completely
offloaded, while with this test program and hw acceleration the cpu is
loaded to a 10%?

Thanks for any help :)
Vittorio