[vlc-devel] [PATCH 1/2] vout: vulkan: add support for custom user shaders

[Alexandre Janniaux]

Hi,

I find it very interesting that we get custom shaders in
the libplacebo pipeline, but also quite annoying that the
user must supply the shader directly to the video output.

Using GLSL file directly doesn't seem to be a good UX for
most users, that will only want to have a list of filters
and enable them if required. The GLSL textbox is not a
good idea in my opinion.

It would make sense to have a dedicated «custom» filter
that expose this functionality though.

Is it planned to move to such case instead of just exposing
it directly in the video output module?

Regards,
--
Alexandre Janniaux
Videolabs

On Sat, Jun 20, 2020 at 12:41:54PM +0200, Niklas Haas wrote:
> From: Niklas Haas <git at haasn.xyz>
>
> It's finally time to use RAVU/FSRCNN(X)/NNEDI3/Anime4K in VLC.
>
> Currently limited to only one shader, which isn't a huge limitation
> seeing as you can just `cat` together as many shaders as you want to use
> into one big file. But patches welcome(tm).
>
> In theory it would also be cool if we could just make it a big textbox,
> but I couldn't figure out how.
> ---
>  modules/video_output/placebo_utils.h  |  3 ++
>  modules/video_output/vulkan/display.c | 76 +++++++++++++++++++++++++++
>  2 files changed, 79 insertions(+)
>
> diff --git a/modules/video_output/placebo_utils.h b/modules/video_output/placebo_utils.h
> index 99c3f318b5..7e460093a2 100644
> --- a/modules/video_output/placebo_utils.h
> +++ b/modules/video_output/placebo_utils.h
> @@ -496,4 +496,7 @@ static const struct pl_filter_function *const filter_fun[] = {
>  #define DELAYED_PEAK_TEXT "Allow delaying peak detection by up to one frame"
>  #define DELAYED_PEAK_LONGTEXT "In some cases, peak detection may be more convenient to compute if the results are delayed by a frame. When this option is disabled, libplacebo will use an indirect buffer simply to force peak detection results to be up-to-date. Enabling it allows skipping this indirection in order to improve performance at the cost of some potentially noticeable brightness flickering immediately after a scene change."
>
> +#define USER_SHADER_FILE_TEXT N_("Custom shader")
> +#define USER_SHADER_FILE_LONGTEXT N_("Path to a file containing a custom user shader, in mpv .hook format.")
> +
>  #endif // VLC_PLACEBO_UTILS_H
> diff --git a/modules/video_output/vulkan/display.c b/modules/video_output/vulkan/display.c
> index 226165f283..a3c928f6d5 100644
> --- a/modules/video_output/vulkan/display.c
> +++ b/modules/video_output/vulkan/display.c
> @@ -30,6 +30,7 @@
>  #include <vlc_common.h>
>  #include <vlc_plugin.h>
>  #include <vlc_vout_display.h>
> +#include <vlc_fs.h>
>
>  #include "../placebo_utils.h"
>  #include "instance.h"
> @@ -65,6 +66,10 @@ struct vout_display_sys_t
>      struct pl_color_space target;
>  #if PL_API_VER >= 13
>      struct pl_peak_detect_params peak_detect;
> +#endif
> +#if PL_API_VER >= 58
> +    const struct pl_hook *hook;
> +    char *hook_path;
>  #endif
>      enum pl_chroma_location yuv_chroma_loc;
>      int dither_depth;
> @@ -170,6 +175,11 @@ static void Close(vout_display_t *vd)
>          free(sys->overlay_tex);
>      }
>
> +#if PL_API_VER >= 58
> +    pl_mpv_user_shader_destroy(&sys->hook);
> +    free(sys->hook_path);
> +#endif
> +
>      pl_renderer_destroy(&sys->renderer);
>
>      vlc_vk_Release(sys->vk);
> @@ -359,6 +369,57 @@ static int Control(vout_display_t *vd, int query, va_list ap)
>      return VLC_EGENERIC;
>  }
>
> +#if PL_API_VER >= 58
> +
> +static void load_user_shader(vout_display_sys_t *sys, const char *filepath)
> +{
> +    if (!filepath || !*filepath) {
> +        pl_mpv_user_shader_destroy(&sys->hook);
> +        return;
> +    }
> +
> +    if (sys->hook_path && strcmp(filepath, sys->hook_path) == 0)
> +        return; // same shader
> +
> +    const struct pl_gpu *gpu = sys->vk->vulkan->gpu;
> +    char *shader_str = NULL;
> +    FILE *fs = NULL;
> +
> +    free(sys->hook_path);
> +    sys->hook_path = strdup(filepath);
> +
> +    fs = vlc_fopen(filepath, "rb");
> +    int ret = fseek(fs, 0, SEEK_END);
> +    if (ret == -1)
> +        goto error;
> +    long length = ftell(fs);
> +    if (length == -1 || length >= 1024*1024) // 1 MB
> +        goto error;
> +    rewind(fs);
> +
> +    shader_str = vlc_alloc(length, sizeof(*shader_str));
> +    if (!shader_str)
> +        goto error;
> +    ret = fread(shader_str, length, 1, fs);
> +    if (ret != 1)
> +        goto error;
> +    sys->hook = pl_mpv_user_shader_parse(gpu, shader_str, length);
> +    if (!sys->hook)
> +        goto error;
> +
> +    fclose(fs);
> +    free(shader_str);
> +    return;
> +
> +error:
> +    free(shader_str);
> +    if (fs)
> +        fclose(fs);
> +    return;
> +}
> +
> +#endif // PL_API_VER >= 58
> +
>  // Options
>
>  #define VK_TEXT N_("Vulkan surface extension")
> @@ -377,6 +438,11 @@ vlc_module_begin ()
>      add_shortcut ("vulkan", "vk")
>      add_module ("vk", "vulkan", NULL, VK_TEXT, PROVIDER_LONGTEXT)
>
> +#if PL_API_VER >= 58
> +    set_section("Custom shaders", NULL)
> +    add_loadfile("user-shader-file", NULL, USER_SHADER_FILE_TEXT, USER_SHADER_FILE_LONGTEXT)
> +#endif
> +
>      set_section("Scaling", NULL)
>      add_integer("upscaler-preset", SCALE_BUILTIN,
>              UPSCALER_PRESET_TEXT, SCALER_PRESET_LONGTEXT, false)
> @@ -626,4 +692,14 @@ static void UpdateParams(vout_display_t *vd)
>          .transfer = var_InheritInteger(vd, "target-trc"),
>          .sig_avg = var_InheritFloat(vd, "target-avg"),
>      };
> +
> +#if PL_API_VER >= 58
> +    load_user_shader(sys, var_InheritString(vd, "user-shader-file"));
> +    if (sys->hook) {
> +        sys->params.hooks = &sys->hook;
> +        sys->params.num_hooks = 1;
> +    } else {
> +        sys->params.num_hooks = 0;
> +    }
> +#endif
>  }
> --
> 2.27.0
>
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