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/*
 * yt - A fully featured command line YouTube client
 *
 * Copyright (C) 2018 the mpv developers
 * Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * This file is part of Yt.
 *
 * You should have received a copy of the License along with this program.
 * If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
 */

#ifndef MPV_CLIENT_API_RENDER_H_
#define MPV_CLIENT_API_RENDER_H_

#include "client.h"

#ifdef __cplusplus
extern "C"
{
#endif

  /**
   * Overview
   * --------
   *
   * This API can be used to make mpv render using supported graphic APIs (such
   * as OpenGL). It can be used to handle video display.
   *
   * The renderer needs to be created with mpv_render_context_create() before
   * you start playback (or otherwise cause a VO to be created). Then (with
   * most backends) mpv_render_context_render() can be used to explicitly
   * render the current video frame. Use
   * mpv_render_context_set_update_callback() to get notified when there is a
   * new frame to draw.
   *
   * Preferably rendering should be done in a separate thread. If you call
   * normal libmpv API functions on the renderer thread, deadlocks can result
   * (these are made non-fatal with timeouts, but user experience will
   * obviously suffer). See "Threading" section below.
   *
   * You can output and embed video without this API by setting the mpv "wid"
   * option to a native window handle (see "Embedding the video window" section
   * in the client.h header). In general, using the render API is recommended,
   * because window embedding can cause various issues, especially with GUI
   * toolkits and certain platforms.
   *
   * Supported backends
   * ------------------
   *
   * OpenGL: via MPV_RENDER_API_TYPE_OPENGL, see render_gl.h header.
   * Software: via MPV_RENDER_API_TYPE_SW, see section "Software renderer"
   *
   * Threading
   * ---------
   *
   * You are recommended to do rendering on a separate thread than normal
   * libmpv use.
   *
   * The mpv_render_* functions can be called from any thread, under the
   * following conditions:
   *  - only one of the mpv_render_* functions can be called at the same time
   *    (unless they belong to different mpv cores created by mpv_create())
   *  - never can be called from within the callbacks set with
   *    mpv_set_wakeup_callback() or mpv_render_context_set_update_callback()
   *  - if the OpenGL backend is used, for all functions the OpenGL context
   *    must be "current" in the calling thread, and it must be the same OpenGL
   *    context as the mpv_render_context was created with. Otherwise,
   * undefined behavior will occur.
   *  - the thread does not call libmpv API functions other than the
   * mpv_render_* functions, except APIs which are declared as safe (see
   * below). Likewise, there must be no lock or wait dependency from the render
   * thread to a thread using other libmpv functions. Basically, the situation
   * that your render thread waits for a "not safe" libmpv API function to
   * return must not happen. If you ignore this requirement, deadlocks can
   * happen, which are made non-fatal with timeouts; then playback quality will
   * be degraded, and the message mpv_render_context_render() not being called
   * or stuck. is logged. If you set MPV_RENDER_PARAM_ADVANCED_CONTROL, you
   * promise that this won't happen, and must absolutely guarantee it, or a
   * real deadlock will freeze the mpv core thread forever.
   *
   * libmpv functions which are safe to call from a render thread are:
   *  - functions marked with "Safe to be called from mpv render API threads."
   *  - client.h functions which don't have an explicit or implicit mpv_handle
   *    parameter
   *  - mpv_render_* functions; but only for the same mpv_render_context
   * pointer. If the pointer is different, mpv_render_context_free() is not
   * safe. (The reason is that if MPV_RENDER_PARAM_ADVANCED_CONTROL is set, it
   * may have to process still queued requests from the core, which it can do
   * only for the current context, while requests for other contexts would
   * deadlock. Also, it may have to wait and block for the core to terminate
   * the video chain to make sure no resources are used after context
   * destruction.)
   *  - if the mpv_handle parameter refers to a different mpv core than the one
   *    you're rendering for (very obscure, but allowed)
   *
   * Note about old libmpv version:
   *
   *      Before API version 1.105 (basically in mpv 0.29.x), simply enabling
   *      MPV_RENDER_PARAM_ADVANCED_CONTROL could cause deadlock issues. This
   * can be worked around by setting the "vd-lavc-dr" option to "no". In
   * addition, you were required to call all mpv_render*() API functions from
   * the same thread on which mpv_render_context_create() was originally run
   * (for the same the mpv_render_context). Not honoring it led to UB
   *      (deadlocks, use of invalid mp_thread handles), even if you moved your
   * GL context to a different thread correctly. These problems were addressed
   * in API version 1.105 (mpv 0.30.0).
   *
   * Context and handle lifecycle
   * ----------------------------
   *
   * Video initialization will fail if the render context was not initialized
   * yet (with mpv_render_context_create()), or it will revert to a VO that
   * creates its own window.
   *
   * Currently, there can be only 1 mpv_render_context at a time per mpv core.
   *
   * Calling mpv_render_context_free() while a VO is using the render context
   * is active will disable video.
   *
   * You must free the context with mpv_render_context_free() before the mpv
   * core is destroyed. If this doesn't happen, undefined behavior will result.
   *
   * Software renderer
   * -----------------
   *
   * MPV_RENDER_API_TYPE_SW provides an extremely simple (but slow) renderer to
   * memory surfaces. You probably don't want to use this. Use other render API
   * types, or other methods of video embedding.
   *
   * Use mpv_render_context_create() with MPV_RENDER_PARAM_API_TYPE set to
   * MPV_RENDER_API_TYPE_SW.
   *
   * Call mpv_render_context_render() with various MPV_RENDER_PARAM_SW_* fields
   * to render the video frame to an in-memory surface. The following fields
   * are required: MPV_RENDER_PARAM_SW_SIZE, MPV_RENDER_PARAM_SW_FORMAT,
   * MPV_RENDER_PARAM_SW_STRIDE, MPV_RENDER_PARAM_SW_POINTER.
   *
   * This method of rendering is very slow, because everything, including color
   * conversion, scaling, and OSD rendering, is done on the CPU,
   * single-threaded. In particular, large video or display sizes, as well as
   * presence of OSD or subtitles can make it too slow for realtime. As with
   * other software rendering VOs, setting "sw-fast" may help. Enabling or
   * disabling zimg may help, depending on the platform.
   *
   * In addition, certain multimedia job creation measures like HDR may not
   * work properly, and will have to be manually handled by for example
   * inserting filters.
   *
   * This API is not really suitable to extract individual frames from video
   * etc. (basically non-playback uses) - there are better libraries for this.
   * It can be used this way, but it may be clunky and tricky.
   *
   * Further notes:
   * - MPV_RENDER_PARAM_FLIP_Y is currently ignored (unsupported)
   * - MPV_RENDER_PARAM_DEPTH is ignored (meaningless)
   */

  /**
   * Opaque context, returned by mpv_render_context_create().
   */
  typedef struct mpv_render_context mpv_render_context;

  /**
   * Parameters for mpv_render_param (which is used in a few places such as
   * mpv_render_context_create().
   *
   * Also see mpv_render_param for conventions and how to use it.
   */
  typedef enum mpv_render_param_type
  {
    /**
     * Not a valid value, but also used to terminate a params array. Its value
     * is always guaranteed to be 0 (even if the ABI changes in the future).
     */
    MPV_RENDER_PARAM_INVALID = 0,
    /**
     * The render API to use. Valid for mpv_render_context_create().
     *
     * Type: char*
     *
     * Defined APIs:
     *
     *   MPV_RENDER_API_TYPE_OPENGL:
     *      OpenGL desktop 2.1 or later (preferably core profile compatible to
     *      OpenGL 3.2), or OpenGLES 2.0 or later.
     *      Providing MPV_RENDER_PARAM_OPENGL_INIT_PARAMS is required.
     *      It is expected that an OpenGL context is valid and "current" when
     *      calling mpv_render_* functions (unless specified otherwise). It
     *      must be the same context for the same mpv_render_context.
     */
    MPV_RENDER_PARAM_API_TYPE = 1,
    /**
     * Required parameters for initializing the OpenGL renderer. Valid for
     * mpv_render_context_create().
     * Type: mpv_opengl_init_params*
     */
    MPV_RENDER_PARAM_OPENGL_INIT_PARAMS = 2,
    /**
     * Describes a GL render target. Valid for mpv_render_context_render().
     * Type: mpv_opengl_fbo*
     */
    MPV_RENDER_PARAM_OPENGL_FBO = 3,
    /**
     * Control flipped rendering. Valid for mpv_render_context_render().
     * Type: int*
     * If the value is set to 0, render normally. Otherwise, render it flipped,
     * which is needed e.g. when rendering to an OpenGL default framebuffer
     * (which has a flipped coordinate system).
     */
    MPV_RENDER_PARAM_FLIP_Y = 4,
    /**
     * Control surface depth. Valid for mpv_render_context_render().
     * Type: int*
     * This implies the depth of the surface passed to the render function in
     * bits per channel. If omitted or set to 0, the renderer will assume 8.
     * Typically used to control dithering.
     */
    MPV_RENDER_PARAM_DEPTH = 5,
    /**
     * ICC profile blob. Valid for mpv_render_context_set_parameter().
     * Type: mpv_byte_array*
     * Set an ICC profile for use with the "icc-profile-auto" option. (If the
     * option is not enabled, the ICC data will not be used.)
     */
    MPV_RENDER_PARAM_ICC_PROFILE = 6,
    /**
     * Ambient light in lux. Valid for mpv_render_context_set_parameter().
     * Type: int*
     * This can be used for automatic gamma correction.
     */
    MPV_RENDER_PARAM_AMBIENT_LIGHT = 7,
    /**
     * X11 Display, sometimes used for hwdec. Valid for
     * mpv_render_context_create(). The Display must stay valid for the
     * lifetime of the mpv_render_context. Type: Display*
     */
    MPV_RENDER_PARAM_X11_DISPLAY = 8,
    /**
     * Wayland display, sometimes used for hwdec. Valid for
     * mpv_render_context_create(). The wl_display must stay valid for the
     * lifetime of the mpv_render_context.
     * Type: struct wl_display*
     */
    MPV_RENDER_PARAM_WL_DISPLAY = 9,
    /**
     * Better control about rendering and enabling some advanced features.
     * Valid for mpv_render_context_create().
     *
     * This conflates multiple requirements the API user promises to abide if
     * this option is enabled:
     *
     *  - The API user's render thread, which is calling the mpv_render_*()
     *    functions, never waits for the core. Otherwise deadlocks can happen.
     *    See "Threading" section.
     *  - The callback set with mpv_render_context_set_update_callback() can
     * now be called even if there is no new frame. The API user should call
     * the mpv_render_context_update() function, and interpret the return value
     *    for whether a new frame should be rendered.
     *  - Correct functionality is impossible if the update callback is not
     * set, or not set soon enough after mpv_render_context_create() (the core
     * can block while waiting for you to call mpv_render_context_update(), and
     *    if the update callback is not correctly set, it will deadlock, or
     *    block for too long).
     *
     * In general, setting this option will enable the following features (and
     * possibly more):
     *
     *  - "Direct rendering", which means the player decodes directly to a
     *    texture, which saves a copy per video frame ("vd-lavc-dr" option
     *    needs to be enabled, and the rendering backend as well as the
     *    underlying GPU API/driver needs to have support for it).
     *  - Rendering screenshots with the GPU API if supported by the backend
     *    (instead of using a suboptimal software fallback via libswscale).
     *
     * Warning: do not just add this without reading the "Threading" section
     *          above, and then wondering that deadlocks happen. The
     *          requirements are tricky. But also note that even if advanced
     *          control is disabled, not adhering to the rules will lead to
     *          playback problems. Enabling advanced controls simply makes
     *          violating these rules fatal.
     *
     * Type: int*: 0 for disable (default), 1 for enable
     */
    MPV_RENDER_PARAM_ADVANCED_CONTROL = 10,
    /**
     * Return information about the next frame to render. Valid for
     * mpv_render_context_get_info().
     *
     * Type: mpv_render_frame_info*
     *
     * It strictly returns information about the _next_ frame. The implication
     * is that e.g. mpv_render_context_update()'s return value will have
     * MPV_RENDER_UPDATE_FRAME set, and the user is supposed to call
     * mpv_render_context_render(). If there is no next frame, then the
     * return value will have is_valid set to 0.
     */
    MPV_RENDER_PARAM_NEXT_FRAME_INFO = 11,
    /**
     * Enable or disable video timing. Valid for mpv_render_context_render().
     *
     * Type: int*: 0 for disable, 1 for enable (default)
     *
     * When video is timed to audio, the player attempts to render video a bit
     * ahead, and then do a blocking wait until the target display time is
     * reached. This blocks mpv_render_context_render() for up to the amount
     * specified with the "video-timing-offset" global option. You can set
     * this parameter to 0 to disable this kind of waiting. If you do, it's
     * recommended to use the target time value in mpv_render_frame_info to
     * wait yourself, or to set the "video-timing-offset" to 0 instead.
     *
     * Disabling this without doing anything in addition will result in A/V
     * sync being slightly off.
     */
    MPV_RENDER_PARAM_BLOCK_FOR_TARGET_TIME = 12,
    /**
     * Use to skip rendering in mpv_render_context_render().
     *
     * Type: int*: 0 for rendering (default), 1 for skipping
     *
     * If this is set, you don't need to pass a target surface to the render
     * function (and if you do, it's completely ignored). This can still call
     * into the lower level APIs (i.e. if you use OpenGL, the OpenGL context
     * must be set).
     *
     * Be aware that the render API will consider this frame as having been
     * rendered. All other normal rules also apply, for example about whether
     * you have to call mpv_render_context_report_swap(). It also does timing
     * in the same way.
     */
    MPV_RENDER_PARAM_SKIP_RENDERING = 13,
    /**
     * Deprecated. Not supported. Use MPV_RENDER_PARAM_DRM_DISPLAY_V2 instead.
     * Type : struct mpv_opengl_drm_params*
     */
    MPV_RENDER_PARAM_DRM_DISPLAY = 14,
    /**
     * DRM draw surface size, contains draw surface dimensions.
     * Valid for mpv_render_context_create().
     * Type : struct mpv_opengl_drm_draw_surface_size*
     */
    MPV_RENDER_PARAM_DRM_DRAW_SURFACE_SIZE = 15,
    /**
     * DRM display, contains drm display handles.
     * Valid for mpv_render_context_create().
     * Type : struct mpv_opengl_drm_params_v2*
     */
    MPV_RENDER_PARAM_DRM_DISPLAY_V2 = 16,
    /**
     * MPV_RENDER_API_TYPE_SW only: rendering target surface size, mandatory.
     * Valid for MPV_RENDER_API_TYPE_SW & mpv_render_context_render().
     * Type: int[2] (e.g.: int s[2] = {w, h}; param.data = &s[0];)
     *
     * The video frame is transformed as with other VOs. Typically, this means
     * the video gets scaled and black bars are added if the video size or
     * aspect ratio mismatches with the target size.
     */
    MPV_RENDER_PARAM_SW_SIZE = 17,
    /**
     * MPV_RENDER_API_TYPE_SW only: rendering target surface pixel format,
     * mandatory.
     * Valid for MPV_RENDER_API_TYPE_SW & mpv_render_context_render().
     * Type: char* (e.g.: char *f = "rgb0"; param.data = f;)
     *
     * Valid values are:
     *  "rgb0", "bgr0", "0bgr", "0rgb"
     *      4 bytes per pixel RGB, 1 byte (8 bit) per component, component
     * bytes with increasing address from left to right (e.g. "rgb0" has r at
     *      address 0), the "0" component contains uninitialized garbage (often
     *      the value 0, but not necessarily; the bad naming is inherited from
     *      FFmpeg)
     *      Pixel alignment size: 4 bytes
     *  "rgb24"
     *      3 bytes per pixel RGB. This is strongly discouraged because it is
     *      very slow.
     *      Pixel alignment size: 1 bytes
     *  other
     *      The API may accept other pixel formats, using mpv internal format
     *      names, as long as it's internally marked as RGB, has exactly 1
     *      plane, and is supported as conversion output. It is not a good idea
     *      to rely on any of these. Their semantics and handling could change.
     */
    MPV_RENDER_PARAM_SW_FORMAT = 18,
    /**
     * MPV_RENDER_API_TYPE_SW only: rendering target surface bytes per line,
     * mandatory.
     * Valid for MPV_RENDER_API_TYPE_SW & mpv_render_context_render().
     * Type: size_t*
     *
     * This is the number of bytes between a pixel (x, y) and (x, y + 1) on the
     * target surface. It must be a multiple of the pixel size, and have space
     * for the surface width as specified by MPV_RENDER_PARAM_SW_SIZE.
     *
     * Both stride and pointer value should be a multiple of 64 to facilitate
     * fast SIMD operation. Lower alignment might trigger slower code paths,
     * and in the worst case, will copy the entire target frame. If mpv is
     * built with zimg (and zimg is not disabled), the performance impact might
     * be less. In either cases, the pointer and stride must be aligned at
     * least to the pixel alignment size. Otherwise, crashes and undefined
     * behavior is possible on platforms which do not support unaligned
     * accesses (either through normal memory access or aligned SIMD memory
     * access instructions).
     */
    MPV_RENDER_PARAM_SW_STRIDE = 19,
    /*
     * MPV_RENDER_API_TYPE_SW only: rendering target surface pixel data
     * pointer, mandatory. Valid for MPV_RENDER_API_TYPE_SW &
     * mpv_render_context_render(). Type: void*
     *
     * This points to the first pixel at the left/top corner (0, 0). In
     * particular, each line y starts at (pointer + stride * y). Upon
     * rendering, all data between pointer and (pointer + stride * h) is
     * overwritten. Whether the padding between (w, y) and (0, y + 1) is
     * overwritten is left unspecified (it should not be, but unfortunately
     * some scaler backends will do it anyway). It is assumed that even the
     * padding after the last line (starting at bytepos(w, h) until (pointer +
     * stride * h)) is writable.
     *
     * See MPV_RENDER_PARAM_SW_STRIDE for alignment requirements.
     */
    MPV_RENDER_PARAM_SW_POINTER = 20,
  } mpv_render_param_type;

/**
 * For backwards compatibility with the old naming of
 * MPV_RENDER_PARAM_DRM_DRAW_SURFACE_SIZE
 */
#define MPV_RENDER_PARAM_DRM_OSD_SIZE MPV_RENDER_PARAM_DRM_DRAW_SURFACE_SIZE

  /**
   * Used to pass arbitrary parameters to some mpv_render_* functions. The
   * meaning of the data parameter is determined by the type, and each
   * MPV_RENDER_PARAM_* documents what type the value must point to.
   *
   * Each value documents the required data type as the pointer you cast to
   * void* and set on mpv_render_param.data. For example, if
   * MPV_RENDER_PARAM_FOO documents the type as Something* , then the code
   * should look like this:
   *
   *   Something foo = {...};
   *   mpv_render_param param;
   *   param.type = MPV_RENDER_PARAM_FOO;
   *   param.data = & foo;
   *
   * Normally, the data field points to exactly 1 object. If the type is char*,
   * it points to a 0-terminated string.
   *
   * In all cases (unless documented otherwise) the pointers need to remain
   * valid during the call only. Unless otherwise documented, the API functions
   * will not write to the params array or any data pointed to it.
   *
   * As a convention, parameter arrays are always terminated by type==0. There
   * is no specific order of the parameters required. The order of the 2 fields
   * in this struct is guaranteed (even after ABI changes).
   */
  typedef struct mpv_render_param
  {
    enum mpv_render_param_type type;
    void *data;
  } mpv_render_param;

/**
 * Predefined values for MPV_RENDER_PARAM_API_TYPE.
 */
// See render_gl.h
#define MPV_RENDER_API_TYPE_OPENGL "opengl"
// See section "Software renderer"
#define MPV_RENDER_API_TYPE_SW "sw"

  /**
   * Flags used in mpv_render_frame_info.flags. Each value represents a bit in
   * it.
   */
  typedef enum mpv_render_frame_info_flag
  {
    /**
     * Set if there is actually a next frame. If unset, there is no next frame
     * yet, and other flags and fields that require a frame to be queued will
     * be unset.
     *
     * This is set for _any_ kind of frame, even for redraw requests.
     *
     * Note that when this is unset, it simply means no new frame was
     * decoded/queued yet, not necessarily that the end of the video was
     * reached. A new frame can be queued after some time.
     *
     * If the return value of mpv_render_context_render() had the
     * MPV_RENDER_UPDATE_FRAME flag set, this flag will usually be set as well,
     * unless the frame is rendered, or discarded by other asynchronous events.
     */
    MPV_RENDER_FRAME_INFO_PRESENT = 1 << 0,
    /**
     * If set, the frame is not an actual new video frame, but a redraw
     * request. For example if the video is paused, and an option that affects
     * video rendering was changed (or any other reason), an update request can
     * be issued and this flag will be set.
     *
     * Typically, redraw frames will not be subject to video timing.
     *
     * Implies MPV_RENDER_FRAME_INFO_PRESENT.
     */
    MPV_RENDER_FRAME_INFO_REDRAW = 1 << 1,
    /**
     * If set, this is supposed to reproduce the previous frame perfectly. This
     * is usually used for certain "video-sync" options ("display-..." modes).
     * Typically the renderer will blit the video from a FBO. Unset otherwise.
     *
     * Implies MPV_RENDER_FRAME_INFO_PRESENT.
     */
    MPV_RENDER_FRAME_INFO_REPEAT = 1 << 2,
    /**
     * If set, the player timing code expects that the user thread blocks on
     * vsync (by either delaying the render call, or by making a call to
     * mpv_render_context_report_swap() at vsync time).
     *
     * Implies MPV_RENDER_FRAME_INFO_PRESENT.
     */
    MPV_RENDER_FRAME_INFO_BLOCK_VSYNC = 1 << 3,
  } mpv_render_frame_info_flag;

  /**
   * Information about the next video frame that will be rendered. Can be
   * retrieved with MPV_RENDER_PARAM_NEXT_FRAME_INFO.
   */
  typedef struct mpv_render_frame_info
  {
    /**
     * A bitset of mpv_render_frame_info_flag values (i.e. multiple flags are
     * combined with bitwise or).
     */
    uint64_t flags;
    /**
     * Absolute time at which the frame is supposed to be displayed. This is in
     * the same unit and base as the time returned by mpv_get_time_us(). For
     * frames that are redrawn, or if vsync locked video timing is used (see
     * "video-sync" option), then this can be 0. The "video-timing-offset"
     * option determines how much "headroom" the render thread gets (but a high
     * enough frame rate can reduce it anyway). mpv_render_context_render()
     * will normally block until the time is elapsed, unless you pass it
     * MPV_RENDER_PARAM_BLOCK_FOR_TARGET_TIME = 0.
     */
    int64_t target_time;
  } mpv_render_frame_info;

  /**
   * Initialize the renderer state. Depending on the backend used, this will
   * access the underlying GPU API and initialize its own objects.
   *
   * You must free the context with mpv_render_context_free(). Not doing so
   * before the mpv core is destroyed may result in memory leaks or crashes.
   *
   * Currently, only at most 1 context can exists per mpv core (it represents
   * the main video output).
   *
   * You should pass the following parameters:
   *  - MPV_RENDER_PARAM_API_TYPE to select the underlying backend/GPU API.
   *  - Backend-specific init parameter, like
   * MPV_RENDER_PARAM_OPENGL_INIT_PARAMS.
   *  - Setting MPV_RENDER_PARAM_ADVANCED_CONTROL and following its rules is
   *    strongly recommended.
   *  - If you want to use hwdec, possibly hwdec interop resources.
   *
   * @param res set to the context (on success) or NULL (on failure). The value
   *            is never read and always overwritten.
   * @param mpv handle used to get the core (the mpv_render_context won't
   * depend on this specific handle, only the core referenced by it)
   * @param params an array of parameters, terminated by type==0. It's left
   *               unspecified what happens with unknown parameters. At least
   *               MPV_RENDER_PARAM_API_TYPE is required, and most backends
   * will require another backend-specific parameter.
   * @return error code, including but not limited to:
   *      MPV_ERROR_UNSUPPORTED: the OpenGL version is not supported
   *                             (or required extensions are missing)
   *      MPV_ERROR_NOT_IMPLEMENTED: an unknown API type was provided, or
   *                                 support for the requested API was not
   *                                 built in the used libmpv binary.
   *      MPV_ERROR_INVALID_PARAMETER: at least one of the provided parameters
   * was not valid.
   */
  MPV_EXPORT int mpv_render_context_create (mpv_render_context **res,
                                            mpv_handle *mpv,
                                            mpv_render_param *params);

  /**
   * Attempt to change a single parameter. Not all backends and parameter types
   * support all kinds of changes.
   *
   * @param ctx a valid render context
   * @param param the parameter type and data that should be set
   * @return error code. If a parameter could actually be changed, this returns
   *         success, otherwise an error code depending on the parameter type
   *         and situation.
   */
  MPV_EXPORT int mpv_render_context_set_parameter (mpv_render_context *ctx,
                                                   mpv_render_param param);

  /**
   * Retrieve information from the render context. This is NOT a counterpart to
   * mpv_render_context_set_parameter(), because you generally can't read
   * parameters set with it, and this function is not meant for this purpose.
   * Instead, this is for communicating information from the renderer back to
   * the user. See mpv_render_param_type; entries which support this function
   * explicitly mention it, and for other entries you can assume it will fail.
   *
   * You pass param with param.type set and param.data pointing to a variable
   * of the required data type. The function will then overwrite that variable
   * with the returned value (at least on success).
   *
   * @param ctx a valid render context
   * @param param the parameter type and data that should be retrieved
   * @return error code. If a parameter could actually be retrieved, this
   * returns success, otherwise an error code depending on the parameter type
   *         and situation. MPV_ERROR_NOT_IMPLEMENTED is used for unknown
   *         param.type, or if retrieving it is not supported.
   */
  MPV_EXPORT int mpv_render_context_get_info (mpv_render_context *ctx,
                                              mpv_render_param param);

  typedef void (*mpv_render_update_fn) (void *cb_ctx);

  /**
   * Set the callback that notifies you when a new video frame is available, or
   * if the video display configuration somehow changed and requires a redraw.
   * Similar to mpv_set_wakeup_callback(), you must not call any mpv API from
   * the callback, and all the other listed restrictions apply (such as not
   * exiting the callback by throwing exceptions).
   *
   * This can be called from any thread, except from an update callback. In
   * case of the OpenGL backend, no OpenGL state or API is accessed.
   *
   * Calling this will raise an update callback immediately.
   *
   * @param callback callback(callback_ctx) is called if the frame should be
   *                 redrawn
   * @param callback_ctx opaque argument to the callback
   */
  MPV_EXPORT void
  mpv_render_context_set_update_callback (mpv_render_context *ctx,
                                          mpv_render_update_fn callback,
                                          void *callback_ctx);

  /**
   * The API user is supposed to call this when the update callback was invoked
   * (like all mpv_render_* functions, this has to happen on the render thread,
   * and _not_ from the update callback itself).
   *
   * This is optional if MPV_RENDER_PARAM_ADVANCED_CONTROL was not set
   * (default). Otherwise, it's a hard requirement that this is called after
   * each update callback. If multiple update callback happened, and the
   * function could not be called sooner, it's OK to call it once after the
   * last callback.
   *
   * If an update callback happens during or after this function, the function
   * must be called again at the soonest possible time.
   *
   * If MPV_RENDER_PARAM_ADVANCED_CONTROL was set, this will do additional work
   * such as allocating textures for the video decoder.
   *
   * @return a bitset of mpv_render_update_flag values (i.e. multiple flags are
   *         combined with bitwise or). Typically, this will tell the API user
   *         what should happen next. E.g. if the MPV_RENDER_UPDATE_FRAME flag
   * is set, mpv_render_context_render() should be called. If flags unknown to
   * the API user are set, or if the return value is 0, nothing needs to be
   * done.
   */
  MPV_EXPORT uint64_t mpv_render_context_update (mpv_render_context *ctx);

  /**
   * Flags returned by mpv_render_context_update(). Each value represents a bit
   * in the function's return value.
   */
  typedef enum mpv_render_update_flag
  {
    /**
     * A new video frame must be rendered. mpv_render_context_render() must be
     * called.
     */
    MPV_RENDER_UPDATE_FRAME = 1 << 0,
  } mpv_render_context_flag;

  /**
   * Render video.
   *
   * Typically renders the video to a target surface provided via
   * mpv_render_param (the details depend on the backend in use). Options like
   * "panscan" are applied to determine which part of the video should be
   * visible and how the video should be scaled. You can change these options
   * at runtime by using the mpv property API.
   *
   * The renderer will reconfigure itself every time the target surface
   * configuration (such as size) is changed.
   *
   * This function implicitly pulls a video frame from the internal queue and
   * renders it. If no new frame is available, the previous frame is redrawn.
   * The update callback set with mpv_render_context_set_update_callback()
   * notifies you when a new frame was added. The details potentially depend on
   * the backends and the provided parameters.
   *
   * Generally, libmpv will invoke your update callback some time before the
   * video frame should be shown, and then lets this function block until the
   * supposed display time. This will limit your rendering to video FPS. You
   * can prevent this by setting the "video-timing-offset" global option to 0.
   * (This applies only to "audio" video sync mode.)
   *
   * You should pass the following parameters:
   *  - Backend-specific target object, such as MPV_RENDER_PARAM_OPENGL_FBO.
   *  - Possibly transformations, such as MPV_RENDER_PARAM_FLIP_Y.
   *
   * @param ctx a valid render context
   * @param params an array of parameters, terminated by type==0. Which
   * parameters are required depends on the backend. It's left unspecified what
   *               happens with unknown parameters.
   * @return error code
   */
  MPV_EXPORT int mpv_render_context_render (mpv_render_context *ctx,
                                            mpv_render_param *params);

  /**
   * Tell the renderer that a frame was flipped at the given time. This is
   * optional, but can help the player to achieve better timing.
   *
   * Note that calling this at least once informs libmpv that you will use this
   * function. If you use it inconsistently, expect bad video playback.
   *
   * If this is called while no video is initialized, it is ignored.
   *
   * @param ctx a valid render context
   */
  MPV_EXPORT void mpv_render_context_report_swap (mpv_render_context *ctx);

  /**
   * Destroy the mpv renderer state.
   *
   * If video is still active (e.g. a file playing), video will be disabled
   * forcefully.
   *
   * @param ctx a valid render context. After this function returns, this is
   * not a valid pointer anymore. NULL is also allowed and does nothing.
   */
  MPV_EXPORT void mpv_render_context_free (mpv_render_context *ctx);

#ifdef MPV_CPLUGIN_DYNAMIC_SYM

  MPV_DEFINE_SYM_PTR (mpv_render_context_create)
#define mpv_render_context_create pfn_mpv_render_context_create
  MPV_DEFINE_SYM_PTR (mpv_render_context_set_parameter)
#define mpv_render_context_set_parameter pfn_mpv_render_context_set_parameter
  MPV_DEFINE_SYM_PTR (mpv_render_context_get_info)
#define mpv_render_context_get_info pfn_mpv_render_context_get_info
  MPV_DEFINE_SYM_PTR (mpv_render_context_set_update_callback)
#define mpv_render_context_set_update_callback                                \
  pfn_mpv_render_context_set_update_callback
  MPV_DEFINE_SYM_PTR (mpv_render_context_update)
#define mpv_render_context_update pfn_mpv_render_context_update
  MPV_DEFINE_SYM_PTR (mpv_render_context_render)
#define mpv_render_context_render pfn_mpv_render_context_render
  MPV_DEFINE_SYM_PTR (mpv_render_context_report_swap)
#define mpv_render_context_report_swap pfn_mpv_render_context_report_swap
  MPV_DEFINE_SYM_PTR (mpv_render_context_free)
#define mpv_render_context_free pfn_mpv_render_context_free

#endif

#ifdef __cplusplus
}
#endif

#endif