video: refactor how VO exports hwdec device handles

The main change is with video/hwdec.h. mp_hwdec_info is made opaque (and
renamed to mp_hwdec_devices). Its accessors are mainly thread-safe (or
documented where not), which makes the whole thing saner and cleaner. In
particular, thread-safety rules become less subtle and more obvious.

The new internal API makes it easier to support multiple OpenGL interop
backends. (Although this is not done yet, and it's not clear whether it
ever will.)

This also removes all the API-specific fields from mp_hwdec_ctx and
replaces them with a "ctx" field. For d3d in particular, we drop the
mp_d3d_ctx struct completely, and pass the interfaces directly.

Remove the emulation checks from vaapi.c and vdpau.c; they are
pointless, and the checks that matter are done on the VO layer.

The d3d hardware decoders might slightly change behavior: dxva2-copy
will not use the VO device anymore if the VO supports proper interop.
This pretty much assumes that any in such cases the VO will not use any
form of exclusive mode, which makes using the VO device in copy mode
unnecessary.

This is a big refactor. Some things may be untested and could be broken.

16 files changed, 135 insertions, 131 deletions

diff --git a/video/out/opengl/hwdec.c b/video/out/opengl/hwdec.c
index 9c3bec1a0f..b4b5c23580 100644
--- a/video/out/opengl/hwdec.c
+++ b/video/out/opengl/hwdec.c
@@ -61,6 +61,7 @@ static const struct gl_hwdec_driver *const mpgl_hwdec_drivers[] = {
 
 static struct gl_hwdec *load_hwdec_driver(struct mp_log *log, GL *gl,
                                           struct mpv_global *global,
+                                          struct mp_hwdec_devices *devs,
                                           const struct gl_hwdec_driver *drv,
                                           bool is_auto)
 {
@@ -70,6 +71,7 @@ static struct gl_hwdec *load_hwdec_driver(struct mp_log *log, GL *gl,
         .log = mp_log_new(hwdec, log, drv->name),
         .global = global,
         .gl = gl,
+        .devs = devs,
         .gl_texture_target = GL_TEXTURE_2D,
         .probing = is_auto,
     };
@@ -79,19 +81,19 @@ static struct gl_hwdec *load_hwdec_driver(struct mp_log *log, GL *gl,
         mp_verbose(log, "Loading failed.\n");
         return NULL;
     }
-    if (hwdec->hwctx && !hwdec->hwctx->driver_name)
-        hwdec->hwctx->driver_name = hwdec->driver->name;
     return hwdec;
 }
 
-struct gl_hwdec *gl_hwdec_load_api_id(struct mp_log *log, GL *gl,
-                                      struct mpv_global *g, int id)
+struct gl_hwdec *gl_hwdec_load_api(struct mp_log *log, GL *gl,
+                                   struct mpv_global *g,
+                                   struct mp_hwdec_devices *devs,
+                                   enum hwdec_type api)
 {
-    bool is_auto = id == HWDEC_AUTO;
+    bool is_auto = api == HWDEC_AUTO;
     for (int n = 0; mpgl_hwdec_drivers[n]; n++) {
         const struct gl_hwdec_driver *drv = mpgl_hwdec_drivers[n];
-        if (is_auto || id == drv->api) {
-            struct gl_hwdec *r = load_hwdec_driver(log, gl, g, drv, is_auto);
+        if (is_auto || api == drv->api) {
+            struct gl_hwdec *r = load_hwdec_driver(log, gl, g, devs, drv, is_auto);
             if (r)
                 return r;
         }
@@ -99,19 +101,6 @@ struct gl_hwdec *gl_hwdec_load_api_id(struct mp_log *log, GL *gl,
     return NULL;
 }
 
-// Like gl_hwdec_load_api_id(), but use option names.
-struct gl_hwdec *gl_hwdec_load_api(struct mp_log *log, GL *gl,
-                                   struct mpv_global *g, const char *api_name)
-{
-    int id = HWDEC_NONE;
-    for (const struct m_opt_choice_alternatives *c = mp_hwdec_names; c->name; c++)
-    {
-        if (strcmp(c->name, api_name) == 0)
-            id = c->value;
-    }
-    return gl_hwdec_load_api_id(log, gl, g, id);
-}
-
 void gl_hwdec_uninit(struct gl_hwdec *hwdec)
 {
     if (hwdec)
diff --git a/video/out/opengl/hwdec.h b/video/out/opengl/hwdec.h
index a9d524a1d7..fcc6d3c11e 100644
--- a/video/out/opengl/hwdec.h
+++ b/video/out/opengl/hwdec.h
@@ -4,14 +4,12 @@
 #include "common.h"
 #include "video/hwdec.h"
 
-struct mp_hwdec_info;
-
 struct gl_hwdec {
     const struct gl_hwdec_driver *driver;
     struct mp_log *log;
     struct mpv_global *global;
     GL *gl;
-    struct mp_hwdec_ctx *hwctx;
+    struct mp_hwdec_devices *devs;
     // For free use by hwdec driver
     void *priv;
     // For working around the vdpau vs. vaapi mess.
@@ -33,7 +31,7 @@ struct gl_hwdec_driver {
     enum hwdec_type api;
     // The hardware surface IMGFMT_ that must be passed to map_image later.
     int imgfmt;
-    // Create the hwdec device. It must fill in hw->info, if applicable.
+    // Create the hwdec device. It must add it to hw->devs, if applicable.
     // This also must set hw->converted_imgfmt.
     int (*create)(struct gl_hwdec *hw);
     // Prepare for rendering video. (E.g. create textures.)
@@ -49,9 +47,9 @@ struct gl_hwdec_driver {
 };
 
 struct gl_hwdec *gl_hwdec_load_api(struct mp_log *log, GL *gl,
-                                   struct mpv_global *g, const char *api_name);
-struct gl_hwdec *gl_hwdec_load_api_id(struct mp_log *log, GL *gl,
-                                      struct mpv_global *g, int id);
+                                   struct mpv_global *g,
+                                   struct mp_hwdec_devices *devs,
+                                   enum hwdec_type api);
 
 void gl_hwdec_uninit(struct gl_hwdec *hwdec);
 
diff --git a/video/out/opengl/hwdec_d3d11egl.c b/video/out/opengl/hwdec_d3d11egl.c
index de872d1396..caf27e1dc4 100644
--- a/video/out/opengl/hwdec_d3d11egl.c
+++ b/video/out/opengl/hwdec_d3d11egl.c
@@ -27,11 +27,10 @@
 #include "osdep/timer.h"
 #include "osdep/windows_utils.h"
 #include "hwdec.h"
-#include "video/d3d.h"
 #include "video/hwdec.h"
 
 struct priv {
-    struct mp_d3d_ctx ctx;
+    struct mp_hwdec_ctx hwctx;
 
     ID3D11Device *d3d11_device;
     ID3D11VideoDevice *video_dev;
@@ -94,6 +93,8 @@ static void destroy(struct gl_hwdec *hw)
 
     destroy_objects(hw);
 
+    hwdec_devices_remove(hw->devs, &p->hwctx);
+
     if (p->video_ctx)
         ID3D11VideoContext_Release(p->video_ctx);
     p->video_ctx = NULL;
@@ -109,9 +110,6 @@ static void destroy(struct gl_hwdec *hw)
 
 static int create(struct gl_hwdec *hw)
 {
-    if (hw->hwctx)
-        return -1;
-
     EGLDisplay egl_display = eglGetCurrentDisplay();
     if (!egl_display)
         return -1;
@@ -199,11 +197,13 @@ static int create(struct gl_hwdec *hw)
 
     hw->converted_imgfmt = IMGFMT_RGB0;
 
-    p->ctx.d3d11_device = p->d3d11_device;
-    p->ctx.hwctx.type = HWDEC_D3D11VA;
-    p->ctx.hwctx.d3d_ctx = &p->ctx;
+    p->hwctx = (struct mp_hwdec_ctx){
+        .type = HWDEC_D3D11VA,
+        .driver_name = hw->driver->name,
+        .ctx = p->d3d11_device,
+    };
+    hwdec_devices_add(hw->devs, &p->hwctx);
 
-    hw->hwctx = &p->ctx.hwctx;
     return 0;
 fail:
     destroy(hw);
diff --git a/video/out/opengl/hwdec_dxva2.c b/video/out/opengl/hwdec_dxva2.c
index f72c817a20..35d091f14f 100644
--- a/video/out/opengl/hwdec_dxva2.c
+++ b/video/out/opengl/hwdec_dxva2.c
@@ -1,8 +1,9 @@
+#include <d3d9.h>
+
 #include "common/common.h"
 
 #include "hwdec.h"
 #include "utils.h"
-#include "video/d3d.h"
 #include "video/hwdec.h"
 
 // This does not provide real (zero-copy) interop - it merely exists for
@@ -10,35 +11,39 @@
 // may help with OpenGL fullscreen mode.
 
 struct priv {
-    struct mp_d3d_ctx ctx;
+    struct mp_hwdec_ctx hwctx;
 };
 
 static void destroy(struct gl_hwdec *hw)
 {
     struct priv *p = hw->priv;
-    if (p->ctx.d3d9_device)
-        IDirect3DDevice9_Release(p->ctx.d3d9_device);
+    hwdec_devices_remove(hw->devs, &p->hwctx);
+    if (p->hwctx.ctx)
+        IDirect3DDevice9_Release((IDirect3DDevice9 *)p->hwctx.ctx);
 }
 
 static int create(struct gl_hwdec *hw)
 {
     GL *gl = hw->gl;
-    if (hw->hwctx || !gl->MPGetNativeDisplay)
+    if (!gl->MPGetNativeDisplay)
         return -1;
 
     struct priv *p = talloc_zero(hw, struct priv);
     hw->priv = p;
 
-    p->ctx.d3d9_device = gl->MPGetNativeDisplay("IDirect3DDevice9");
-    if (!p->ctx.d3d9_device)
+    IDirect3DDevice9 *d3d = gl->MPGetNativeDisplay("IDirect3DDevice9");
+    if (!d3d)
         return -1;
 
-    p->ctx.hwctx.type = HWDEC_DXVA2_COPY;
-    p->ctx.hwctx.d3d_ctx = &p->ctx;
+    MP_VERBOSE(hw, "Using libmpv supplied device %p.\n", d3d);
 
-    MP_VERBOSE(hw, "Using libmpv supplied device %p.\n", p->ctx.d3d9_device);
+    p->hwctx = (struct mp_hwdec_ctx){
+        .type = HWDEC_DXVA2_COPY,
+        .driver_name = hw->driver->name,
+        .ctx = d3d,
+    };
+    hwdec_devices_add(hw->devs, &p->hwctx);
 
-    hw->hwctx = &p->ctx.hwctx;
     hw->converted_imgfmt = 0;
     return 0;
 }
diff --git a/video/out/opengl/hwdec_dxva2egl.c b/video/out/opengl/hwdec_dxva2egl.c
index ed1a6e66b7..1384e2bb47 100644
--- a/video/out/opengl/hwdec_dxva2egl.c
+++ b/video/out/opengl/hwdec_dxva2egl.c
@@ -17,6 +17,8 @@
 
 #include <assert.h>
 #include <windows.h>
+#include <d3d9.h>
+
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 
@@ -25,11 +27,10 @@
 #include "osdep/windows_utils.h"
 #include "hwdec.h"
 #include "video/dxva2.h"
-#include "video/d3d.h"
 #include "video/hwdec.h"
 
 struct priv {
-    struct mp_d3d_ctx ctx;
+    struct mp_hwdec_ctx hwctx;
 
     HMODULE             d3d9_dll;
     IDirect3D9Ex       *d3d9ex;
@@ -77,6 +78,8 @@ static void destroy(struct gl_hwdec *hw)
 
     destroy_textures(hw);
 
+    hwdec_devices_remove(hw->devs, &p->hwctx);
+
     if (p->query9)
         IDirect3DQuery9_Release(p->query9);
 
@@ -92,9 +95,6 @@ static void destroy(struct gl_hwdec *hw)
 
 static int create(struct gl_hwdec *hw)
 {
-    if (hw->hwctx)
-        return -1;
-
     EGLDisplay egl_display = eglGetCurrentDisplay();
     if (!egl_display)
         return -1;
@@ -207,11 +207,13 @@ static int create(struct gl_hwdec *hw)
 
     hw->converted_imgfmt = IMGFMT_RGB0;
 
-    p->ctx.d3d9_device = (IDirect3DDevice9 *)p->device9ex;
-    p->ctx.hwctx.type = HWDEC_DXVA2;
-    p->ctx.hwctx.d3d_ctx = &p->ctx;
+    p->hwctx = (struct mp_hwdec_ctx){
+        .type = HWDEC_DXVA2,
+        .driver_name = hw->driver->name,
+        .ctx = (IDirect3DDevice9 *)p->device9ex,
+    };
+    hwdec_devices_add(hw->devs, &p->hwctx);
 
-    hw->hwctx = &p->ctx.hwctx;
     return 0;
 fail:
     destroy(hw);
diff --git a/video/out/opengl/hwdec_dxva2gldx.c b/video/out/opengl/hwdec_dxva2gldx.c
index 69be0ccd18..97f1918a2c 100644
--- a/video/out/opengl/hwdec_dxva2gldx.c
+++ b/video/out/opengl/hwdec_dxva2gldx.c
@@ -15,13 +15,13 @@
  * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <d3d9.h>
 #include <assert.h>
 
 #include "common/common.h"
 #include "osdep/windows_utils.h"
 #include "hwdec.h"
 #include "video/hwdec.h"
-#include "video/d3d.h"
 #include "video/dxva2.h"
 
 // for  WGL_ACCESS_READ_ONLY_NV
@@ -30,7 +30,7 @@
 #define SHARED_SURFACE_D3DFMT D3DFMT_X8R8G8B8
 #define SHARED_SURFACE_MPFMT  IMGFMT_RGB0
 struct priv {
-    struct mp_d3d_ctx ctx;
+    struct mp_hwdec_ctx hwctx;
     IDirect3DDevice9Ex *device;
     HANDLE device_h;
 
@@ -74,6 +74,8 @@ static void destroy(struct gl_hwdec *hw)
     struct priv *p = hw->priv;
     destroy_objects(hw);
 
+    hwdec_devices_remove(hw->devs, &p->hwctx);
+
     if (p->device)
         IDirect3DDevice9Ex_Release(p->device);
 }
@@ -81,10 +83,8 @@ static void destroy(struct gl_hwdec *hw)
 static int create(struct gl_hwdec *hw)
 {
     GL *gl = hw->gl;
-    if (hw->hwctx || !gl->MPGetNativeDisplay ||
-        !(gl->mpgl_caps & MPGL_CAP_DXINTEROP)) {
+    if (!gl->MPGetNativeDisplay || !(gl->mpgl_caps & MPGL_CAP_DXINTEROP))
         return -1;
-    }
 
     struct priv *p = talloc_zero(hw, struct priv);
     hw->priv = p;
@@ -100,12 +100,14 @@ static int create(struct gl_hwdec *hw)
     if (!p->device)
         return -1;
     IDirect3DDevice9Ex_AddRef(p->device);
-    p->ctx.d3d9_device = (IDirect3DDevice9 *)p->device;
 
-    p->ctx.hwctx.type = HWDEC_DXVA2;
-    p->ctx.hwctx.d3d_ctx = &p->ctx;
+    p->hwctx = (struct mp_hwdec_ctx){
+        .type = HWDEC_DXVA2,
+        .driver_name = hw->driver->name,
+        .ctx = (IDirect3DDevice9 *)p->device,
+    };
+    hwdec_devices_add(hw->devs, &p->hwctx);
 
-    hw->hwctx = &p->ctx.hwctx;
     hw->converted_imgfmt = SHARED_SURFACE_MPFMT;
     return 0;
 }
diff --git a/video/out/opengl/hwdec_osx.c b/video/out/opengl/hwdec_osx.c
index addc16f404..5aa4d3dcd4 100644
--- a/video/out/opengl/hwdec_osx.c
+++ b/video/out/opengl/hwdec_osx.c
@@ -43,9 +43,11 @@ struct vt_format {
 };
 
 struct priv {
+    struct mp_hwdec_ctx hwctx;
+    struct mp_vt_ctx vtctx;
+
     CVPixelBufferRef pbuf;
     GLuint gl_planes[MP_MAX_PLANES];
-    struct mp_hwdec_ctx hwctx;
 };
 
 static struct vt_format vt_formats[] = {
@@ -147,9 +149,9 @@ static bool check_hwdec(struct gl_hwdec *hw)
     return true;
 }
 
-static uint32_t get_vt_fmt(struct mp_hwdec_ctx *ctx)
+static uint32_t get_vt_fmt(struct mp_vt_ctx *vtctx)
 {
-    struct gl_hwdec *hw = ctx->priv;
+    struct gl_hwdec *hw = vtctx->priv;
     struct vt_format *f =
         vt_get_gl_format_from_imgfmt(hw->global->opts->videotoolbox_format);
     return f ? f->cvpixfmt : (uint32_t)-1;
@@ -167,15 +169,21 @@ static int create(struct gl_hwdec *hw)
 
     hw->priv = p;
     hw->converted_imgfmt = f->imgfmt;
-    hw->hwctx = &p->hwctx;
-    hw->hwctx->download_image = download_image;
-    hw->hwctx->type = HWDEC_VIDEOTOOLBOX;
-    hw->hwctx->get_vt_fmt = get_vt_fmt;
 
     hw->gl_texture_target = GL_TEXTURE_RECTANGLE;
     hw->gl->GenTextures(MP_MAX_PLANES, p->gl_planes);
 
-    hw->hwctx->priv = hw;
+    p->vtctx = (struct mp_vt_ctx){
+        .priv = hw,
+        .get_vt_fmt = get_vt_fmt,
+    };
+    p->hwctx = (struct mp_hwdec_ctx){
+        .type = HWDEC_VIDEOTOOLBOX,
+        .download_image = download_image,
+        .ctx = &p->vtctx,
+    };
+    hwdec_devices_add(hw->devs, &p->hwctx);
+
     return 0;
 }
 
@@ -251,6 +259,8 @@ static void destroy(struct gl_hwdec *hw)
 
     CVPixelBufferRelease(p->pbuf);
     gl->DeleteTextures(MP_MAX_PLANES, p->gl_planes);
+
+    hwdec_devices_remove(hw->devs, &p->hwctx);
 }
 
 const struct gl_hwdec_driver gl_hwdec_videotoolbox = {
diff --git a/video/out/opengl/hwdec_vaegl.c b/video/out/opengl/hwdec_vaegl.c
index 6356ec4e8c..84e6e83a73 100644
--- a/video/out/opengl/hwdec_vaegl.c
+++ b/video/out/opengl/hwdec_vaegl.c
@@ -169,6 +169,8 @@ static void destroy(struct gl_hwdec *hw)
     struct priv *p = hw->priv;
     unref_image(hw);
     destroy_textures(hw);
+    if (p->ctx)
+        hwdec_devices_remove(hw->devs, &p->ctx->hwctx);
     va_destroy(p->ctx);
 }
 
@@ -181,8 +183,6 @@ static int create(struct gl_hwdec *hw)
     p->current_image.buf = p->current_image.image_id = VA_INVALID_ID;
     p->log = hw->log;
 
-    if (hw->hwctx)
-        return -1;
     if (!eglGetCurrentContext())
         return -1;
 
@@ -229,7 +229,8 @@ static int create(struct gl_hwdec *hw)
         return -1;
     }
 
-    hw->hwctx = &p->ctx->hwctx;
+    p->ctx->hwctx.driver_name = hw->driver->name;
+    hwdec_devices_add(hw->devs, &p->ctx->hwctx);
     return 0;
 }
 
diff --git a/video/out/opengl/hwdec_vaglx.c b/video/out/opengl/hwdec_vaglx.c
index 77b1f27c51..a9c5d03af4 100644
--- a/video/out/opengl/hwdec_vaglx.c
+++ b/video/out/opengl/hwdec_vaglx.c
@@ -64,13 +64,13 @@ static void destroy(struct gl_hwdec *hw)
 {
     struct priv *p = hw->priv;
     destroy_texture(hw);
+    if (p->ctx)
+        hwdec_devices_remove(hw->devs, &p->ctx->hwctx);
     va_destroy(p->ctx);
 }
 
 static int create(struct gl_hwdec *hw)
 {
-    if (hw->hwctx)
-        return -1;
     Display *x11disp = glXGetCurrentDisplay();
     if (!x11disp)
         return -1;
@@ -126,7 +126,8 @@ static int create(struct gl_hwdec *hw)
         return -1;
     }
 
-    hw->hwctx = &p->ctx->hwctx;
+    p->ctx->hwctx.driver_name = hw->driver->name;
+    hwdec_devices_add(hw->devs, &p->ctx->hwctx);
     hw->converted_imgfmt = IMGFMT_RGB0;
     return 0;
 }
diff --git a/video/out/opengl/hwdec_vdpau.c b/video/out/opengl/hwdec_vdpau.c
index 99e5a1414a..e3b69941bf 100644
--- a/video/out/opengl/hwdec_vdpau.c
+++ b/video/out/opengl/hwdec_vdpau.c
@@ -92,14 +92,14 @@ static void destroy(struct gl_hwdec *hw)
 
     destroy_objects(hw);
     mp_vdpau_mixer_destroy(p->mixer);
+    if (p->ctx)
+        hwdec_devices_remove(hw->devs, &p->ctx->hwctx);
     mp_vdpau_destroy(p->ctx);
 }
 
 static int create(struct gl_hwdec *hw)
 {
     GL *gl = hw->gl;
-    if (hw->hwctx)
-        return -1;
     Display *x11disp = glXGetCurrentDisplay();
     if (!x11disp)
         return -1;
@@ -119,7 +119,8 @@ static int create(struct gl_hwdec *hw)
         destroy(hw);
         return -1;
     }
-    hw->hwctx = &p->ctx->hwctx;
+    p->ctx->hwctx.driver_name = hw->driver->name;
+    hwdec_devices_add(hw->devs, &p->ctx->hwctx);
     hw->converted_imgfmt = IMGFMT_RGB0;
     return 0;
 }
diff --git a/video/out/vo.c b/video/out/vo.c
index 3e7999a698..3390f364f7 100644
--- a/video/out/vo.c
+++ b/video/out/vo.c
@@ -43,6 +43,7 @@
 #include "options/m_config.h"
 #include "common/msg.h"
 #include "common/global.h"
+#include "video/hwdec.h"
 #include "video/mp_image.h"
 #include "sub/osd.h"
 #include "osdep/io.h"
diff --git a/video/out/vo.h b/video/out/vo.h
index f6bc270afd..f417d5b522 100644
--- a/video/out/vo.h
+++ b/video/out/vo.h
@@ -61,9 +61,8 @@ enum mp_voctrl {
     VOCTRL_SET_EQUALIZER,               // struct voctrl_set_equalizer_args*
     VOCTRL_GET_EQUALIZER,               // struct voctrl_get_equalizer_args*
 
-    /* for hardware decoding */
-    VOCTRL_GET_HWDEC_INFO,              // struct mp_hwdec_info**
-    VOCTRL_LOAD_HWDEC_API,              // private to vo_opengl
+    /* private to vo_opengl */
+    VOCTRL_LOAD_HWDEC_API,
 
     // Redraw the image previously passed to draw_image() (basically, repeat
     // the previous draw_image call). If this is handled, the OSD should also
@@ -297,6 +296,7 @@ struct vo {
     struct vo_w32_state *w32;
     struct vo_cocoa_state *cocoa;
     struct vo_wayland_state *wayland;
+    struct mp_hwdec_devices *hwdec_devs;
     struct input_ctx *input_ctx;
     struct osd_state *osd;
     struct encode_lavc_context *encode_lavc_ctx;
diff --git a/video/out/vo_opengl.c b/video/out/vo_opengl.c
index dfef6ec500..306e893f3b 100644
--- a/video/out/vo_opengl.c
+++ b/video/out/vo_opengl.c
@@ -59,7 +59,6 @@ struct gl_priv {
     struct gl_lcms *cms;
 
     struct gl_hwdec *hwdec;
-    struct mp_hwdec_info hwdec_info;
 
     // Options
     struct gl_video_opts *renderer_opts;
@@ -196,25 +195,23 @@ static int reconfig(struct vo *vo, struct mp_image_params *params)
     return 0;
 }
 
-static void request_hwdec_api(struct gl_priv *p, const char *api_name)
+static void request_hwdec_api(struct vo *vo, void *api)
 {
+    struct gl_priv *p = vo->priv;
+
     if (p->hwdec)
         return;
 
-    p->hwdec = gl_hwdec_load_api(p->vo->log, p->gl, p->vo->global, api_name);
+    p->hwdec = gl_hwdec_load_api(p->vo->log, p->gl, p->vo->global,
+                                 vo->hwdec_devs, (intptr_t)api);
     gl_video_set_hwdec(p->renderer, p->hwdec);
-    if (p->hwdec)
-        p->hwdec_info.hwctx = p->hwdec->hwctx;
 }
 
-static void call_request_hwdec_api(struct mp_hwdec_info *info,
-                                   const char *api_name)
+static void call_request_hwdec_api(void *ctx, enum hwdec_type type)
 {
-    struct vo *vo = info->load_api_ctx;
-    assert(&((struct gl_priv *)vo->priv)->hwdec_info == info);
     // Roundabout way to run hwdec loading on the VO thread.
     // Redirects to request_hwdec_api().
-    vo_control(vo, VOCTRL_LOAD_HWDEC_API, (void *)api_name);
+    vo_control(ctx, VOCTRL_LOAD_HWDEC_API, (void *)(intptr_t)type);
 }
 
 static void get_and_update_icc_profile(struct gl_priv *p, int *events)
@@ -325,13 +322,8 @@ static int control(struct vo *vo, uint32_t request, void *data)
         *(struct mp_image **)data = screen;
         return true;
     }
-    case VOCTRL_GET_HWDEC_INFO: {
-        struct mp_hwdec_info **arg = data;
-        *arg = &p->hwdec_info;
-        return true;
-    }
     case VOCTRL_LOAD_HWDEC_API:
-        request_hwdec_api(p, data);
+        request_hwdec_api(vo, data);
         return true;
     case VOCTRL_SET_COMMAND_LINE: {
         char *arg = data;
@@ -373,6 +365,8 @@ static void uninit(struct vo *vo)
 
     gl_video_uninit(p->renderer);
     gl_hwdec_uninit(p->hwdec);
+    hwdec_devices_set_loader(vo->hwdec_devs, NULL, NULL);
+    hwdec_devices_destroy(vo->hwdec_devs);
     mpgl_uninit(p->glctx);
 }
 
@@ -424,17 +418,17 @@ static int preinit(struct vo *vo)
     gl_lcms_set_options(p->cms, p->icc_opts);
     get_and_update_icc_profile(p, &(int){0});
 
-    p->hwdec_info.load_api = call_request_hwdec_api;
-    p->hwdec_info.load_api_ctx = vo;
+    vo->hwdec_devs = hwdec_devices_create();
+
+    hwdec_devices_set_loader(vo->hwdec_devs, call_request_hwdec_api, vo);
 
     int hwdec = vo->opts->hwdec_preload_api;
     if (hwdec == HWDEC_NONE)
         hwdec = vo->global->opts->hwdec_api;
     if (hwdec != HWDEC_NONE) {
-        p->hwdec = gl_hwdec_load_api_id(p->vo->log, p->gl, vo->global, hwdec);
+        p->hwdec = gl_hwdec_load_api(p->vo->log, p->gl, vo->global,
+                                     vo->hwdec_devs, hwdec);
         gl_video_set_hwdec(p->renderer, p->hwdec);
-        if (p->hwdec)
-            p->hwdec_info.hwctx = p->hwdec->hwctx;
     }
 
     return 0;
diff --git a/video/out/vo_opengl_cb.c b/video/out/vo_opengl_cb.c
index 40930fbcae..06e0013a96 100644
--- a/video/out/vo_opengl_cb.c
+++ b/video/out/vo_opengl_cb.c
@@ -89,13 +89,16 @@ struct mpv_opengl_cb_context {
     struct vo *active;
     int hwdec_api;
 
+    // --- This is only mutable while initialized=false, during which nothing
+    //     except the OpenGL context manager is allowed to access it.
+    struct mp_hwdec_devices *hwdec_devs;
+
     // --- All of these can only be accessed from the thread where the host
     //     application's OpenGL context is current - i.e. only while the
     //     host application is calling certain mpv_opengl_cb_* APIs.
     GL *gl;
     struct gl_video *renderer;
     struct gl_hwdec *hwdec;
-    struct mp_hwdec_info hwdec_info; // it's also semi-immutable after init
 };
 
 static void update(struct vo_priv *p);
@@ -180,11 +183,10 @@ int mpv_opengl_cb_init_gl(struct mpv_opengl_cb_context *ctx, const char *exts,
     if (!ctx->renderer)
         return MPV_ERROR_UNSUPPORTED;
 
-    ctx->hwdec = gl_hwdec_load_api_id(ctx->log, ctx->gl, ctx->global,
-                                      ctx->hwdec_api);
+    ctx->hwdec_devs = hwdec_devices_create();
+    ctx->hwdec = gl_hwdec_load_api(ctx->log, ctx->gl, ctx->global,
+                                   ctx->hwdec_devs, ctx->hwdec_api);
     gl_video_set_hwdec(ctx->renderer, ctx->hwdec);
-    if (ctx->hwdec)
-        ctx->hwdec_info.hwctx = ctx->hwdec->hwctx;
 
     pthread_mutex_lock(&ctx->lock);
     // We don't know the exact caps yet - use a known superset
@@ -222,6 +224,8 @@ int mpv_opengl_cb_uninit_gl(struct mpv_opengl_cb_context *ctx)
     ctx->renderer = NULL;
     gl_hwdec_uninit(ctx->hwdec);
     ctx->hwdec = NULL;
+    hwdec_devices_destroy(ctx->hwdec_devs);
+    ctx->hwdec_devs = NULL;
     talloc_free(ctx->gl);
     ctx->gl = NULL;
     talloc_free(ctx->new_opts_cfg);
@@ -514,11 +518,6 @@ static int control(struct vo *vo, uint32_t request, void *data)
         char *arg = data;
         return reparse_cmdline(p, arg);
     }
-    case VOCTRL_GET_HWDEC_INFO: {
-        struct mp_hwdec_info **arg = data;
-        *arg = p->ctx ? &p->ctx->hwdec_info : NULL;
-        return true;
-    }
     }
 
     return VO_NOTIMPL;
@@ -561,6 +560,8 @@ static int preinit(struct vo *vo)
     p->ctx->eq_changed = true;
     pthread_mutex_unlock(&p->ctx->lock);
 
+    vo->hwdec_devs = p->ctx->hwdec_devs;
+
     return 0;
 }
 
diff --git a/video/out/vo_vaapi.c b/video/out/vo_vaapi.c
index 5275d4d28d..dc8aaacf9e 100644
--- a/video/out/vo_vaapi.c
+++ b/video/out/vo_vaapi.c
@@ -68,7 +68,6 @@ struct priv {
     struct vo               *vo;
     VADisplay                display;
     struct mp_vaapi_ctx     *mpvaapi;
-    struct mp_hwdec_info     hwdec_info;
 
     struct mp_image_params   image_params;
     struct mp_rect           src_rect;
@@ -515,11 +514,6 @@ static int control(struct vo *vo, uint32_t request, void *data)
     struct priv *p = vo->priv;
 
     switch (request) {
-    case VOCTRL_GET_HWDEC_INFO: {
-        struct mp_hwdec_info **arg = data;
-        *arg = &p->hwdec_info;
-        return true;
-    }
     case VOCTRL_SET_EQUALIZER: {
         struct voctrl_set_equalizer_args *eq = data;
         return set_equalizer(p, eq->name, eq->value);
@@ -561,6 +555,11 @@ static void uninit(struct vo *vo)
         free_subpicture(p, &part->image);
     }
 
+    if (vo->hwdec_devs) {
+        hwdec_devices_remove(vo->hwdec_devs, &p->mpvaapi->hwctx);
+        hwdec_devices_destroy(vo->hwdec_devs);
+    }
+
     va_destroy(p->mpvaapi);
 
     vo_x11_uninit(vo);
@@ -591,8 +590,6 @@ static int preinit(struct vo *vo)
         goto fail;
     }
 
-    p->hwdec_info.hwctx = &p->mpvaapi->hwctx;
-
     if (va_guess_if_emulated(p->mpvaapi)) {
         MP_WARN(vo, "VA-API is most likely emulated via VDPAU.\n"
                     "It's better to use VDPAU directly with: --vo=vdpau\n");
@@ -645,6 +642,10 @@ static int preinit(struct vo *vo)
             p->va_num_display_attrs = 0;
         p->mp_display_attr = talloc_zero_array(vo, int, p->va_num_display_attrs);
     }
+
+    vo->hwdec_devs = hwdec_devices_create();
+    hwdec_devices_add(vo->hwdec_devs, &p->mpvaapi->hwctx);
+
     return 0;
 
 fail:
diff --git a/video/out/vo_vdpau.c b/video/out/vo_vdpau.c
index 1dc5dc3b36..15472b2189 100644
--- a/video/out/vo_vdpau.c
+++ b/video/out/vo_vdpau.c
@@ -71,7 +71,6 @@ struct vdpctx {
     struct vdp_functions              *vdp;
     VdpDevice                          vdp_device;
     uint64_t                           preemption_counter;
-    struct mp_hwdec_info               hwdec_info;
 
     struct m_color                     colorkey;
 
@@ -1028,6 +1027,9 @@ static void uninit(struct vo *vo)
 {
     struct vdpctx *vc = vo->priv;
 
+    hwdec_devices_remove(vo->hwdec_devs, &vc->mpvdp->hwctx);
+    hwdec_devices_destroy(vo->hwdec_devs);
+
     /* Destroy all vdpau objects */
     mp_vdpau_mixer_destroy(vc->video_mixer);
     destroy_vdpau_objects(vo);
@@ -1053,7 +1055,8 @@ static int preinit(struct vo *vo)
         return -1;
     }
 
-    vc->hwdec_info.hwctx = &vc->mpvdp->hwctx;
+    vo->hwdec_devs = hwdec_devices_create();
+    hwdec_devices_add(vo->hwdec_devs, &vc->mpvdp->hwctx);
 
     vc->video_mixer = mp_vdpau_mixer_create(vc->mpvdp, vo->log);
 
@@ -1117,11 +1120,6 @@ static int control(struct vo *vo, uint32_t request, void *data)
     check_preemption(vo);
 
     switch (request) {
-    case VOCTRL_GET_HWDEC_INFO: {
-        struct mp_hwdec_info **arg = data;
-        *arg = &vc->hwdec_info;
-        return true;
-    }
     case VOCTRL_GET_PANSCAN:
         return VO_TRUE;
     case VOCTRL_SET_PANSCAN: