modules/video_output/opengl/interop.h

@@ -76,11 +76,11 @@ struct vlc_gl_interop_ops {
      *
      * This function pointer can be NULL. If it is set, it may return NULL.
      *
-     * Otherwise, it must return a 4x4 matrix, as an array of 16 floats in
+     * Otherwise, it must return a 3x3 matrix, as an array of 9 floats in
      * column-major order.
      *
      * This transform matrix maps 2D homogeneous texture coordinates of the
-     * form (s, t, 0, 1) with s and t in the inclusive range [0, 1] to the
+     * form (s, t, 1) with s and t in the inclusive range [0, 1] to the
      * texture coordinate that should be used to sample that location from the
      * texture.
      *
@@ -88,7 +88,7 @@ struct vlc_gl_interop_ops {
      * freed before the module is closed.
      *
      * \param interop the OpenGL interop
-     * \return a 4x4 transformatoin matrix (possibly NULL)
+     * \return a 3x3 transformation matrix (possibly NULL)
      */
     const float *
     (*get_transform_matrix)(const struct vlc_gl_interop *interop);

modules/video_output/opengl/interop_android.c

@@ -34,12 +34,48 @@
 
 struct priv
 {
+    float mtx_3x3[3*3];
     const float *transform_mtx;
+
     bool stex_attached;
     struct vlc_asurfacetexture *previous_texture;
     picture_t *current_picture;
 };
 
+static void
+ReductMatrix(float *mtx_3x3, const float *mtx_4x4)
+{
+    /*
+     * The transform matrix provided by Android is 4x4:
+     * <https://developer.android.com/reference/android/graphics/SurfaceTexture#getTransformMatrix(float%5B%5D)>
+     *
+     * However, the third column is never used, since the input vector is in
+     * the form (s, t, 0, 1). Similarly, the third row is never used either,
+     * since only the two first coordinates of the output vector are kept.
+     *
+     *       mat_4x4        mat_3x3
+     *
+     *     / a b . c \     / a b c \
+     *     | d e . f | --> | d e f |
+     *     | . . . . |     \ g h i /
+     *     \ g h . i /
+     */
+
+#define MTX4(COL,ROW) mtx_4x4[(COL)*4 + (ROW)]
+#define MTX3(COL,ROW) mtx_3x3[(COL)*3 + (ROW)]
+    MTX3(0,0) = MTX4(0,0); // a
+    MTX3(1,0) = MTX4(1,0); // b
+    MTX3(2,0) = MTX4(3,0); // c
+    MTX3(0,1) = MTX4(0,1); // d
+    MTX3(1,1) = MTX4(1,1); // e
+    MTX3(2,1) = MTX4(3,1); // f
+    MTX3(0,2) = MTX4(0,3); // g
+    MTX3(1,2) = MTX4(1,3); // h
+    MTX3(2,2) = MTX4(3,3); // i
+#undef MTX4
+#undef MTX3
+}
+
 static int
 tc_anop_allocate_textures(const struct vlc_gl_interop *interop, GLuint *textures,
                           const GLsizei *tex_width, const GLsizei *tex_height)
@@ -103,13 +139,17 @@ tc_anop_update(struct vlc_gl_interop *interop, GLuint *textures,
     if (previous_texture && previous_texture != texture)
         SurfaceTexture_releaseTexImage(previous_texture);
 
-    if (SurfaceTexture_updateTexImage(texture, &priv->transform_mtx)
+    const float *mtx_4x4;
+    if (SurfaceTexture_updateTexImage(texture, &mtx_4x4)
         != VLC_SUCCESS)
     {
         priv->transform_mtx = NULL;
         goto error;
     }
 
+    ReductMatrix(priv->mtx_3x3, mtx_4x4);
+    priv->transform_mtx = priv->mtx_3x3;
+
     interop->vt->ActiveTexture(GL_TEXTURE0);
     interop->vt->BindTexture(interop->tex_target, textures[0]);
 

modules/video_output/opengl/sampler.c

@@ -47,7 +47,7 @@ struct vlc_gl_sampler_priv {
     const opengl_vtable_t *vt; /* for convenience, same as &api->vt */
 
     struct {
-        GLfloat OrientationMatrix[4*4];
+        GLfloat OrientationMatrix[3*3];
         GLfloat TexCoordsMap[3*3];
     } var;
     struct {
@@ -332,7 +332,7 @@ GetTransformMatrix(const struct vlc_gl_interop *interop)
     if (interop && interop->ops && interop->ops->get_transform_matrix)
         tm = interop->ops->get_transform_matrix(interop);
     if (!tm)
-        tm = MATRIX4_IDENTITY;
+        tm = MATRIX3_IDENTITY;
     return tm;
 }
 
@@ -362,9 +362,9 @@ sampler_base_load(struct vlc_gl_sampler *sampler)
 
     /* Return the expected transform matrix if interop == NULL */
     const GLfloat *tm = GetTransformMatrix(priv->interop);
-    vt->UniformMatrix4fv(priv->uloc.TransformMatrix, 1, GL_FALSE, tm);
+    vt->UniformMatrix3fv(priv->uloc.TransformMatrix, 1, GL_FALSE, tm);
 
-    vt->UniformMatrix4fv(priv->uloc.OrientationMatrix, 1, GL_FALSE,
+    vt->UniformMatrix3fv(priv->uloc.OrientationMatrix, 1, GL_FALSE,
                          priv->var.OrientationMatrix);
 
     if (priv->tex_target == GL_TEXTURE_RECTANGLE)
@@ -446,9 +446,9 @@ sampler_xyz12_load(struct vlc_gl_sampler *sampler)
 
     /* Return the expected transform matrix if interop == NULL */
     const GLfloat *tm = GetTransformMatrix(priv->interop);
-    vt->UniformMatrix4fv(priv->uloc.TransformMatrix, 1, GL_FALSE, tm);
+    vt->UniformMatrix3fv(priv->uloc.TransformMatrix, 1, GL_FALSE, tm);
 
-    vt->UniformMatrix4fv(priv->uloc.OrientationMatrix, 1, GL_FALSE,
+    vt->UniformMatrix3fv(priv->uloc.OrientationMatrix, 1, GL_FALSE,
                          priv->var.OrientationMatrix);
 }
 
@@ -479,13 +479,13 @@ xyz12_shader_init(struct vlc_gl_sampler *sampler)
         "    0.0,      0.0,         0.0,        1.0 "
         " );"
 
-        "uniform mat4 TransformMatrix;\n"
-        "uniform mat4 OrientationMatrix;\n"
+        "uniform mat3 TransformMatrix;\n"
+        "uniform mat3 OrientationMatrix;\n"
         "uniform mat3 TexCoordsMap;\n"
         "vec4 vlc_texture(vec2 pic_coords)\n"
         "{ "
         " vec4 v_in, v_out;"
-        " vec2 tex_coords = (TexCoordsMap * vec3((TransformMatrix * OrientationMatrix * vec4(pic_coords, 0.0, 1.0)).xy, 1.0)).xy;\n"
+        " vec2 tex_coords = (TransformMatrix * TexCoordsMap * OrientationMatrix * vec3(pic_coords, 1.0)).xy;\n"
         " v_in  = texture2D(Textures[0], tex_coords);\n"
         " v_in = pow(v_in, xyz_gamma);"
         " v_out = matrix_xyz_rgb * v_in ;"
@@ -563,30 +563,26 @@ opengl_init_swizzle(struct vlc_gl_sampler *sampler,
 }
 
 static void
-InitOrientationMatrix(GLfloat matrix[static 4*4],
+InitOrientationMatrix(GLfloat matrix[static 3*3],
                       video_orientation_t orientation)
 {
-    memcpy(matrix, MATRIX4_IDENTITY, sizeof(MATRIX4_IDENTITY));
+    memcpy(matrix, MATRIX3_IDENTITY, sizeof(MATRIX3_IDENTITY));
 
 /**
- * / C0R0  C1R0     0  C3R0 \
- * | C0R1  C1R1     0  C3R1 |
- * |    0     0     1     0 |  <-- keep the z coordinate unchanged
- * \    0     0     0     1 /
- *                  ^
- *                  |
- *                  z never impacts the orientation
+ * / C0R0  C1R0  C3R0 \
+ * | C0R1  C1R1  C3R1 |
+ * \    0     0     1 /
  *
  * (note that in memory, the matrix is stored in column-major order)
  */
 #define MATRIX_SET(C0R0, C1R0, C3R0, \
                    C0R1, C1R1, C3R1) \
-    matrix[0*4 + 0] = C0R0; \
-    matrix[1*4 + 0] = C1R0; \
-    matrix[3*4 + 0] = C3R0; \
-    matrix[0*4 + 1] = C0R1; \
-    matrix[1*4 + 1] = C1R1; \
-    matrix[3*4 + 1] = C3R1;
+    matrix[0*3 + 0] = C0R0; \
+    matrix[1*3 + 0] = C1R0; \
+    matrix[2*3 + 0] = C3R0; \
+    matrix[0*3 + 1] = C0R1; \
+    matrix[1*3 + 1] = C1R1; \
+    matrix[2*3 + 1] = C3R1;
 
     /**
      * The following schemas show how the video picture is oriented in the
@@ -804,9 +800,9 @@ sampler_planes_load(struct vlc_gl_sampler *sampler)
 
     /* Return the expected transform matrix if interop == NULL */
     const GLfloat *tm = GetTransformMatrix(priv->interop);
-    vt->UniformMatrix4fv(priv->uloc.TransformMatrix, 1, GL_FALSE, tm);
+    vt->UniformMatrix3fv(priv->uloc.TransformMatrix, 1, GL_FALSE, tm);
 
-    vt->UniformMatrix4fv(priv->uloc.OrientationMatrix, 1, GL_FALSE,
+    vt->UniformMatrix3fv(priv->uloc.OrientationMatrix, 1, GL_FALSE,
                          priv->var.OrientationMatrix);
 
     if (priv->tex_target == GL_TEXTURE_RECTANGLE)
@@ -835,14 +831,14 @@ sampler_planes_init(struct vlc_gl_sampler *sampler)
 
     ADDF("uniform %s Texture;\n", sampler_type);
     ADD("uniform mat3 TexCoordsMap;\n"
-        "uniform mat4 TransformMatrix;\n"
-        "uniform mat4 OrientationMatrix;\n");
+        "uniform mat3 TransformMatrix;\n"
+        "uniform mat3 OrientationMatrix;\n");
 
     if (tex_target == GL_TEXTURE_RECTANGLE)
         ADD("uniform vec2 TexSize;\n");
 
     ADD("vec4 vlc_texture(vec2 pic_coords) {\n"
-        " vec2 tex_coords = (TexCoordsMap * vec3((TransformMatrix * OrientationMatrix * vec4(pic_coords, 0.0, 1.0)).xy, 1.0)).xy;\n");
+        " vec2 tex_coords = (TransformMatrix * TexCoordsMap * OrientationMatrix * vec3(pic_coords, 1.0)).xy;\n");
 
     if (tex_target == GL_TEXTURE_RECTANGLE)
     {
@@ -929,8 +925,8 @@ opengl_fragment_shader_init(struct vlc_gl_sampler *sampler, GLenum tex_target,
 #define ADD(x) vlc_memstream_puts(&ms, x)
 #define ADDF(x, ...) vlc_memstream_printf(&ms, x, ##__VA_ARGS__)
 
-    ADD("uniform mat4 TransformMatrix;\n"
-        "uniform mat4 OrientationMatrix;\n");
+    ADD("uniform mat3 TransformMatrix;\n"
+        "uniform mat3 OrientationMatrix;\n");
     ADDF("uniform %s Textures[%u];\n", glsl_sampler, tex_count);
     ADD("uniform mat3 TexCoordsMap;\n");
 
@@ -1022,7 +1018,7 @@ opengl_fragment_shader_init(struct vlc_gl_sampler *sampler, GLenum tex_target,
         ADD("uniform mat4 ConvMatrix;\n");
 
     ADD("vec4 vlc_texture(vec2 pic_coords) {\n"
-        " vec2 tex_coords = (TexCoordsMap * vec3((TransformMatrix * OrientationMatrix * vec4(pic_coords, 0.0, 1.0)).xy, 1.0)).xy;\n");
+        " vec2 tex_coords = (TransformMatrix * TexCoordsMap * OrientationMatrix * vec3(pic_coords, 1.0)).xy;\n");
 
     unsigned color_count;
     if (is_yuv) {