tweak matrix guess by video size

Author: seiya-git

docs/CHANGELOG.md

@@ -1,18 +1,13 @@
 ## Change log
 
-### 0.36.0-dev.3 (20251202)
-* Use frame properties if they available for "YCbCr Matrix: None"
-
-### 0.36.0-dev.2 (20251201)
-* Restore x86-32 assrender.dll build
-
-### 0.36.0-dev.1 (20251201)
+### 0.36.0-dev.4 (20251201)
 * Switch submodule build system to meson
 * Update avisynth(plus) headers to v12
+* Update libass to 0.17.4
 * Unicode-safe file reading
 * Add frame size parameters
 * Add set_default_storage_size boolean
-* Update libass to 0.17.4
+* Use frame properties if they available for "YCbCr Matrix: None"
 
 ### 0.35 (20210304)
 * Windows MSVC: Update to libass v0.15

docs/README.md

@@ -81,8 +81,7 @@ Default is to use the ASS script's "YCbCr Matrix" or "Video Colorspace" property
 
 Recognized .ASS properties: "TV.601" "TV.709", "PC.601" "PC.709" "TV.240m" "PC.240m" "TV.fcc" "PC.fcc" and "none". 
 
-"none" and "guess" decides upon on video resolution: width > 1280 or height > 576 → BT.709, else → BT.601.
-When no hint found in ASS script and 'colorspace' parameter is empty then the default is BT.601.
+"none" and "guess" determine the colorspace based on the video's `_Matrix` frame property if available. Otherwise, if the resolution is width > 1024 or height > 576, BT.709 is used; otherwise BT.601.
 
 ## Build instructions
 See: [BUILD.md](BUILD.md)

src/assrender.c

@@ -450,13 +450,6 @@ AVS_Value AVSC_CC assrender_create(AVS_ScriptEnvironment* env, AVS_Value args,
         color_mt = MATRIX_BT2020;
       }
       else if (!strcasecmp(tmpcsp, "none") || !strcasecmp(tmpcsp, "guess")) {
-        /* not yet
-        * Theoretically only for 10 and 12 bits:
-        if (fi->vi.width > 1920 || fi->vi.height > 1080)
-          color_mt = MATRIX_BT2020;
-        else 
-        */
-
         int mt_from_props_ok = 0;
         matrix_type mt_from_props = MATRIX_NONE;
 
@@ -467,10 +460,16 @@ AVS_Value AVSC_CC assrender_create(AVS_ScriptEnvironment* env, AVS_Value args,
         if (mt_from_props_ok && mt_from_props != MATRIX_NONE) {
             color_mt = mt_from_props;
         } else {
-            if (vi->width >= 1280 || vi->height >= 576) {
-                color_mt = MATRIX_PC709;
+            /* not yet
+            * Theoretically only for 10 and 12 bits:
+            if (fi->vi.width > 1920 || fi->vi.height > 1080)
+            color_mt = MATRIX_BT2020;
+            else
+            */
+            if (vi->width > 1024 || vi->height > 576) {
+                color_mt = MATRIX_BT709;
             } else {
-                color_mt = MATRIX_PC601;
+                color_mt = MATRIX_BT601;
             }
         }
       }
@@ -501,7 +500,6 @@ AVS_Value AVSC_CC assrender_create(AVS_ScriptEnvironment* env, AVS_Value args,
       return v;
     }
 
-
     switch (fi->vi.pixel_type)
     {
     case AVS_CS_YV12: