Add support for ASS “Video Colorspace” property

This property has been introduced with recent versions of Aegisub and
should be taken into account if possible.

README.txt

@@ -41,6 +41,7 @@ string srt_font:
     Defaults to whatever Fontconfig chooses for “Sans”.
 string colorspace:
     The color space of your (YUV) video. Possible values:
-        - auto, guess (guess based on video resolution)
         - Rec709, BT.709
         - Rec601, BT.601
+    Default is to use the ASS script’s “Video Colorspace” property, else guess
+    based on video resolution (width > 1280 or height > 576 → BT.709).

src/assrender.c

@@ -60,6 +60,9 @@ AVS_Value AVSC_CC assrender_create(AVS_ScriptEnvironment *env, AVS_Value args,
     const char *colorspace = avs_as_string(avs_array_elt(args, 16)) ?
                              avs_as_string(avs_array_elt(args, 16)) : "guess";
 
+    char *tmpcsp = calloc(1, BUFSIZ);
+    memcpy(tmpcsp, colorspace, BUFSIZ - 1);
+
     ASS_Hinting hinting;
     udata *data;
     ASS_Track *ass;
@@ -110,8 +113,10 @@ AVS_Value AVSC_CC assrender_create(AVS_ScriptEnvironment *env, AVS_Value args,
 
     if (!strcasecmp(strrchr(f, '.'), ".srt"))
         ass = parse_srt(f, data, srt_font);
-    else
+    else {
         ass = ass_read_file(data->ass_library, (char *) f, (char *) cs);
+        ass_read_colorspace(f, tmpcsp);
+    }
 
     if (!ass) {
         sprintf(e, "AssRender: unable to parse '%s'", f);
@@ -169,15 +174,18 @@ AVS_Value AVSC_CC assrender_create(AVS_ScriptEnvironment *env, AVS_Value args,
         data->isvfr = 0;
     }
 
-    if (!strcasecmp(colorspace, "guess") || !strcasecmp(colorspace, "auto")) {
+    if (!strcasecmp(tmpcsp, "bt.709") || !strcasecmp(tmpcsp,"rec709"))
+        data->colorspace = BT709;
+    else if (!strcasecmp(tmpcsp, "bt.601") || !strcasecmp(tmpcsp, "rec601"))
+        data->colorspace = BT601;
+    else {
         if (fi->vi.width > 1280 || fi->vi.height > 576)
             data->colorspace = BT709;
         else
             data->colorspace = BT601;
-    } else if (!strcasecmp(colorspace, "bt.709") || !strcasecmp(colorspace,"rec709"))
-        data->colorspace = BT709;
-    else if (!strcasecmp(colorspace, "bt.601") || !strcasecmp(colorspace, "rec601"))
-        data->colorspace = BT601;
+    }
+
+    free(tmpcsp);
 
     data->uv_tmp[0] = malloc(fi->vi.width * fi->vi.height);
     data->uv_tmp[1] = malloc(fi->vi.width * fi->vi.height);

src/sub.c

@@ -4,6 +4,25 @@
 
 #include "assrender.h"
 
+void ass_read_colorspace(const char *f, char *csp) {
+    char buf[BUFSIZ];
+    FILE *fh = fopen(f, "r");
+
+    if (!fh)
+        return;
+
+    while (fgets(buf, BUFSIZ - 1, fh) != NULL) {
+        if (buf[0] == 0 || buf[0] == '\n' || buf[0] == '\r')
+            continue;
+
+        if (sscanf(buf, "Video Colorspace: %s", csp) == 1)
+            break;
+
+        if (!strcmp(buf, "[Events]"))
+            break;
+    }
+}
+
 ASS_Track *parse_srt(const char *f, udata *ud, const char *srt_font)
 {
     char l[BUFSIZ], buf[BUFSIZ];

src/sub.h

@@ -1,3 +1,5 @@
+void ass_read_colorspace(const char *f, char *csp);
+
 ASS_Track *parse_srt(const char *f, udata *ud, const char *srt_font);
 
 void msg_callback(int level, const char *fmt, va_list va, void *data);