v0.11.2: Detect and reject bitmap subtitles (PGS/VobSub)

Bitmap subtitle formats (hdmv_pgs_subtitle, dvd_subtitle, dvb_subtitle, xsub)
contain images, not text, and cannot be translated. Previously these were
extracted as binary data and sent to DeepL, producing garbled output.

- find_source_subtitle(): filter out bitmap codecs, prefer text tracks
- translate_subtitle(): check codec before extraction, raise clear error
- Log warning when only bitmap subtitles available

Fixes: Grand Designs UK S27E06 producing 86% corrupted output

Author: Daniel Nylander

CHANGELOG.md

@@ -1,3 +1,14 @@
+## v0.11.2 — Bitmap subtitle detection
+
+**Bug fix: Reject bitmap subtitles (PGS/VobSub/DVB)**
+
+- Detect bitmap subtitle codecs (`hdmv_pgs_subtitle`, `dvd_subtitle`, `dvb_subtitle`, `xsub`) before extraction
+- Skip bitmap tracks in `find_source_subtitle()` — prefer text-based tracks (SRT/ASS/SSA/VTT)
+- Show clear error message when only bitmap subtitles are available
+- Prevents sending binary PGS data to DeepL (which produced garbled output)
+
+Reported by Daniel via Grand Designs UK S27E06 subtitle with PGS tracks.
+
 ## v0.11.0 (2026-03-22)
 
 ### New: Context-Aware Translation

addon.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <addon id="service.subtitletranslator"
        name="Subtitle Translator"
-       version="0.11.1"
+       version="0.11.2"
        provider-name="yeager">
     <requires>
         <import addon="xbmc.python" version="3.0.0"/>

service.py

@@ -553,20 +553,36 @@ def find_source_subtitle(self, subtitles):
         """Find the best source subtitle for translation."""
         source_lang = self.source_language.lower()
 
+        # Filter out bitmap subtitle formats (PGS, VobSub, DVB) — can't translate those
+        BITMAP_CODECS = {'hdmv_pgs_subtitle', 'dvd_subtitle', 'dvb_subtitle', 'xsub'}
+        text_subs = [s for s in subtitles if s.get('codec', '').lower() not in BITMAP_CODECS]
+        bitmap_subs = [s for s in subtitles if s.get('codec', '').lower() in BITMAP_CODECS]
+        
+        if not text_subs and bitmap_subs:
+            log(f"Only bitmap subtitles found ({len(bitmap_subs)} tracks, codecs: "
+                f"{', '.join(s.get('codec','?') for s in bitmap_subs)}). "
+                f"Bitmap subtitles cannot be translated — they contain images, not text.",
+                xbmc.LOGWARNING)
+            return None
+        
+        if bitmap_subs:
+            log(f"Skipping {len(bitmap_subs)} bitmap subtitle track(s), "
+                f"using {len(text_subs)} text-based track(s)")
+        
         # First, try to find the specified source language
         if source_lang != 'auto':
-            for sub in subtitles:
+            for sub in text_subs:
                 if self._lang_match(sub.get('language', ''), source_lang):
                     return sub
 
         # Fallback: look for English
-        for sub in subtitles:
+        for sub in text_subs:
             if self._lang_match(sub.get('language', ''), 'en'):
                 return sub
 
-        # Last resort: take the first subtitle
-        if subtitles:
-            return subtitles[0]
+        # Last resort: take the first text subtitle
+        if text_subs:
+            return text_subs[0]
 
         return None
 
@@ -620,6 +636,21 @@ def translate_subtitle(self, source_sub):
             progress.set_stage('extract', get_string(30707))  # "Extracting subtitles..."
             get_debug_logger().debug(f"Extracting subtitle index {source_sub.get('index', 0)}", 'ffmpeg')
 
+            # Check if subtitle is a bitmap format (PGS/VobSub) — can't translate those
+            BITMAP_CODECS = {'hdmv_pgs_subtitle', 'dvd_subtitle', 'dvb_subtitle', 'xsub'}
+            sub_codec = source_sub.get('codec', 'unknown').lower()
+            if sub_codec in BITMAP_CODECS:
+                error_msg = (
+                    f"Cannot translate bitmap subtitles (codec: {sub_codec}). "
+                    f"This subtitle track contains images, not text. "
+                    f"Only text-based subtitles (SRT, ASS, SSA, VTT) can be translated."
+                )
+                log(error_msg, xbmc.LOGWARNING)
+                if self.show_notification:
+                    notify(get_string(30720) if get_string(30720) != '' else 
+                           "Bitmap subtitles cannot be translated")
+                raise Exception(error_msg)
+            
             extractor = SubtitleExtractor(ffmpeg_path)
             subtitle_content = extractor.extract(
                 self.current_file,