Bug Fix: M3U profile URL rewriting now uses the regex module instead of re across all URL transform code paths (url_utils.transform_url, core/views.py, vod_proxy/_transform_url, tasks.get_transformed_credentials, and the WebSocket live-preview handler in consumers.py). The regex module natively accepts JavaScript/PCRE-style named capture groups ((?<name>...)) without any conversion, eliminating the root cause of patterns that matched in the frontend live preview but failed on the backend with a re.error. As a further improvement, regex also supports variable-length lookbehind assertions (e.g. (?<=a+)), which re rejects with an error; patterns using these will now work correctly on the backend as well. Replace-pattern JS tokens are still normalised before calling regex.sub: $<name> → \g<name> and $1/$2/… → \1/\2/… (Python replacement syntax). Also fixed a bug in the WebSocket preview handler where a pattern error was incorrectly returning the search pattern string as the preview output instead of the original URL. (Fixes #1005)

CHANGELOG.md

@@ -59,6 +59,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- M3U profile URL rewriting now uses the `regex` module instead of `re` across all URL transform code paths (`url_utils.transform_url`, `core/views.py`, `vod_proxy/_transform_url`, `tasks.get_transformed_credentials`, and the WebSocket live-preview handler in `consumers.py`). The `regex` module natively accepts JavaScript/PCRE-style named capture groups (`(?<name>...)`) without any conversion, eliminating the root cause of patterns that matched in the frontend live preview but failed on the backend with a `re.error`. As a further improvement, `regex` also supports variable-length lookbehind assertions (e.g. `(?<=a+)`), which `re` rejects with an error; patterns using these will now work correctly on the backend as well. Replace-pattern JS tokens are still normalised before calling `regex.sub`: `$<name>` → `\g<name>` and `$1`/`$2`/… → `\1`/`\2`/… (Python replacement syntax). Also fixed a bug in the WebSocket preview handler where a pattern error was incorrectly returning the search pattern string as the preview output instead of the original URL. (Fixes #1005)
 - Web UI stream preview (`FloatingVideo`) was calling `mpegts.createPlayer()` with all `Config` options (e.g. `enableWorker`, `liveSync`, `headers`) merged into the first `MediaDataSource` argument. mpegts.js only reads `Config` from the optional second argument; unrecognised fields in the first are silently ignored. As a result all player configuration was effectively the library defaults — worker offloading was disabled, latency management had no effect, and the `Authorization: Bearer` header (required for user identification) was never sent. Fixed by splitting into the correct two-argument call. Both `liveBufferLatencyChasing` and `liveSync` have been disabled, eliminating playback-rate fluctuations that caused audible stuttering on live streams. SourceBuffer cleanup thresholds were also relaxed from 10s/5s to 120s/60s to prevent frequent SourceBuffer pauses.
 - HTML named entities in XMLTV EPG files are now resolved to Unicode characters before lxml parsing. Some EPG providers (particularly French and other European sources) use HTML named entities like `&eacute;`, `&icirc;`, `&uuml;` in channel names, program titles, and metadata. These are not valid XML entities — lxml 6.0.2 with `recover=True` silently drops them, causing characters to go missing (e.g., "Chaîne Télé" becomes "Chane Tl"). A preprocessing step in `fetch_xmltv()` now resolves HTML named entities while preserving the 5 XML-predefined entities, detecting encoding from the XML declaration (falling back to UTF-8), and processing line-by-line to a temp file before atomically replacing the original. (Closes #1095) — Thanks [@CodeBormen](https://github.com/CodeBormen)
 - Duplicate recordings created when EPG sources refresh and re-evaluate series rules (Fixes #940) — Thanks [@CodeBormen](https://github.com/CodeBormen):

apps/m3u/tasks.py

@@ -1,6 +1,7 @@
 # apps/m3u/tasks.py
 import logging
 import re
+import regex
 import requests
 import os
 import gc
@@ -2399,11 +2400,13 @@ def get_transformed_credentials(account, profile=None):
         # Apply profile-specific transformations if profile is provided
         if profile and profile.search_pattern and profile.replace_pattern:
             try:
-                # Handle backreferences in the replacement pattern
-                safe_replace_pattern = re.sub(r'\$(\d+)', r'\\\1', profile.replace_pattern)
+                # Handle backreferences: convert JS-style $<name> -> \g<name>, $1 -> \1
+                # regex module accepts JS-style (?<name>...) named groups natively
+                safe_replace_pattern = regex.sub(r'\$<([^>]+)>', r'\\g<\1>', profile.replace_pattern)
+                safe_replace_pattern = regex.sub(r'\$(\d+)', r'\\\1', safe_replace_pattern)
 
                 # Apply transformation to the complete URL
-                transformed_complete_url = re.sub(profile.search_pattern, safe_replace_pattern, complete_url)
+                transformed_complete_url = regex.sub(profile.search_pattern, safe_replace_pattern, complete_url)
                 logger.info(f"Transformed complete URL: {complete_url} -> {transformed_complete_url}")
 
                 # Extract components from the transformed URL

apps/proxy/ts_proxy/url_utils.py

@@ -3,7 +3,7 @@ Utilities for handling stream URLs and transformations.
 """
 
 import logging
-import re
+import regex
 from typing import Optional, Tuple, List
 from django.shortcuts import get_object_or_404
 from apps.channels.models import Channel, Stream
@@ -146,13 +146,14 @@ def transform_url(input_url: str, search_pattern: str, replace_pattern: str) ->
         logger.debug(f"  base URL: {input_url}")
         logger.debug(f"  search: {search_pattern}")
 
-        # Handle backreferences in the replacement pattern
-        safe_replace_pattern = re.sub(r'\$(\d+)', r'\\\1', replace_pattern)
+        # Convert JS-style backreferences in replace pattern: $<name> -> \g<name>, $1 -> \1
+        safe_replace_pattern = regex.sub(r'\$<([^>]+)>', r'\\g<\1>', replace_pattern)
+        safe_replace_pattern = regex.sub(r'\$(\d+)', r'\\\1', safe_replace_pattern)
         logger.debug(f"  replace: {replace_pattern}")
         logger.debug(f"  safe replace: {safe_replace_pattern}")
 
-        # Apply the transformation
-        stream_url = re.sub(search_pattern, safe_replace_pattern, input_url)
+        # Apply the transformation (regex module accepts JS-style (?<name>...) natively)
+        stream_url = regex.sub(search_pattern, safe_replace_pattern, input_url)
         logger.info(f"Generated stream url: {stream_url}")
 
         return stream_url

apps/proxy/vod_proxy/views.py

@@ -270,17 +270,20 @@ def _get_m3u_profile(m3u_account, profile_id, session_id=None):
 def _transform_url(original_url, m3u_profile):
     """Transform URL based on M3U profile settings"""
     try:
-        import re
+        import regex
 
         if not original_url:
             return None
 
         search_pattern = m3u_profile.search_pattern
         replace_pattern = m3u_profile.replace_pattern
-        safe_replace_pattern = re.sub(r'\$(\d+)', r'\\\1', replace_pattern)
+        # Convert JS-style backreferences in replace: $<name> -> \g<name>, $1 -> \1
+        safe_replace_pattern = regex.sub(r'\$<([^>]+)>', r'\\g<\1>', replace_pattern)
+        safe_replace_pattern = regex.sub(r'\$(\d+)', r'\\\1', safe_replace_pattern)
 
         if search_pattern and replace_pattern:
-            transformed_url = re.sub(search_pattern, safe_replace_pattern, original_url)
+            # regex module accepts JS-style (?<name>...) named groups natively
+            transformed_url = regex.sub(search_pattern, safe_replace_pattern, original_url)
             return transformed_url
 
         return original_url

core/views.py

@@ -4,7 +4,7 @@ from shlex import split as shlex_split
 import sys
 import subprocess
 import logging
-import re
+import regex
 import redis
 
 from django.conf import settings
@@ -132,10 +132,13 @@ def stream_view(request, channel_uuid):
         # Prepare the pattern replacement.
         logger.debug("Executing the following pattern replacement:")
         logger.debug(f"  search: {active_profile.search_pattern}")
-        safe_replace_pattern = re.sub(r'\$(\d+)', r'\\\1', active_profile.replace_pattern)
+        # Convert JS-style backreferences in replace: $<name> -> \g<name>, $1 -> \1
+        safe_replace_pattern = regex.sub(r'\$<([^>]+)>', r'\\g<\1>', active_profile.replace_pattern)
+        safe_replace_pattern = regex.sub(r'\$(\d+)', r'\\\1', safe_replace_pattern)
         logger.debug(f"  replace: {active_profile.replace_pattern}")
         logger.debug(f"  safe replace: {safe_replace_pattern}")
-        stream_url = re.sub(active_profile.search_pattern, safe_replace_pattern, input_url)
+        # regex module accepts JS-style (?<name>...) named groups natively
+        stream_url = regex.sub(active_profile.search_pattern, safe_replace_pattern, input_url)
         logger.debug(f"Generated stream url: {stream_url}")
 
         # Get the stream profile set on the channel.

dispatcharr/consumers.py

@@ -1,6 +1,6 @@
 import json
 from channels.generic.websocket import AsyncWebsocketConsumer
-import re, logging
+import regex, logging
 
 logger = logging.getLogger(__name__)
 
@@ -54,9 +54,9 @@ class MyWebSocketConsumer(AsyncWebsocketConsumer):
 
             # Apply the transformation using the replace_with_mark function
             try:
-                search_preview = re.sub(data["search"], replace_with_mark, data["url"])
+                search_preview = regex.sub(data["search"], replace_with_mark, data["url"])
             except Exception as e:
-                search_preview = data["search"]
+                search_preview = data["url"]
                 logger.error(f"Failed to generate replace preview: {e}")
 
             result = transform_url(data["url"], data["search"], data["replace"])

frontend/src/components/forms/M3UProfile.jsx

@@ -290,7 +290,7 @@ const RegexFormAndView = ({ profile = null, m3u, isOpen, onClose }) => {
     setXcMode(mode);
   };
 
-  // Local regex testing for immediate visual feedback
+  // Local regex for the live demo preview
   const getHighlightedSearchText = () => {
     if (!searchPattern || !sampleInput) return sampleInput;
     try {