--- /dev/null
+# Library Replacement Recommendations for Tvheadend
+
+This document provides a comprehensive analysis of custom implementations in the Tvheadend codebase that could potentially be replaced by well-established external libraries. Each recommendation includes the current implementation, suggested library alternatives, and considerations for migration.
+
+---
+
+## Table of Contents
+
+1. [JSON Parsing and Serialization](#1-json-parsing-and-serialization)
+2. [XML Parsing](#2-xml-parsing)
+3. [URL Parsing](#3-url-parsing)
+4. [UUID Generation and Handling](#4-uuid-generation-and-handling)
+5. [HTTP Client/Server](#5-http-clientserver)
+6. [Buffer Management](#6-buffer-management)
+7. [Message/Data Serialization](#7-messagedata-serialization)
+8. [Cron Expression Parsing](#8-cron-expression-parsing)
+9. [String Manipulation](#9-string-manipulation)
+10. [Character Encoding Conversion](#10-character-encoding-conversion)
+11. [Compression (zlib wrapper)](#11-compression-zlib-wrapper)
+12. [Configuration Management](#12-configuration-management)
+13. [Logging System](#13-logging-system)
+14. [Thread Pool and Async Operations](#14-thread-pool-and-async-operations)
+15. [File System Monitoring](#15-file-system-monitoring)
+16. [Regular Expression Handling](#16-regular-expression-handling)
+17. [M3U Parsing](#17-m3u-parsing)
+18. [Double/Float String Conversion](#18-doublefloat-string-conversion)
+
+---
+
+## 1. JSON Parsing and Serialization
+
+### Current Implementation
+- **Files**: `src/misc/json.c`, `src/misc/json.h`, `src/htsmsg_json.c`, `src/htsmsg_json.h`
+- **Description**: Custom JSON parser/serializer integrated with the htsmsg message format
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **cJSON** | MIT | ~30KB | Lightweight, widely used, easy to integrate |
+| **json-c** | MIT | ~250KB | Full-featured, stable, good performance |
+| **Jansson** | MIT | ~200KB | Well-documented, easy API, actively maintained |
+| **yyjson** | MIT | ~50KB | Fastest JSON parser for C, read-only support |
+| **parson** | MIT | ~30KB | Single-file, simple API |
+
+### Recommendation
+**cJSON** or **Jansson** would be the best choices:
+- cJSON is extremely lightweight and easy to integrate
+- Jansson provides better error handling and documentation
+- Both are MIT licensed and actively maintained
+
+### Migration Considerations
+- The current implementation is tightly integrated with `htsmsg_t` structure
+- Would need adapter functions to convert between library format and htsmsg
+- Consider keeping htsmsg as the internal format and using JSON library only for I/O
+
+---
+
+## 2. XML Parsing
+
+### Current Implementation
+- **Files**: `src/htsmsg_xml.c`, `src/htsmsg_xml.h`
+- **Description**: Custom XML parser supporting UTF-8, ISO-8859-1, CDATA, comments, namespaces, and basic XPath
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libxml2** | MIT | ~2MB | Full-featured, industry standard |
+| **expat** | MIT | ~300KB | SAX parser, event-based, fast |
+| **mxml** | Apache 2.0 | ~150KB | Lightweight, easy API |
+| **pugixml** | MIT | ~150KB | C++, fast DOM parser |
+| **yxml** | MIT | ~10KB | Ultra-lightweight, streaming parser |
+
+### Recommendation
+**expat** is the best choice:
+- Lightweight and fast
+- Event-based parsing fits TV stream processing
+- Widely used, stable, well-tested
+- MIT licensed
+
+### Migration Considerations
+- Current implementation has custom XPath support
+- Would need to implement XPath separately or use libxml2 for full XPath
+- Consider expat for basic parsing, libxml2 for complex XPath needs
+
+---
+
+## 3. URL Parsing
+
+### Current Implementation
+- **Files**: `src/url.c`, `src/url.h`
+- **Description**: URL parsing using regex or liburiparser (already conditional)
+- **Note**: Already has optional liburiparser support via `ENABLE_URIPARSER`
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **liburiparser** | BSD-3 | ~100KB | Already optionally used, full RFC 3986 support |
+| **curl** (URL API) | MIT | N/A | If already using libcurl |
+| **yuarel** | MIT | ~5KB | Single-file, minimal |
+
+### Recommendation
+**Make liburiparser mandatory** instead of optional:
+- Already integrated and tested
+- Full RFC 3986 compliance
+- Removes maintenance burden of regex fallback
+
+### Migration Considerations
+- Simply make `ENABLE_URIPARSER` always enabled
+- Remove the regex-based fallback code
+- Minimal effort required
+
+---
+
+## 4. UUID Generation and Handling
+
+### Current Implementation
+- **Files**: `src/uuid.c`, `src/uuid.h`
+- **Description**: Custom UUID generation using `/dev/urandom`, hex conversion utilities
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libuuid** | BSD-3 | ~50KB | Standard on Linux, part of util-linux |
+| **uuid4** | MIT | ~5KB | Single-header, UUID v4 only |
+| **ossp-uuid** | MIT | ~200KB | Full UUID versions support |
+
+### Recommendation
+**libuuid** (from util-linux):
+- Standard on all Linux systems
+- Supports UUID v1, v3, v4, v5
+- Thread-safe
+- Already a dependency on most systems
+
+### Migration Considerations
+- Current implementation is simple and functional
+- libuuid would provide proper UUID versioning
+- Low priority change - current implementation is adequate
+
+---
+
+## 5. HTTP Client/Server
+
+### Current Implementation
+- **Files**: `src/http.c`, `src/httpc.c`, `src/tcp.c`
+- **Description**: Custom HTTP/1.1 client and server implementation
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libcurl** | MIT | ~1MB | Industry standard, full HTTP/2/3 support |
+| **libmicrohttpd** | LGPL | ~300KB | Embedded HTTP server |
+| **libevent** | BSD-3 | ~500KB | Event-driven networking |
+| **mongoose** | GPL/Commercial | ~300KB | Embedded web server |
+
+### Recommendation
+**Not recommended to replace entirely**:
+- Current implementation is well-tuned for TV streaming needs
+- However, consider using **libcurl** for outbound HTTP requests (EPG fetching, etc.)
+- Keep custom server for HTSP protocol needs
+
+### Migration Considerations
+- HTTP client portion could use libcurl
+- Server portion is specialized for streaming
+- Partial migration is possible
+
+---
+
+## 6. Buffer Management
+
+### Current Implementation
+- **Files**: `src/htsbuf.c`, `src/htsbuf.h`, `src/sbuf.h`
+- **Description**: Custom queue-based buffer implementation for streaming data
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **klib** (kvec) | MIT | ~20KB | Header-only dynamic arrays |
+| **uthash** (utarray) | BSD | ~20KB | Header-only arrays |
+| **GLib** (GByteArray) | LGPL | Large | Full featured |
+
+### Recommendation
+**Keep current implementation**:
+- Custom buffer is optimized for streaming use case
+- Minimal overhead, well-tested
+- No significant benefit from migration
+
+---
+
+## 7. Message/Data Serialization
+
+### Current Implementation
+- **Files**: `src/htsmsg.c`, `src/htsmsg_binary.c`, `src/htsmsg_binary2.c`
+- **Description**: Custom hierarchical message format (htsmsg) with binary serialization
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **Protocol Buffers** | BSD-3 | ~2MB | Google's serialization, requires schema |
+| **MessagePack** | BSL-1.0 | ~100KB | Binary JSON, schemaless |
+| **FlatBuffers** | Apache 2.0 | ~1MB | Zero-copy access |
+| **CBOR (tinycbor)** | MIT | ~50KB | Binary JSON, RFC 8949 |
+
+### Recommendation
+**Keep current implementation for internal use**:
+- htsmsg is deeply integrated throughout codebase
+- Optimized for TV metadata structures
+- Consider **MessagePack** or **CBOR** for external interoperability if needed
+
+### Migration Considerations
+- Very high effort to replace
+- Current implementation is well-suited to the application
+- Not recommended for replacement
+
+---
+
+## 8. Cron Expression Parsing
+
+### Current Implementation
+- **Files**: `src/cron.c`, `src/cron.h`
+- **Description**: Custom cron expression parser for scheduling
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **ccronexpr** | Apache 2.0 | ~30KB | Full cron expression support |
+| **libcron** | MIT | ~50KB | C++ cron library |
+| **cron-parser** | MIT | ~20KB | Simple cron parser |
+
+### Recommendation
+**ccronexpr**:
+- Full standard cron expression support
+- Well-tested
+- Small footprint
+
+### Migration Considerations
+- Current implementation is functional but limited
+- Migration would add support for more cron features
+- Medium priority
+
+---
+
+## 9. String Manipulation
+
+### Current Implementation
+- **Files**: `src/htsstr.c`, `src/tvh_string.h`
+- **Description**: String escaping, argument parsing, substitution
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **bstrlib** | BSD | ~100KB | Better string library for C |
+| **sds** | BSD-2 | ~30KB | Simple dynamic strings (Redis) |
+| **GLib** (GString) | LGPL | Large | Full string utilities |
+
+### Recommendation
+**Keep current implementation**:
+- Functions are simple and well-tested
+- No significant benefit from migration
+- Would require extensive code changes
+
+---
+
+## 10. Character Encoding Conversion
+
+### Current Implementation
+- **Files**: `src/intlconv.c`, `src/intlconv.h`
+- **Description**: Character encoding conversion wrapper around iconv
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **glibc iconv** | LGPL | N/A | Standard on Linux (system-provided) |
+| **libiconv** | LGPL | ~2MB | GNU iconv for non-glibc systems |
+| **ICU** | Unicode License | ~25MB | Full Unicode support |
+| **utf8proc** | MIT | ~200KB | UTF-8 specific |
+
+### Recommendation
+**Keep current implementation**:
+- Already using system iconv (glibc iconv or libiconv) efficiently
+- Custom wrapper in `intlconv.c` provides caching for performance
+- No benefit from changing to a different encoding library
+
+---
+
+## 11. Compression (zlib wrapper)
+
+### Current Implementation
+- **Files**: `src/zlib.c`
+- **Description**: Wrapper around zlib for gzip compression/decompression
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **zlib** | zlib License | ~200KB | Already used |
+| **zlib-ng** | zlib License | ~200KB | Performance optimized fork |
+| **lz4** | BSD-2 | ~100KB | Faster compression |
+| **zstd** | BSD-3 | ~500KB | Better compression ratio |
+
+### Recommendation
+**Consider zlib-ng**:
+- Drop-in replacement for zlib
+- Better performance on modern CPUs
+- Same API, minimal changes needed
+
+### Migration Considerations
+- zlib-ng is API compatible
+- Could be a configure option
+- Low risk change
+
+---
+
+## 12. Configuration Management
+
+### Current Implementation
+- **Files**: `src/settings.c`, `src/settings.h`, `src/config.c`
+- **Description**: JSON-based configuration storage using htsmsg
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libconfig** | LGPL | ~200KB | Human-readable config files |
+| **inih** | BSD-3 | ~10KB | INI file parser |
+| **tomlc99** | MIT | ~50KB | TOML parser |
+
+### Recommendation
+**Keep current implementation**:
+- JSON-based config is flexible
+- Works well with htsmsg system
+- Migration would break existing configs
+
+---
+
+## 13. Logging System
+
+### Current Implementation
+- **Files**: `src/tvhlog.c`, `src/tvhlog.h`
+- **Description**: Custom logging with subsystems, levels, file rotation
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **syslog** | N/A | N/A | Standard Unix logging |
+| **log4c** | LGPL | ~200KB | Flexible logging framework |
+| **zlog** | LGPL | ~100KB | High-performance logging |
+
+### Recommendation
+**Keep current implementation**:
+- Well-suited to application needs
+- Subsystem-based logging is important for debugging
+- Would lose TV-specific features
+
+---
+
+## 14. Thread Pool and Async Operations
+
+### Current Implementation
+- **Files**: `src/tvh_thread.c`, `src/tvhpoll.c`
+- **Description**: Custom thread management and epoll/kqueue wrapper
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libevent** | BSD-3 | ~500KB | Event-driven I/O |
+| **libuv** | MIT | ~500KB | Cross-platform async I/O |
+| **libev** | BSD-2 | ~100KB | Lightweight event loop |
+
+### Recommendation
+**Consider libevent or libuv for new code**:
+- Current implementation works but limits portability
+- New features could use libuv for better cross-platform support
+- Not recommended for full replacement due to deep integration
+
+---
+
+## 15. File System Monitoring
+
+### Current Implementation
+- **Files**: `src/fsmonitor.c`, `src/fsmonitor.h`
+- **Description**: inotify-based file system monitoring
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libfswatch** | GPL | ~500KB | Cross-platform file watching |
+| **libuv** | MIT | ~500KB | Includes fs events |
+| **inotify-tools** | GPL | ~100KB | Linux specific |
+
+### Recommendation
+**Keep current implementation for Linux**:
+- inotify is efficient and well-suited
+- Consider libuv if cross-platform support needed
+
+---
+
+## 16. Regular Expression Handling
+
+### Current Implementation
+- **Files**: `src/tvhregex.h` (wrapper header)
+- **Description**: Wrapper around PCRE or POSIX regex
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **PCRE2** | BSD | ~1MB | Already optionally supported |
+| **RE2** | BSD-3 | ~1MB | Google's safe regex |
+| **TRE** | BSD-2 | ~200KB | POSIX-like, approximate matching |
+
+### Recommendation
+**Make PCRE2 mandatory**:
+- Already conditionally supported
+- Better performance than POSIX regex
+- More features for EPG scraping
+
+---
+
+## 17. M3U Parsing
+
+### Current Implementation
+- **Files**: `src/misc/m3u.c`, `src/misc/m3u.h`
+- **Description**: Custom M3U/M3U8 playlist parser
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **libm3u** | MIT | ~20KB | Dedicated M3U parser |
+| **hls-parser** | Various | ~50KB | HLS specific parsing |
+
+### Recommendation
+**Keep current implementation**:
+- M3U format is simple
+- Current parser handles TV-specific extensions
+- No significant benefit from migration
+
+---
+
+## 18. Double/Float String Conversion
+
+### Current Implementation
+- **Files**: `src/misc/dbl.c`, `src/misc/dbl.h`
+- **Description**: Custom locale-independent float/string conversion
+
+### Recommended Libraries
+
+| Library | License | Size | Notes |
+|---------|---------|------|-------|
+| **double-conversion** | BSD-3 | ~100KB | Google's library |
+| **ryu** | Apache/BSL | ~50KB | Fast float printing |
+| **dragonbox** | Apache/BSL | ~30KB | Fastest float-to-string |
+
+### Recommendation
+**Consider ryu or dragonbox**:
+- Generally faster than custom implementations (based on published benchmarks)
+- Guaranteed correct rounding per IEEE 754
+- Well-tested in production (used by V8, Swift, etc.)
+
+### Migration Considerations
+- Low risk, isolated functionality
+- Potential performance improvement for JSON serialization
+
+---
+
+## Summary Priority Matrix
+
+| Category | Current Quality | Migration Effort | Benefit | Priority |
+|----------|----------------|------------------|---------|----------|
+| JSON (cJSON/Jansson) | Good | Medium | Medium | **Medium** |
+| XML (expat) | Good | High | Medium | **Low** |
+| URL (liburiparser) | Excellent | Low | Low | **High** (make mandatory) |
+| UUID (libuuid) | Good | Low | Low | **Low** |
+| HTTP Client (libcurl) | Good | Medium | High | **Medium** |
+| Cron (ccronexpr) | Fair | Low | Medium | **Medium** |
+| Regex (PCRE2) | Good | Low | Medium | **High** (make mandatory) |
+| Compression (zlib-ng) | Good | Low | Medium | **Medium** |
+| Float conversion (ryu) | Good | Low | Medium | **Low** |
+
+---
+
+## Recommended Action Plan
+
+### Phase 1 (Low Effort, High Value)
+1. Make liburiparser mandatory (remove regex fallback)
+2. Make PCRE2 mandatory for regex operations
+3. Consider zlib-ng as optional high-performance alternative
+
+### Phase 2 (Medium Effort)
+1. Evaluate libcurl for HTTP client operations
+2. Replace cron parser with ccronexpr
+3. Evaluate cJSON for JSON parsing (with htsmsg adapter)
+
+### Phase 3 (Future Consideration)
+1. Consider libuv for new async features
+2. Evaluate MessagePack/CBOR for external APIs
+3. Consider expat for XML parsing improvements
+
+---
+
+## Notes
+
+- Many custom implementations are well-suited to Tvheadend's specific needs
+- The htsmsg system is central to the architecture and should be preserved
+- Library replacements should be evaluated for both functionality and performance
+- Consider backwards compatibility with existing configurations
+- Some libraries (liburiparser, PCRE2, zlib) are already optionally supported
+
+---
+
+*Document generated: 2026-01-02*
+*Based on analysis of Tvheadend source code*
projects / thirdparty / tvheadend.git / commitdiff
