Fast and local neural text-to-speech engine
This report presents the forensic synthetic code analysis of OHF-Voice/piper1-gpl, a C++ project with 4,784 GitHub stars. SynthScan v2.0 examined 36,973 lines of code across 91 source files, recording 270 pattern matches distributed across 9 syntactic categories. The overall adjusted score of 7.7 places this repository in the Low AI signal band.
The scanner applied 160+ deterministic lexical heuristics, multi-line block detectors, abstract syntax tree depth profilers, and a cross-file Jaccard similarity matrix to construct a statistically normalised synthetic code estimate. All matches are individually weighted by severity coefficient and contextual multiplier before summation, and the resulting headline score is temporally discounted to account for the repository's development history relative to the commercial emergence of large language model coding tooling (November 2022 onward).
Longitudinal tracking requires multiple scan runs. Once this repository is re-scanned after new commits land, this chart will visualise how the synthetic code signal evolves over time — enabling you to detect whether AI authorship is growing, stabilising, or being actively corrected by human engineers.
Classifies detected patterns by their diagnostic confidence and structural impact. CRITICAL patterns (coefficient 10) represent definitive synthetic signatures — hallucinated imports, explicit LLM attribution metadata — virtually never produced by human authors. HIGH (5) indicates strong structural tells such as cross-file repetition or cross-linguistic idioms. MEDIUM (2) covers recognisable conversational padding and AI-specific vocabulary. LOW (1) captures subtle indicators like tautological comments and generic boilerplate that require density to carry independent signal.
This horizontal bar chart decomposes the repository's raw synthetic code score by top-level directory, allowing you to pinpoint precisely which modules or components carry the highest AI authorship density. Directories with disproportionately high scores relative to their size warrant targeted manual review: concentrated AI signatures often trace back to mass-generated configuration layers, auto-ported test suites, LLM-scaffolded boilerplate classes, or entire subsystems authored under heavy copilot assistance. Use this view to prioritise your human code-review effort.
The scanner identified 270 distinct pattern matches across 9 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a statistically significant AI authorship indicator. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.
Reading the findings table: The Severity column indicates the diagnostic confidence level (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — comment-context matches receive a ×1.5 weight because LLMs systematically over-annotate. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier as dense clusters constitute far stronger evidence of synthetic authorship than isolated hits.
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | tests/test_piper.py | 457 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 165 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 167 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 170 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 172 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 178 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 180 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 183 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 185 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 189 | # ------------------------ | COMMENT |
| MEDIUM⚡ | tests/test_chinese_phonemizer.py | 191 | # ------------------------ | COMMENT |
| MEDIUM | tests/generate_test_voice.py | 87 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM | libpiper/CMakeLists.txt | 192 | # ---------------- | COMMENT |
| MEDIUM | libpiper/CMakeLists.txt | 194 | # ---------------- | COMMENT |
| MEDIUM | src/piper/phonemize_chinese.py | 55 | # -------------------- | COMMENT |
| MEDIUM | src/piper/phonemize_chinese.py | 57 | # -------------------- | COMMENT |
| MEDIUM | src/piper/phonemize_chinese.py | 82 | # -------------------- | COMMENT |
| MEDIUM | src/piper/phonemize_chinese.py | 84 | # -------------------- | COMMENT |
| MEDIUM⚡ | src/piper/phonemize_chinese.py | 127 | # -------------------- | COMMENT |
| MEDIUM⚡ | src/piper/phonemize_chinese.py | 129 | # -------------------- | COMMENT |
| MEDIUM⚡ | src/piper/phonemize_chinese.py | 135 | # -------------------- | COMMENT |
| MEDIUM⚡ | src/piper/phonemize_chinese.py | 137 | # -------------------- | COMMENT |
| MEDIUM⚡ | src/piper/phonemize_chinese.py | 144 | # -------------------- | COMMENT |
| MEDIUM⚡ | src/piper/phonemize_chinese.py | 146 | # -------------------- | COMMENT |
| MEDIUM | src/piper/download_voices.py | 63 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/download_voices.py | 135 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/__main__.py | 252 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/train/export_onnx.py | 40 | # ------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/train/export_onnx.py | 109 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/train/export_generator.py | 36 | # ------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/train/export_generator.py | 59 | # ----------------------------------------------------------------------------- | COMMENT |
| MEDIUM | src/piper/train/__main__.py | 34 | # ----------------------------------------------------------------------------- | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | libpiper/include/json.hpp | 21 | #include <algorithm> // all_of, find, for_each | COMMENT |
| LOW | libpiper/include/json.hpp | 41 | // SPDX-FileCopyrightText: 2013-2022 Niels Lohmann <https://nlohmann.me> | COMMENT |
| LOW | libpiper/include/json.hpp | 61 | #ifndef JSON_SKIP_LIBRARY_VERSION_CHECK | COMMENT |
| LOW | libpiper/include/json.hpp | 81 | #if JSON_DIAGNOSTICS | COMMENT |
| LOW | libpiper/include/json.hpp | 141 | { | COMMENT |
| LOW | libpiper/include/json.hpp | 161 | #include <algorithm> // transform | COMMENT |
| LOW | libpiper/include/json.hpp | 181 | COMMENT | |
| LOW | libpiper/include/json.hpp | 201 | #include <array> // array | COMMENT |
| LOW | libpiper/include/json.hpp | 221 | // | | |__ | | | | | | version 3.11.2 | COMMENT |
| LOW | libpiper/include/json.hpp | 321 | // | | |__ | | | | | | version 3.11.2 | COMMENT |
| LOW | libpiper/include/json.hpp | 341 | #define JSON_HEDLEY_STRINGIFY_EX(x) #x | COMMENT |
| LOW | libpiper/include/json.hpp | 361 | #define JSON_HEDLEY_CONCAT3_EX(a,b,c) a##b##c | COMMENT |
| LOW | libpiper/include/json.hpp | 381 | #define JSON_HEDLEY_VERSION_DECODE_MINOR(version) (((version) % 1000000) / 1000) | COMMENT |
| LOW | libpiper/include/json.hpp | 401 | #define JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_GNUC_VERSION >= JSON_HEDLEY_VERSION_ENCODE(ma | COMMENT |
| LOW | libpiper/include/json.hpp | 421 | #define JSON_HEDLEY_MSVC_VERSION_CHECK(major,minor,patch) (0) | COMMENT |
| LOW | libpiper/include/json.hpp | 441 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 461 | #define JSON_HEDLEY_INTEL_CL_VERSION_CHECK(major,minor,patch) (0) | COMMENT |
| LOW | libpiper/include/json.hpp | 481 | #undef JSON_HEDLEY_SUNPRO_VERSION | COMMENT |
| LOW | libpiper/include/json.hpp | 501 | COMMENT | |
| LOW | libpiper/include/json.hpp | 521 | #if defined(__CC_ARM) && defined(__ARMCOMPILER_VERSION) | COMMENT |
| LOW | libpiper/include/json.hpp | 541 | #elif defined(__xlC__) && defined(__xlC_ver__) | COMMENT |
| LOW | libpiper/include/json.hpp | 561 | ( \ | COMMENT |
| LOW | libpiper/include/json.hpp | 581 | #undef JSON_HEDLEY_TI_CL2000_VERSION | COMMENT |
| LOW | libpiper/include/json.hpp | 601 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 621 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 641 | #define JSON_HEDLEY_TI_CL6X_VERSION_CHECK(major,minor,patch) (0) | COMMENT |
| LOW | libpiper/include/json.hpp | 661 | #undef JSON_HEDLEY_TI_CLPRU_VERSION | COMMENT |
| LOW | libpiper/include/json.hpp | 681 | #define JSON_HEDLEY_CRAY_VERSION JSON_HEDLEY_VERSION_ENCODE(_RELEASE_MAJOR, _RELEASE_MINOR, _RELEASE_PATCHLEVEL) | COMMENT |
| LOW | libpiper/include/json.hpp | 701 | #define JSON_HEDLEY_IAR_VERSION JSON_HEDLEY_VERSION_ENCODE((__VER__ / 1000000), ((__VER__ / 1000) % 1000), (__VE | COMMENT |
| LOW | libpiper/include/json.hpp | 721 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 741 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 761 | #define JSON_HEDLEY_COMPCERT_VERSION_CHECK(major,minor,patch) (0) | COMMENT |
| LOW | libpiper/include/json.hpp | 781 | #undef JSON_HEDLEY_MCST_LCC_VERSION | COMMENT |
| LOW | libpiper/include/json.hpp | 821 | #if defined(JSON_HEDLEY_GCC_VERSION) | COMMENT |
| LOW | libpiper/include/json.hpp | 841 | #undef JSON_HEDLEY_GNUC_HAS_ATTRIBUTE | COMMENT |
| LOW | libpiper/include/json.hpp | 861 | #if \ | COMMENT |
| LOW | libpiper/include/json.hpp | 881 | #else | COMMENT |
| LOW | libpiper/include/json.hpp | 901 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 921 | #if defined(JSON_HEDLEY_GCC_HAS_BUILTIN) | COMMENT |
| LOW | libpiper/include/json.hpp | 941 | #endif | COMMENT |
| LOW | libpiper/include/json.hpp | 961 | #define JSON_HEDLEY_HAS_EXTENSION(extension) __has_extension(extension) | COMMENT |
| LOW | libpiper/include/json.hpp | 981 | #define JSON_HEDLEY_GCC_HAS_EXTENSION(extension,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch) | COMMENT |
| LOW | libpiper/include/json.hpp | 1001 | COMMENT | |
| LOW | libpiper/include/json.hpp | 1021 | #undef JSON_HEDLEY_GNUC_HAS_WARNING | COMMENT |
| LOW | libpiper/include/json.hpp | 1061 | #define JSON_HEDLEY_PRAGMA(value) | COMMENT |
| LOW | libpiper/include/json.hpp | 1081 | JSON_HEDLEY_INTEL_CL_VERSION_CHECK(2021,1,0) | COMMENT |
| LOW | libpiper/include/json.hpp | 1101 | #define JSON_HEDLEY_DIAGNOSTIC_POP | COMMENT |
| LOW | libpiper/include/json.hpp | 1141 | #if defined(JSON_HEDLEY_CONST_CAST) | COMMENT |
| LOW | libpiper/include/json.hpp | 1161 | #undef JSON_HEDLEY_REINTERPRET_CAST | COMMENT |
| LOW | libpiper/include/json.hpp | 1181 | #if defined(__cplusplus) | COMMENT |
| LOW | libpiper/include/json.hpp | 1201 | #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED | COMMENT |
| LOW | libpiper/include/json.hpp | 1241 | #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED | COMMENT |
| LOW | libpiper/include/json.hpp | 1261 | JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,0,0) || \ | COMMENT |
| LOW | libpiper/include/json.hpp | 1281 | #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("GCC diagnostic ignored \"-Wdeprecated-declara | COMMENT |
| LOW | libpiper/include/json.hpp | 1301 | #elif JSON_HEDLEY_MCST_LCC_VERSION_CHECK(1,25,10) | COMMENT |
| LOW | libpiper/include/json.hpp | 1321 | #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNUSED_FUNCTION | COMMENT |
| LOW | libpiper/include/json.hpp | 1381 | #define JSON_HEDLEY_DEPRECATED(since) __attribute__((__deprecated__)) | COMMENT |
| LOW | libpiper/include/json.hpp | 1401 | JSON_HEDLEY_HAS_ATTRIBUTE(warning) || \ | COMMENT |
| LOW | libpiper/include/json.hpp | 1441 | #define JSON_HEDLEY_WARN_UNUSED_RESULT_MSG(msg) JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[nodiscard]]) | COMMENT |
| LOW | libpiper/include/json.hpp | 1461 | #define JSON_HEDLEY_SENTINEL(position) | COMMENT |
| 127 more matches not shown… | ||||
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | tests/test_espeak_phonemizer.py | 65 | def test_vowel_clusters_without_terminator() -> None: | CODE |
| LOW | tests/test_piper.py | 35 | def test_phonemize_synthesize() -> None: | CODE |
| LOW | tests/test_piper.py | 111 | def test_language_switch_flags_removed() -> None: | CODE |
| LOW | tests/test_piper.py | 203 | def test_synthesize_alignment() -> None: | CODE |
| LOW | tests/test_piper.py | 390 | def test_add_alignment_output_autodetect() -> None: | CODE |
| LOW | tests/test_piper.py | 410 | def test_add_alignment_output_errors() -> None: | CODE |
| LOW | tests/test_piper.py | 431 | def test_load_include_alignments_in_memory(tmp_path: Path) -> None: | CODE |
| LOW | tests/test_piper.py | 450 | def test_load_include_alignments_no_ceil() -> None: | CODE |
| LOW | tests/test_piper.py | 474 | def test_phonemize_with_vowel_clusters() -> None: | CODE |
| LOW | tests/test_piper.py | 549 | def test_training_phonemize_matches_inference_with_vowel_clusters() -> None: | CODE |
| LOW | src/piper/phonemize_chinese.py | 348 | def _split_initial_final_tone(syl: str): | CODE |
| LOW | src/piper/phonemize_espeak.py | 74 | def _merge_known_vowel_clusters( | CODE |
| LOW | src/piper/tashkeel/__init__.py | 115 | def _annotate_text_with_diacritics( | CODE |
| LOW | src/piper/tashkeel/__init__.py | 132 | def _annotate_text_with_diacritics_taskeen( | CODE |
| LOW | src/piper/tashkeel/__init__.py | 160 | def _extract_chars_and_diacritics( | CODE |
| LOW | src/piper/train/vits/mel_processing.py | 8 | def dynamic_range_compression_torch(x, C=1, clip_val=1e-5): | CODE |
| LOW | src/piper/train/vits/mel_processing.py | 17 | def dynamic_range_decompression_torch(x, C=1): | CODE |
| LOW | src/piper/train/vits/mel_processing.py | 31 | def spectral_de_normalize_torch(magnitudes): | CODE |
| LOW | src/piper/train/vits/transforms.py | 10 | def piecewise_rational_quadratic_transform( | CODE |
| LOW | src/piper/train/vits/transforms.py | 50 | def unconstrained_rational_quadratic_spline( | CODE |
| LOW | src/piper/train/vits/transforms.py | 101 | def rational_quadratic_spline( | CODE |
| LOW | src/piper/train/vits/attentions.py | 274 | def _matmul_with_relative_values(self, x, y): | CODE |
| LOW | src/piper/train/vits/attentions.py | 283 | def _matmul_with_relative_keys(self, x, y): | CODE |
| LOW | src/piper/train/vits/attentions.py | 311 | def _relative_position_to_absolute_position(self, x): | CODE |
| LOW | src/piper/train/vits/attentions.py | 333 | def _absolute_position_to_relative_position(self, x): | CODE |
| LOW | src/piper/train/vits/commons.py | 100 | def fused_add_tanh_sigmoid_multiply(input_a, input_b, n_channels): | CODE |
| LOW | src/piper/train/vits/lightning.py | 319 | def _warmstart_vocoder_from_ckpt(self, ckpt_path: str): | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | src/piper/http_server.py | 21 | CODE | |
| LOW | src/piper/http_server.py | 217 | CODE | |
| LOW | src/piper/phonemize_chinese.py | 217 | CODE | |
| LOW | src/piper/voice.py | 300 | CODE | |
| LOW | src/piper/__main__.py | 22 | CODE | |
| LOW | src/piper/__main__.py | 108 | CODE | |
| LOW | src/piper/train/vits/models.py | 349 | CODE | |
| LOW | src/piper/train/vits/dataset.py | 140 | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | src/piper/train/vits/mel_processing.py | 28 | CODE | |
| LOW | src/piper/train/vits/mel_processing.py | 33 | CODE | |
| LOW | src/piper/train/vits/transforms.py | 101 | CODE | |
| LOW | src/piper/train/vits/attentions.py | 281 | CODE | |
| LOW | src/piper/train/vits/attentions.py | 290 | CODE | |
| LOW | src/piper/train/vits/dataset.py | 49 | CODE | |
| LOW | src/piper/train/vits/lightning.py | 24 | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | src/piper/__init__.py | 3 | CODE | |
| LOW | src/piper/__init__.py | 3 | CODE | |
| LOW | src/piper/__init__.py | 3 | CODE | |
| LOW | src/piper/__init__.py | 4 | CODE | |
| LOW | src/piper/__init__.py | 4 | CODE | |
| LOW | src/piper/phonemize_espeak.py | 6 | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | tests/test_piper.py | 196 | # Check if entire text is just phonemes | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | src/piper/__init__.py | 6 | __all__ = [ | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | src/piper/audio_playback.py | 43 | except Exception: | CODE |