esp_tts_parse_pinyin crashes with assert failure instead of returning error (AIS-2253)

[cnadler86]

Checklist

• Checked the issue tracker for similar issues to ensure this is not a duplicate
• Read the documentation to confirm the issue is not addressed there and your configuration is set correctly
• Tested with the latest version to ensure the issue hasn't been fixed

How often does this bug occurs?

always

Expected behavior

int esp_tts_parse_pinyin(esp_tts_handle_t tts_handle, const char *pinyin);

The function should:

1. Return 0 if parsing fails (syllable not found in voice set)
2. Return 1 if parsing succeeds
3. NOT crash the system under any circumstances

Actual behavior (suspected bug)

The function crashes with an assert failure before returning:

E (16568) tts_parser: Fail to search ni3 hao3 in voice set xiaole_20220719

assert failed: esp_tts_utt_append esp_tts_parser.c:93 (syll_idx>=0)

Error logs or terminal output

Steps to reproduce the behavior

Steps to Reproduce

Code Example

#include "esp_tts.h"
#include "esp_tts_voice_template.h"
#include "esp_partition.h"

// Initialize voice set from partition
const esp_partition_t* part = esp_partition_find_first(
    ESP_PARTITION_TYPE_DATA, 
    ESP_PARTITION_SUBTYPE_DATA_FAT, 
    "voice_data"
);

spi_flash_mmap_handle_t mmap;
uint16_t *voicedata;
esp_partition_mmap(part, 0, part->size, ESP_PARTITION_MMAP_DATA, 
                   (const void**)&voicedata, &mmap);

esp_tts_voice_t *voice = esp_tts_voice_set_init(&esp_tts_voice_template, voicedata);
esp_tts_handle_t tts_handle = esp_tts_create(voice);

// Test 1: Pinyin with tone numbers (crashes)
esp_tts_stream_reset(tts_handle);
int result = esp_tts_parse_pinyin(tts_handle, "ni3 hao3");
// Never reaches here - system crashes with assert

// Test 2: Pinyin without tone numbers (also crashes)
esp_tts_stream_reset(tts_handle);
result = esp_tts_parse_pinyin(tts_handle, "ni hao");
// Never reaches here - system crashes with assert

// Test 3: Single syllable (also crashes)
esp_tts_stream_reset(tts_handle);
result = esp_tts_parse_pinyin(tts_handle, "ma");
// Never reaches here - system crashes with assert

Project release version

latest

System architecture

Intel/AMD 64-bit (modern PC, older Mac)

Operating system

Linux

Operating system version

WSL ubuntu 22.04

Shell

Bash

Additional context

Decoded Backtrace

0x420c6149: esp_tts_utt_append at esp_tts_parser.c:93
0x420c678f: esp_tts_parser_pinyin at esp_tts_parser.c:488  
0x420c58b4: esp_tts_parse_pinyin at esp_tts.c:144

Console Output

input:ni3 hao3
data:ni3 hao3
word_num:1, i:8
E (16568) tts_parser: Fail to search ni3 hao3 in voice set xiaole_20220719

A fatal error occurred. The crash dump printed below may be used to help
determine what caused it.

assert failed: esp_tts_utt_append esp_tts_parser.c:93 (syll_idx>=0)

Backtrace: [see above]

ELF file SHA256: 8e92259d3

Rebooting...

Analysis

The issue is in the precompiled library libesp_tts_chinese.a. The function esp_tts_utt_append() uses assert(syll_idx >= 0) instead of proper error handling when a syllable is not found in the voice set.

The error flow is:

1. esp_tts_parse_pinyin() is called
2. esp_tts_parser_pinyin() tries to find syllables
3. esp_tts_utt_append() is called with syll_idx = -1 (not found)
4. Assert fires → System crashes
5. Function never returns the documented error code

[sun-xiangyu]

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