Android TTS backend not detected on Onyx Boox Go 7 despite tts_helper.dex being present

[yusuke-br]

Hi! I'm trying to use Audiobook Read-Along on an Onyx Boox Go 7, but the Android TTS backend is not detected.

Device:

• Onyx Boox Go 7
• Android 13 / SDK 33
• arch: aarch64
• KOReader: v2026.03
• Audiobook Read-Along: v0.1.9.0

What I confirmed:

• The plugin is installed at:
  /sdcard/koreader/plugins/audiobook.koplugin/

• The Android TTS helper exists at:
  /sdcard/koreader/plugins/audiobook.koplugin/android/tts_helper.dex

• Android system TTS works normally from the Boox settings.

• The plugin loads and can generate the bug report.

• However, the plugin still reports:

tts_backend: nil (none detected)
tts_backend_error: No TTS engine available on this device.

It seems the plugin is not detecting/loading the Android TTS backend, even though tts_helper.dex is present and system TTS works.

Full bug report:

=== Audiobook Read-Along Bug Report (v0.1.9.0) ===
Generated: 2026-05-22T02:22:12Z

── Device ──
android_brand: Onyx
android_device: Go7
android_sdk: 33
android_version: 13
arch: aarch64
has_eink: no
is_android: yes
is_kindle: no
is_kobo: no
is_pocketbook: no
model: unknown
platform: unknown
screen_dpi: 300
screen_height: 1680
screen_width: 1264
uname: Linux localhost 4.19.157-perf-g3d47a6619220-dirty #245 SMP PREEMPT Fri Apr 10 15:19:22 CST 2026 aarch64 Toybox

── KOReader ──
koreader_version: v2026.03

── Plugin ──
audio_player_cached: not set
audio_player_type: not set
bt_hci0_address: missing
cwd: /data/data/org.koreader.launcher/files
espeak_bin_ls: total 28
-rw-rw---- 1 root everybody 26924 2026-05-21 17:07 espeak-ng.bin
has_bundled_espeak: yes
has_bundled_piper: yes
has_bundled_wav_play: yes
has_piper_model: yes
no_real_audio_output: no
pb_pre_flight: not yet evaluated
piper_bin_ls: total 66927
-rw-rw---- 1 root everybody 63104526 2026-05-21 17:30 en_US-danny-low.onnx
-rw-rw---- 1 root everybody 4166 2026-05-21 17:30 en_US-danny-low.onnx.json
drwxrwx--- 4 root everybody 8192 2026-05-21 23:20 espeak-ng-data
-rw-rw---- 1 root everybody 23816 2026-05-21 17:30 espeak-ng.bin
drwxrwx--- 2 root everybody 3488 2026-05-21 23:20 lib
-rw-rw---- 1 root everybody 4291748 2026-05-21 17:30 piper.bin
-rw-rw---- 1 root everybody 1018932 2026-05-21 17:30 piper_phonemize.bin
piper_models: en_US-danny-low.onnx
player_error: no
plugin_dir: /sdcard/koreader/plugins//audiobook.koplugin/
plugin_fullname: Audiobook Read-Along
plugin_name: audiobook
plugin_version: 0.1.9.0
settings:
auto_advance: true
bt_media_control: true
espeak_cold_start: true
highlight_sentences: true
highlight_style: background
highlight_words: true
keep_playing_on_lid_close: false
piper_model: none
speech_pitch: 50
speech_rate: 1
speech_volume: 1
tts_backend: auto
tts_backend: nil (none detected)
tts_backend_cmd: nil
tts_backend_error: No TTS engine available on this device.

The plugin needs the Android TTS helper (.dex) which is not yet included.

As a workaround, install espeak-ng via Termux:
pkg install espeak-ng

Then add Termux to your PATH before launching KOReader.

── Audio & TTS ──
alsa_cards: not available (/proc/asound/cards missing)
alsa_default_pcm: sh: aplay: inaccessible or not found
alsa_mixer: not available
bluealsa_bundled: yes
bluealsa_running: no
bt_abstract_socket: none
bt_available: no
bt_daemon_path: not found
bt_daemon_running: not running
bt_gst_sink: none (aplay fallback)
bt_hci_devices: none
bt_printf_test: 2
bt_rfkill: rfkill not available
bt_sdio_bt_pwr: not loaded
bt_sleep_test: ok
bt_stack: bluez
players_in_path:
tmp_writable: no
tts_in_path:
wav_play_gst_status: none
wav_play_last_log: none

── Resources ──
disk_tmp: Filesystem Size Used Avail Use% Mounted on
disk_var: Filesystem Size Used Avail Use% Mounted on
disk_var_usage: n/a
meminfo: MemTotal: 3533780 kB
MemFree: 56776 kB
MemAvailable: 1469048 kB
Buffers: 1428 kB
Cached: 1469796 kB

=== End of Bug Report ===

[stradichenko]

Hi @yusuke-br, please try again on v0.1.9.1 if the issue persists, keep sharing the related reports.

Cheers :)

[yusuke-br]

Thanks, man! In fact, I've just tried the new version out, but the issue persists. I'm going to paste the bug report below. The funny thing is that on my Boox Note Air 5c, it does work. It just ocurred to me that maybe it could be something related to the Android version, is that possible? Since the GO 7 is Android 13 and the Note Air 5c is Android 15. I don't know, I'm illiterate when it comes to this level of tech. 😂

=== Audiobook Read-Along Bug Report (v0.1.9.13) ===
Generated: 2026-05-24T20:39:27Z

── Device ──
android_brand: Onyx
android_device: Go7
android_sdk: 33
android_version: 13
arch: aarch64
has_eink: no
is_android: yes
is_kindle: no
is_kobo: no
is_pocketbook: no
model: unknown
platform: unknown
screen_dpi: 300
screen_height: 1680
screen_width: 1264
uname: Linux localhost 4.19.157-perf-g3d47a6619220-dirty #245 SMP PREEMPT Fri Apr 10 15:19:22 CST 2026 aarch64 Toybox

── KOReader ──
koreader_version: v2026.03

── Plugin ──
audio_player_cached: not set
audio_player_type: not set
bt_hci0_address: missing
cwd: /data/data/org.koreader.launcher/files
espeak_bin_ls: total 32
-rw-rw---- 1 root everybody 26968 2026-05-24 16:29 espeak-ng.bin
-rw-rw---- 1 root everybody 851 2026-05-24 16:29 mbrola
has_bundled_espeak: yes
has_bundled_piper: yes
has_bundled_wav_play: yes
has_piper_model: yes
no_real_audio_output: no
pb_pre_flight: not yet evaluated
piper_bin_ls: total 66927
-rw-rw---- 1 root everybody 63104526 2026-05-24 16:49 en_US-danny-low.onnx
-rw-rw---- 1 root everybody 4166 2026-05-24 16:49 en_US-danny-low.onnx.json
drwxrwx--- 4 root everybody 8192 2026-05-24 17:38 espeak-ng-data
-rw-rw---- 1 root everybody 23816 2026-05-24 16:49 espeak-ng.bin
drwxrwx--- 2 root everybody 3488 2026-05-24 17:38 lib
-rw-rw---- 1 root everybody 4291748 2026-05-24 16:49 piper.bin
-rw-rw---- 1 root everybody 1018932 2026-05-24 16:49 piper_phonemize.bin
piper_models: en_US-danny-low.onnx
player_error: no
plugin_dir: /sdcard/koreader/plugins/audiobook.koplugin/
plugin_fullname: Audiobook Read-Along
plugin_name: audiobook
plugin_version: 0.1.9.13
settings:
auto_advance: true
bt_media_control: true
espeak_cold_start: true
highlight_sentences: true
highlight_style: background
highlight_words: true
keep_playing_on_lid_close: false
piper_model: none
speech_pitch: 50
speech_rate: 1
speech_volume: 1
tts_backend: auto
tts_backend: nil (none detected)
tts_backend_cmd: nil
tts_backend_error: No TTS engine available on this device.

The Android TTS helper (.dex) was not found at the expected path.

Please verify that tts_helper.dex exists inside the plugin's android/ folder.

As a workaround, install espeak-ng via Termux:
pkg install espeak-ng

Then add Termux to your PATH before launching KOReader.

── Audio & TTS ──
alsa_cards: not available (/proc/asound/cards missing)
alsa_default_pcm: sh: aplay: inaccessible or not found
alsa_mixer: not available
bluealsa_bundled: yes
bluealsa_running: no
bt_abstract_socket: none
bt_available: no
bt_daemon_path: not found
bt_daemon_running: not running
bt_gst_sink: none (aplay fallback)
bt_hci_devices: none
bt_printf_test: 2
bt_rfkill: rfkill not available
bt_sdio_bt_pwr: not loaded
bt_sleep_test: ok
bt_stack: bluez
kindle_deleted_var_files: none_found
players_in_path:
tmp_writable: no
tts_in_path:
wav_play_gst_status: none
wav_play_last_log: none

── Resources ──
disk_tmp: Filesystem Size Used Avail Use% Mounted on
disk_var: Filesystem Size Used Avail Use% Mounted on
disk_var_usage: n/a
meminfo: MemTotal: 3533784 kB
MemFree: 74192 kB
MemAvailable: 1519548 kB
Buffers: 1572 kB
Cached: 1482248 kB

=== End of Bug Report ===

[stradichenko]

Hi @yusuke-br; finally I can come back to debug these issues, please retest on the latests versions, you should be able to generate a report if the issue persists, cheers!