[Development]: License plate recognition issues for Chinese vehicles

[ZhaiSoul]

Checklist

• I have updated to the latest available Frigate version.
• I have cleared the cache of my browser.
• I have tried a different browser to see if it is related to my browser.
• I have tried reproducing the issue in incognito mode to rule out problems with any third party extensions or plugins I have installed.
• I have asked the AI at https://docs.frigate.video about my issue.

Describe the problem you are having

In the PR for version 0.17, Chinese license plate recognition was added to the LPR system. However, the current error rate is relatively high, and in many cases, the recognition fails to work properly.

For example, take the license plate in the image below—it should be 渝AAE9908, but the system only recognizes AAE9908(missing the leading 渝).

Even when I configured a strict regex pattern to only accept valid Chinese license plates, the system still failed to detect it correctly:
^[京津沪渝冀豫云辽黑湘皖鲁新苏浙赣鄂桂甘晋蒙陕吉闽贵粤青藏川宁琼使领A-Z]{1}[A-Z]{1}[A-Z0-9]{4}[A-Z0-9挂学警港澳]{1}$

Additionally, I manually adjusted ppocr_keys_v1.txt to better match the characters used in Chinese license plates, but this didn’t resolve the issue either.

Steps to reproduce

Version

0.17.0-576f692

In which browser(s) are you experiencing the issue with?

No response

Frigate config file

ffmpeg:
  hwaccel_args: preset-intel-qsv-h265
  output_args:
    record: preset-record-generic-audio-aac
detectors:
  ov:
    type: openvino
    device: GPU
objects:
  track:
    - person
    - face
    - cat
    - dog
    - car
    - bicycle
    - umbrella
    - motorcycle
    - bird
    - package
    - license_plate
cameras:
  garage_gate:
    friendly_name: 地下车库
    lpr:
      enabled: true
    enabled: true
    audio:
      # 可选：启用音频事件（默认值：如下所示）
      enabled: true
    ffmpeg:
      inputs:
        - path: rtsp://127.0.0.1:8554/garage_gate # <----- The stream you want to use for detection
          input_args: preset-rtsp-restream
          roles:
            - detect
            - record
            - audio
    live:
      streams:
        Main Stream: garage_gate
        Sub Stream: garage_gate_sub
    detect:
      enabled: true # <---- disable detection until you have a working camera feed
      max_disappeared: 80
      min_initialized: 4
      stationary:
        classifier: true
        interval: 60  # 检测间隔帧数
        threshold: 60 # 静止判定阈值
      width: 1366
      height: 768
      fps: 8
      annotation_offset: -5
    review:
      alerts:
        required_zones: garage_gate_park
      detections:
        required_zones: garage_gate_park
    objects:
      track:
        - license_plate
        - car
        - person
        - motorcycle
lpr:
  enabled: true
  match_distance: 1
  debug_save_plates: true
  device: CPU
  recognition_threshold: 0.7
  model_size: small
  # format: 
   # ^[京津沪渝冀豫云辽黑湘皖鲁新苏浙赣鄂桂甘晋蒙陕吉闽贵粤青藏川宁琼使领A-Z]{1}[A-Z]{1}[A-Z0-9]{4}[A-Z0-9挂学警港澳]{1}$
  enhancement: 1

docker-compose file or Docker CLI command

-

Relevant Frigate log output

2025-10-31 00:55:31.394289406  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:31.475812785  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : park: Area for license plate box 931 is less than min_area 1000
2025-10-31 00:55:31.557238814  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : park: Area for license plate box 980 is less than min_area 1000
2025-10-31 00:55:31.612384034  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : park: Area for license plate box 931 is less than min_area 1000
2025-10-31 00:55:31.696355639  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:31.762728232  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:31.819116268  [2025-10-31 00:55:31] frigate.data_processing.common.license_plate.mixin DEBUG   : park: Area for license plate box 931 is less than min_area 1000
2025-10-31 00:55:31.819116268  [LOGGING] Last message repeated 1 times
2025-10-31 00:55:32.481045549  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : park: No attributes to parse.
2025-10-31 00:55:32.541257477  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:32.618564760  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:32.646332049  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:32.715999119  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:32.774744666  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:32.848427281  [2025-10-31 00:55:32] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:33.441829498  [2025-10-31 00:55:33] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:33.519149896  [2025-10-31 00:55:33] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:34.661995588  [2025-10-31 00:55:34] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:34.692148764  [2025-10-31 00:55:34] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:35.091959525  [2025-10-31 00:55:35] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:35.223210716  [2025-10-31 00:55:35] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:35.865434765  [2025-10-31 00:55:35] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:35.960673594  [2025-10-31 00:55:35] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:36.469399888  [2025-10-31 00:55:36] frigate.api.camera             ERROR   : Failed to fetch streams from go2rtc
2025-10-31 00:55:36.827009603  [2025-10-31 00:55:36] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:36.883438830  [2025-10-31 00:55:36] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:37.594491756  [2025-10-31 00:55:37] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:37.664581432  [2025-10-31 00:55:37] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:38.726629512  [2025-10-31 00:55:38] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:38.774225986  [2025-10-31 00:55:38] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:40.036248484  [2025-10-31 00:55:40] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:40.252999349  [2025-10-31 00:55:40] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:40.401297634  [2025-10-31 00:55:40] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:40.472779079  [2025-10-31 00:55:40] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:41.511153482  [2025-10-31 00:55:41] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:41.602598554  [2025-10-31 00:55:41] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:42.088059916  [2025-10-31 00:55:42] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:42.088059916  [LOGGING] Last message repeated 1 times
2025-10-31 00:55:42.774122911  [2025-10-31 00:55:42] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:44.089996008  [2025-10-31 00:55:44] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:44.158044374  [2025-10-31 00:55:44] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:46.040281337  [2025-10-31 00:55:46] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:46.203733760  [2025-10-31 00:55:46] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:46.299313644  [2025-10-31 00:55:46] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-wcoa3h with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:46.400778092  [2025-10-31 00:55:46] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: Skipping LPR for non-stationary car object 1761843289.628618-vb08sd with no position changes.  (Detected in 5 concurrent frames, threshold to run is 6 frames)
2025-10-31 00:55:46.490024362  [2025-10-31 00:55:46] frigate.data_processing.common.license_plate.mixin DEBUG   : garage_gate: No attributes to parse.
2025-10-31 00:55:46.490024362  [LOGGING] Last message repeated 5 times

Relevant go2rtc log output

-

Operating system

UNRAID

Install method

Docker Compose

Network connection

Wired

Camera make and model

TP-Link

Screenshots of the Frigate UI's System metrics pages

Any other information that may be helpful

ppocr_keys_v1.txt

京
沪
津
渝
冀
晋
蒙
辽
吉
黑
苏
浙
皖
闽
赣
鲁
豫
鄂
湘
粤
桂
琼
川
贵
云
藏
陕
甘
青
宁
新
警
使
领
港
澳
A
B
C
D
E
F
G
H
J
K
L
M
N
P
Q
R
S
T
U
V
W
X
Y
Z
0
1
2
3
4
5
6
7
8
9

[hawkeye217]

We are not yet accepting feedback / bug reports or providing support for unreleased, development versions of Frigate.

With that said, the quality of the image is quite poor, especially the leading 渝 character.

For now, you should follow the debugging steps for LPR as outlined in the official documentation. https://docs.frigate.video/configuration/license_plate_recognition/#how-do-i-debug-lpr-issues