[Android] Sticky AlprSdk error 20004 after long lock/screen-off — init OK but process never recovers without process kill

[sid-metiz]

Summary

After a long live-scanning session (especially device lock / screen-off for ~25–50+ minutes), UltALPR (org.buyun.alpr.sdk.AlprSdk) enters a sticky failure state:

• AlprSdk.process(...) → isOK() == false
• code() == 20004
• phrase() ≈ Internal processing failed

Camera frames still flow. Preview can still work.
AlprSdk.deInit() + AlprSdk.init(...) reports success, but every following process() immediately returns 20004 again.

Soft re-init, hard re-init, and Activity recreate() do not fix it.
Only killing the process that hosts the native SDK restores recognition.

This is not “no plate in view” (isOK()==true, numPlates==0).

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Environment

Item	Value
Platform	Android (minSdk 28)
SDK	org.buyun.alpr.sdk (AlprSdk / UltALPR)
Package	libttvalpr.aar
Pipeline	Camera YUV → AlprSdk.yuv2Bitmap → process(RGBA32)
Frame size	1280×720
Use case	Long-running patrol LPR with frequent lock/unlock

Device (please fill):

• Model:
• Android version:
• Chipset/GPU:
• Date of logs:

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Steps to reproduce

1. Open live scanner; confirm plates are recognized.
2. Lock device / leave idle for ~25–50+ minutes.
3. Unlock and return to scanner.
4. Point at clear license plates.

Controls (usually OK): continuous scan; short Plate Detail trip (few minutes).

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Expected

After unlock: init OK, process OK, plates detected when in view. Empty scene → OK + numPlates==0.

---

Actual

1. Frames keep arriving.
2. init succeeds.
3. Every process() returns 20004 / Internal processing failed.
4. Soft/hard re-init and Activity recreate still sticky 20004.
5. Process kill (or force-stop app) restores scanning.

---

API usage

AlprSdk.setActivation(...)
AlprSdk.init(assets, jsonConfig, null)

// per frame (single-threaded; one process at a time)
bitmap = AlprSdk.yuv2Bitmap(yuv, w, h, exifOrientation)
copy RGBA → direct ByteBuffer
result = AlprSdk.process(
  SDK_IMAGE_TYPE.ULTALPR_SDK_IMAGE_TYPE_RGBA32,
  nativeBuffer, width, height
)

// on SCREEN_OFF / lock
AlprSdk.deInit()

// on unlock / resume
AlprSdk.init(...)

[sid-metiz]

@justin200914 Can you please check on this?

[sid-metiz]

@ml13571