Fix Android 9 H.264 streaming and server resilience

[sabag]

1. Android 9 H.264 compatibility

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/helpers/H264HardwareEncoder.kt

• Removes the Android 10-only SPS/PPS prepend option.
• Reads SPS/PPS from csd-0 and csd-1.
• Handles partial MediaCodec buffers.
• Detects actual IDR frames.
• Releases codec buffers before downstream processing.
• Avoids a shutdown locking problem.

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/helpers/H264Bitstream.kt — new

• Normalizes Annex-B, avcC, length-prefixed AVC and raw NAL data.
• Caches SPS/PPS.
• Prepends SPS/PPS to every IDR.
• Drops configuration-only buffers.
• Reassembles partial access units.
• Validates malformed H.264 input.

2. Stalled NVR protection

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/helpers/H264StreamingEncoder.kt

• Moves network writing away from MediaCodec.
• Uses one ordered writer thread.
• Adds a bounded 30-access-unit queue.
• Disconnects stalled clients when the queue fills.
• Invalidates queued frames after encoder restart.
• Prevents old frames from reaching new clients.
• Waits for a successfully transmitted keyframe before activating clients.

3. True configured frame rate

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/StreamingService.kt

• Passes the configured FPS into the GL camera pipeline.

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/helpers/CameraGlPipe.kt

• Consumes all camera frames but sends only correctly paced frames to the encoder.
• Uses camera timestamps with a system-clock fallback.
• Resets pacing state when stopped.

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/helpers/FrameRateLimiter.kt — new

• Provides timestamp-based 1–60 fps limiting.
• Drops excess frames without accumulating timing drift.
• Handles timestamps moving backwards.

4. Platform TLS and server lifecycle

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/kotlin/com/github/digitallyrefined/androidipcamera/helpers/StreamingServerHelper.kt

• Uses Android’s built-in TLS provider.

• Automatic mode selects:

  • Android 7–9: TLS 1.2.
  • Android 10+: TLS 1.3.

• Explicit TLS 1.2 remains supported.

• Does not permanently rewrite the automatic preference.

• Generates and securely stores a random certificate password.

• Generates a device-local certificate when needed.

• Adds server-generation tracking for safe restarts.

• Prevents old server jobs and clients from surviving restarts.

• Tracks and closes H.264, MJPEG and audio clients.

• Makes client removal idempotent.

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/res/values/strings.xml

• Renames the first TLS option to automatic platform selection.

projects/mi6-ip-camera/android-ip-camera-src/app/src/main/res/xml/preferences.xml

• Clarifies automatic TLS, forced TLS 1.2 and disabled HTTPS behavior.

5. Build configuration

projects/mi6-ip-camera/android-ip-camera-src/app/build.gradle

• Adds JUnit 4.13.2.

6. Tests

projects/mi6-ip-camera/android-ip-camera-src/app/src/test/kotlin/com/github/digitallyrefined/androidipcamera/helpers/H264BitstreamTest.kt — new

• Ten H.264 normalization, SPS/PPS, IDR and partial-buffer tests.

projects/mi6-ip-camera/android-ip-camera-src/app/src/test/kotlin/com/github/digitallyrefined/androidipcamera/helpers/FrameRateLimiterTest.kt — new

• Four frame-pacing and timestamp-handling tests.