Prudynt Dev

prudynt-dev

Complete onboarding for working on the prudynt-t streamer (Thingino's default video streamer). Covers local development setup via overrides, rebuild/deploy loop, config management, diagnostics, and known hardware constraints.

Architecture overview

prudynt-t is a C++20 video streamer for Ingenic SoC cameras. Key subsystems:

Pipeline: Sensor → FrameSource → Encoder → VideoWorker → MsgChannel → RTSP tap → RTP → Client

Local development setup

Overrides

prudynt's source is checked out in overrides/prudynt-t/. This is a git repo tracking origin/stable. The firmware's Buildroot package (package/prudynt-t/) is configured to rsync from this override directory.

# Navigate to the override
cd overrides/prudynt-t

# Check current branch and status
git branch
git log --oneline -5

The local.mk in the firmware root should have PRUDYNT_T_OVERRIDE_SRCDIR pointing to the override. Check with:

grep prudynt local.mk

Rebuild and deploy

The firmware Makefile provides rebuild-prudynt-t which does a full dirclean+build+reinstall of the prudynt package AND copies the binary to NFS:

# Build for a specific camera (NFS destination auto-detected from IP)
CAMERA=<camera_name> IP=<camera_ip> make rebuild-prudynt-t

Examples:

CAMERA=cinnado_d1_t31l_sc2336_atbm6031 IP=192.168.88.121 make rebuild-prudynt-t
CAMERA=wyze_cam3_t31x_gc2053_atbm6031   IP=192.168.88.127 make rebuild-prudynt-t

The build output goes to:

• Binary: output/<branch>/<camera>-<kernel>-<libc>-<ip>/per-package/prudynt-t/target/usr/bin/prudynt
• NFS: /nfs/prudynt (host path, accessible from camera at /mnt/nfs/prudynt)

Save the full compilation log when rebuilding — errors may scroll by:

CAMERA=... IP=... make rebuild-prudynt-t 2>&1 | tee /tmp/rebuild-prudynt.log

Deploy to camera

The camera mounts the host's /nfs at /mnt/nfs via NFS. To deploy:

# Kill old instance, start new one
ssh root@<camera_ip> 'killall -9 prudynt; sleep 1; /mnt/nfs/prudynt > /tmp/p.log 2>&1 &'

# Verify it started
ssh root@<camera_ip> 'pidof prudynt; grep -E "STREAM PROFILE|fps capped" /tmp/p.log'

The binary is also installed to the camera's firmware image during full builds. For quick iteration, the NFS path avoids reflashing.

Config management

Config file

Config is stored in /etc/prudynt.json on the camera. This is a JSON file loaded at startup. Changes require a restart to take effect (except for a few runtime settings like running_mode, isp_bypass, and some image controls).

Runtime API

The prudyntctl tool sends JSON to prudynt's HTTP API (/api/v1/config). Important: Most settings changed via the API only update the in-memory config and the JSON file — they do NOT take effect until prudynt restarts. Exceptions:

# Read a config value
prudyntctl config get stream0.fps

# Set a config value (writes to file, needs restart for most settings)
prudyntctl json '{"stream0":{"fps":25,"bitrate":3000}}'

# Use jct for direct JSON manipulation
jct /etc/prudynt.json set stream0.fps 25
jct /etc/prudynt.json get stream0.fps

Key config settings

{
  "stream0": {
    "enabled": true,
    "width": 1920, "height": 1080,
    "fps": 0,           // 0 = auto (sensor max), clamped by platform caps
    "bitrate": 3000,    // kbps
    "gop": 30,          // keyframe interval in frames
    "profile": 1,       // 0=Baseline, 1=Main, 2=High
    "mode": "CBR",      // CBR, VBR, CAPPED_VBR, CAPPED_QUALITY
    "audio_enabled": true
  },
  "stream1": {
    "enabled": true,
    "width": 640, "height": 360,
    "fps": 0,
    "bitrate": 1000,
    "profile": 1
  },
  "audio": {
    "mic_enabled": true,
    "mic_format": "OPUS",   // OPUS, AAC, PCM, G711A, G711U
    "mic_hq": false,        // true=48kHz/128kbps, false=16kHz/32kbps
    "spk_enabled": true
  },
  "image": {
    "running_mode": 0,      // 0=day, 1=night
    "isp_bypass": true
  },
  "osd": {
    "sei": { "enabled": true },
    "burnin": { "enabled": true, "format": "%F %T" }
  },
  "rtsp": {
    "port": 554,
    "username": "thingino",
    "password": "thingino",
    "auth_required": true,
    "send_buffer_size": 307200
  }
}

Diagnostics

Stream analysis with ffprobe

# Show SDP info
ffprobe rtsp://thingino:thingino@192.168.88.121/ch0

# Count frames in 10 seconds
timeout 10 ffprobe -v error -show_entries frame=pkt_pts_time \
  -select_streams v:0 rtsp://thingino:thingino@192.168.88.121/ch0 | wc -l

# Detailed frame timing and sizes
timeout 25 ffprobe -v error \
  -show_entries frame=pts_time,pkt_size,pict_type \
  -select_streams v:0 \
  -of compact=nk=1 rtsp://thingino:thingino@192.168.88.121/ch0 > /tmp/frames.txt

# Analyze gaps
awk -F'|' '$2 != "N/A" && $2+0 > 0 {
  if (prev>0) { gap=$2-prev; sum+=gap; n++; if(gap>0.05) big++ }
  prev=$2; total++
}
END { printf "frames:%d avg:%.1fms(%.1ffps) gaps>50ms:%d\n",
  total, (sum/n)*1000, n/sum, big }' /tmp/frames.txt

Camera-side checks

# Check encoder configuration from startup log
grep "STREAM PROFILE" /tmp/p.log

# Check sensor FPS and integration time
cat /proc/jz/isp/isp-m0 | grep -E "OUTPUT FPS|Integration"

# Check available RAM
grep MemTotal /proc/meminfo

# Check kernel warnings
dmesg | grep -i "frame interrupt\|encoder\|sensor"

# Check prudynt log level and recent messages
jct /etc/prudynt.json get general.loglevel
grep -E "WARN|ERROR" /tmp/p.log | tail -20

Binary search for performance regressions

When bisecting to find which feature kills encoder performance:

1. Disable ALL optional features in the config
2. Measure baseline fps at 1080p
3. Re-enable one feature at a time, restart, re-measure
4. The drop reveals the costly feature

# Quick disable-all
jct /etc/prudynt.json set stream1.enabled false
jct /etc/prudynt.json set stream2.enabled false
jct /etc/prudynt.json set osd.sei.enabled false
jct /etc/prudynt.json set osd.burnin.enabled false
jct /etc/prudynt.json set audio.mic_enabled false
jct /etc/prudynt.json set audio.spk_enabled false
jct /etc/prudynt.json set motion.enabled false
jct /etc/prudynt.json set rtsp.audio_only_enabled false
# Restart and measure

Git bisect for regressions

cd overrides/prudynt-t
# Create a test branch at a known-good commit
git checkout -b test-bisect <commit_hash>
# Cherry-pick the <unistd.h> fix if needed for GCC 16
git cherry-pick 0bbb467
# Rebuild
cd /home/paul/thingino-builder-image/workspace/firmware
CAMERA=... IP=... make rebuild-prudynt-t

Known hardware constraints

T31 1080p framerate cap

All T31 variants (T31L, T31X, T31N, T31A) have an encoder hardware limit at 1080p: ~26fps maximum sustained. When configured above 26fps, the encoder collapses to ~14fps (approximately half). This is NOT a RAM issue — both 36MB and 93MB devices show identical behavior.

prudynt auto-caps 1080p streams to 25fps on PLATFORM_T31 builds. This cap is applied in IMPSystem.cpp:clamp_stream_to_sensor_limits().

ISP bypass + night mode

Starting the ISP in night mode (running_mode: 1) causes encoder pipeline stalls at 1080p. The init sequence intentionally starts in DAY mode and lets daynightd switch to night via the API after everything is initialized.

Profile 0 (Baseline) halves framerate

The Ingenic encoder emits frames at half the requested rate when H264 profile is set to Baseline (0). Always use Main (1) or High (2) for normal operation.

Common pitfalls

1. API changes don't take effect: Most prudyntctl json settings require a restart. Don't debug based on API changes alone — check the startup log.

2. Wrong sensor driver: If you've been testing sensor drivers, verify the correct one is loaded: cat /proc/jz/sensor/name

3. Config corruption: Manual JSON edits can introduce syntax errors. Use jct for programmatic changes. Validate with:

   python3 -c "import json; json.load(open('/etc/prudynt.json'))"
   

4. NFS share not mounted: If /mnt/nfs/prudynt is missing, check NFS:

   mount | grep nfs
   

5. Old binary still running: killall -9 prudynt before starting a new one.

6. Concurrent streams: Both ch0 and ch1 share encoder hardware. Disable unused streams when debugging ch0 performance.

7. Stale config values: Previous tests may have modified the config file. Reset to defaults before drawing conclusions.

Encoder watchdog

prudynt has an encoder watchdog in VideoWorker.cpp. After 10 consecutive IMP_Encoder_PollingStream timeouts (~5 seconds at 500ms timeout), it force-cycles the encoder + framesource:

1. IMP_Encoder_StopRecvPic
2. IMP_FrameSource_DisableChn / IMP_FrameSource_EnableChn
3. IMP_Encoder_StartRecvPic
4. IMP_Encoder_RequestIDR

This recovers from DMA buffer exhaustion and other pipeline stalls without requiring a full prudynt restart.

Related skills

• nfs-dev-deploy — generic NFS deployment workflow
• local-package-overrides — managing Buildroot package overrides
• build-and-ota — full firmware builds and OTA deployment
• rtsp-stress-test — RTSP stability and performance testing