# cv-mmap Streamer

A standalone C++ downstream project that reads frames from cv-mmap IPC, encodes with NVIDIA NVENC (with software fallback), and publishes RTMP + RTP streams with low-latency tuning on localhost.

## Overview

This project consumes video frames from the cv-mmap shared memory interface and publishes them as encoded streams. It operates as a downstream consumer only, never writing to the cv-mmap shared memory.

**Key Features:**
- Reads cv-mmap IPC frames via POSIX shared memory + ZeroMQ synchronization
- NVENC H.264/H.265 encoding with deterministic software fallback
- RTP UDP-unicast publisher with automatic SDP generation
- RTMP publisher with dual H.265 modes (Enhanced-RTMP + domestic extension)
- Embedded standalone testers for server-independent validation
- Low-latency bounded queues with latest-frame semantics

## Quickstart

### Prerequisites

- C++23 compatible compiler (GCC 13+, Clang 16+)
- CMake 3.20+
- GStreamer 1.20+ with development headers
- ZeroMQ (cppzmq) with development headers
- spdlog
- NVIDIA GPU with NVENC support (optional, falls back to software encoding)

**Arch Linux:**
```bash
sudo pacman -S cmake gstreamer gst-plugins-base gst-plugins-good \
    gst-plugins-bad gst-plugins-ugly gst-libav cppzmq spdlog
```

### Build

```bash
cmake -B build -S .
cmake --build build
```

**Verify binaries exist:**
```bash
ls -la build/{cvmmap_streamer,rtp_receiver_tester,rtmp_stub_tester}
```

### Mandatory Acceptance (Standalone)

Run the full mandatory acceptance suite. This executes the complete protocol/codec matrix without requiring external servers.

```bash
./scripts/acceptance_standalone.sh
```

**Expected result:** Exit code 0 with summary showing `total=5 pass=5 fail=0 skip=0`

**Individual matrix rows verified:**
1. RTP + H.264
2. RTP + H.265
3. RTMP + H.264 (enhanced mode)
4. RTMP + H.265 enhanced mode
5. RTMP + H.265 domestic mode

### Fault Suite Baseline

Run the fault injection and latency validation suite.

```bash
./scripts/fault_suite.sh
```

**Expected result:** Exit code 0 with all scenarios passing.

**Scenarios tested:**
- Torn read handling (coherent snapshot validation)
- Sink stall resilience (backpressure containment)
- Reset storm recovery (stream reset handling)

### Manual Component Testing

**1. Start the simulator:**
```bash
./build/cvmmap_streamer \
    --run-mode pipeline \
    --codec h264 \
    --shm-name test_stream \
    --zmq-endpoint "ipc:///tmp/test_sync.ipc" \
    --input-mode dummy \
    --dummy-label teststream \
    --dummy-frames 300 \
    --dummy-fps 30 \
    --dummy-width 640 \
    --dummy-height 360
```

**2. Test RTP output:**
```bash
# Terminal 1: Start receiver tester
./build/rtp_receiver_tester \
    --port 5004 \
    --expect-pt 96 \
    --packet-threshold 1 \
    --timeout-ms 10000

# Terminal 2: Start streamer
./build/cvmmap_streamer \
    --run-mode pipeline \
    --codec h264 \
    --shm-name test_stream \
    --zmq-endpoint "ipc:///tmp/test_sync.ipc" \
    --rtp \
    --rtp-endpoint "127.0.0.1:5004" \
    --rtp-payload-type 96 \
    --rtp-sdp /tmp/test.sdp
```

**3. Test RTMP output (enhanced mode):**
```bash
# Terminal 1: Start RTMP stub tester
./build/rtmp_stub_tester \
    --mode h264 \
    --listen-host 127.0.0.1 \
    --listen-port 1935 \
    --video-threshold 1 \
    --timeout-ms 10000

# Terminal 2: Start streamer
./build/cvmmap_streamer \
    --run-mode pipeline \
    --codec h264 \
    --shm-name test_stream \
    --zmq-endpoint "ipc:///tmp/test_sync.ipc" \
    --rtmp \
    --rtmp-url "rtmp://127.0.0.1:1935/live/test" \
    --rtmp-mode enhanced
```

## Compatibility Matrix

| Protocol | Codec | RTMP Mode | Status | Notes |
|----------|-------|-----------|--------|-------|
| RTP | H.264 | N/A | MANDATORY | Full support |
| RTP | H.265 | N/A | MANDATORY | Full support |
| RTMP | H.264 | enhanced | MANDATORY | Legacy codec-id 7 |
| RTMP | H.265 | enhanced | MANDATORY | FourCC `hvc1`, [Enhanced-RTMP spec](https://github.com/veovera/enhanced-rtmp) |
| RTMP | H.265 | domestic | MANDATORY | FLV codec-id 12, legacy CDN compatibility |
| RTMP | H.264 | domestic | INVALID | Rejected at startup with clear error |

**Legend:**
- **MANDATORY**: Must pass for release acceptance
- **INVALID**: Explicitly rejected, exits non-zero

## Runtime Configuration

### Input Options

| Flag | Description | Default |
|------|-------------|---------|
| `--shm-name NAME` | POSIX shared memory segment name | required |
| `--zmq-endpoint URI` | ZeroMQ PUB endpoint for sync/status | required |
| `--queue-size N` | Ingest queue capacity (1 = latest-frame) | 1 |

### Codec Options

| Flag | Description |
|------|-------------|
| `--codec h264\|h265` | Video codec selection (required) |

### Output Options

| Flag | Description |
|------|-------------|
| `--rtp` | Enable RTP output |
| `--rtp-endpoint HOST:PORT` | RTP destination (required if --rtp) |
| `--rtp-payload-type PT` | Dynamic payload type [96,127] | 96 |
| `--rtp-sdp PATH` | SDP output path |
| `--rtmp` | Enable RTMP output |
| `--rtmp-url URL` | RTMP publish URL (required if --rtmp) |
| `--rtmp-mode enhanced\|domestic` | H.265 packaging mode (required for H.265) |

### Latency Knobs

| Flag | Description | Default |
|------|-------------|---------|
| `--gop N` | GOP size (keyframe interval) | 30 |
| `--b-frames N` | B-frame count (0 = lowest latency) | 0 |
| `--queue-size N` | Ingest queue depth | 1 |

### Operational Limits

| Flag | Description | Default |
|------|-------------|---------|
| `--ingest-max-frames N` | Process at most N frames then exit | 0 (unlimited) |
| `--ingest-idle-timeout-ms MS` | Exit if idle for MS milliseconds | 0 (disabled) |

## Architecture

### Data Flow

```
cv-mmap producer ──> SHM + ZMQ sync ──> Ingest Runtime
                                            │
                                            v
                                    ┌───────────────┐
                                    │ Bounded Queue │
                                    │ (size=1)      │
                                    └───────┬───────┘
                                            │
                                            v
                                    NVENC Pipeline
                                    (NVENC -> fallback)
                                            │
                                    ┌───────┴───────┐
                                    v               v
                              RTP Publisher    RTMP Publisher
                              (UDP unicast)    (TCP + FLV)
```

### Key Design Decisions

**Latest-Frame Semantics:** The ingest queue has size 1 by default. When a new frame arrives while the previous is still queued, the old frame is dropped. This prevents latency accumulation under backpressure.

**Coherent Snapshot:** Frame metadata is read twice around the payload copy. If `frame_count` or `timestamp_ns` changed, the frame is rejected as torn. This prevents consuming partially-updated frames.

**NVENC with Fallback:** The pipeline attempts NVENC first for hardware acceleration. If NVENC produces zero encoded access units after 60 frames, it falls back to software encoding (`x264enc` or `x265enc`).

**Dual-Mode H.265:** H.265 RTMP supports two packaging modes:
- **Enhanced-RTMP**: Uses FourCC `hvc1`, modern standard, supported by FFmpeg 6.0+, SRS 6.0+, ZLMediaKit
- **Domestic extension**: Uses FLV codec-id 12, legacy Chinese CDN compatibility

The mode must be explicitly selected via `--rtmp-mode` and cannot be mixed within a session.

## Environment Caveats

### Simulator Label Length
Simulator labels (`--label`) have a hard maximum of 24 bytes. Exceeding this causes immediate exit with code 2. Use compact deterministic labels like `acc_1_rtp_h264` instead of descriptive names.

### Deterministic Simulator Sizing
For reliable RTMP validation, use simulator frame sizes of at least 640x360. Smaller frames may trigger GStreamer caps negotiation failures before the first encoded access unit on some hosts.

### Build Path
Always use `downstream/cvmmap-streamer/build` for the build directory. Using the root `build/` folder causes cache collision with the main cv-mmap project.

### Fresh Configure
If you encounter configure errors referencing sibling repo paths, run:
```bash
cmake --fresh -B build -S .
```

## Optional Server Smoke Tests

Interoperability tests with SRS and ZLMediaKit are provided for reference but are **NOT** mandatory for acceptance. See:

- [SRS Smoke Test Profile](docs/smoke/srs.md)
- [ZLMediaKit Smoke Test Profile](docs/smoke/zlm.md)

If the server environment is unavailable, these tests should be skipped without failing the mandatory acceptance criteria.

## Project Structure

```
cvmmap-streamer/
├── CMakeLists.txt          # Build configuration
├── README.md               # This file
├── docs/
│   ├── smoke/
│   │   ├── srs.md          # SRS interoperability guide
│   │   └── zlm.md          # ZLMediaKit interoperability guide
│   ├── compat_matrix.md    # Detailed compatibility matrix
│   └── caveats.md          # Environment and operational caveats
├── include/cvmmap_streamer/# Public headers
│   ├── config/
│   │   └── runtime_config.hpp
│   ├── ipc/
│   │   └── cvmmap_contract.hpp
│   └── pipeline/
│       └── pipeline_types.hpp
├── scripts/
│   ├── acceptance_standalone.sh  # Mandatory acceptance runner
│   ├── fault_suite.sh            # Fault injection suite
│   └── *_helper.py               # Summary generators
└── src/
    ├── config/             # Runtime configuration
    ├── core/               # Ingest runtime and supervision
    ├── ipc/                # cv-mmap contract parsing
    ├── pipeline/           # NVENC encoding
    ├── protocol/           # RTP and RTMP publishers
    └── testers/            # Simulator and test stubs
```

## Evidence Artifacts

All test runs produce machine-readable evidence in `.sisyphus/evidence/`:

- `task-14-acceptance.txt` - Latest acceptance run metadata
- `task-14-acceptance-summary.json` - JSON summary of acceptance results
- `task-15-fault-suite.txt` - Latest fault suite run metadata
- `task-15-fault-suite-summary.json` - JSON summary of fault suite results

Each run creates timestamped subdirectories with full logs for every matrix row or fault scenario.

## Exit Codes

| Code | Meaning |
|------|---------|
| 0 | Success |
| 1 | Invalid arguments |
| 2 | Invalid arguments or configuration |
| 3 | RTP payload type mismatch |
| 4 | Packet/frame threshold not met |
| 5 | Pipeline initialization error (missing encoder) |
| 6 | RTMP mode mismatch (tester validation) |
| 7 | Protocol validation error |
| 124 | Timeout |

## References

- [Enhanced RTMP Specification](https://github.com/veovera/enhanced-rtmp)
- [cv-mmap IPC Contract](https://github.com/k2wanko/cv-mmap/blob/main/docs/cvmmap.ksy)
- SRS Documentation: https://ossrs.io/lts/en-us/docs/v7/doc/rtmp
- ZLMediaKit: https://github.com/ZLMediaKit/ZLMediaKit