docs: Deltacast SDI capture implementation plan

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Zac Gaetano 2026-06-01 07:45:58 -04:00
parent 298cb18914
commit 96f4f2dd3b

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# Deltacast SDI Capture — Implementation Plan
> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
**Goal:** Wire up Deltacast VideoMaster SDI cards in the capture service using a C bridge binary that streams raw video to FFmpeg via pipe, with embedded audio via a named FIFO.
**Architecture:** A `deltacast-capture` C binary opens the VideoMaster board, waits for signal lock, emits a JSON format line to stderr, then streams raw UYVY video frames to stdout and 2-channel PCM audio to a named FIFO. `capture-manager.js` reads the JSON, spawns FFmpeg with `-f rawvideo -i pipe:0` for video and `-f s16le -i <fifo>` for audio, and pipes bridge stdout into FFmpeg stdin. Two concurrent SDK streams share the same board handle — `VHD_SDI_STPROC_DISJOINED_VIDEO` for video and `VHD_SDI_STPROC_DISJOINED_ANC` for audio.
**Tech Stack:** Deltacast VideoMaster C SDK 6.34.1 (`libvideomasterhd.so`, `libvideomasterhd_audio.so`), C17, CMake, Node.js ES modules, Docker multi-stage build.
---
## File Map
| Action | Path | Responsibility |
|---|---|---|
| Create | `services/capture/deltacast-bridge/CMakeLists.txt` | Build config for the bridge binary |
| Create | `services/capture/deltacast-bridge/main.c` | Bridge: board open, signal detect, video stream, audio thread |
| Modify | `services/capture/Dockerfile` | SDK extraction stage, bridge build stage, runtime .so install |
| Modify | `services/capture/src/capture-manager.js` | `readFirstStderrLine` helper, deltacast `_buildInputArgs`, bridge lifecycle in `start()`/`stop()` |
| Modify | `services/capture/src/routes/capture.js` | Accept `deltacast` as a valid `source_type` |
---
## Task 1: Bridge CMakeLists.txt
**Files:**
- Create: `services/capture/deltacast-bridge/CMakeLists.txt`
- [ ] **Step 1: Create the CMakeLists.txt**
```cmake
cmake_minimum_required(VERSION 3.16)
project(deltacast-bridge C)
set(CMAKE_C_STANDARD 17)
set(SDK_ROOT "/sdk" CACHE PATH "Path to extracted VideoMaster SDK")
add_executable(deltacast-capture main.c)
target_include_directories(deltacast-capture PRIVATE
${SDK_ROOT}/include/videomaster
)
target_link_directories(deltacast-capture PRIVATE
${SDK_ROOT}/lib
)
target_link_libraries(deltacast-capture PRIVATE
videomasterhd
videomasterhd_audio
pthread
)
# Embed the SDK RPATH so the binary finds the .so at runtime
set_target_properties(deltacast-capture PROPERTIES
INSTALL_RPATH "/usr/local/lib/deltacast"
BUILD_WITH_INSTALL_RPATH TRUE
)
```
- [ ] **Step 2: Commit**
```bash
git add services/capture/deltacast-bridge/CMakeLists.txt
git commit -m "build(capture): add CMakeLists for deltacast-capture bridge binary"
```
---
## Task 2: Bridge main.c
**Files:**
- Create: `services/capture/deltacast-bridge/main.c`
The binary: parses CLI args, opens the board, waits for signal lock, emits one JSON line to stderr, then spawns an audio thread writing to a FIFO and runs a video capture loop writing raw UYVY frames to stdout.
- [ ] **Step 1: Create the bridge source file**
```c
/* services/capture/deltacast-bridge/main.c
*
* Deltacast VideoMaster SDI capture bridge.
* Writes raw UYVY video to stdout and stereo PCM to a named FIFO.
* Emits one JSON line to stderr on signal lock before streaming starts.
*
* Usage:
* deltacast-capture --device <N> --port <N> --audio-pipe <path>
* [--signal-timeout <sec>]
*/
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <signal.h>
#include <stdatomic.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "VideoMasterHD_Core.h"
#include "VideoMasterHD_Sdi.h"
#include "VideoMasterHD_Sdi_Audio.h"
/* ── Globals ─────────────────────────────────────────────────────────── */
static atomic_int g_stop = 0;
static void on_signal(int s) { (void)s; atomic_store(&g_stop, 1); }
/* ── Stream type by port index ───────────────────────────────────────── */
static ULONG rx_streamtype(unsigned port) {
switch (port) {
case 0: return VHD_ST_RX0;
case 1: return VHD_ST_RX1;
case 2: return VHD_ST_RX2;
case 3: return VHD_ST_RX3;
default: return VHD_ST_RX0;
}
}
/* ── Loopback board property by port index ───────────────────────────── */
static ULONG loopback_prop(unsigned port) {
switch (port) {
case 0: return VHD_CORE_BP_PASSIVE_LOOPBACK_0;
case 1: return VHD_CORE_BP_PASSIVE_LOOPBACK_1;
case 2: return VHD_CORE_BP_PASSIVE_LOOPBACK_2;
case 3: return VHD_CORE_BP_PASSIVE_LOOPBACK_3;
default: return VHD_CORE_BP_PASSIVE_LOOPBACK_0;
}
}
/* ── Video standard → width/height/fps/interlaced ───────────────────── */
typedef struct { int width, height, fps_num, fps_den; int interlaced; } VideoInfo;
static VideoInfo video_info(VHD_VIDEOSTANDARD std, VHD_CLOCKDIVISOR div) {
int ntsc = (div == VHD_CLOCKDIV_1001);
switch (std) {
case VHD_VIDEOSTD_S274M_1080p_25Hz: return (VideoInfo){1920,1080,25,1,0};
case VHD_VIDEOSTD_S274M_1080p_30Hz: return (VideoInfo){1920,1080,ntsc?30000:30,ntsc?1001:1,0};
case VHD_VIDEOSTD_S274M_1080p_24Hz: return (VideoInfo){1920,1080,ntsc?24000:24,ntsc?1001:1,0};
case VHD_VIDEOSTD_S274M_1080p_50Hz: return (VideoInfo){1920,1080,50,1,0};
case VHD_VIDEOSTD_S274M_1080p_60Hz: return (VideoInfo){1920,1080,ntsc?60000:60,ntsc?1001:1,0};
case VHD_VIDEOSTD_S274M_1080psf_24Hz: return (VideoInfo){1920,1080,ntsc?24000:24,ntsc?1001:1,0};
case VHD_VIDEOSTD_S274M_1080psf_25Hz: return (VideoInfo){1920,1080,25,1,0};
case VHD_VIDEOSTD_S274M_1080psf_30Hz: return (VideoInfo){1920,1080,ntsc?30000:30,ntsc?1001:1,0};
case VHD_VIDEOSTD_S274M_1080i_50Hz: return (VideoInfo){1920,1080,25,1,1};
case VHD_VIDEOSTD_S274M_1080i_60Hz: return (VideoInfo){1920,1080,ntsc?30000:30,ntsc?1001:1,1};
case VHD_VIDEOSTD_S296M_720p_50Hz: return (VideoInfo){1280,720,50,1,0};
case VHD_VIDEOSTD_S296M_720p_60Hz: return (VideoInfo){1280,720,ntsc?60000:60,ntsc?1001:1,0};
case VHD_VIDEOSTD_S296M_720p_25Hz: return (VideoInfo){1280,720,25,1,0};
case VHD_VIDEOSTD_S296M_720p_30Hz: return (VideoInfo){1280,720,ntsc?30000:30,ntsc?1001:1,0};
case VHD_VIDEOSTD_S296M_720p_24Hz: return (VideoInfo){1280,720,ntsc?24000:24,ntsc?1001:1,0};
case VHD_VIDEOSTD_3840x2160p_24Hz: return (VideoInfo){3840,2160,ntsc?24000:24,ntsc?1001:1,0};
case VHD_VIDEOSTD_3840x2160p_25Hz: return (VideoInfo){3840,2160,25,1,0};
case VHD_VIDEOSTD_3840x2160p_30Hz: return (VideoInfo){3840,2160,ntsc?30000:30,ntsc?1001:1,0};
case VHD_VIDEOSTD_3840x2160p_50Hz: return (VideoInfo){3840,2160,50,1,0};
case VHD_VIDEOSTD_3840x2160p_60Hz: return (VideoInfo){3840,2160,ntsc?60000:60,ntsc?1001:1,0};
case VHD_VIDEOSTD_S259M_NTSC_480: return (VideoInfo){720,480,ntsc?30000:30,ntsc?1001:1,1};
default: return (VideoInfo){1920,1080,25,1,0};
}
}
/* ── Audio thread ────────────────────────────────────────────────────── */
typedef struct {
HANDLE board;
unsigned port;
ULONG video_std;
ULONG clock_div;
const char *fifo_path;
} AudioArgs;
static void *audio_thread(void *arg) {
AudioArgs *a = (AudioArgs *)arg;
HANDLE stream = NULL;
ULONG r = VHD_OpenStreamHandle(a->board, rx_streamtype(a->port),
VHD_SDI_STPROC_DISJOINED_ANC,
NULL, &stream, NULL);
if (r != VHDERR_NOERROR) {
fprintf(stderr, "[audio] VHD_OpenStreamHandle failed: %lu\n", r);
return NULL;
}
VHD_SetStreamProperty(stream, VHD_SDI_SP_VIDEO_STANDARD, a->video_std);
VHD_SetStreamProperty(stream, VHD_SDI_SP_CLOCK_SYSTEM, a->clock_div);
VHD_SetStreamProperty(stream, VHD_CORE_SP_TRANSFER_SCHEME, VHD_TRANSFER_SLAVED);
/* Stereo pair, 16-bit, 48kHz on group 0 channel 0 */
ULONG max_samples = VHD_GetNbSamples((VHD_VIDEOSTANDARD)a->video_std,
(VHD_CLOCKDIVISOR)a->clock_div,
VHD_ASR_48000, 0);
ULONG block_size = VHD_GetBlockSize(VHD_AF_16, VHD_AM_STEREO);
ULONG buf_sz = (max_samples + 4) * block_size; /* +4 for 29.97 variation */
unsigned char *buf = calloc(1, buf_sz);
if (!buf) { VHD_CloseStreamHandle(stream); return NULL; }
VHD_AUDIOINFO ai;
memset(&ai, 0, sizeof(ai));
ai.pAudioGroups[0].pAudioChannels[0].Mode = VHD_AM_STEREO;
ai.pAudioGroups[0].pAudioChannels[0].BufferFormat = VHD_AF_16;
ai.pAudioGroups[0].pAudioChannels[0].pData = buf;
if (VHD_StartStream(stream) != VHDERR_NOERROR) {
free(buf); VHD_CloseStreamHandle(stream); return NULL;
}
/* Open FIFO for writing — blocks until FFmpeg opens the read end */
int fd = open(a->fifo_path, O_WRONLY);
if (fd < 0) {
fprintf(stderr, "[audio] open FIFO failed: %s\n", strerror(errno));
VHD_StopStream(stream); VHD_CloseStreamHandle(stream); free(buf);
return NULL;
}
HANDLE slot = NULL;
while (!atomic_load(&g_stop)) {
r = VHD_LockSlotHandle(stream, &slot);
if (r == VHDERR_NOERROR) {
ai.pAudioGroups[0].pAudioChannels[0].DataSize = buf_sz;
if (VHD_SlotExtractAudio(slot, &ai) == VHDERR_NOERROR) {
ULONG sz = ai.pAudioGroups[0].pAudioChannels[0].DataSize;
if (sz > 0) write(fd, buf, sz);
}
VHD_UnlockSlotHandle(slot);
} else if (r != VHDERR_TIMEOUT) {
break;
}
}
close(fd);
VHD_StopStream(stream);
VHD_CloseStreamHandle(stream);
free(buf);
return NULL;
}
/* ── Main ────────────────────────────────────────────────────────────── */
int main(int argc, char *argv[]) {
unsigned device_id = 0;
unsigned port_id = 0;
int sig_timeout = 30;
const char *audio_pipe = NULL;
for (int i = 1; i < argc; i++) {
if (!strcmp(argv[i], "--device") && i+1 < argc) device_id = (unsigned)atoi(argv[++i]);
else if (!strcmp(argv[i], "--port") && i+1 < argc) port_id = (unsigned)atoi(argv[++i]);
else if (!strcmp(argv[i], "--audio-pipe") && i+1 < argc) audio_pipe = argv[++i];
else if (!strcmp(argv[i], "--signal-timeout") && i+1 < argc) sig_timeout = atoi(argv[++i]);
}
signal(SIGINT, on_signal);
signal(SIGTERM, on_signal);
/* ── Init API ─────────────────────────────────────────────────── */
ULONG dll_ver, nb_boards;
if (VHD_GetApiInfo(&dll_ver, &nb_boards) != VHDERR_NOERROR) {
fprintf(stderr, "{\"error\":\"VHD_GetApiInfo failed\"}\n");
return 1;
}
if (device_id >= nb_boards) {
fprintf(stderr, "{\"error\":\"board %u not found (%lu detected)\"}\n", device_id, nb_boards);
return 1;
}
/* ── Open board ───────────────────────────────────────────────── */
HANDLE board = NULL;
if (VHD_OpenBoardHandle(device_id, &board, NULL, 0) != VHDERR_NOERROR) {
fprintf(stderr, "{\"error\":\"VHD_OpenBoardHandle failed for board %u\"}\n", device_id);
return 1;
}
/* Disable passive (relay) loopback so RX is live */
VHD_SetBoardProperty(board, loopback_prop(port_id), FALSE);
/* ── Wait for signal lock ──────────────────────────────────────── */
ULONG video_std = (ULONG)NB_VHD_VIDEOSTANDARDS;
struct timespec deadline;
clock_gettime(CLOCK_MONOTONIC, &deadline);
deadline.tv_sec += sig_timeout;
while (!atomic_load(&g_stop)) {
struct timespec now;
clock_gettime(CLOCK_MONOTONIC, &now);
if (now.tv_sec > deadline.tv_sec ||
(now.tv_sec == deadline.tv_sec && now.tv_nsec >= deadline.tv_nsec)) break;
VHD_GetChannelProperty(board, VHD_RX_CHANNEL, port_id,
VHD_SDI_CP_VIDEO_STANDARD, &video_std);
if (video_std != (ULONG)NB_VHD_VIDEOSTANDARDS) break;
struct timespec ts = {0, 200000000L}; /* 200ms */
nanosleep(&ts, NULL);
}
if (atomic_load(&g_stop) || video_std == (ULONG)NB_VHD_VIDEOSTANDARDS) {
fprintf(stderr,
"{\"error\":\"no signal on board %u port %u within %ds\"}\n",
device_id, port_id, sig_timeout);
VHD_CloseBoardHandle(board);
return 1;
}
ULONG clock_div = VHD_CLOCKDIV_1;
VHD_GetChannelProperty(board, VHD_RX_CHANNEL, port_id,
VHD_SDI_CP_CLOCK_DIVISOR, &clock_div);
VideoInfo vi = video_info((VHD_VIDEOSTANDARD)video_std,
(VHD_CLOCKDIVISOR)clock_div);
/* ── Emit format JSON to stderr (one line, flushed) ─────────────── */
fprintf(stderr,
"{\"width\":%d,\"height\":%d,\"fps_num\":%d,\"fps_den\":%d,"
"\"interlaced\":%s,\"pix_fmt\":\"uyvy422\","
"\"audio_channels\":2,\"audio_rate\":48000,"
"\"device\":%u,\"port\":%u}\n",
vi.width, vi.height, vi.fps_num, vi.fps_den,
vi.interlaced ? "true" : "false",
device_id, port_id);
fflush(stderr);
/* ── Open video stream ───────────────────────────────────────────── */
HANDLE video_stream = NULL;
if (VHD_OpenStreamHandle(board, rx_streamtype(port_id),
VHD_SDI_STPROC_DISJOINED_VIDEO,
NULL, &video_stream, NULL) != VHDERR_NOERROR) {
fprintf(stderr, "{\"error\":\"VHD_OpenStreamHandle (video) failed\"}\n");
VHD_CloseBoardHandle(board);
return 1;
}
VHD_SetStreamProperty(video_stream, VHD_SDI_SP_VIDEO_STANDARD, video_std);
VHD_SetStreamProperty(video_stream, VHD_SDI_SP_CLOCK_SYSTEM, clock_div);
VHD_SetStreamProperty(video_stream, VHD_CORE_SP_TRANSFER_SCHEME, VHD_TRANSFER_SLAVED);
VHD_SetStreamProperty(video_stream, VHD_CORE_SP_SLOTS_QUEUE_DEPTH, 8);
/* ── Launch audio thread (FIFO open blocks until FFmpeg connects) ── */
pthread_t audio_tid = 0;
AudioArgs audio_args = { board, port_id, video_std, clock_div, audio_pipe };
if (audio_pipe) {
pthread_create(&audio_tid, NULL, audio_thread, &audio_args);
}
/* ── Start video stream ──────────────────────────────────────────── */
if (VHD_StartStream(video_stream) != VHDERR_NOERROR) {
atomic_store(&g_stop, 1);
if (audio_tid) pthread_join(audio_tid, NULL);
VHD_CloseStreamHandle(video_stream);
VHD_CloseBoardHandle(board);
return 1;
}
/* ── Video capture loop ──────────────────────────────────────────── */
HANDLE slot = NULL;
while (!atomic_load(&g_stop)) {
ULONG r = VHD_LockSlotHandle(video_stream, &slot);
if (r == VHDERR_NOERROR) {
BYTE *buf = NULL;
ULONG sz = 0;
if (VHD_GetSlotBuffer(slot, VHD_SDI_BT_VIDEO, &buf, &sz) == VHDERR_NOERROR) {
ULONG written = 0;
while (written < sz) {
ssize_t n = write(STDOUT_FILENO, buf + written, sz - written);
if (n <= 0) { atomic_store(&g_stop, 1); break; }
written += (ULONG)n;
}
}
VHD_UnlockSlotHandle(slot);
} else if (r != VHDERR_TIMEOUT) {
break;
}
}
/* ── Cleanup ─────────────────────────────────────────────────────── */
VHD_StopStream(video_stream);
VHD_CloseStreamHandle(video_stream);
if (audio_tid) pthread_join(audio_tid, NULL);
VHD_CloseBoardHandle(board);
return 0;
}
```
- [ ] **Step 2: Commit**
```bash
git add services/capture/deltacast-bridge/main.c
git commit -m "feat(capture): add deltacast-capture bridge binary source"
```
---
## Task 3: Dockerfile — SDK extraction + bridge build + runtime
**Files:**
- Modify: `services/capture/Dockerfile`
The existing Dockerfile has three logical sections: FFmpeg build, runtime. We add two new stages before FFmpeg and patch the runtime stage.
- [ ] **Step 1: Read the current Dockerfile**
Read `services/capture/Dockerfile` and verify it starts with `FROM debian:bookworm AS ffmpeg-builder`.
- [ ] **Step 2: Prepend two new stages and patch runtime**
The full new Dockerfile:
```dockerfile
# ── Stage 0: Extract Deltacast VideoMaster SDK ───────────────────────────
FROM debian:bookworm AS sdk-extractor
COPY videomaster-linux.x64-6.34.1-dev.tar.gz /tmp/
RUN mkdir -p /sdk && tar -xzf /tmp/videomaster-linux.x64-6.34.1-dev.tar.gz -C /sdk
# ── Stage 1: Build deltacast-capture bridge binary ───────────────────────
FROM debian:bookworm AS bridge-builder
RUN apt-get update && apt-get install -y --no-install-recommends \
build-essential cmake ca-certificates \
&& rm -rf /var/lib/apt/lists/*
COPY --from=sdk-extractor /sdk /sdk
COPY deltacast-bridge/ /bridge/
RUN cmake -S /bridge -B /bridge/build \
-DCMAKE_BUILD_TYPE=Release \
-DSDK_ROOT=/sdk \
&& cmake --build /bridge/build -j$(nproc)
# ── Stage 2: Build FFmpeg with DeckLink + NVENC (HEVC/H264) support ──────
# (unchanged — keep original content here)
FROM debian:bookworm AS ffmpeg-builder
# ... (rest of the existing ffmpeg-builder stage unchanged) ...
# ── Stage 3: Runtime image ───────────────────────────────────────────────
FROM node:20-bookworm
# Runtime deps for compiled ffmpeg libs (unchanged)
RUN apt-get update && apt-get install -y --no-install-recommends \
libx264-164 libx265-199 libvpx7 libopus0 libmp3lame0 \
libsrt1.5-openssl libzmq5 libstdc++6 libc++1 libc++abi1 \
&& rm -rf /var/lib/apt/lists/*
# Copy compiled ffmpeg/ffprobe (unchanged)
COPY --from=ffmpeg-builder /usr/local/bin/ffmpeg /usr/local/bin/ffmpeg
COPY --from=ffmpeg-builder /usr/local/bin/ffprobe /usr/local/bin/ffprobe
COPY --from=ffmpeg-builder /usr/local/lib/ /usr/local/lib/
# DeckLink runtime .so (unchanged)
COPY lib/libDeckLinkAPI.so /usr/lib/libDeckLinkAPI.so
COPY lib/libDeckLinkPreviewAPI.so /usr/lib/libDeckLinkPreviewAPI.so
# Deltacast bridge binary + SDK runtime libs
COPY --from=bridge-builder /bridge/build/deltacast-capture /usr/local/bin/deltacast-capture
COPY --from=sdk-extractor /sdk/lib/libvideomasterhd.so.6.34.1 /usr/local/lib/deltacast/
COPY --from=sdk-extractor /sdk/lib/libvideomasterhd_audio.so.6.34.1 /usr/local/lib/deltacast/
RUN ln -sf libvideomasterhd.so.6.34.1 /usr/local/lib/deltacast/libvideomasterhd.so.6 \
&& ln -sf libvideomasterhd.so.6.34.1 /usr/local/lib/deltacast/libvideomasterhd.so \
&& ln -sf libvideomasterhd_audio.so.6.34.1 /usr/local/lib/deltacast/libvideomasterhd_audio.so.6 \
&& ln -sf libvideomasterhd_audio.so.6.34.1 /usr/local/lib/deltacast/libvideomasterhd_audio.so \
&& ldconfig /usr/local/lib/deltacast \
&& ldconfig
RUN mkdir -p /live /growing
WORKDIR /app
COPY package*.json ./
RUN npm install --omit=dev
COPY . .
EXPOSE 3001
CMD ["node", "src/index.js"]
```
**Implementation note:** Edit the existing Dockerfile. Prepend the two new FROM stages (sdk-extractor, bridge-builder) before the existing `FROM debian:bookworm AS ffmpeg-builder` line. Then in the final runtime stage, add the Deltacast `COPY` and `RUN` lines after the DeckLink `.so` lines (before the `RUN mkdir -p /live /growing` line).
- [ ] **Step 3: Commit**
```bash
git add services/capture/Dockerfile
git commit -m "build(capture): add Deltacast SDK extraction and bridge build stages to Dockerfile"
```
---
## Task 4: capture-manager.js — `readFirstStderrLine` helper
**Files:**
- Modify: `services/capture/src/capture-manager.js` (add helper near top, after imports)
- [ ] **Step 1: Add the helper function after the existing imports (after line 6 `import { v4 as uuidv4 } from 'uuid';`)**
```js
/**
* Reads the first line from a spawned process's stderr stream.
* Resolves with the parsed JSON object when the first '\n' arrives.
* Rejects if the process exits with a non-zero code before emitting a line,
* or if timeoutMs elapses.
*/
function readFirstStderrLine(proc, timeoutMs = 35_000) {
return new Promise((resolve, reject) => {
let buf = '';
let settled = false;
const settle = (fn) => { if (settled) return; settled = true; fn(); };
const timer = setTimeout(() => {
settle(() => reject(new Error(`deltacast-capture: timed out waiting for format JSON after ${timeoutMs}ms`)));
}, timeoutMs);
proc.stderr.setEncoding('utf8');
proc.stderr.on('data', (chunk) => {
buf += chunk;
const nl = buf.indexOf('\n');
if (nl === -1) return;
const line = buf.slice(0, nl).trim();
clearTimeout(timer);
try {
const parsed = JSON.parse(line);
if (parsed.error) {
settle(() => reject(new Error(`deltacast-capture: ${parsed.error}`)));
} else {
settle(() => resolve(parsed));
}
} catch (e) {
settle(() => reject(new Error(`deltacast-capture: invalid JSON on stderr: ${line}`)));
}
});
proc.on('exit', (code) => {
clearTimeout(timer);
settle(() => reject(new Error(`deltacast-capture: exited with code ${code} before emitting format JSON`)));
});
});
}
```
- [ ] **Step 2: Commit**
```bash
git add services/capture/src/capture-manager.js
git commit -m "feat(capture): add readFirstStderrLine helper for deltacast bridge handshake"
```
---
## Task 5: capture-manager.js — Deltacast `_buildInputArgs`
**Files:**
- Modify: `services/capture/src/capture-manager.js` — replace the `deltacast` branch of `_buildInputArgs` (currently lines 160191)
- [ ] **Step 1: Replace the existing deltacast branch**
Find the block starting with `// Deltacast SDI via VideoMaster SDK FFmpeg plugin.` and ending at the closing `}` of the `if (sourceType === 'deltacast')` block. Replace the entire `if (sourceType === 'deltacast') { ... }` block with:
```js
if (sourceType === 'deltacast') {
const idx = (typeof device === 'number' || /^\d+$/.test(String(device)))
? parseInt(device, 10) : 0;
const audioFifo = `/tmp/dc-audio-${this._sessionIdForBridge}`;
// Create the audio FIFO before spawning the bridge.
const { execSync: _exec } = await import('child_process');
try { _exec(`mkfifo ${audioFifo}`); } catch (_) { /* may already exist */ }
const bridge = spawn('deltacast-capture', [
'--device', String(idx),
'--port', String(idx),
'--audio-pipe', audioFifo,
'--signal-timeout', '30',
], { stdio: ['ignore', 'pipe', 'pipe'] });
// Log bridge stderr after the first line (non-JSON diagnostic output)
let firstLineDone = false;
bridge.stderr.on('data', (d) => {
if (firstLineDone) console.error(`[deltacast-bridge] ${d}`);
else if (d.toString().includes('\n')) firstLineDone = true;
});
const fmt = await readFirstStderrLine(bridge, 35_000);
// fmt: { width, height, fps_num, fps_den, interlaced, pix_fmt,
// audio_channels, audio_rate, device, port }
return {
inputArgs: [
'-f', 'rawvideo',
'-pix_fmt', fmt.pix_fmt,
'-video_size', `${fmt.width}x${fmt.height}`,
'-framerate', `${fmt.fps_num}/${fmt.fps_den}`,
'-i', 'pipe:0',
'-f', 's16le',
'-ar', String(fmt.audio_rate),
'-ac', String(fmt.audio_channels),
'-i', audioFifo,
],
isNetwork: false,
bridgeProcess: bridge,
audioFifo,
interlaced: !!fmt.interlaced,
};
}
```
- [ ] **Step 2: Commit**
```bash
git add services/capture/src/capture-manager.js
git commit -m "feat(capture): replace deltacast _buildInputArgs stub with real bridge spawn"
```
---
## Task 6: capture-manager.js — `start()` bridge lifecycle + `stop()` cleanup
**Files:**
- Modify: `services/capture/src/capture-manager.js`
Four changes to `start()` and one to `stop()`.
- [ ] **Step 1: Store session ID before `_buildInputArgs` call**
In `start()`, before the `const { inputArgs, isNetwork } = await this._buildInputArgs(...)` call (currently around line 307), add:
```js
this._sessionIdForBridge = sessionId;
```
- [ ] **Step 2: Store bridge state after `_buildInputArgs` returns**
After `const { inputArgs, isNetwork } = await this._buildInputArgs(...)`, change the destructuring to also capture `bridgeProcess` and `audioFifo`:
```js
const { inputArgs, isNetwork, bridgeProcess = null, audioFifo = null, interlaced = false } = await this._buildInputArgs({
sourceType, device, sourceUrl, listen, listenPort, streamKey,
});
```
- [ ] **Step 3: Pipe bridge stdout into FFmpeg stdin for deltacast**
After `const hiresProcess = spawn('ffmpeg', hiresArgs, { stdio: hiresStdio });`, add:
```js
// For deltacast, the bridge writes raw video to its stdout.
// Pipe it into FFmpeg's stdin so FFmpeg reads -i pipe:0.
if (bridgeProcess) {
bridgeProcess.stdout.pipe(hiresProcess.stdin);
}
```
- [ ] **Step 4: Add bridge to `processes` map and `audioFifo` to `currentSession`**
Change the existing `const processes = { hires: hiresProcess };` line to:
```js
const processes = { hires: hiresProcess };
if (bridgeProcess) processes.bridge = bridgeProcess;
```
And in the `this.state.currentSession = { ... }` object (near the end of `start()`), add:
```js
audioFifo,
```
to the object literal (alongside `sourceType`, `device`, etc.).
- [ ] **Step 5: Fix deinterlace filter to include deltacast interlaced signals**
Find the line (currently ~321):
```js
const sdiFilterArgs = (sourceType === 'sdi') ? ['-vf', 'yadif=mode=1:deint=1'] : [];
```
Replace with:
```js
const isInterlacedSource = sourceType === 'sdi' || (sourceType === 'deltacast' && interlaced);
const sdiFilterArgs = isInterlacedSource ? ['-vf', 'yadif=mode=1:deint=1'] : [];
```
- [ ] **Step 6: Include deltacast in the HLS split-output branch**
Find the line (currently ~334):
```js
if (sourceType === 'sdi' && this._assetIdForHls) {
```
Replace with:
```js
if ((sourceType === 'sdi' || sourceType === 'deltacast') && this._assetIdForHls) {
```
- [ ] **Step 7: Kill bridge in `stop()` and clean up FIFO**
In the `stop()` method, find the existing kill block:
```js
if (processes.hires) processes.hires.kill('SIGINT');
if (processes.proxy) processes.proxy.kill('SIGINT');
if (processes.hls) { try { processes.hls.kill('SIGINT'); } catch (_) {} }
```
Add a bridge kill and FIFO cleanup:
```js
if (processes.hires) processes.hires.kill('SIGINT');
if (processes.proxy) processes.proxy.kill('SIGINT');
if (processes.hls) { try { processes.hls.kill('SIGINT'); } catch (_) {} }
if (processes.bridge) { try { processes.bridge.kill('SIGINT'); } catch (_) {} }
```
Then after the existing `await Promise.all(uploadPromises);` block (around line 462), add FIFO cleanup:
```js
if (currentSession.audioFifo) {
try { (await import('node:fs')).unlinkSync(currentSession.audioFifo); } catch (_) {}
}
```
- [ ] **Step 8: Commit**
```bash
git add services/capture/src/capture-manager.js
git commit -m "feat(capture): wire bridge process lifecycle into start/stop for deltacast"
```
---
## Task 7: routes/capture.js — Accept `deltacast` source_type
**Files:**
- Modify: `services/capture/src/routes/capture.js` (line 329)
- [ ] **Step 1: Find the source_type validation block in `/start` handler (around line 318)**
Current code:
```js
} else {
return res.status(400).json({
error: `Unknown source_type: ${source_type}. Must be sdi, srt, or rtmp`,
});
}
```
This `else` branch fires when source_type isn't `sdi`, `srt`, or `rtmp`. Add `deltacast` to the accepted list.
- [ ] **Step 2: Add deltacast validation before the else block**
After the `} else if (source_type === 'srt' || source_type === 'rtmp') {` block, add:
```js
} else if (source_type === 'deltacast') {
if (device === undefined || device === null) {
return res.status(400).json({ error: 'deltacast source requires: device (board/port index)' });
}
} else {
return res.status(400).json({
error: `Unknown source_type: ${source_type}. Must be sdi, srt, rtmp, or deltacast`,
});
}
```
- [ ] **Step 3: Commit**
```bash
git add services/capture/src/routes/capture.js
git commit -m "feat(capture): accept deltacast as valid source_type in /start handler"
```
---
## Task 8: Smoke test — verify the build and Node.js changes
**Files:** None created.
- [ ] **Step 1: Verify the bridge compiles on the capture host (or in Docker)**
On the Deltacast machine (once it is available), run:
```bash
cd services/capture
tar -xzf ../../videomaster-linux.x64-6.34.1-dev.tar.gz -C /tmp/sdk
cmake -S deltacast-bridge -B /tmp/bridge-build -DSDK_ROOT=/tmp/sdk -DCMAKE_BUILD_TYPE=Release
cmake --build /tmp/bridge-build -j$(nproc)
ls -lh /tmp/bridge-build/deltacast-capture
```
Expected: binary present, size ~50200KB.
Until the hardware machine is available, verify the CMakeLists.txt syntax is correct by running the configure step only:
```bash
cmake -S services/capture/deltacast-bridge -B /tmp/bridge-test \
-DSDK_ROOT=C:/Users/zacga/Nextcloud/Claude/Projects/Dragonflight \
--check-system-vars 2>&1 | head -20
```
- [ ] **Step 2: Verify capture-manager.js has no syntax errors**
```bash
cd services/capture
node --input-type=module < src/capture-manager.js 2>&1 | head -5
```
Expected: no output (file imports fine) or a module-not-found error for uuid (acceptable — the file is correct).
- [ ] **Step 3: Verify routes/capture.js has no syntax errors**
```bash
node --input-type=module < services/capture/src/routes/capture.js 2>&1 | head -5
```
Expected: no output or dependency error only.
- [ ] **Step 4: Confirm deltacast recorder creation is rejected correctly without device param**
Start the capture service locally (if possible) and POST:
```bash
curl -s -X POST http://localhost:3001/capture/start \
-H 'Content-Type: application/json' \
-d '{"project_id":"test","clip_name":"test","source_type":"deltacast"}' | jq .
```
Expected response:
```json
{"error":"deltacast source requires: device (board/port index)"}
```
- [ ] **Step 5: Final commit if any fixups were needed**
```bash
git add -A
git commit -m "fix(capture): deltacast smoke-test fixups"
```
---
## Hardware Validation Checklist (run on the Deltacast machine)
After the hardware machine is available:
1. Build the Docker image: `docker compose build capture`
2. Create a recorder with `source_type=deltacast`, `device=0`
3. Confirm capture container logs show the JSON format line within 5s of feed going live
4. Confirm recorder status shows `signal: "receiving"`
5. Record a 30s clip → verify asset created, proxy + HLS generated
6. Test stop mid-record → file finalized correctly
7. Test no-signal path → recorder stays idle, no asset created
8. Test container restart mid-record → existing asset finalized via `/finalize` endpoint