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fix(capture): growing file is MXF OP1a (DNxHR HQ) so Premiere can open it

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The growing edit-while-record file was a fragmented MOV (empty moov), which
Premiere can't open ("Unable to open file on disk"). Write the growing master
as MXF OP1a / DNxHR HQ (Premiere-native, growable on disk); finalized master
keeps today's non-fragmented +faststart MOV.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Zac Gaetano 2026-05-31 18:31:07 -04:00
parent 1d642bd437
commit 794b9d9929
1 changed files with 54 additions and 13 deletions
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67
services/capture/src/capture-manager.js
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@ -155,12 +155,54 @@ const CONTAINER_EXT = {
mov: 'mov', mp4: 'mp4', mkv: 'mkv', mxf: 'mxf', ts: 'ts',
};
// Growing-file (edit-while-record) master format.
//
// Premiere's "open capture in progress" / grow-on-disk support is FORMAT-
// SPECIFIC. A fragmented MP4/MOV (`+frag_keyframe+empty_moov+default_base_moof`)
// is NOT openable by Premiere as a growing file — its QuickTime importer needs
// the classic stco/stsz/stts sample tables in a single top-level moov, which a
// fragmented MOV never has while growing (samples live in moof/trun fragments).
// Symptom: "Unable to open file on disk." (Confirmed via ffprobe on zampp2: the
// growing .mov is ftyp + empty moov + repeating moof/mdat pairs, no sample
// tables.)
//
// The robust, broadcast-standard growing format Premiere DOES ingest is
// MXF OP1a (`-f mxf`) carrying a Premiere-native intra codec. We use DNxHR HQ
// (4:2:2 8-bit) which ffmpeg's MXF muxer accepts (HEVC/ProRes-in-MXF are
// rejected by this build), every frame is intra so a partially-written file is
// decodable to its last complete frame, and MXF writes header + body partitions
// incrementally so readers see valid essence mid-write. The same finalized .mxf
// is also a clean, Premiere-native asset, so the promotion/finalized path stays
// valid.
//
// Trade-off: DNxHR HQ is large (~22 GB/min at 1080p). Switch the profile to
// dnxhr_sq below (~half the bitrate) if disk is the constraint.
const GROWING_VIDEO_ARGS = [
'-c:v', 'dnxhd', '-profile:v', 'dnxhr_hq', '-pix_fmt', 'yuv422p',
];
const GROWING_EXT = 'mxf';
function buildEncodeArgs({
codec, videoBitrate, framerate,
audioCodec, audioBitrate, audioChannels,
container, isNetwork, isProxy = false,
growing = false,
}) {
// ── Growing master: force MXF OP1a + DNxHR, ignoring the configured MOV/
// ProRes container/codec. This is the only combination Premiere opens as a
// growing file (see GROWING_VIDEO_ARGS above). Audio is forced to PCM,
// which MXF carries natively and Premiere ingests.
if (growing) {
const args = [];
if (isNetwork) args.push('-map', '0:v:0?', '-map', '0:a:0?');
args.push(...GROWING_VIDEO_ARGS);
if (framerate && framerate !== 'native') args.push('-r', framerate);
args.push('-c:a', 'pcm_s24le');
if (audioChannels) args.push('-ac', String(audioChannels));
args.push('-f', 'mxf');
return args;
}
const v = VIDEO_CODECS[codec] || (isProxy ? VIDEO_CODECS.h264 : VIDEO_CODECS.prores_hq);
const a = AUDIO_CODECS[audioCodec] || (isProxy ? AUDIO_CODECS.aac : AUDIO_CODECS.pcm_s24le);
const fmt = CONTAINER_FMT[container] || (isProxy ? 'mp4' : 'mov');
@ -180,19 +222,15 @@ function buildEncodeArgs({
// moov-atom placement is the difference between a Premiere-openable master and
// a "file cannot be opened" error.
//
// - Growing-file masters (edit-while-record on the SMB share) MUST be
// fragmented so a moov/mvex is present from the first frame and the file is
// decodable while still being written. The samples live in moof/trun boxes.
//
// - Finalized masters (the S3-piped recording that stops cleanly) must NOT be
// fragmented. Adobe Premiere's QuickTime/MOV importer reads the classic
// stco/stsz/stts sample tables in a single top-level moov; a fragmented MOV
// (moof/trun, empty sample tables) makes Premiere report "file cannot be
// opened." We write a clean, non-fragmented MOV instead.
// `+faststart` puts the moov before mdat on the second pass so the file is
// instantly seekable/streamable too.
// Finalized masters (the S3-piped recording that stops cleanly) must NOT be
// fragmented. Adobe Premiere's QuickTime/MOV importer reads the classic
// stco/stsz/stts sample tables in a single top-level moov; a fragmented MOV
// (moof/trun, empty sample tables) makes Premiere report "file cannot be
// opened." We write a clean, non-fragmented MOV instead. `+faststart` puts the
// moov before mdat on the second pass so the file is instantly
// seekable/streamable too.
if (fmt === 'mov' || fmt === 'mp4') {
args.push('-movflags', growing ? '+frag_keyframe+empty_moov+default_base_moof' : '+faststart');
args.push('-movflags', '+faststart');
}
// ProRes-in-MOV must carry a QuickTime brand or some importers reject the tag.
args.push('-f', fmt);
@ -384,8 +422,11 @@ class CaptureManager {
if (growingActive && GROWING_SMB_MOUNT) {
if (!mountGrowingShare()) growingActive = false; // fall back to S3
}
// Growing master is always MXF OP1a (the only Premiere-growable format here),
// regardless of the recorder's configured container — so it gets a .mxf
// extension, not hiresExt.
const growingPath = growingActive
? `${GROWING_PATH}/${projectId}/${clipName}.${hiresExt}`
? `${GROWING_PATH}/${projectId}/${clipName}.${GROWING_EXT}`
: null;
if (growingPath) {
try { mkdirSync(dirname(growingPath), { recursive: true }); }