- articleWhich of Pro Tools, REAPER and Resolve document keeping the bext TimeReference when a file is rendered, trimmed or sample-rate converted, and what does REAPER's history actually promise?
REAPER's version history documents preserving the source start offset on render (v7.16, adjusted for take offset), a batch-converter choice between keeping the BWF start or using item position (v5.985), clearing offset data on consolidate/glue with source metadata (v7.35), and adjusting the written position after trimming silence (v7.37). No entry or API text says how a stored sample-count start is rescaled when the sample rate changes (no pull-up/pulldown terms). Pro Tools and Resolve remain unresolved here.
- articleHow do I get a field-recorder WAV to land at its embedded timecode in REAPER, and what do Avid Media Composer and Final Cut Pro do differently with the file's timecode frame-rate flag?
To land a field-recorder WAV at its timecode in REAPER, use the source-preferred-position actions (move items, since v1.01; Media Explorer insert, v6.17) or InsertMedia flag &4096; since v6.19 REAPER also reads time references in mp3/flac/ogg/opus/wavpack. The stored start is a sample count since midnight (bext TimeReference), so the frame rate only matters for display and for editors that reinterpret it: per a 2019 Sound Devices note, Avid plays 48 kHz files at 48 kHz and asks which TC rate to use, while Final Cut Pro 6.02+ changes playback speed when iXML TIMECODE_RATE differs from the project.
- articleHow do Opus R128_TRACK_GAIN tags, Vorbis-comment ReplayGain tags and the output gain header differ in reference level, and which players document or implement applying each?
RFC 7845 makes the Opus ID-header output gain the default gain. The optional R128_TRACK_GAIN/R128_ALBUM_GAIN tags are Q7.8 dB values relative to the EBU R128 reference, applied on top of the output gain, and must be updated or removed if the output gain changes; REPLAYGAIN_* tags should not appear in Opus comments. Players map R128 tags to ReplayGain's reference by adding 5 dB (mpv: ReplayGain 2 at -18 LUFS; MPD: ReplayGain 89 dB). mpv applies no replay gain unless asked, and album mode falls back to track gain. In the FFmpeg files read, only REPLAYGAIN_* tags are exported as side data and the Opus header gain read is commented out of the demuxer.
- articleWhen shots are pulled for VFX as EXR plates, which header attributes can carry timecode, reel, frame rate, camera and framing, and what do the ACES/AMF documents say about carrying colour intent with plates?
An EXR plate header can carry optional editorial attributes (timeCode, reelName, framesPerSecond - assume 24 fps if absent - keyCode, imageCounter), an ASC framing decision list, camera identity and state, and acesImageContainerFlag (ST 2065-4 layout); renderingTransform and lookModTransform are deprecated. AMF is the ACES document for colour intent: it can travel with plates to describe how to view each one, but carries no timeline data (EDL/ALE may reference it), no demosaic settings, and an optional clipId link to material.
- articleWhich of Kdenlive, Shotcut, Olive and Blender Video Sequencer can hand a timeline to another tool, and in which interchange format?
Of four free editors: Kdenlive documents and implements OpenTimelineIO import and export (.otio); Shotcut's main window offers only an EDL export (no OTIO, FCPXML or AAF strings in that file); Olive reads and writes OTIO only when built with OpenTimelineIO, and every published Olive release is a prerelease (README: alpha, highly unstable); the Blender 5.2 manual has no EDL, OTIO, FCPXML or AAF terms in its search index and no interchange chapter in Video Editing. Manual absence does not rule out add-ons.
- articleCan I get an edit list (EDL or OpenTimelineIO) of a cinematic out of Unity or Godot, or do their exporters only write animation?
In the documents read, neither Unity nor Godot offers an edit-decision-list export for cinematics: Unity's FBX Exporter writes one Timeline animation clip at a time (animation data, not an edit), and the OpenTimelineIO adapter list has no Unity, Godot or Unreal adapter (Maya sequencer is the only DCC sequencer), although custom adapters can be registered. This is a limited-search negative.
- articleFrom camera card to final delivery, which of timecode, reel/clip name, colour intent and lens data does each handoff have a documented place for?
Across the pipeline the slots differ: an ASC MHL manifest records file paths, sizes and hashes (optional custom metadata), not timecode or reel; AMF records the ACES colour pipeline and explicitly carries no timeline metadata such as edit points; OpenEXR offers optional timeCode, reelName and framesPerSecond attributes; the IMF Application 2E public page constrains colorimetry and references ST 2086 mastering-display metadata, with no timecode, ACES or CDL terms. Clip identity and timing therefore travel in ALE/EDL/EXR headers, colour intent in CDL/AMF/LUT sidecars, and lens data only as far as the camera records it.
- articleWhen I render or record a cinematic from Unreal, Unity or Godot, which stage tone-maps and tags colour before the file is written, and what do the engines' docs leave unstated?
Unreal 5.1's Movie Render Queue documentation says 8-bit image sequences (BMP, JPG, PNG) are clamped to [0-1] with the sRGB encoding curve, while EXR keeps HDR values: roughly [0-1] with the Tone Curve enabled, linear [0-100] or more with it disabled, and never sRGB-encoded. Godot's Movie Maker documentation and PNG writer state no colour space or transfer for written frames, so an agent must measure or assume; Unity's inspected HDR pages (producer) cover display output, not recorded frames.
- articleWhat does Olive 0.2 (master head 7e0e94abf6610026aebb9ddce8564c39522fac6e) write to and read from OTIO, and does a cross dissolve keep its length?
At Olive master 7e0e94a (alpha software), OTIO save/load exists only in builds linked with OpenTimelineIO. On save, each transition is written as a fresh default OTIO Transition: the label and in/out offsets set on a separate object are never appended, so they are lost (code reading, not run). On load, every OTIO Transition becomes a cross-dissolve, unknown blocks become gaps, and only Video/Audio tracks are accepted.
- articleI turned on proxies in Shotcut, Kdenlive or Blender: where do the proxy files go, and does my saved project point at the original or the proxy?
Shotcut writes hash-named proxy files (with GoPro .LRV/DJI .LRF recognised) to a 'proxies' folder in the project folder when that option is on, otherwise to a configured proxy folder, and its save filter replaces proxy resources with the original paths (made relative to the project root). Kdenlive tracks each clip's proxy and original URL as clip properties and reuses an existing non-empty proxy unless asked to overwrite. Blender 5.2 by default stores proxies in a BL_proxy/<clip name> folder beside the original footage, or in a custom directory.
- articleHow do Silverstack and Livegrade carry CDL and LUT colour to editorial and Resolve, what is the application order, and what does not travel?
In Pomfort's documentation, CDL can travel in Silverstack ALE ASC-SOP/ASC-SAT columns into Avid, where (2016 page) the CDL must sit above the added 3D LUT because transformations apply top to bottom; Livegrade's exportable look formats depend on the grading mode; Silverstack lets CDL/LUT order be switched in CDL Advanced to support CDL in log or video gamma, so the receiving tool's order must match the authoring order; and transcodes bake looks per Look source, with From File falling back to a default Log-to-Rec.709 conversion when no look is embedded.
- articleWhat does an ASC MHL offload record and not record about camera files, what happens when files are renamed or sidecars appear, and which keys do dailies tools then use to join metadata?
ASC MHL records per-file hash records (with optional list-level custom metadata) and has no timecode or reel field (curator text search), so clip identity for editorial lives in the files or the ALE/dailies layer; a rename keeps its history only when recorded with ASC MHL Rename (previousPath), otherwise verification fails and the file is likely registered as new; mutable sidecars such as RED .RMD may be ignored, and ignored files cannot be un-ignored within a history. Separately, Silverstack warns that ALE and MXF tape names must match for merge or relink.
- articleI have colour (CDL) values from dailies in an EDL or ALE: what are ASC_SOP and ASC_SAT in Media Composer and what setting makes them take effect?
In the 2013 Avid guide, CDL values arrive via EDL or ALE in ASC_SOP/ASC_SAT, live as bin-column clip metadata and travel on AAF/ALE/EDL export, but are applied only after enabling the Color Management setting; already-linked clips need Source Settings > Color Encoding > Auto (or the CDL color transformation).
- articleI am new to review: what is a timeline marker or annotation in OTIO, RV, Kitsu and an EDL, and which one holds a frame-accurate note?
A frame note is stored differently in each tool: RV keeps per-frame paint and markers as node properties, Kitsu keeps text comments as their own records while drawn annotations live as JSON on the preview file, and a CMX3600 EDL can carry only comment lines such as '* LOC: timecode colour text'; no shared note identifier links them, so round trips need a mapping table.
- articleWhat does an FDX file carry for breakdown tagging versus what the Scheduling Export (.sex) path carries, and is there an open specification?
Final Draft does not publish an FDX schema; a community reverse-engineered spec (MIT) finds tag category definitions in FDX but could not confirm per-scene tag assignments; Final Draft's own support says Movie Magic Scheduling can import an .fdx (sluglines, speaking characters) but not its tags, which must travel in a .sex export whose format no inspected page documents.
- articleWhat do practitioner and delivery documents say about ADR session setup, cueing, mic matching and what a dialogue editor expects back?
One ADR recordist/editor describes a fairly standard dialogue-editor delivery: 24-bit 48 kHz stereo tracks with boom on the left and lavalier on the right, selected takes at the top and everything else removed, plus fill tracks, cueing and playback reverb/EQ to sell the match. Practitioner testimony, not a specification.
- articleWhich exact node, component and property names in an Open RV v4.0.2 session carry pen strokes, text and shape annotations, and what is documented versus only in code?
The RV reference manual documents pen and text component properties (width, gauss/circle brush, normalised points, join, cap, over/erase mode, start frame and duration; text position, colour, spacing) under names pen:id:frame:user; the interactive Mu mode actually appends the user and a process id, and Python/OTIO writers use the literal 'annotation' (CA-AM-0040). The node code also handles rect, ellipse, arrow and line components not listed in the table (producer reading).
- articleDoes an Open RV .rv session file keep my drawn annotations and text notes, and where do they live in it?
Open RV .rv session files are GTO files, and RVPaint nodes store per-frame annotations as named components plus an order stack and a redo stack per frame, so annotations travel inside the session file and can be read with GTO tools.
- articleOverview: from the set recorder to the delivered package, which carrier holds which kind of information at each audio handoff, and where does the timing or metadata thin out?
Along the production-audio chain each carrier has one job: bext a sample-count timestamp, iXML scene/take/track/speed metadata, AAF edit decisions, stems and M&E as separate files that must sum to the mix, and loudness as a measurement whose metadata must match it. Foley handoff had no primary document in the producer's sources (gap).
- articleWhich Ofcom Broadcasting Code rules apply to material that could mislead viewers (factual programmes, simulated news) and to dramatised reconstructions of real events?
In the January 2019 Ofcom Broadcasting Code, Section Two requires that factual programmes and portrayals of factual matters not materially mislead (2.2) and that simulated news in drama or documentary cannot reasonably be mistaken for real news (2.10); rules naming reconstructions sit in the fairness and privacy sections (7.9, 7.10, 8.19), not in Section Two. Later amendments are not covered.
- articleWhat audio deliverables, loudness, true-peak and stem/M&E rules does Netflix's Post Production Branded Delivery Specification state (2026-06-06 observation)?
Netflix branded delivery v5.2 asks for 48 kHz/24-bit original-language and M&E mixes at -27 LKFS +/-2 LU dialogue-gated (BS.1770-1), true peak no higher than -2 dBFS for 5.1/2.0 and recommended limiters at -2.3 or lower on Atmos beds and objects, plus 5.1 dialogue/music/effects stems that sum to the mix; the page gives no numeric M&E loudness and no audio file-naming scheme.
- articleWhich of the bext chunk and the iXML chunk should I trust for timecode, speed and take identity when a recorder file reaches the dialogue editor?
Production audio carries its timestamp as a bext sample count (no frame rate) while iXML adds scene, take, circled/take type, notes, track names, speed ratios and history; when both exist the official bext/fmt values take precedence, so timecode display needs iXML TIMECODE_RATE/FLAG and any tool that rewrites bext without updating iXML leaves them inconsistent.
- articleWhat channel layouts, stem separations and sidecar file rules does Paramount state for programme audio (including M&E and LFE)?
Paramount sidecar audio must be 1, 2 or 6 interleaved channels in RF64 WAV with channel labels matching the layout, start together and match the video duration within one frame, and every 5.1 needs a matching stereo; LFE may hold only content under 120 Hz (full-range LFE fails QC); Atmos beds and objects must at least separate dialogue, narration, music and effects.
- articleWhat programme-loudness and true-peak limits do Paramount and Apple state for sidecar, Atmos and immersive-music deliveries?
Paramount requires near-field full mixes at -24 LKFS +/-2 dB (BS.1770-3, without LFE for 5.1) with true peak at or below -2 dBTP for US deliveries, or EBU R 128-2020 -23.0 LUFS +/-1 LU with -1 dBTP for Europe; theatrical mixes are exempt; the Atmos home mix targets -24.0 LKFS +/-2.0 LU with true peak at or below -0.1 dBTP, measured in the Dolby Atmos Renderer or an equivalent.
- articleHow does a documented DAW (Ardour) treat embedded BWF timestamps, sample-rate mismatches and film/video pull-up when importing?
Ardour's import dialog shows a Broadcast WAVE file's embedded timestamp, can place the file at that timestamp (or zero if none), and marks a sample rate that differs from the session in red because the file must be resampled; the page does not mention iXML.
- articleHow is SMPTE LTC structured per libltc documentation and code, and where do 23.976, 29.97 and 59.94 behave differently?
libltc encodes LTC as 80-bit frames (2400 bit/s at 30 fps) with drop-frame at bit 10 and colour-frame at bit 11, and sets the drop-frame bit only when the frame rate rounds to 29.97 (rint(fps*100)==2997, in src/ltc.c); so 23.976 material is labelled as non-drop 24-frame counts (code reading).
- articleHow do iXML SPEED tags express NTSC frame rates and pulled-up recordings (for example 48048 Hz labelled as 48000), and which field should a conform tool trust when they disagree?
iXML SPEED gives rates as integer ratios (e.g. 30000/1001 rather than 29.97), separates timecode display rate and flag, and adds file, digitiser and timestamp sample rates so pulled-up recordings (48048 Hz labelled 48000) can be identified; readers must take the authoritative rate and timestamp from the fmt and bext chunks, not iXML copies.
- articleWhat does the BWF bext TimeReference field actually store, and what does FFmpeg's WAV code do with it when I copy, re-encode or resample a recorder file?
A BWF bext TimeReference is a 64-bit count of samples since midnight at the file's own sample rate, with no frame-rate field; FFmpeg's WAV demuxer (4bef4614) reports that raw count as time_reference metadata without converting it and does not parse iXML, so tools must divide by the file sample rate (and know the project rate) to get timecode.
- articleWhich language-code system applies where: DCNC title-string codes versus CPL metadata tags, and what extra rules does ISDCF Doc 7 add?
Two layers carry language in a DCP: DCNC codes in the title (case carries subtitle-rendering meaning) and BCP 47 tags in CPL metadata, which ISDCF Doc 7 says must be treated case-insensitively; tools converting between them must not copy case semantics across, must keep region subtags (es vs es-419) and should use RFC 4647 matching for playback selection.
- articleHow do I read the audio-language and subtitle-language parts of an ISDCF digital cinema package name, and where do the same values sit in the CPL?
In ISDCF digital cinema naming the language field lists the audio language first and subtitle languages after it; upper case means the projector renders the subtitles and lower case means they are burned in; the same languages are mirrored in the CPL (MainSound and MainSubtitle Language, MainSubtitleLanguageList).
- articleHow can an archive verify that an FFV1/Matroska transcode is lossless, and what do MediaConch policies and FADGI say?
To verify a lossless transcode, compare decoded-frame hashes: FFmpeg's framemd5 gives per-packet MD5, while its crc and framecrc muxers use Adler-32 (not CRC-32) on frames converted to raw; MediaConch's sample digitization policy checks Matroska v4+, a unique ID, FFV1 3.4+, GOP size 1 and slice CRCs, plus SD geometry.
- articleWhat fixity and error-detection does FFV1 (RFC 9043) and Matroska (RFC 9559) build in, and how do documented tools use it?
FFV1 (RFC 9043) supports frame fixity: ec=0 puts a 32-bit CRC only in the configuration record, ec=1 also in every slice, using the IEEE polynomial 0x104C11DB7 with initial value 0 and no pre- or post-inversion; so per-slice damage is detectable only when ec=1.
- articleWhat do WPT results for the CSS features that WebVTT and IMSC rendering rely on (ruby, writing modes, bidi, emphasis) show per engine?
The CSS layout tests beneath subtitle styling tell a different story from the WebVTT cue reftests: css-writing-modes bidi tests pass 88 of 94 in all four engines, while css-ruby passes 114, 114, 111 and 64 of 179 and text-emphasis tests 77, 90, 125 and 20 of 145 (Chrome, Edge, Firefox, Safari). So engine differences in WebVTT bidi are not explained by generic CSS bidi support; whether ruby results explain the cue failures is not established.
- articleWhat do the BBC Casualty accessible-audio trial, a Fraunhofer-linked thesis and Dolby's white paper report about how much viewers adjust dialogue-versus-background balance, and how variable it is?
Older listeners in one small study (11 listeners aged 66-75, no hearing devices; 2020 bachelor thesis using the Fraunhofer IIS listener pool) chose speech-to-background differences far above the 8.4 LU default: about 15.3 LU with separately produced objects and 13.5 LU with dialogue-separated material, with wide interquartile ranges (11.8-20.8 and 9.8-17.1 LU). The BBC's 2019 Casualty trial let viewers slide between the broadcast mix and a simplified mix; Dolby reports widely differing preferences; SVT chose one fixed Enhanced Speech track. Together they support personal control where separated or object audio exists, with a pre-rendered alternative as the simpler delivery (cross-source synthesis, not a measured comparison).
- articleAt the archive handoff (access file or package to FFV1/Matroska, BagIt and PREMIS/OAIS), what does each primary text guarantee, which package-level information has no home in the archive container, and which records must be written explicitly?
Integrity checks work at different layers: FFV1 with ec=1 stores a CRC in every slice (MediaConch's sample digitisation policy requires per-slice CRCs), ffmpeg's framemd5/framehash hash decoded frames so two files can be compared by content, and a BagIt 'valid' result only says every manifest checksum matched the stored files. PREMIS 3.0 leaves which events to record to the repository and provides eventOutcome/eventOutcomeDetail for results, so validation outcomes are not automatic archive metadata. Matroska (RFC 9559) can flag hearing-impaired, visually-impaired and text-description tracks, so access roles have a place if a transcode step sets them; the LoC FFV1/Matroska page says timecode support is still in development, so DCP/IMF structure and timecode need separate records (no inspected source maps CPL reels/edit rate/KDM into Matroska).
- articleWhich Open RV v4.0.2 render-path code decides which paint properties are read, and what happens to extra per-stroke properties?
Open RV's PaintIPNode recompiles drawings when a pen/text/rect/line/arrow/ellipse/frame component changes and reads a fixed property list; uuid, softDeleted and undo/redo data are stored in the session but never read by this node, so they have no render effect here (deleted shapes disappear because they are left out of the order list).
- articleHow do the properties written by the Python OTIO annotation hook differ from those written by the Mu Annotate mode for the same pen stroke or text box?
The OTIO import hook writes pen strokes with fixed constants (debug 1, join 3, cap 1, splat 0), copies uuid and soft-deleted state from the OTIO layer, treats invisible layers as deleted and leaves them out of frame:N.order, and writes no undo/redo stacks; the interactive Mu mode generates uuid4 ids and keeps per-user undo/redo stacks. Imported drawings therefore are not undoable like hand-drawn ones.
- articleWhat does PDF/X-4 require for print and how does it handle transparency, fonts and colour?
Per the Library of Congress format description (secondary), PDF/X-4 (ISO 15930-7:2010, PDF 1.6) is the PDF/X level that permits transparency and optional content (layers); PDF/X-4p differs only in allowing an external ICC OutputIntent. The ISO text was not read.
- articleWhich SVG features are documented as unsupported or unreliable when rasterising or converting SVG, and how mature is SVG 2?
resvg (commit 5192641d) declares SVG fonts, external-SVG use, colour profiles and the direction/unicode-bidi attributes unsupported, and its SVG 2 checklist marks 31 items done and 69 not done; its claim that browsers fail some static SVG cases is the project's own (README not re-read).
- articleHow do the open-source Maya Alembic exporter, maya-usd and Houdini handle sub-frames and non-integer frame rates like 23.976 and 29.97?
maya-usd v0.37.0 maps Maya's 23.976, 29.97 and 29.97 drop-frame units to exact rational rates (24000/1001, 30000/1001) and writes the value as both timeCodesPerSecond and framesPerSecond, unlike Blender's USD exporter which writes only timeCodesPerSecond.
- articleWhen Blender exports USD or Alembic from a 23.976 fps scene, which time values and sub-frame samples does it actually write?
Blender v5.2.2's USD exporter writes stage timeCodesPerSecond from the scene rate (e.g. 24000/1001) and exports whole frames only, so it cannot emit sub-frame motion samples, and it does not write framesPerSecond; its Alembic exporter writes shutter-based sub-frame samples and stores the scene fps as FramesPerTimeUnit metadata.
- articleWhat does an ASC CDL carry (SOP + saturation, .cc/.ccc/.cdl) and how do tools differ in applying it from set to post?
An ASC CDL is ten numbers (slope, offset, power per channel plus saturation); the v1.2 math clamps to [0,1], but many applications omit clamping, so CLF defines clamped and no-clamp styles and OCIO defaults to no-clamp; the same CDL can therefore render differently across tools, and a CDL names no colour space (ACES AMF adds a cdlWorkingSpace, per producer reading).
- articleWhat does a storyboard tool carry into an animatic export for an editor (names, timing, dialogue audio, notes), and what does OTIO core offer to hold what the export drops?
Storyboarder's FCP7 XML exporter names each board clip from its dialogue, else action, else filename, and puts notes into the clip description; the FCPX exporter names clips by filename and assigns an audio role; neither exporter has a scene-ID or shot-label field, so those survive only if carried in names. Storyboarder does not emit OTIO (producer reading).
- articleWhat exactly do Silverstack's audio sync, burn-in and metadata-export settings do, and what are the documented limits?
Silverstack Lab syncs external audio by timecode with an auditable preview and offset controls, but an ALE handed to editorial does not reflect half-frame audio offsets, and metadata export after transcoding (like dynamic-metadata burn-ins) is Lab-only, so Silverstack XT users lack it. No page reports sync accuracy.
- articleAt the master-to-package handoff (IMF or DCP), what do the open validators actually check on structure, hashes, picture and sound, and what stays unchecked?
'Verified' means different things across open DCP validators: libdcp checks asset hashes only when the option is on and the file is under a configurable size limit, and ClairMeta check profiles can bypass the PKL hash test and downgrade checks to warnings. A stored validation report is interpretable only with its options. No inspected validator checks creative decisions (grade, mix levels).
- articleWhat exactly does Shotcut v26.9.27 write in an EDL export, and could proxies change the reel and clip names in it?
Shotcut's EDL exporter writes one section per playlist with cuts and dissolves from program time 0 and no header lines; by default the reel name is the media base name (cut at the first dot, non-word characters replaced, padded or truncated to 8 characters), so files sharing their first eight characters collide; an option uses the stored hash instead. With proxies on, names may come from proxy files (producer inference).
- articleWhat does Kdenlive v26.08.2 write to and read from an OpenTimelineIO file, and what is not carried?
Kdenlive's OTIO exporter writes tracks (incl. subtitle kind), clips with media references and source ranges, gaps, mixes as SMPTE_Dissolve transitions, colour clips as generator references and markers/guides; it has no effect or speed handling, and the importer leaves image-sequence references as a TODO.
- articleWhich audiovisual-media and e-book products and services does Directive (EU) 2019/882 (the EAA) cover from 28 June 2025, and what are the main carve-outs and transition dates?
The EAA covers consumer terminals used to access AV media services and e-readers (products), and services providing access to AV media services (incl. EPGs) and e-books/dedicated software (services) after 28 June 2025, not AV content itself. The 28 June 2030 transition lets service providers keep using products already in use; it is not a general deadline extension. Microenterprises providing services are exempt.
- articleI have a Fountain or FDX screenplay and need an edit timeline: at which handoffs does a scene number, a clip name or a timecode survive, and where must I carry it myself?
Across screenplay, breakdown, storyboard, animatic and edit timeline, no single identifier is defined end to end in the sources read: scene numbers survive script-to-storyboard, while reel/clip names and timecode become the keys once a cut exists; EDL drops what it has no slot for.
- articleHow does the VR180 format define projection meshes, per-eye UV adjustment by stereo mode, and camera-motion metadata?
VR180 is a profile of Spherical V2 metadata: two projection meshes (one per eye; ~40x40 grids typical), per-eye UV adjustment by stereo mode, and optional camm camera-motion metadata. Mesh index bit widths are ceil(log2(count*2)) with zig-zag deltas (defined in the V2 RFC mesh box, cited by VR180).