Editing and finishing

Timelines, conform, interchange, codecs, exports, subtitles and delivery

• articleWhat is the 180-degree line, how do screen direction and eyelines depend on it, and what do open textbooks say about avoiding or deliberately crossing it in a two-person scene?
  Corrected 2026-10-24 - see C3-B1094-01; the original statements below are kept for history and are superseded where the correction says so. LMU's Screen Direction chapter defines screen direction as the direction a character faces within a shot, gives the check 'person on left looks right, person on right looks left', and defines the line as the invisible line between the two characters; shooting from one side keeps real space. It lists ways to cross legitimately (characters move across, camera moves across in one take, camera placed on the line, or the next shot sets a new line) but announces 'three ways' above a list that has four items. Reich's editing chapter restates the 180-degree rule from Wikipedia. Empirical effects of crossing the line are in cycle-2 C2-B01-A-06 and are not repeated here.
• articleWhat does Sargent (1916) say about writing telegram, newspaper, document, book and music inserts: marking, sizing, length and name hygiene?
  Corrected 2026-10-24 - see C3-B1100-03; the original statements below are kept for history and are superseded where the correction says so. 1916 practice (Sargent): telegrams only when the situation calls for one; newspaper inserts sized to the news (headline proportionate, 'not more than ten feet' when only the fact is needed, frame filled with newspaper-style text); documents indicated by a short marking, forms left to the studio; book covers or pages marked 'On screen'; no music; no real names or addresses. His headline examples are invented. Each rule is his claim; footage figures are estimates.
• articleWhat do split edits do for continuity and pace, and when do they fail, according to open sources?
  Corrected 2026-10-24 - see C3-B1093-01; the original statements below are kept for history and are superseded where the correction says so. Partially verified: the curator re-read none of the cited sources; S6, S5, S3 rest on the producer's pinned reading. Barry Salt's counts of dialogue cuts in 35 films (from 1934 to 2014, his table) and an open Ohio State textbook agree that sound is rarely cut exactly with picture; the textbook says overlap feels natural and its absence can read as deliberately artificial. Salt says L-edits show the listener's reaction and let the pause be shorter, so the story moves faster, and that J-edits can confuse who is speaking in crowded scenes. These are one scholar's counts of within-scene dialogue cuts and a textbook's readings of clips; neither measures audience response, and neither gives a scene-transition-specific test.
• articlePROPOSAL (1916 practice as the basis): what checks could an agent run on a draft scene list for plot-by-action, continuity and establishment, using only what Sargent's Chapters XLIII-XLV state, and what in the check is only the lead's or worker's addition?
  Corrected 2026-10-24 - see C3-B1088-01; the original statements below are kept for history and are superseded where the correction says so. Agent check, steps 1-8 labelled '1916 practice' (each tied to a Sargent claim in this candidate's evidence) and steps 9-10 labelled PROPOSAL (worker additions, not in Sargent). The check reads a numbered scene list, locates the first vital action, the premise treatment, the establishing scene for each plot role, and each scene break's time, room, dress and entrance. It reports violations by rule and scene number. Sargent gives no test, no measured threshold and no props rule; the only criterion he states for casual setup is the 'reason-back' contrast. The check has not been run. It is not a validated detector and the rules are 1916 silent-film conventions.
• articleWhich caption file formats does YouTube accept, and which support styling/positioning?
  Corrected 2026-10-24 - see C3-B1064-01; the original statements below are kept for history and are superseded where the correction says so. YouTube Help (captured 2026-10-23): basic formats recommended for beginners are SubRip (.srt) and SubViewer (.sbv/.sub), timing-only and editable in plain text. Advanced formats: SAMI (.smi/.sami) and RealText (.rt) with simple markup and no positioning; WebVTT (.vtt) "in initial implementation" with positioning but styling limited to b/i/u; TTML (.ttml, .dfxp; iTT subset) partially implemented; Scenarist (.scc) is YouTube's preferred broadcast format as exact CEA-608. TikTok/Instagram caption documentation not yet retrieved: gap.
• articleWhat are YouTube's rules for remixing other videos into Shorts and editing your own long-form into a Short?
  Corrected 2026-10-24 - see C3-B1037-01; the original statements below are kept for history and are superseded where the correction says so. YouTube Help (captured 2026-10-23): with YouTube's Shorts tools you can remix others' content via Green Screen (sample as background, visual only or audio+video), Cut (a 1-5 second audio+video segment) or Sound (up to 90 s of audio; some partner content limited to 30 s); sources are credited automatically (sound page / link in the player). Remixing is opt-out: creators' Shorts and long-form are available to remix by default unless they turn off "Shorts remixing" in Studio; private videos and some third-party-claimed videos are unavailable. Copyrighted material used outside YouTube's tools can get Content ID claims or removals. Edit into a Short: only the owner can do it, for public long-form uploads (not private/unlisted or third-party-claimed); select up to 60 s and optionally record more segments up to 60 s. Completes CA-DR-0001-04 (C3-B336-04).
• articleWhat is HDR10+ dynamic metadata, what does it contain, and what happens on a display or tool that does not support it?
  Corrected 2026-10-24 - see C3-B1058-02; the original statements below are kept for history and are superseded where the correction says so. HDR10+ is HDR10 (PQ, BT.2020, static ST 2086 + optional MaxCLL/MaxFALL) plus per-scene or per-frame metadata standardised as SMPTE ST 2094-40 (Application #4). The metadata carries scene statistics (MaxSCL per colour component, average maxRGB, a percentile distribution of maxRGB) and optionally a Bezier tone curve with a knee point and a targeted display luminance. It travels as an ITU-T T.35 SEI message in the video stream, so a non-supporting display ignores it and falls back to HDR10. The public statements about licensing differ in tone: HDR10+ Technologies says no licensing fees; the SMPTE standard's foreword records claimed IPR licensable on reasonable terms.
• articleWhat controls do vendor video-to-video tools (Runway Aleph, Luma Modify Video, Moonvalley Marey) document, and do any expose depth, segmentation or edge weights like ControlNet?
  Corrected 2026-10-24 - see C3-B1045-01; the original statements below are kept for history and are superseded where the correction says so. On the pages read, none documents depth, segmentation, edge or normal control inputs or numeric control weights. Aleph is prompt-driven (action verb plus change description, optional image) with a 5 s limit; Luma Modify Video exposes nine adhere/flex/reimagine presets; Marey's ComfyUI node offers Motion Transfer or Pose Transfer from a reference video. Adherence is therefore steered by presets or prompts, not by documented structural-channel weights (bounded to these pages).
• articleWhat do the BBC File v6.0.2 (2026) and Channel 4/UK DPP File v5.2 delivery specifications say about up-converted, lower-resolution and frame-rate-converted material?
  Corrected 2026-10-24 - see C3-B1042-03; the original statements below are kept for history and are superseded where the correction says so. Both specs accept up-converted SD archive provided it meets the full technical requirements; both cap lower-resolution material at 25 percent of programme duration unless agreed; both require motion-compensated standards conversion and forbid simple timeline conversion. The Channel 4 spec adds that up-converted SD must look no worse than the original, requires removing half-line and blanking artefacts (hence a slight zoom), and requires agreement in advance for 50p to 25p film-motion conversion. In the passages read neither spec has a field or rule for declaring up-conversion; neither mentions AI (bounded: BBC text searched for "declar", "artificial", "generative" and the "AI" token with 0 hits; Channel 4 text searched for "declar" with 0 hits).
• articleAgent-controlled Blender and DaVinci Resolve via MCP (Oct 2026): what the leading open servers do, and their security, telemetry and licensing catches
  Corrected 2026-10-24 - see C3-B1037-03; the original statements below are kept for history and are superseded where the correction says so. Follows up the creator claims in C3-B393-03. Blender: the dominant server is the community "mcp-for-blender" (renamed; not affiliated with the Blender Foundation; MIT): an MCP server plus a Blender add-on that opens a socket inside Blender to receive and execute commands; one-line installer configures many clients (Claude Desktop/Code, Codex, Cursor, VS Code, etc.). Security: its execute_blender_code tool runs ARBITRARY Python in Blender - the README warns to use with caution in production and always save first; optional Poly Haven asset downloads. Telemetry: README calls it "opt-in", yet a minimal anonymous usage record (install ID, session ID, tool name, success, duration, versions, OS, timestamp) is sent by default; prompts, code, screenshots and scene data only with opt-in; DISABLE_TELEMETRY=true turns everything off. DaVinci Resolve: davinc...
• articleWhich ffprobe and MediaInfo fields tell me a file's colour tags and range, and what are the value names?
  Corrected 2026-10-24 - see C3-B1054-01; the original statements below are kept for history and are superseded where the correction says so. At FFmpeg commit 9047fa1b, ffprobe stream output uses the keys color_range (unknown/tv/pc), color_space (e.g. bt709, gbr, unknown), color_transfer and color_primaries, and prints unknown when unspecified; a real user paste confirms these keys. MediaInfoLib (commit 153ad67a) lists colour_range, colour_primaries, transfer_characteristics, matrix_coefficients and colour_description_present, with _Source and _Original variants. Nothing was run; the checklist below is derived from these sources.
• articleWhere does YouTube show its AI label since May 2026, which content gets the prominent label, and does a label change recommendations or monetization?
  Corrected 2026-10-24 - see C3-B968-03; the original statements below are kept for history and are superseded where the correction says so. Problem: creators fear that an AI label hurts reach or earnings. Conditions: YouTube, photorealistic or meaningfully AI-altered content versus unrealistic or lightly edited content. Method (platform statements): from May 2026 a single prominent label format applies to photorealistic and meaningfully AI-altered or generated content: below the player and above the description for long-form, as an overlay on the video for Shorts. Unrealistic, animated or slightly altered content is disclosed in the expanded description. Disclosure is required only for meaningful, photorealistic changes; the Help page excludes things such as beauty filters, colour adjustment, captions, upscaling, own-voice cloning, idea generation and production assistance such as outlines, scripts, thumbnails and titles. YouTube states the label alone does not change recommendation ...
• articleWhat can WebVTT, IMSC and YouTube caption files express, and do the specs enforce reading speed or line limits?
  Problem. Assuming a file format validates caption quality. Conditions. Choosing a delivery file. Method. WebVTT (W3C CRD, 20 May 2026): cues have start and end times, may overlap, voice spans (<v>) can name speakers and positioning exists; IMSC 1.2 (W3C Rec, 4 Aug 2020): TTML profile with ttm:agent speaker metadata and ebutts:linePadding for line-box padding. I searched both pages for 'characters per second', 'reading speed', 'words per minute', 'line length' and 'maximum number of lines': IMSC1.2 has no match and WebVTT has only an example comment on balanced wrapping, so neither specifies numeric quality limits. YouTube supports many file types and recommends .srt or .sbv as basic types, noting other types carry position and style info. Failure modes. A valid WebVTT or IMSC file can still break every limit above; Netflix additionally constrains TTML technical values (percentages, fontSize 100%). Limitations. Search was of the fetched text only; a limit could be in a linked profile...
• articleHow should speakers and non-speech sounds be labelled in captions, and how does that map from diarization output?
  Problem. Diarization gives anonymous speaker ids and no sound events. Conditions. SDH or captions for viewers who cannot hear audio. Method. Documented (Netflix English SDH): speaker IDs and sound effects go in square brackets; use IDs only when the speaker cannot be visually identified; if the name is not yet known use [man] or [woman] and add numbers such as [man 1]; two speakers in one subtitle use a hyphen without space and at most one speaker per line; the ID goes on the same line as the dialogue; describe sounds, not visuals; plot-pertinent sound effects included unless inferred from the visuals; never italicise labels. Music: lyrics between music notes, unknown song titles omitted and music described. BBC: colour is the preferred way to separate speakers, dashes are legacy and used with white text, single quotes mark out-of-vision speakers, and ttm:agent metadata may carry speaker information. Failure modes. Labelling every sound clutters the 20 cps budget; a wrong name given...
• articleShould captions follow shot changes, and what numbers do Netflix and BBC give?
  Problem. A caption that straddles a cut looks like a flash or lingers over a new shot. Conditions. Edited video where shot boundaries are known (an EDL, or shot detection run on the picture). Method. Documented: BBC says avoid subtitles that straddle a shot change by splitting the sentence or delaying the next one, merge subtitles for short shots if the merged event then ends at the second shot change, and authoring tools may use automated shot detection. Netflix: if dialogue starts on or within half a second after a cut, set the in-time to the first frame of the shot; if an out-time is within half a second before a cut, extend it to the cut keeping a 2-frame gap; if dialogue ends before a cut and no subtitle follows, still end 2 frames before the cut; as a last resort the out-time may be 12 frames after the cut provided no lingering effect. Failure modes. Snapping to cuts can shorten a caption below minimum duration or push reading speed over the cps limit; BBC lists this as a reas...
• articleHow do I turn word-level ASR or forced-alignment timestamps into caption events that meet Netflix and BBC timing rules?
  Problem. ASR returns words with start/end times, not caption events. Conditions. Word timestamps available (see C3-B636-12, C3-B844). Method. Inference-based pipeline anchored on documented rules: (1) group words into sentences/clauses by punctuation and long pauses; BBC prefers a single sentence per subtitle and clause-boundary splits for long ones. (2) Fill each event up to the line limit (for example 2 x 42 characters) but cut it earlier if the reading speed would exceed the cps limit (20 cps adult Netflix, 17 children) or if the event would exceed 7 s. (3) Set in-time at the first word start: Netflix puts it on the first frame of audio, 1-2 frames tolerance. (4) Set out-time to the last word end plus about half a second where no subtitle follows (Netflix); BBC allows up to 1.5 s hang-over. (5) Chain: where the gap to the next event is under half a second, extend the previous out-time to 2 frames before the next in-time (Netflix 'chaining'). (6) Enforce minimum 5/6 s by extending...
• articleHow should I break caption lines and split long sentences across events?
  Problem. Auto line wrapping breaks mid-phrase and hurts comprehension. Conditions. Any caption or subtitle with more than one line or event per sentence. Method. Documented: break after punctuation, before conjunctions and before prepositions (Netflix); do not separate article from noun, adjective from noun, first from last name, subject pronoun from verb, prepositional verb from preposition, verb from auxiliary/reflexive/negation. Prefer a bottom-heavy pyramid, avoid one or two words alone on the top line (Netflix English). BBC: ideal break at punctuation; each subtitle should be a single sentence, but a long sentence may extend across several subtitles, segmented at clause boundaries in preference to phrase boundaries; BBC also says well-edited text and timing matter more than perfect line breaks. Netflix: when one sentence continues across continuous subtitles, no ellipsis or dash is used if the pause is under 2 seconds. Example. BBC's own long-sentence example breaks after 'When...
• articleWhich numeric caption limits (cps, words per minute, characters per line, lines, min/max duration, gap) do Netflix, BBC and the FCC state, and how do I pick by context?
  Problem. Sources give different numbers and no single 'best'. Conditions. Choose the profile by delivery context. Method. Documented figures (page dates in bibliography): NETFLIX (streaming, English): 42 characters per line, max 2 lines, reading speed up to 20 cps adult / 17 cps children, min duration 5/6 s (20 frames at 24 fps), max 7 s, minimum 2-frame gap (all frame rates). BBC (UK broadcast and online): 160-180 words per minute (0.33-0.375 s/word), target minimum about 0.3 s per word, 37 characters per line for broadcast Teletext, online lines limited to 68% of 16:9 width (90% for 4:3, 1:1 and 9:16), max 2 lines landscape or square, 3 lines recommended for 9:16, a deliberate gap must be at least 1 s (preferably 1.5 s). FCC 47 CFR 79.1(j): states quality criteria (accuracy, synchronicity, completeness, placement) with no cps, line or duration numbers; only a live-caption accuracy metric formula (correct words / total words). Example. A 6-word line needs about 1.8-2.0 s at BBC rat...
• articleHow do word timestamps and speaker labels map into WebVTT (cue timing, in-cue word timestamps, voice spans, line breaks), and what makes a file invalid?
  Problem: turning an aligned, diarized word table into subtitle files that parse. Conditions: WebVTT per the W3C Candidate Recommendation Draft of 20 May 2026. Method: one cue block per readable chunk; cue start must be greater than or equal to every earlier cue's start and end must be greater than start; cues may overlap, which suits simultaneous speakers; speaker names go in voice spans (<v Name>), which need no closing tag when they cover the whole cue; word-level timing inside a cue uses cue timestamps, each greater than any previous one in the cue, greater than the cue start and less than the cue end; the spec's own guidance is to write cues on one line except where a break is definitely needed, since user agents insert wrapping breaks. WhisperX's CLI can also write word-highlighted SRT. Failure modes: Inference: word times from an aligner that equal the cue start or end, or that decrease, produce invalid timestamps; clamp to the open interval and drop duplicates; a mislabeled s...
• articleWhat is the difference between a noise gate and a downward expander in FFmpeg terms, and does adrc offer both?
  Problem: Choose between hard gating and gentle expansion for dialogue. Conditions: FFmpeg agate states that range 0 turns it into an expander, so one filter spans both. Method: adrc (spectral dynamic range controller; attack default 50 ms range 1-1000, release default 100 ms range 5-2000) takes a transfer expression in dB per frequency power and ships both examples: spectral noise gate at -85 dB with attack 1 and release 5 ms, and spectral expansion at -10 dB threshold 1:2 ratio with attack 50 and release 100. Conclusion (inference): expansion reduces low levels proportionally and gives a gentler transition; a gate cuts hard, so it needs longer release for speech tails. Failure modes: the gate example with 1 ms attack is the fast, chatter-prone setting (inference). Limitations: adrc works per frequency bin, not whole-signal level. Version/date: ffmpeg.org page fetched 2026-10-24.
• articleHow do I make a noise gate or downward expander with FFmpeg's compand points, and which documented examples apply to speech?
  Problem: Gate or expand dialogue in a single filter with a transfer curve. Conditions: points are in dB relative to full scale as x/y pairs in strictly increasing x; 0/0 is assumed unless overridden. Method: attacks and decays (seconds per channel) set envelope averaging; the doc advises attack shorter than decay, typical 0.3 s and 0.8 s; soft-knee defaults to 0.01 dB; gain and volume (initial level, e.g. -90 for quiet start) are optional. Documented examples: a noise gate when noise is below the signal: compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1 ; a hard noise gate at -35 dB: compand=attacks=0:points=-80/-115|-35.1/-80|-35/-35|20/20 ; and an Expander curve. A curve that drops below a knee point steeper than 1:1 is a downward expander; an infinite drop is a gate (inference). Failure modes: very steep curves with attacks=0 give instantaneous gain change, audible as chatter or clicks (inference). Limitations: examples are generic audio, not tuned for speech. Version...
• articleHow does FFmpeg's agate work for dialogue (threshold, ratio, range, attack, release), and what does range=0 or mode=upward do?
  Problem: Remove low-level noise between spoken phrases without chopping words. Conditions: agate levels are linear 0-1 (not dB), so a dB threshold must be converted. Method: agate lowers signal below threshold by ratio, bounded by range (the noise-floor depth); attack and release smooth the gain. Documented defaults: range 0.06125 (allowed 0-1), threshold 0.125, ratio 2 (1-9000), attack 20 ms (0.01-9000), release 250 ms, knee 2.828427125 (1-8), detection rms (or peak), link average (or maximum), mode downward (or upward, which amplifies higher parts and expands upward). Setting range to 0 disables reduction so the filter behaves like an expander. Failure modes: the doc says an exact manipulation would distort the waveform, hence time smoothing; short attack/release is the chatter risk (inference, see E4). Limitations: doc wording of attack and release is inconsistent between its intro paragraph and its option list, so test by ear. Version/date: current ffmpeg.org page fetched 2026-1...
• articleIf YouTube's top moments occur late in my video, what does YouTube say to change in the edit?
  Problem: the best material sits late and most viewers leave first. Conditions: top moments (where almost no one dropped off) appear in a later portion. Method per YouTube: introduce the compelling content earlier, and consider new content expanding on top moments. For the intro figure (percentage still watching after 30 seconds) YouTube suggests aligning thumbnail and title with the content, and modifying the first 30 seconds with different styles. Failure modes: moving payoff earlier without checking the setup it depends on; changing thumbnail only when the opening is the cause. Limitations: advice is generic, with no tested thresholds or example. Version/date: help page fetched 2026-10-24.
• articleIs a retention spike or dip good or bad, and can I tell skipping from quitting?
  Problem: editors over-read spikes as wins and dips as failures. Conditions: video meets eligibility (60 s, 100 views). Method: treat each marker as a prompt to inspect the footage at that timecode. YouTube lists two readings of a spike: viewers watched it more than earlier parts, or the content was unclear so viewers rewatched. A dip means skipped or stopped watching, and the page asks you to review why interest was lost. Also flat means watched start to finish, and gradual decline is normal tapering. Failure modes: assuming a spike means quality when it may mean confusion; assuming a dip means quitting when it may be skipping. Limitations: the report as described does not separate skip from exit or rewatch from share; segment views can exceed total views. Version/date: help page fetched 2026-10-24.
• articleWhat does the YouTube 'typical retention' comparison compare against: my 10 latest videos or all similar-length YouTube videos?
  Problem: benchmark claims about retention are ambiguous. Conditions: same Audience retention report. Method: the page names two baselines in different places: typical retention is described as comparing your 10 latest videos of similar length, while the SEE MORE view is described as comparing against all YouTube videos of similar length. Before quoting a benchmark, state which baseline the figure came from. Failure modes: calling a channel-relative figure a platform norm, or the reverse; comparing a long video to a short one (the baseline is length-matched). Limitations: the page does not give the length buckets, sample sizes or averaging method. Version/date: help page fetched 2026-10-24.
• articleWhy does my YouTube video show no key moments (intro, spikes, dips), and what minimum length, views and data delay apply?
  Problem: an agent or editor expects key-moment markers on every video and cannot tell missing data from a failed report. Conditions: Studio, video-level Analytics only. Method: check (1) video at least 60 seconds, (2) at least 100 views, (3) allow 1-2 days processing, (4) open the video's Analytics, Overview or Engagement tab, Audience retention report. Moments are highlighted only if detected, so any single type may be absent even on an eligible video. Failure modes: treating absence as proof of no spikes or dips; trying to read it at channel level; judging a Short under 60 s with this report. Limitations: the page states thresholds without saying whether views are all views or engaged views; the thresholds are the page's stated minimums, not guarantees of marker output. Version/date: help page fetched 2026-10-24, hl=en.
• articleHow does Take Recorder's slate and take numbering turn a recording into a Level Sequence with subsequences?
  Problem. Keeping takes organised for shot-by-shot work. Conditions. Take Recorder panel open. Method. Set slate name, take number, description, fps and Record Speed; record via the red button, stop with Esc. The pending take is a Level Sequence; sources record into a subsequence (colour-coded per source); Takes Browser lists saved takes with metadata in column view; Review Last Recording opens the result; Root Take Save Dir and Take Save Dir use {take}/{slate} tokens; auto-save keeps sequences and subscenes. Failure modes. Reusing a take number triggers a warning (click to jump to next number); unsaved assets are lost. Limitations. How a take is placed into a Level Sequence with Shots is not shown in this page. Version/date. Current page as fetched.
• articleHow is a mobile live stream archive created and what privacy default can it get, beyond the 12-hour archive limit?
  Problem. Knowing what exists after a live stream ends. Conditions. Streams under 12 hours archive automatically for encoder, webcam and mobile; 1440p and 2160p streams also archive. Method. On mobile, tapping Finish creates an archive on the channel and a recap; a Short highlight can be saved and lands as private by default. Privacy can be edited, or the archive deleted, from My videos or the Content page. Failure modes. A stream over 12 hours may not be captured at all; for restricted streams the archive defaults to private and can take weeks to reflect. Limitations. Prior finding covers the limit itself; this adds privacy defaults and highlights. Keep a local recording as YouTube recommends. Version/date. Fetched 2026-10-24.
• articleWhat do viewers and the video itself experience during and after a YouTube Premiere (countdown, seeking, chat, view counts, reminders)?
  Problem. Designing a Premiere so the countdown, chat and later watch behaviour match expectations. Conditions. A Premiere that has reached its start time. Method. Before start the public watch page exists, appears in search/home/recommendations, and accepts reminders, comments and chat. At start the chosen countdown theme runs for the chosen length, then the video plays for everyone together. Afterwards the video stays as a regular upload without the countdown, chat replay is available and the Premiere view count transfers to the video. Failure modes. Viewers can rewind but cannot skip ahead past what has been shown live; do not bake a countdown into the edit, since YouTube adds its own. Limitations. The two Help pages describe the countdown differently (a chosen length on one, two minutes before start on the other), so treat length as a setting to verify in Studio. Version/date. Fetched 2026-10-24.
• articleWhat chapter format, count and title rules does Apple Podcasts state, when does it auto-create chapters, and how do chapters relate to transcripts?
  Problem: make chapters display well in Apple Podcasts. Conditions: chapters provided in the episode description, in the RSS feed via the podcast:chapters tag (through a supporting host), or in file metadata (MP4 header, ID3 on MP3 or AAC). Method: in a description, start the first chapter at 00:00:00 with at least three chapters. Stated guidelines: at least three chapters; no more than six per hour; provide chapters for episodes over 10 minutes; chapters no shorter than two minutes; titles at most 45 characters and fewer than five words; avoid repeated words; title case; numbers one to nine spelled out, digits above 10. If none are provided, Apple creates chapters (iOS 26.2 onward, English full and bonus episodes, not trailers or episodes under 10 minutes) labelled Automatically Created; the TXT list can be downloaded in Apple Podcasts Connect, edited and added to the description. Chapter titles appear as section headers in the transcript view. Failure modes: chapters shorter than t...
• articleHow do I supply my own transcript to Apple Podcasts, what does Apple generate itself, and which languages, formats and limits apply?
  Problem: control whether Apple Podcasts shows auto-generated or publisher-provided transcripts. Conditions: episodes distributed to the Apple Podcasts catalogue (private feeds are not processed, so show no transcripts); iOS 17.4 or later; supported languages English, Danish, Dutch, Finnish, French, German, Italian, Norwegian, Portuguese, Spanish and Swedish. Method: by default Apple generates transcripts after publication and labels them Automatically generated; to use your own, change the show's transcript setting in Apple Podcasts Connect (Availability tab), link the file with the RSS transcript tag, and set episodes to Display transcripts I provide; the app then shows Provided by the show name. Accepted file types are VTT or SRT, and a VTT lets every speaker be named per line. For subscriber episodes upload VTT or SRT in Connect. Apple lets you download its transcript, edit and relink it. Best practice: correct language, spelling of host and guest names in descriptions, correct e...
• articleWhat does the Podcasting 2.0 JSON chapters file contain, which fields are required, and how do I add silent chapters, art and links?
  Problem: add navigable chapters to an episode without editing the audio file. Conditions: feed uses the podcast:chapters tag. Method: the item gets one podcast:chapters tag with url and type (JSON preferred, application/json+chapters). The file is JSON with required version and chapters array; each chapter requires only startTime (seconds, float) and may carry title, img (chapter art), url, toc, endTime and a location object (name and geo as an RFC 5870 geo URI). toc set to false makes a silent chapter that does not show in the table of contents, useful for changing artwork. Chapters are read as ascending by startTime. The file should be served with content type application/json+chapters. Benefits stated by the spec: chapters can be edited after publishing and images are fetched on playback rather than embedded. Example: a first chapter at startTime 0 titled Intro. Failure modes: out-of-order startTime values break the assumed ascending order. Limitations: the page examples show ver...
• articleWhich transcript file format should a podcast publish (WebVTT, SRT, JSON or HTML), how are speakers and word timing carried, and what does the spec recommend if I can support only one?
  Problem: choose transcript formats that work across apps and browsers. Conditions: publishing via the podcast:transcript tag. Method: the namespace transcript document names four formats. WebVTT is listed as recommended: it carries medium-fidelity timestamps, optional speaker names through a voice span tag at the start of a caption when the speaker changes, is supported natively by browsers via the track element, and is what Apple Podcasts ingests; if only one format can be supported, the document says to choose WebVTT. A maximum line length of 65 characters is recommended for caption display (the document suggests whisper-cpp options --split-on-word --max-len 65 to achieve this; I did not run them). HTML is the low-fidelity option for transcripts with little or no timing: cite for speaker, time for start of a monologue, p for content. JSON (listed as in use) has version and segments with speaker, startTime, endTime and body, and at the finest grain enables word-by-word highlighting...
• articleHow do I declare a transcript or caption file in a podcast RSS item: which attributes are required, what mime types, and what does rel=captions change?
  Problem: a podcast episode needs a machine-discoverable link to its transcript or captions. Conditions: RSS 2.0 feed using the podcast namespace (https://podcastindex.org/namespace/1.0). Method: add one podcast:transcript child per format inside the item; url and type are required; type is a mime type such as text/plain, text/html, text/vtt, application/json or application/x-subrip; language is optional and defaults to the feed's RSS language element; rel="captions" marks the file as closed captions, so timecodes are assumed present whatever the mime type. Several tags may be given for several formats. Example from the spec: a VTT file with type text/vtt, and an SRT file with type application/x-subrip and rel=captions. Failure modes: omitting language on a non-feed-language file makes it be treated as the feed language; the spec says hyperlink URLs must be https, not http. Limitations: the tag only links the file; format content rules are in the separate transcript-file document. Ve...
• articleWhat limit does WCAG state on how much a standard, user-selectable AD track can carry compared with an extended version?
  Problem. Choosing between a standard description track (G78) and a second extended version (G8). Conditions. Prerecorded media where a separate audio track or version can be offered. Method. G78: a second, user-selectable audio track adds descriptions during pauses in dialogue and sound effects, so that new information neither obscures key audio nor is obscured by loud effects. G8 states the cost: narrators sometimes must fit a lot of information into very short pauses; extended description removes that squeeze. G78 test: check that gaps in dialogue are used to convey important visual information. Failure modes. Squeezing key description into short pauses on the standard track; or obscuring effects. Limitations. G78 gives no durations; relation to the F113 usability test is in C3-B797-01. Version/date. WCAG 2.2 technique pages as fetched.
• articleWhen gaps are too short, what does WCAG 1.2.7 extended audio description require, how is it delivered, and what does the G8 test check?
  Problem. Dense dialogue leaves no gap long enough for the description that conveys the sense of the video. Conditions. Prerecorded synchronized media at WCAG Level AAA (SC 1.2.7). Method. Extended audio description periodically freezes the presentation, plays additional description, then resumes. Because this disrupts viewers who do not need it, the Understanding page says toggles are often provided, or separate versions with and without extension. G8 describes the second-version approach: the video halts (same frame repeated) while a narrator speaks. G8 test: open the extended version and check the video halts when there is not enough space between natural dialogue. Example (Understanding): a lecture where the video is paused between problems to describe sketches and gestures. Failure modes. Using extension when standard gaps suffice; the Understanding page says it is used only when the sense would be lost and pauses are too short. Limitations. No pause-length cap, no rule on how m...
• articleWhich pauses in dialogue must an audio describer use under WCAG, and what makes a pause unusable (under about 2 seconds, far from the visual event, important non-speech audio)?
  Problem. Describers need a testable rule for when a dialogue pause must carry description and when it should be left alone. Conditions. Standard (non-extended) audio description of prerecorded synchronized media, WCAG 1.2.5 (AA). Method. WCAG failure F113 says important actions, characters, scene changes and on-screen text conveyed only visually need appropriate pauses in dialogue. It notes that not all pauses are usable: pauses that are too short (example given: under 2 seconds) or not near the visual content may be unsuitable. Where visual information coincides with music or sound effects, audio ducking (lowering the overall level) can make added narration easier to distinguish. The test has two checks: all missing important visual information is conveyed, and no remaining pause in dialogue is one where description would be appropriate. Failure modes. Ducking can mask non-spoken audio that carries much of the sense of the video; some pauses should not be filled because the non-spo...
• articleCan I feed licensed Getty or iStock footage into an AI tool to upscale, extend or animate it for a documentary?
  Problem. Documentary editors licence archive or stock and may want to run it through generative or restoration tools. Conditions. Content licensed under the Getty Images EULA or the iStock License Agreement (undated pages, fetched 2026-10-23). Method. Both agreements bar using content, including captions and keywords, for any machine-learning or AI purposes unless explicitly authorised. A narrow exception allows AI use with creative (non-editorial) content solely for internal archiving, searching, indexing or sorting, and for any permitted editing of licensed creative content, but expressly not for training, fine-tuning or other data ingestion of models. 'Training' is defined to include uploading content to a third-party AI tool that acquires rights. Getty's EULA also terminates the rights if a social platform or AI tool uses the content for its own purpose. Failure modes. Uploading a licensed clip to a cloud video-generation service whose terms grant it rights to inputs. Limitation...
• articleWhat recommendation inputs do YouTube, Instagram and TikTok each say they use besides engagement (surveys, channel quality, moderation eligibility)? Comparison is inference.
  Problem. Agents assume all three rank on engagement only. Conditions. Official explanatory pages. Method. YouTube cites satisfaction surveys, channel reputation and quality, external evaluators; Instagram cites worth-your-time surveys for Reels; TikTok cites moderation as a precondition and similarity and rules steps. Failure modes. Over-reading. Limitations. Different dates (2023, 2020, undated) and none give weights. Version and date. 2026-10-23.
• articleHow much longer will my translated narration be than the English, and what does the W3C say about it?
  Problem. Translated voice-over often overruns the picture. Conditions. Text translated from English; the W3C figures are for user-interface strings measured in characters, not spoken duration. Method. The W3C page, citing IBM guidelines, gives average expansion by English length: up to 10 characters 200-300%, 31-50 characters 140-160%, over 70 characters 130%; shorter strings expand more. Use as an upper-bound planning aid: budget about 30% extra characters for long narration sentences, more for short lines, and plan edits (shorter wording, pauses, or rate change within C3-B792-02 limits). Failure modes. Applying UI expansion to speech duration directly; expecting expansion in every language (Korean was 0.8, Chinese 1.2 in the Flickr example). Limitations. Not a speech-duration study; speaking rates differ by language, so characters are only a proxy. Version/date. As fetched 24 Oct 2026. Links C3-B591-01 on isochrony.
• articleCan Azure TTS be told to finish in an exact duration, and what are the limits?
  Problem. Voice-over must end on a picture cut. Conditions. Azure Speech SSML with mstts:audioduration. Method. Wrap text in a voice element and add <mstts:audioduration value="20s"/>; the service speeds or slows the speech to match. Requested duration must be within 0.5 to 2 times the original unmodified audio (for 30s requested, original must be 15-60s); maximum 300 seconds; the setting applies to all text in the enclosing voice element, so split per shot. Failure modes. Out-of-range request; long multi-shot text under one value. Limitations. Documentation does not state how out-of-range is handled beyond the range rule in the part I read, and does not report quality at the ends of the range. Version/date. As fetched 24 Oct 2026. Links C3-B664-08 for cross-vendor SSML.
• articleWhat narration speaking rate (words per minute) does the evidence support for instructional voice-over, and how strong is it?
  Problem. A narrator or TTS script needs a target words-per-minute figure. Conditions. Narrated instructional or lecture video for university students. Method. A 2026 scoping review (12 included studies out of 2679 identified) reports that cited researchers give about 150 wpm as usual speech, with comprehension spanning 150 to 270 wpm; one included experiment (Simonds et al.) found a moderate rate of 172 wpm gave higher perceived instructor credibility and nonverbal immediacy, with no significant difference in clarity or recall across rates. Use roughly 150-175 wpm as a starting script budget, then check by timing a read-through. Failure modes. Treating 172 wpm as a measured optimum (it was the moderate condition in one study); the 150-270 range is a literature claim relayed by the review, not its own measurement. Limitations. Review covers playback-speed and rate studies on university students 2017-2024, not audio description or entertainment narration; most papers did not report wo...
• articleHow do I turn my own long-form video into a Short, what are the limits, why is the option missing, and how is it credited?
  Problem. Repurposing long-form into Shorts has hard limits. Conditions. Own, public, long-form videos without third-party claims, opted in to sampling. Method. Watch page, Remix then Edit into a Short, select up to 60 seconds, add text or filters, upload; if you select under 60 seconds you can record more with the Shorts camera, e.g. 45 plus 15. The Short links back to the original. Audio Library music cannot be used. Missing option: Studio, Content, video, Show more, Shorts remixing, tick Allow people to sample this content, Save. Only the owner can do this, unlike general remixing. Failure modes. Private, unlisted or claimed videos do not offer it. Limitations. 60-second cap is stated here although Shorts can be 3 minutes (inference: help pages updated separately; unconfirmed). Version and date. Undated.
• articleWhat makes a Short eligible to be a template, and how do I stop others using my Short as one?
  Problem. Templates copy a Short's structure, so authors want to know what is exposed. Conditions. A template carries the length and number of clips plus text, music and effects. Eligible Shorts are templates by default; the page lists remixable audio, multiple clips and text segments among conditions. Method. Others tap Remix then Use this template (or Use template on the Short), then add their own clips. To block, opt out of Shorts remixing (the Studio setting in C3-B791-04). Failure modes. A Short with non-remixable audio may not offer a template. Limitations. 'Among other conditions' means the full list is not published. Version and date. Undated.
• articleWhat can be remixed into a Short, how is the original credited, and is remixing a remix allowed?
  Problem. Reusing others' Shorts needs the platform's tools and credit rules. Conditions. Mobile app, signed in. Method. Audio: Sound in the Shorts player, or Share, Remix, Use this sound on a long video page. Video: Remix then Cut, Green screen or Collab, with Layouts to change arrangement. Credit is automatic: audio source on the Sound Library page, video source in the player with a link. Remixes of remixes are allowed, and the source and later remixes appear on pivot pages and player metadata. Failure modes. Some videos are unavailable (private, third-party claimed and not opened to Shorts). Content made outside YouTube tools can get a Content ID claim. Limitations. Segment and audio durations are in C3-B578-03; this finding covers attribution and chain behaviour. Version and date. Undated help page.
• articleHow does YouTube decide that a square or vertical video up to three minutes is a Short, which uploads stay long-form by date and channel type, and how do I keep a short vertical video out of Shorts?
  Problem. Whether a clip lands in the Shorts feed or as long-form depends on upload date, shape and length. Conditions. Standard channels: uploads on or after 15 Oct 2024, square or vertical, up to 3 minutes, are categorised as Shorts and monetised under Shorts revenue sharing; earlier uploads stay long-form. Official Artist Channels: same rule from 8 Dec 2025. Method. Upload via the app or Studio; from a computer, Studio takes up to 15 files at a time, each up to 3 minutes and square or vertical, and each needs its details completed before publishing. To avoid Shorts classification, use a wider ratio such as 16:9. Failure modes. A 2:50 vertical clip meant as long-form becomes a Short. Older uploads are not reclassified. Limitations. Page gives no minimum length and no resolution cap; see C3-B791-02 for claim handling. Version and date. Help pages undated; text as fetched.
• articleWhat does Riverside say Magic Audio does, and how should I treat the claim next to my own cleanup chain?
  Problem. Deciding whether to rely on built-in AI enhancement for remote recordings. Conditions. Material recorded in Riverside. Method. Riverside describes Magic Audio as an AI enhancer and equalizer that removes background noise and emulates a richer sound, regardless of microphone. Failure modes. Enhancement applied destructively would remove the raw option; Riverside's FAQ says edits are non-destructive (not tested). Limitations. The page contains an on/off demo, not a measurement; nothing here is a result. Version and date. Fetched 2026-10-23.
• articleWhat do remote-recording vendors say about sync and drift when you do a manual double-ender?
  Problem. When each person records locally with their own software and files are exchanged, tracks must be aligned by hand. Conditions. No platform handling upload and alignment. Method. Riverside's blog (a competing vendor with an interest) describes double-ender as best quality but manual and error-prone, and says platform recording removes sync issues. A common mitigation (a shared clap or tone at start) is my own inference, not in this source. Failure modes. Sample-clock differences between machines can cause slow drift over long takes (inference, not documented in the fetched page). Limitations. No page fetched gives drift numbers; no measurement made. Version and date. Fetched 2026-10-23.
• articleWhy do theatrical films get turned down by AC-3 dialogue normalisation at home, and what dialogue levels does Katz give?
  Problem. Theatrical dialogue sits louder than the -31 dialnorm target, so a film carried to AC-3 home delivery is reduced. Conditions. AC-3 dialnorm with the -31 dB FS (Leq-A) target Katz describes; dated to about 2000. Method. Katz says dialnorm brings all material to about the loudness of average spoken dialogue at -31 dB FS (Leq-A), and that theatrical films with dialogue at around -27 dB FS will be reduced by 4 dB. Example. Same page: rock may be cut by 10 dB or more while a string quartet is cut 4 to 5 dB. Failure modes. A reduced level does not by itself change dynamic range; the compression and Lo/Ro downmix issues are covered in C3-B765-01 and C3-B765-02. Limitations. The page expresses -31 as Leq-A and -27 as dB FS without detail; modern streaming uses integrated loudness (LKFS) targets from the platform spec, which I could not read. Version/date. Article updated from September 2000.
• articleWhich YouTube Analytics API metrics can an agent rely on for channel performance (views, engagedViews, estimatedMinutesWatched, averageViewDuration), and which are 'core' and so protected by the deprecation policy?
  Problem. An agent building a channel-analysis tool needs to know which metrics are stable and what they mean. Conditions. Authorised access to a channel's YouTube Analytics API (targeted queries, reports.query). Method. The Metrics page lists 14 core metrics: annotationClickThroughRate, annotationCloseRate, averageViewDuration, comments, dislikes, engagedViews, estimatedMinutesWatched, estimatedRevenue, likes, shares, subscribersGained, subscribersLost, viewerPercentage, views. Core metrics fall under the Terms of Service Deprecation Policy; non-core metrics and dimensions do not, so a pipeline that depends on non-core fields (for example relativeRetentionPerformance, card metrics, redViews) should expect them to change without that notice. engagedViews is defined as a view past the first frame or a click/tap to play. Failure modes. Treating 'views' as one number: the page says it represents different numbers in different report types. Limitations. Revenue metrics need the monetary ...

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