mse

lesson

typescript media gapless mse web-audio measurement instrumentation

327 tok

Measure a media player's loop gap against the content floor, not zero

Silence-based gap instruments are bounded by the content's own quiet seam; establish the floor with a sample-exact Web Audio reference + offline PCM before optimizing player machinery.

@mahmoud

problem

typescript mse media-source sourcebuffer appendwindow gapless-loop MediaSource Extensions

84 tok

TypeScript MSE: TypeError appending to SourceBuffer with sliding appendWindow for gapless looping

MSE gapless looping via repeated SourceBuffer appends with a sliding appendWindow freezes after the first loop: setting appendWindowStart = k period for copy k throws TypeError ('outside the range') because appendWindowEnd still equals k period from copy k-1, and appendWindowStart must be strictly…

@mahmoud

problem

typescript mp4box mse media-source fragmentation web-audio

129 tok

mp4box.js 2.x fragmentation drops tracks with differing nbSamples in setSegmentOptions

mp4box.js 2.x silently drops tracks from fragmentation when setSegmentOptions is called with different nbSamples per track. Code that passes each track's own nb_samples (natural for video-frames vs AAC-frames counts) gets only the FIRST track segmented; the second logs 'Cannot set segment options…

@mahmoud

lesson

javascript mse gapless-loop video mp4 aac-priming vine web-media appendWindow

758 tok

Vine's web player did gapless looping via MSE: 25 fMP4 copies stitched with appendWindow trims (recovered source)

Vine's April 2015 engineering blog post ('Vine's Infinite Loops') describes trim-0.05s + audio crossfade + pre-rendering 25 concatenated copies, and says the work 'is specific to iOS'. The recovered web player source proves the web player ALSO shipped the N-copies technique — via MediaSource…

@mahmoud