Bug: BRAJDE reel showed subtitles 2-3 seconds out of sync with audio.
Soniox returned correct word timestamps:
- 'Ajmo,' at 41.82s
- 'Janezi!' at 42.18s
- 'Pejd' greva, ajde,' at 43.44-44.40s
But generate_srt_from_segments() ignored word timestamps and split long
segments into evenly-spaced 2.5s chunks based on segment duration:
chunk_dur = duration / n_parts ← assumes even pacing
for i in range(n_parts):
cs = rel_start + i * chunk_dur
This produces wrong timing because singers don't sing evenly. Real audio
had 'Ajmo, Janezi!' in 0.9s and 'Pejd' greva, ajde, na traktorju od Majde'
in 6s — the 2.5s chunks didn't align with vocals.
Fix: when word-level timestamps are available (Soniox/Scribe), group
words into chunks where each chunk's start/end match the actual first/last
word timestamps. Each chunk is at most MAX_CHUNK_DURATION (2.5s) but
respects natural word boundaries.
Before:
00:00.000 → 01.900 AJMO, JANEZI! PEJD' GREVA, AJDE, NA TRAKTORJU OD
00:01.900 → 03.800 MAJDE, NOBEN NAJU NE NAJDE, KO PELJEM TE
After:
00:00.020 → 02.120 AJMO, JANEZI! PEJD' GREVA,
00:02.360 → 04.820 AJDE, NA TRAKTORJU OD MAJDE, NOBEN
Subtitles now perfectly align with vocals.
Sebastjan Artič
dc1cb1ad27