Call this first for any new file — duration tells you how to window later
analyses, and channels tells you whether per-speaker (stereo) analysis is possible.

Returns segments with start/end times plus detected language and overall
words-per-minute. On stereo call recordings, pass channel=0 or channel=1 to
transcribe one speaker at a time and interleave the results by timestamp for
an accurate who-said-what transcript. model_size: tiny/base/small/medium/
large-v3/large-v3-turbo — larger is more accurate but slower; the model is
downloaded on first use. word_timestamps=True adds per-word timing (useful
for locating exact moments, at some cost in output size).

On stereo call recordings (one speaker per channel) this also reports
interruption counts per side, overlap ratio, and response latency —
who dominates, who interrupts, how quickly each side responds. On mono
audio only overall speech/silence dynamics are available. Cheap to run
on a whole recording; a good early step for call review.

Returns pitch statistics (median, range in semitones — low range means
monotone delivery), loudness/dynamic range, speech ratio, and pause
patterns (hesitations). Use on specific moments found via transcription or
conversation analysis — e.g. compare an agent's delivery early vs late in a
call, or check whether TTS output sounds flat. Pass channel to isolate one
speaker on stereo recordings.

Flags common problems (clipping, very low level, high background noise,
narrowband telephone audio). Run this before drawing conclusions from other
analyses — poor quality audio degrades transcription and pitch tracking.

Useful for isolating a key moment (an objection, an escalation, a TTS
artifact) to share or analyze further. Returns the path of the new file;
if output_path is omitted the file is written next to the source.

Look at this to spot things metrics miss: hold music, DTMF/beep tones,
hum, dropouts, TTS glitches, where energy concentrates. Time axis is in
absolute seconds so findings map back to transcript timestamps.