Speech-to-Text Transcription Batch English VFast
Fast English-only batch transcription with optional word-level timings and speaker diarization. Trades enrichment features for the lowest possible turnaround.
Authorizations
API key used for authentication and usage tracking.
Body
Audio file to transcribe. Must be non-empty. Supported formats:
.3g2, .3ga, .3gp, .3gpp, .8svx, .aa3, .aac,
.ac3, .act, .adts, .aif, .aifc, .aiff, .alac,
.amb, .amr, .ape, .asf, .at3, .au, .avi,
.avr, .awb, .bwf, .c2, .caf, .dss, .dts,
.dtshd, .eac3, .ec3, .f4a, .f4b, .flac, .flv,
.gsm, .iff, .m2a, .m2ts, .m4a, .m4b, .m4r,
.m4v, .mka, .mkv, .mlp, .mmf, .mov, .mp+,
.mp1, .mp2, .mp3, .mp4, .mpa, .mpc, .mpeg,
.mpg, .mpga, .mpp, .mts, .mxf, .nist, .oga,
.ogg, .ogx, .oma, .omg, .opus, .paf, .pvf,
.qcp, .ra, .rf64, .rka, .rm, .rmvb, .sf,
.shn, .snd, .sph, .svx, .tak, .thd,
.ts, .tta, .vob, .voc, .vqf, .w64, .wav,
.wave, .weba, .webm, .wma, .wmv,
.wv. Maximum file size: 100 MB.
.aac, .aiff, .flac, .mov, .mp3, .mp4, .ogg,
.opus, .wav, .webm. Maximum file size: 100 MB.
When enabled, the response includes a words array giving
the start and end time of every word in text, in seconds
from the start of the file, with an alignment confidence
where one was measured.
Timestamps are produced by aligning the final transcript
against the audio, so the words always match text exactly.
Every whitespace-separated token of text appears in
words exactly once, in order; the per-word timing field
says whether the span was fully measured, measured over a
prefix, or bracketed between neighbours.
On the non-diarized path, word timings are available up to a
maximum audio length configured per deployment (default one
hour). Above it the transcript is returned normally and
words_unavailable carries the
audio_too_long_for_alignment reason. Treat the exact
ceiling as environment-specific: read max_audio_seconds
from that response rather than hard-coding a value.
Setting speaker_diarization=true removes the ceiling
entirely, because each speaker turn is aligned separately.
Speaker diarization identifies different speakers in the
audio. When enabled, the response includes an utterances
array of time-ordered speaker turns with non-empty
transcripts, each attributed to a speaker (e.g., 1, 2)
with its timing, and text is the time-ordered
concatenation of the utterance texts. The array may be
empty when no transcribable speech is found.
Response
Transcription completed successfully.
The complete transcribed text from the audio file. Text includes automatic capitalization and punctuation. May be an empty string if no speech was recognized.
"Hello, how are you doing today?"
The total duration of the processed audio in milliseconds.
x >= 014253
Word-level timings covering text, in document order. Present
only when time_stamps is enabled and timings were produced;
when they were not, words_unavailable is present instead. Absent
otherwise, never null.
Every whitespace-separated token of text appears here exactly
once, so words and text.split() have the same length and the
same order. A word the aligner could not place fully is still
returned, marked partial or estimated - see WordTime.timing.
Times are seconds from the start of the file, including when
speaker_diarization is also enabled. Note this differs from
utterances, whose start_ms and duration_ms are integer
milliseconds.
Why words is absent. Present only when time_stamps is enabled
and words is absent; absent otherwise, never null. Exactly one
of words and words_unavailable appears on a time_stamps=true
request.
Time-ordered speaker turns with non-empty transcripts. Present
only when speaker_diarization is enabled; may be an empty
array when no transcribable speech is found.