Audio info

POST /api/audio-info1 quota unit per call · cache hits free

Inspect an audio file: container, codec, duration, sample rate, channel count, bitrate, bit depth. Supports WAV, MP3, FLAC, and OGG (Vorbis/Opus) — header-only, no decode.

Returns basic information about an audio file without decoding any samples: - Container + codec (WAV/PCM, MP3, FLAC, OGG Vorbis, OGG Opus). - Duration (exact for WAV/FLAC/OGG and VBR MP3 with a Xing/VBRI header; estimated from the first frame's bitrate for CBR MP3). - Sample rate, channel count, bit depth (PCM formats). - Average bitrate and a VBR flag where applicable. Cheap and fast — the audio counterpart of image-info.

Inputs

Name	Type	Default	Description
audio*	file	—	WAV, MP3, FLAC, or OGG (Vorbis/Opus) file.

Response

Modes: json. Cache: yes (24h TTL).

Every response carries x-cache (HIT / MISS / BYPASS), x-cache-signature (stable across identical inputs), and the rate-limit headers listed below.

Quota & limits

Cost per call	1 unit against the 10,000-unit monthly quota. Cache hits are free — only cache misses decrement.
Burst limit	200 requests per rolling minute, shared across all tools.
Max request size	`100 MiB` (base64 inflates file payloads ~33% — the limit applies to the decoded bytes).
Max response size	`4 KiB`
Timeout	10s wall clock.
Rate-limit headers	`X-RateLimit-Limit`, `X-RateLimit-Remaining`, `X-RateLimit-Burst-Limit` on every response; `X-Quota-Warning` once 80% of the monthly quota is spent; `Retry-After` on 429s.

Errors

Errors are JSON with an error string; schema failures add a details object (Zod's flattened field errors).

Status	When	Body
400	Input fails the tool's schema (wrong type, missing required field, malformed base64) or the file bytes can't be parsed as the expected format.	{ "error": "invalid inputs", "details": { "fieldErrors": { … } } }
401	Missing or invalid X-Api-Key / X-Account-Id headers (or no session when called from the browser).	{ "error": "unauthorized" }
404	Unknown tool id, or calling /api/* on the website hostname instead of api.xtract.bot.	{ "error": "not found" }
413	Request body over the tool's max request size, or an image header declaring more megapixels than the tool's pixel budget.	{ "error": "…exceeds maxRequestBytes…" }
415	Content-Type isn't application/json on the json-body transport.	{ "error": "unsupported content-type; expected application/json" }
429	Monthly quota or the 200/min burst limit exhausted. Check Retry-After and the X-RateLimit-* headers.	{ "error": "monthly quota exceeded", "monthRemaining": 0, … }
5xx	Conversion engine failure. Safe to retry; if it persists, the input is hitting a bug — please report it.	{ "error": "…" }

Code samples

Built from the wav example.

# Download or substitute the example input:
#   curl -O https://xtract.bot/examples/audio-info/sample.wav
AUDIO=$(base64 -w0 < sample.wav)

curl -X POST https://api.xtract.bot/api/audio-info \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "X-Account-Id: $XTRACT_ACCOUNT_ID" \
  -H "X-Api-Key: $XTRACT_API_KEY" \
  -d '{
  "audio": "'"$AUDIO"'"
}'