What does it cost to convert AIFF to Opus?

$0.003 per call, paid in USDC on Base via x402.

How large can the AIFF file be?

Up to 100 MB (104,857,600 bytes), and at most 60 min (3,600 s) of media. Past a limit the call answers too_large (413).

What happens if the conversion fails?

The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled.

catalogue / tools / Audio & video / AIFF to Opus

Convert AIFF to Opus

To convert AIFF to Opus, send one POST to /v1/audio-convert with the AIFF source and "to": "opus" in the body. Left out, "to" falls back to its default "mp3", so a Opus request has to send it. Each call costs $0.003 in USDC on Base via x402, with no account and no API key. The source file can be up to 100 MB and 60 min (3,600 s) long.

Endpoint: POST /v1/audio-convert
Price: $0.003 per call
Service: audio-convert
Docs: /docs/audio-convert

01Limits

Limit	Value
Largest source file	100 MB (104,857,600 bytes)
Longest input	60 min (3,600 s)
Timeout	94 s
Source formats	AIFF, AVI, FLAC, MKV, MP3, MP4, Ogg, WAV
Output formats	AAC, FLAC, MP3, Opus, WAV

02Example

A real AIFF to Opus run of audio-convert.

Request

POST /v1/audio-convert
content-type: application/json
payment-signature: <base64 x402 payload>

{
  "url": "https://grist.tools/samples/av/pair-tone.aiff",
  "to": "opus"
}

Response

200 OK
payment-response: <base64 settlement receipt>

{
  "source_url": "https://grist.tools/samples/av/pair-tone.aiff",
  "bytes": 48054,
  "source_container": "aiff",
  "format": "opus",
  "bitrate_kbps": null,
  "sample_rate": null,
  "audio_bytes": 20478,
  "audio_base64": "T2dnUwACAAAAAAAAAAAAAAAAAAAAAGS5xGoBE09wdXNIZWFkAQE4AUAfAAAAAABP..."
}

Source file: av/pair-tone.aiff, 46.9 KB (48,054 bytes). 3 s mono 8 kHz 16-bit PCM AIFF file written directly by the generator: three 0.5 s 500 Hz triangle beeps at rising level, each followed by 0.5 s of silence. The recorded run returned 20 KB (20,478 bytes) of Opus, 43% of the source size, with the source read as the aiff container. Decoded, the Opus in audio_base64 opens with 4F 67 67 53 00 02 00 00 00 00 00 00 (ASCII OggS). Recorded with ffmpeg 8.1.2.

In the sample itself, the FORM container is of type AIFF; the COMM chunk declares 1 channel, 24,000 sample frames of 16 bits and a rate of 8,000 Hz stored as an 80-bit extended float, 3 s; the SSND chunk holds 48,008 bytes, big-endian samples behind an 8-byte offset and block size header. In the returned Opus: the first Ogg page, flagged as the beginning of the stream, has stream serial 0 and one 19-byte packet, the OpusHead: version 1, 1 channel, a pre-skip of 312 samples, an input sample rate of 8,000 Hz and channel mapping family 0.

03Format notes

AIFF as a source

AIFF files start with the IFF marker FORM, and Grist also requires the form type at byte eight to read AIFF or AIFC, the variant that allows compressed audio. Classic AIFF stores its PCM samples big-endian, the opposite byte order to WAV. The format is audio only, so video-thumbnail and subtitle-extract turn it away as a container without a picture or caption stream, and audio-convert is its single reader. That service measures the first audio stream's duration, maps only that stream, and strips metadata and chapters before encoding. AIFF is absent from audio-convert's destination enum, so it can be read here but not written. Converting to WAV rewrites the samples as little-endian PCM through the pinned pcm_s16le codec, which changes byte order without altering the sampled values of a sixteen-bit source.

Opus as a target

An Opus result is libopus-encoded audio inside an Ogg container: the ogg muxer writes it, and the recorded outputs begin with the OggS capture pattern followed by an OpusHead identification header. For that reason a returned Opus file is recognised as ogg if it is submitted again, and opus never appears as a source slug. bitrate_kbps controls the lossy encode, and an optional sample_rate may be chosen from the closed set; left out, ffmpeg normally follows the source rate. The input's duration is checked first, then the first audio stream alone is encoded, excluding video, metadata and chapters. Pinned ffmpeg and bit-exact flags make repeated calls return the same bytes. With no bitrate given the encoder's default rate applies, and for the recorded low-rate mono examples that default produced larger files than the MP3 default.

04Errors

Code	HTTP
`invalid_input`	`400`
`blocked_target`	`403`
`unreachable_target`	`424`
`upstream_timeout`	`424`
`unsupported_content_type`	`415`
`too_large`	`413`
`unprocessable`	`422`
`internal`	`500`

When each is raised, and what it means for payment: /docs/audio-convert.

05Questions

What does it cost to convert AIFF to Opus?: $0.003 per call, paid in USDC on Base via x402.
How large can the AIFF file be?: Up to 100 MB (104,857,600 bytes), and at most 60 min (3,600 s) of media. Past a limit the call answers too_large (413).
What happens if the conversion fails?: The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled.