Sonilo Video Analysis

Hand Sonilo a video and it returns a creative brief for its sound. By default (mode="both") that is two briefs in one result: a music-direction brief — a time-aligned segments plan (what each stretch of footage wants) plus one or more variations, each a single ready-to-use generation prompt — and a sound-design brief — shot-sized sfx_segments plus one whole-clip sfx_prompt. mode="music" or mode="sfx" returns just one of the two, at the same price.

This skill generates nothing. No audio, no video, no file. Its whole output is text, and the text is the input to the next call.

Setup: See the setup-api-key skill to connect the Sonilo MCP server and authenticate — sonilo login (no key) or SONILO_API_KEY.

⚠️ Cost: this is a paid call, even though nothing is generated. Billing has a 10-second floor and variants_num is billed per brief, so 3 variations cost 3×. Only call it when the user has actually asked. Check get_account_services (see the account skill) if you're unsure whether free-trial runs remain.

When to reach for this

Use it when:

• The user doesn't know what the video should sound like. "Make this sound good" is not a prompt. Analyze first, show them the variations, let them pick.
• A first generation missed. A bad result usually means a bad brief, not a bad model. Analyzing beats rerolling: a reroll is a fresh charge on the same weak prompt.
• The video has distinct sections and you want them scored deliberately rather than as one continuous bed. segments gives you the section boundaries the footage actually has.

Do not use it when the user already told you what they want. If they said "tense synths, drop at the 20-second mark", go straight to video-to-music — analysis would just be an extra charge between them and their track.

Transport: MCP or CLI

Pick one at the start of the session and stay on it. Do not mix the two inside a single job, and do not announce the choice.

1. Sonilo MCP tools visible in this session (analyze_video and friends) — use them. This is the preferred path: it needs no shell, and it is the only one that survives a very long generation. If a call fails to authenticate — rather than failing on its inputs — this transport is not usable in this session: go to 2 instead of retrying it.
2. No usable Sonilo MCP tools, but sonilo account exits 0 — use the CLI commands below. Same API, same account, same credential file. Probe with sonilo account, not sonilo whoami: whoami exits 0 even when signed out, so it cannot tell the two states apart.
3. Neither — stop and run the setup-api-key skill. Do not call api.sonilo.com with curl to work around it; both transports handle uploads, polling and retries that a bare request does not.

One difference between the two MCP servers

analyze_video takes a local file only on the local server. The hosted (OAuth plugin) server is URL-only: it exposes video_url and nothing else. If the user's video is a local file and you are on the hosted server, use the CLI or an SDK instead of trying video_path — it is not a parameter there.

Quick Start

MCP tool call (recommended)

analyze_video(
    video_path="~/Desktop/trailer.mp4",
    prompt="focus on the chase",
    variants_num=2
)

Returns the brief inline as JSON. Nothing is saved to disk — unlike every other Sonilo tool, there is no output path, because there is no file.

With no mode, that is both briefs. To ask for a single one:

analyze_video(video_path="~/Desktop/trailer.mp4", mode="sfx")

On the hosted server, pass video_url instead of video_path.

Python (pip install sonilo)

from sonilo import Sonilo

client = Sonilo()  # reads SONILO_API_KEY

brief = client.video_analysis.analyze(
    video="trailer.mp4",
    prompt="focus on the chase",
    variants_num=2,
)

for segment in brief.segments:
    print(f"{segment.start}-{segment.end}s [{segment.label}] {segment.prompt}")
print(brief.sfx_prompt)  # the whole-clip sound-design prompt (present in mode "both")

# Feed a variation's prompt straight into a generation call.
score = client.video_to_music.generate(
    video="trailer.mp4", prompt=brief.variations[0].prompt
)
score.save("score.m4a")

# Only the sound-design brief:
sfx_brief = client.video_analysis.analyze(video="trailer.mp4", mode="sfx")

The method is analyze(), not generate(), and the result has no save() — there is nothing to download.

JavaScript / TypeScript (npm install sonilo)

import { SoniloClient } from "sonilo";

const client = new SoniloClient(); // reads SONILO_API_KEY

const brief = await client.videoAnalysis.analyze({
  video: "./trailer.mp4",
  prompt: "focus on the chase",
  variantsNum: 2,
});

const score = await client.videoToMusic.generate({
  video: "./trailer.mp4",
  prompt: brief.variations![0]!.prompt,
});

const sfx = await client.videoToSfx.generate({
  video: "./trailer.mp4",
  prompt: brief.sfx_prompt!, // the whole-clip sound-design prompt
});

// Only the sound-design brief:
const sfxBrief = await client.videoAnalysis.analyze({ video: "./trailer.mp4", mode: "sfx" });

segments, variations, sfx_segments and sfx_prompt are all optional on the type — a processing or failed poll carries none of them, and a single-brief mode omits the sfx_* pair — so guard with ?? [] rather than asserting.

CLI (npm install -g sonilo-cli or pip install sonilo-cli)

sonilo video-analysis --video trailer.mp4 --prompt "focus on the chase" --variants 2
sonilo video-analysis --video trailer.mp4 --mode sfx   # only the sound-design brief

The brief goes to stdout as JSON, so it pipes:

sonilo video-analysis --video trailer.mp4 --output brief.json
sonilo video-to-music --video trailer.mp4 --prompt "$(jq -r '.variations[0].prompt' brief.json)"

--output is the only way this command writes a file, and it writes the brief, not media.

cURL (raw REST API, no MCP host)

curl -X POST "https://api.sonilo.com/v1/video-analysis" \
  -H "Authorization: Bearer $SONILO_API_KEY" \
  -F "video=@trailer.mp4" \
  -F "variants_num=2"
# -> 202 {"task_id": "...", "status": "processing"}
# Add -F "mode=sfx" (or "mode=music") for a single brief; omitted = both.

curl "https://api.sonilo.com/v1/tasks/<task_id>" -H "Authorization: Bearer $SONILO_API_KEY"

It is async: the POST returns a task_id, and the brief arrives on the task poll. video_url works instead of an uploaded file — pass one or the other, never both.

Tools

Tool	Description
analyze_video(video_path? | video_url?, prompt?, variants_num?, mode?)	Analyze a video and return a creative brief for its sound — a music-direction brief and a sound-design brief by default, or one of them via mode. Generates nothing and writes no file. video_path exists on the local server only — the hosted server is video_url-only.

Parameters

Parameter	Type	Default	Notes
video_path	string	—	Local server only. Absolute path, or relative to SONILO_MCP_BASE_PATH. Max 480s (8 min), subject to the account's upload-size cap.
video_url	string	—	HTTP(S) URL to a video file. Exactly one of video_path/video_url. The only input the hosted server accepts.
prompt	string	—	Optional guidance for the analysis, e.g. "focus on the chase". Max 2000 characters. Steers what the analysis pays attention to; it is not the generation prompt.
variants_num	int	1	1–5. How many independent briefs to author for the same video — different creative directions, not rewordings of one. Billed per brief, so 3 variations cost 3×. Confirm the number with the user before calling.
mode	string	both	both, music or sfx. both returns the music-direction brief (segments + variations) and the sound-design brief (sfx_segments + sfx_prompt). music returns only segments + variations. sfx returns only the sound-design brief, in segments + variations (labels "none"). Same price for all three.

What comes back

{
  "task_id": "…",
  "status": "succeeded",
  "segments": [
    {"start": 0, "end": 12, "label": "intro", "prompt": "sparse piano, rising"},
    {"start": 12, "end": 30, "label": "none", "prompt": "full strings, driving"}
  ],
  "variations": [
    {"prompt": "cinematic strings, 90bpm, building to a brass hit"},
    {"prompt": "lo-fi hip hop, warm keys, steady throughout"}
  ],
  "mode": "both",
  "sfx_segments": [
    {"start": 0, "end": 4, "label": "none", "prompt": "wind across an empty lot, distant traffic hum"},
    {"start": 4, "end": 12, "label": "none", "prompt": "car door slam, engine turning over, tires on gravel"}
  ],
  "sfx_prompt": "urban chase: engine roar, tires skidding on wet asphalt, passing sirens, metal scrape on impact"
}

• variations[i].prompt is the payload: pass it verbatim as the prompt of video_to_music, video_to_sfx, video_to_sound, or their video-to-video counterparts. In both and music mode these are music prompts; in sfx mode they are sound-design prompts. It is written to be used as-is — do not paraphrase it.
• segments are whole-second bounds with a per-stretch direction. label is one of the music section labels, or the string "none". Useful for reading the video's structure back to the user; note the music segments parameter takes {start, prompt, label} (no end) and the SFX one takes {start, end, prompt}, so a brief segment is not a drop-in for either — see the video-to-music and video-to-sfx skills for each shape.
• mode echoes what was requested (both when omitted).
• sfx_segments (both mode only) are the sound-design counterpart of segments: shot-sized {start, end, label, prompt} entries, label always "none", one sound-design direction per shot.
• sfx_prompt (both mode only) is one whole-clip sound-design prompt — pass it verbatim as the prompt of video_to_sfx or video_to_video_sfx. It is authored once per call regardless of variants_num; only the music variations multiply.
• mode: "music" reproduces the pre-mode shape exactly — segments + variations, no sfx_* keys. mode: "sfx" puts the sound-design brief in segments + variations instead (labels "none"), with no sfx_* keys either.

Workflow Tips

• Show, then generate. With variants_num > 1, print the variations and let the user pick before spending on a generation. That is the whole point of paying for the analysis.
• The prompt parameter is not the music prompt. prompt here tells the analyzer what to look at; the music prompt is what comes back. Passing "cinematic strings" as prompt narrows the analysis, it doesn't set the score.
• Cheap relative to a wrong generation. A 10-second billing floor plus one brief usually costs less than one rerolled video-to-video render — but say the price before calling either way.
• Duration cap is 480s (8 min), matching the SFX/sound endpoints; music endpoints are 360s and dubbing 300s. A video can still be analyzable but too long to score with music in one call.
• Content restriction: as everywhere in Sonilo, prompts cannot reference specific artists, bands, or copyrighted lyrics — and the returned variations will not either.

Recovering a Timed-Out Call

analyze_video is async: the backend accepts and charges the task, then a worker runs it. If the call times out, the error message includes a task_id and the brief is still coming. Call get_sfx_task(task_id) — get_generation_task(task_id) on the hosted server — to retrieve it; see the task-recovery skill. Because there is no file to download, recovery hands back the brief itself, inline.

Do not re-run analyze_video after a timeout. That is a second charge for a brief you already own.

Error Handling

Common errors: 401 invalid key, 402 insufficient balance / trial exhausted, 413 file too large, 422 invalid parameters (video over the 480 s cap, a video with no video stream, variants_num outside 1–5, a mode other than both/music/sfx), 429 rate limit. A failed analysis carries error.code ANALYSIS_FAILED and is refunded. 503 means video analysis is temporarily disabled server-side — it is not a key or balance problem and no retry loop will fix it. See the account skill to check trial/usage before a call.