Remix an existing audio sample (a sound effect, ambiance, or music clip) into a variation guided by a text prompt, for example turning a track into an 80s synthwave or metal version. Both the sample and the prompt are required; the sample is uploaded as a URL or base64 audio and must be at most 15MB or the call returns HTTP 400, and duration must be one of the allowed values (0 means match the source, otherwise multiples of 10 up to 180 seconds). Synchronous until September 10, 2026: the call blocks until generation finishes and returns a single audio result containing a URL; there is no separate polling step. The optional modification_strength (0 to 1, default 0.5) controls how far the result departs from the original. Credits are charged on success. Use this to transform existing audio you already have; use createSoundEffect, createAmbiance, or createMusic to generate audio from scratch. Pass an optional request_id to tag the result so you can locate it later via `GET /assets/audio/results`. Requires an API key (user scope). Async is the intended integration pattern: pass `async: true` and the call returns 202 with a job id - poll `GET /assets/jobs/{id}` (`getApiJob` in MCP), honouring poll_after_ms or long-polling with wait=30, until status is succeeded, whose result field is exactly the response documented for this operation. Synchronous responses are deprecated: they remain the default until September 10, 2026, after which requests default to async and return 202 with a job id; set `async: false` explicitly to keep synchronous behavior during and after the transition. Synchronous calls run on the same queue: the response carries an X-Ludo-Job-Id header, and a job still running after 15 minutes comes back as 202 with the job instead of an error. Each account may have up to 50 generations queued or running at once via the API; a request beyond that returns 429 (code PENDING_JOBS_LIMIT).