Background Music for Videos, Games and Podcasts, Made to Fit

There are two ways to put music under something you're making. You can search a library until you find a track that nearly fits, then bend the edit around it. Or you can describe what the scene needs, generate it, and drop the file into your timeline.

The second one changes the part of the job that actually costs you time: the hunting. This post is about what it's good for — which formats it suits, what to describe, and where the fit gets genuinely tight.

The problem with picking from a shelf

A stock library is a fixed set of finished tracks. Every one of them was written before it knew about your project, so the search is a compromise hunt: right mood but too busy, right energy but it peaks in the wrong place, right instrumentation but a minute too short. You audition thirty things, pick the least-wrong one, and then spend the rest of the afternoon making your edit agree with it.

Generation inverts that. The track is written after the brief, so the brief can carry the constraints that were previously unstateable — this exact length, this tempo, this key, this mood, no vocals, sparse enough to talk over. What you're choosing between at the end isn't "thirty tracks by strangers", it's "a few takes of the thing I described".

Where the fit matters most

Video edits

Cuts have geometry. A montage wants a tempo that the cuts can land on, and an edit that has to end on a specific beat wants a track that ends there too. Setting an exact length and a tempo before you generate is the whole trick: a 45-second piece at 96 BPM is a different editing problem from a three-minute piece you have to cut down and fade out. If you already know the BPM you're cutting to — from a BPM check on a reference, or from the rhythm of the footage — pin it and the arrangement is built around it.

Vertical clips

Short-form is unforgiving in a specific way: nothing has time to develop. A track that spends twelve seconds arriving is useless when the whole clip is fifteen. Ask for the thing that hooks immediately — a stated groove, a lead that enters early, a mood that is legible in one bar — and keep the length honest. Briefs that work here read like production notes, not like poetry: "punchy hip-hop beat, dusty drums, single detuned synth line".

Generate it at the length of the clip, download it, and it goes onto the audio track of your TikTok or Reel like any other file. The nice part is that when the edit changes, the music can change with it instead of the other way round.

Indie games

Game music has the one requirement linear media doesn't: it has to survive repetition. A loop the player hears two hundred times can't have a hook sharp enough to notice the two hundredth time. That argues for restraint in the brief — fewer stated events, a texture rather than a melody, "ambient underscore, slow bowed strings, no percussion" over "soaring theme". The practical workflow is to generate a short bed rather than a long piece, then loop it in your engine.

It also argues for consistency across a project. Pin the key and tempo, keep them the same across every cue, and the menu theme and the second-level underscore will belong to the same soundtrack rather than sounding like two downloads. That's what pinning key and tempo is for — they're sent as instructions the generator has to honour, not as suggestions.

For a solo developer this is the difference between shipping with an original score and shipping with whatever was cheapest: a whole set of cues is an afternoon, not a hire.

Podcasts and talking-head video

A bed under a voice has to be interesting enough to notice and boring enough to ignore. The failure mode is midrange: pads and pianos live where speech lives, so they mask it. Describe around that — low sustained textures, sparse high detail, nothing with a melody that competes with a sentence.

Intros are the opposite job: eight to twelve seconds that establish the show's character, which is exactly the case where an exact length and a clean ending earn their keep. Generate the theme once, use it every week.

Presentations and demos

The requirement here is usually "something that doesn't embarrass the deck". Neutral, forward-moving, no vocal to pull attention off the slides. Score a product demo, a conference talk, a walkthrough video — this is the easiest case to get right and the one people most often get wrong by over-describing: a two-clause brief and the instrumental setting will outperform a paragraph of adjectives.

What you actually describe

The brief is where style lives. Genre, instruments, mood, timbre, era and production all land there — "warm lo-fi with electric piano, soft drums, late-night mood", "80s synthwave, gated drums, wide analogue pads", "solo nylon guitar, close-mic'd, room tone". Chips for common genres write into the same box, and you edit freely from there.

The musical facts live in their own fields, not in the sentence:

The split isn't bureaucracy. A brief that argues with the fields — "slow ballad" over a pinned 160 BPM — is the documented way to confuse the generator, and the fields are what get honoured when the two disagree. Say the mood in words and the numbers in the numbers.

If you want the full set of habits — how much detail to write, how to shape sections, what the brief can and can't dictate — that's the prompt guide.

Render a few, then choose

One take is a coin flip; three takes is a decision. The studio can render several at once from the same brief, which is the cheapest way to find out whether your description was clear. If all three come back the same shape, your brief is tight. If they come back wildly different, the brief was vaguer than you thought — and now you know which part to pin down.

This is also the honest answer to "it didn't give me what I asked for". Most of the time the brief was under-specified rather than misread. Generating a handful and reading the spread tells you which.

Starting from music you already have

Sometimes the constraint isn't a mood, it's an existing piece. A theme you want a variation of, a song a scene already uses, a reference the client sent. Analyse it first and the detected key, tempo and chord progression can be handed straight to the studio with the fields prefilled, so the new track starts in the same harmonic world instead of a guessed one.

That's a musical handoff, not an audio one — the same facts a session player would read off a chord chart before playing their own version. If you want the chords of a track you generated, so a guitarist can play over it or so you can write a matching second piece, the generator can run the finished audio through chord, key and tempo detection and hand you a play-along timeline.

Getting good at it quickly

A short list of habits that separate "close enough" from "that's the one":

• Describe the scene, not the genre. "Tense, sparse, waiting for something" gets you further than "thriller music".
• Pin what's load-bearing, leave the rest on auto. Every field you fix is a decision the generator can't make for you — that's the point when the length has to be exact, and a waste when it doesn't.
• Name instruments. Instrumentation is the single most reliable lever in the brief.
• Keep vocals out of the brief. Instrumental is a setting; asking for it in words is the unreliable route.
• Generate in batches, judge in context. A track that sounds great in isolation and wrong under your footage is wrong.
• Reuse what worked. Once a key and tempo suit the project, keep them. Coherence across a set of cues is mostly just consistency of settings.

The shift is small to describe and large in practice: you stop auditioning other people's finished music and start making your own for the thing you're actually building. The searching was never the creative part anyway.