{"slug": "how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openai-fm", "title": "How I recorded my first product demo in 54 seconds (OBS, ffmpeg, openai.fm)", "summary": "A developer documented the toolchain used to create a 54-second product demo for Convertify, a free image converter, employing OBS Studio, ffmpeg, and openai.fm for voiceover. The developer highlighted the importance of starting with the user's pain point and iterating on the script to achieve a concise, effective pitch.", "body_md": "I shipped my first product demo video this week for Convertify (my free image converter). 54 seconds, no team, no budget. Here is the exact toolchain and what I would change next time.\n\n**OBS Studio** for screen recording at 1920x1080, 60fps, CRF 20.\n\nThe 60fps is not vanity. Product demos live and die on smooth scroll and cursor motion. 30fps for a converter tool with drag-and-drop looks laggy even when the tool is fast. CRF 20 instead of the default 23 because text on white backgrounds compresses ugly at higher CRF: you get that faint mosaic around letter edges.\n\nFree, open source, deterministic. No mobile screen recording because I needed the desktop browser context (this is a \"your iPhone photos on Windows\" story).\n\n**ffmpeg** for trim and crop.\n\n```\nffmpeg -i raw.mkv -ss 3.2 -to 57.4 \\\n  -filter:v \"crop=1920:1000:0:40\" \\\n  -c:v libx264 -crf 20 -c:a copy trimmed.mp4\n```\n\nCLI over Kdenlive or DaVinci Resolve because I knew the exact cuts. Two ffmpeg commands beat 20 minutes of GUI timeline scrubbing. Crop removed the taskbar and top window chrome without re-encoding twice.\n\n**openai.fm** for voiceover. Ash voice.\n\nI tested Alloy, Fable, Nova, Ash. Ash landed clearest for technical explanation pacing. Alloy sounded like it was reading a bedtime story, Fable had a slight British lilt that felt wrong for the American tech audience I am targeting, Nova was too energetic.\n\nHiring a voiceover artist starts at $50 for a one-off and rises fast if you iterate. openai.fm generates in 20 seconds per attempt. I regenerated the voiceover 6 times across script rewrites and it cost nothing.\n\n**ffmpeg merge** as the last step.\n\n```\nffmpeg -i trimmed.mp4 -i voiceover.mp3 \\\n  -c:v copy -c:a aac -shortest final.mp4\n```\n\nSeparate audio and video passes. If voiceover timing slips, re-recording audio alone is 30 seconds. Re-recording the screen is 10 minutes plus 3 blown takes.\n\nv1 was 180 words. It opened with \"Convertify is a free tool that converts HEIC files to JPG.\" I wrote it, recorded a test take, listened back, and it was plodding. It sounded like I was describing a product, not solving a problem.\n\nv4 is 118 words. It opens with \"Your iPhone saves photos as HEIC format. Windows does not. Neither do most websites, Slack, or Discord.\"\n\nThe pattern that unstuck me: **start with the user's pain, not the product name**. The product name earns the right to appear once the pain is on screen. In 54 seconds you cannot afford to spend 5 seconds on brand introduction before the viewer knows why they should care.\n\nFour rewrites to arrive at something obvious. That is the honest part.\n\n**Script cursor movements ahead of time.** I improvised on takes 1 through 4 and each felt slightly different, which made editing harder. Take 5 with a mental map was noticeably tighter.\n\n**Test all voices first, not sequentially.** I burned an hour on Alloy before realizing I should have generated one line in each voice on day one.\n\n**Record the screen segment before writing the voiceover, not after.** I wrote v1 first, then discovered the cursor motion was faster than the words. Rewriting to fit visible pacing was easier than the reverse.\n\nConvertify is at [convertifyapp.net](https://convertifyapp.net). Free, no signup, no watermarks, batch up to 20 files.\n\nFeedback on the video welcome, especially if you have shipped product demos as a solo dev and hit different tradeoffs.", "url": "https://wpnews.pro/news/how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openai-fm", "canonical_source": "https://dev.to/serhii_kalyna_730b636889c/how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openaifm-50eg", "published_at": "2026-08-23 04:59:37+00:00", "updated_at": "2026-08-23 05:13:13.404324+00:00", "lang": "en", "topics": ["developer-tools", "generative-ai"], "entities": ["Convertify", "OBS Studio", "ffmpeg", "openai.fm"], "alternates": {"html": "https://wpnews.pro/news/how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openai-fm", "markdown": "https://wpnews.pro/news/how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openai-fm.md", "text": "https://wpnews.pro/news/how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openai-fm.txt", "jsonld": "https://wpnews.pro/news/how-i-recorded-my-first-product-demo-in-54-seconds-obs-ffmpeg-openai-fm.jsonld"}}