The Silent Failure Nobody Explains I was setting up a Telegram video avatar and uploaded a recent iPhone clip. No error, no feedback, just the upload spinner disappeared and my profile photo stayed the same. Tried again. Same result. It took about an hour to figure out. iPhone records HEVC (H.265) by default. Telegram's video avatar API silently rejects it. No error message, nothing. What Telegram Actually Requires The spec for video avatars is specific: Codec: H.264 (not HEVC/H.265, not VP9, not AV1) Resolution: 800x800 pixels, square Duration: 10 seconds maximum File size: 2 MB maximum Audio: must be stripped Pixel format: yuv420p Most modern iPhone videos are HEVC at 1080x1920 or 4K. All of those properties need fixing before Telegram accepts the file. How ffmpeg Handles It The tricky part isn't the encode, it's the crop. A 9:16 portrait video fed directly into scale=800:800 produces a squished result. You need cropdetect first.…