You open a channel. The picture is stretched. People look fat. Or tall and skinny. Or the screen has black bars on all sides.
Your aspect ratio is wrong. The channel is being displayed in the wrong shape.
A settings-savvy British iptv reseller will explain aspect ratio settings. "In your app, look for 'Aspect Ratio' or 'Screen Mode.' Change it to 'Original' or '16:9.'"
The British iptv service I use has an aspect ratio guide. Screenshots for 5 apps. How to fix stretched pictures.
A settings-ignorant IPTV reseller UK will say "that's your TV's problem" and offer no help.
Here's what aspect ratios mean:
4:3 (old TV shape). Square-ish. Black bars on left and right on modern TVs.
16:9 (widescreen). Fills modern TVs. Most channels use this.
21:9 (ultrawide). Very wide. Black bars on top and bottom on normal TVs.
Original. Displays the channel in its native aspect ratio. Usually the best option.
Stretch. Forces the picture to fill your screen. Distorts the image.
Zoom. Cuts off the edges to fill the screen. You lose content.
How to fix:
In TiviMate: While playing, press OK. Look for the aspect ratio icon (a rectangle). Cycle through options. "Original" is usually best.
In Smarters: Settings > Player > Aspect ratio. Same idea.
On your TV: Your TV might have aspect ratio settings too. Check your TV remote for a "P.Size" or "Screen" button.
In your device settings: Firestick has display settings. Ensure it's set to 1080p or 4K, not a weird resolution.
I had a channel that always displayed in 4:3 (black bars on sides). I assumed it was the channel's fault. Then I changed my app's aspect ratio from "16:9" to "Original." The black bars disappeared. The channel was actually widescreen. My app was stretching it incorrectly.
Test this today. Open a channel that looks wrong. Cycle through aspect ratio options. See if one fixes it.
If no aspect ratio setting fixes the problem, the channel itself might be broadcast in an unusual ratio. Some sports channels use 21:9 for cinematic effect. Some old shows are genuine 4:3.
Ask your reseller: "What aspect ratio should I use for your channels?" A good answer: "Original or 16:9, depending on your TV." A bad answer: "I don't know."
Aspect ratio is a small setting. But getting it wrong ruins the picture. Take 2 minutes to fix it. Your eyes will thank you.