Tip #8 – For video, 16 is the magic number

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aspect ratio video 4:3 16:9 golden ratio

Tip #8 – Ten Top Tips for Lightweight Web-Ready and Smooth Playback Video

Welcome to our series of ten top tips for web-ready video

Top Tip Number #8 – Maintain original aspect ratio in multiples of 16

Here we will concentrate on MP4 video produced with a H.264 codec – this is the encoding we recommend, as it means your video will work across the widest range of devices possible, from 1080p TVs to tablets (iPad) and mobile devices (iPhone)

When you encode we recommend that you maintain your aspect ratio from editing

Aspect ratio is the ratio of the width to the height of your video

So let’s say we have a video that is 640 longĀ  x 480 high, which we write as 640:480

This can be simplified (by dividing by common factors) to 4:3

To get your aspect ratio, just put width:height and then simplify

This might be slightly different to your shooting aspect ratio, as you may have cropped the frames

When editing you would normally choose a frame size in either 4:3 or 16:9 format*

*4:3 is the anĀ  aspect ratio – from the days of CRT television sets! But it still looks great on web pages
16:9 is the newer aspect ratio – closer to the golden ratio of proportions that makes your video look slick!

When you render your video, you will need to ensure that either you have selected to use your editing frame size or make sure that you have chosen an output size that fits your aspect ratio

For the H.264 codec the best dimensions are a multiple of 16, as the codec encodes in macroblocks of 16×16 (this is basically the size of the chunks your encoder cuts the video frame into)

Aspect ratio sizes for H264 codec video in 4:3 ratio

Aspect ratio sizes for H264 codec video in 4:3 ratio

And here are the sizes recommended for 16:9 video

Aspect ratio sizes for H264 codec video in 16:9 ratio

Of course, you can always scale up or down from these sizes (in multiples of 16) depending on your target device – smaller for mobile, larger for PCs or TVs

When you then create your player at eZs3, you can enter your output video size, or choose from one the dimensions above – if your video is larger or smaller than your player, you can enable stretching

Stretching will stretch (or squish) your video to fit in your player, if a viewer then clicks on full screen it can be expanded to fill the page

Find out more about aspect ratio at eZs3

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