The animated GIF needs to be 980x500, which is what the video is sized at.
You might find it difficult or impossible to get that GIF file size down as far as you want. The type of compression GIF uses is not efficient for the frame sizes and durations of today’s HD-class videos. Animated GIF was designed for very small animations around 30 years ago, when full size desktop computer screens were around 640 x 480 pixels (or 1024 x 768 pixels if you had a lot of money).
I have opened a 1920 x 1080 px video into Save for Web. Even after I set the output size to 980 x 500 using my favorite settings (balance between quality and file size), the estimated file size is one third larger than the efficiently compressed original H.264 video.
Because animated GIF compression is so bad and outdated, the usual strategies for cutting down the file size are:
- Lower the frame pixel dimensions as far as you can stand. This might not an option for you if the GIF must be delivered at 980 x 500 px.
- Lower the frame rate as far as you can stand.
- Shorten the duration as much as you can.
- Use a design with as few colors as possible, because a GIF color palette cannot contain more than 256 colors. More colors require dithering, with makes file size compression much less effective.
- Minimize the number of pixels that change between frames. The worst case scenarios that prevent file size reduction are camera moves, busy frames where everything moves (e,g, crowd of people), and full frame effects/transitions (e.g., crossfade), because they make every pixel change between frames.
You might not be able to do the last three options if you are required to work with the exact video you were given.
Options for exporting animated GIF from Creative Cloud applications include Adobe Photoshop (Save As and Save for Web offer different GIF export code and options, both not ideal), Premiere Pro, After Effects, Adobe Media Encoder, and Adobe Express. Most of those have almost no options, so if the GIF file size is too large, you can’t change it by much. Save for Web (Legacy) in Photoshop does provide the most options with the most chance of reducing file size, but getting it right is tedious and still limited.
If you need more GIF file size reduction than you can get out of Adobe software, you may need to try something like Gifski (free software), available for Mac, Windows, or Linux. It uses a different approach to GIF color that is capable of much smaller file sizes and better-looking color, with less work than anything else I’ve tried. But you still might not get the animated GIF version to be smaller than the H.264 video file it was originally, or at least not without losing image quality.
In fact, if there is any way to include the video in H.264 (or a similarly modern) format instead of animated GIF on whatever website or app it’s going to, that would be a far better, higher quality, and smaller file size solution than old animated GIF.