Cambridge Nationals Creative iMedia

Revision Notes

4.2 Properties and formats of media files

Moving image files

Moving images are used in media products like films, adverts, music videos, animations and online content. To use them properly, media producers need to understand how they work, what affects the quality, and which file formats are suitable for different platforms.

What is frame rate?

Frame rate is the number of individual images (frames) shown per second in a video or animation. It is measured in frames per second (fps).

Higher frame rates make motion look smoother. Lower frame rates may appear jumpy but can be used for stylised effects or animations. Common frame rates include:

  • 24 fps – used in cinema for a traditional film look
  • 30 fps – common for TV and online video
  • 60 fps – used for smooth motion in sports, gaming and some YouTube videos

What is resolution?

Resolution describes the number of pixels in each frame. Higher resolution means better picture quality and more detail.

Common resolution types include:

  • SD (Standard Definition) – 720x480 pixels (lower quality)
  • HD (High Definition) – 1280x720 or 1920x1080 pixels
  • UHD / 4K – 3840x2160 pixels (very high detail)
  • 8K – 7680x4320 pixels (extremely high detail, used in cinema or specialist work)

Video and animation file types

Moving images can be stored as either video or animation files. Both have their own uses and characteristics.

Video files

These contain footage recorded with a camera or screen capture. They are used in films, YouTube videos, documentaries, and more.

  • Examples: .mp4, .mov, .avi, .wmv
  • Strengths: Good quality, widely supported, includes sound
  • Limitations: Large files at high quality; can lose quality if compressed too much

Animation files

These are used for content created frame-by-frame, often in 2D or 3D. They are common in adverts, explainer videos and games.

  • Examples: .swf, .flv, .gif, .mov (also used for animation)
  • Strengths: Great for vector animations or looping content
  • Limitations: Not always high quality; limited sound support (e.g. .gif)

Compressed and uncompressed formats

Video and animation files can be stored in either compressed or uncompressed formats.

Uncompressed formats

These keep all the original image and sound data. They are high quality but take up a lot of space.

  • Examples: .avi (can be uncompressed), .mov (high-quality formats)
  • Best for: editing and production, where quality matters
  • Limitations: very large files, not ideal for sharing online

Compressed formats

These reduce the size of files, making them easier to store or share. Compression can be lossy (removing data) or lossless (reducing size without quality loss).

  • Examples: .mp4 (lossy), .webm, .flv, .mov (compressed)
  • Best for: uploading to the web, mobile viewing
  • Limitations: may lose detail, especially after editing or re-saving

Choosing the right file format

The right format depends on how and where the video or animation will be used:

  • .mp4 – most common for online use, good balance of quality and size
  • .mov – high quality for Apple/macOS platforms and editing
  • .avi – sometimes used in editing; very large files
  • .gif – small animations or loops with no sound
  • .webm – lightweight format for web use

Choosing the correct frame rate, resolution and file format ensures your media product looks smooth, plays correctly and suits the platform it’s shown on.