4.1 Types of video formats

A video format is the way moving pictures and their sound are stored in a digital file. Every video file has two layers: the container, which is the file type shown by the extension (such as .mp4 or .mov), and the codec, which is the method used to compress and decompress the picture and sound inside it. A multimedia designer on a news desk must choose the right format at each stage: a high-quality format for editing, and a small, widely supported format for publishing on a website, a social media page or a broadcast channel.

Example: a reporter films an interview on a mirrorless camera that records in MOV with the H.264 codec. The editor converts the clips to an editing format for smooth playback, finishes the story, then exports an MP4 for the news website and a vertical MP4 for short-video platforms.

Containers and codecs

The container holds the video stream, one or more audio streams, subtitles and metadata (date, camera, duration) together in one file. The codec decides how much the picture is compressed and therefore how good it looks and how large the file is. The same container can hold different codecs, so two .mp4 files may behave very differently in an editing program.

Common video containers

• MP4 (.mp4): the most widely supported container on phones, browsers and social platforms. It usually carries H.264, H.265 or AV1 video with AAC audio, and is the safe choice for publishing news clips online.
• MOV (.mov): Apple's QuickTime container, used by many cameras and by editing software. It often carries high-quality editing codecs such as Apple ProRes.
• MKV (.mkv): an open container that can hold many audio and subtitle tracks. It is useful for archiving but is not accepted by every editing program or platform.
• WebM (.webm): an open web format carrying VP9 or AV1 video. Browsers play it natively, so it suits video embedded in web pages and interactive stories.
• AVI (.avi): an older Windows container. It is still met in old archive footage but has largely been replaced by MP4.
• MXF (.mxf): a professional container used by broadcast cameras and television playout systems, often carrying codecs such as XDCAM or DNxHD.

Common video codecs

Delivery codecs make small files but are heavy for a computer to edit. Intermediate codecs make much larger files that edit smoothly and keep quality through several rounds of export.

Resolution, frame rate and aspect ratio

A format is also described by its picture settings:

• Resolution: the number of pixels across and down the frame, for example 1280 × 720 (HD), 1920 × 1080 (Full HD) and 3840 × 2160 (4K UHD).
• Frame rate: the number of pictures shown each second (fps). Kenya uses 50 Hz mains power, so broadcast work is normally done at 25 or 50 fps; 24 fps gives a film look and 30 or 60 fps is common on phones.
• Aspect ratio: the shape of the frame. 16:9 is used for television and websites, 9:16 for vertical stories and short videos, 1:1 and 4:5 for social media feeds.
• Bitrate: the amount of data used per second of video, usually given in megabits per second (Mbps). A higher bitrate gives better quality and a bigger file.
• Scan type: progressive (p) shows each full frame at once and is used for online video; interlaced (i) is still used in some television broadcasting (for example 1080i at 50 fields a second) and in older archive material.

Estimating file size from bitrate

A designer can estimate how large an export will be before sending it over a slow connection.

File size (megabytes) = bitrate (megabits per second) × duration (seconds) ÷ 8

Example: a two-minute news clip exported at 10 Mbps.

File size = 10 × 120 ÷ 8

File size = 1,200 ÷ 8

File size = 150 MB (plus a small amount for the audio track)

Choosing a format for each stage

1. Record in the highest quality the camera or phone offers that the project needs, keeping one frame rate for the whole shoot.
2. Copy the original files from the SD card to two separate drives before editing.
3. Where the computer struggles to play the camera files, create proxies or convert to an intermediate codec such as ProRes or DNxHR.
4. Edit and finish the project at the resolution and frame rate of the final output.
5. Export a high-quality master file and keep it in the archive.
6. Export delivery copies (MP4 with H.264 or H.265, correct aspect ratio and bitrate) for each platform that will carry the story.