Video formats, codecs and numbers

Export MP4 for anything you upload or share, because every platform and player accepts it. The other containers have their place: MP4 vs MOV covers editing on a Mac, MKV vs MP4 covers recording, AVI vs MP4 explains the older Windows format, and what a WebM file is shows how to open or convert the web format. Remember that the container is only the wrapper: two MP4 files can hold very different video inside, so the codec and bitrate matter more for quality and size than the file extension.

Use H.264 for delivery unless you need smaller files and know the destination supports a newer codec. H.264 vs H.265 weighs file size against compatibility, AV1 vs HEVC compares the two newer codecs, and ProRes vs H.264 explains why editors record and edit in a large intermediate format and deliver in a small one. Newer codecs squeeze more quality into each megabyte, but they take longer to encode and older phones, browsers and editors may not play them. When in doubt, deliver H.264 and keep the newer codec for archives.

Our test: we re-encoded our own clips in H.264, H.265, AV1 and VP9 and measured size, quality (VMAF) and encode time: see H.264 vs H.265 vs AV1, our re-encode test.

File size is bitrate multiplied by length, so pick the bitrate the destination needs and the size follows. The video bitrate guide for YouTube, Instagram and TikTok gives the rates to export at, and video file size per minute turns them into megabytes for 720p, 1080p and 4K. Audio adds a little: 44.1 kHz vs 48 kHz explains which sample rate video uses. Platforms re-compress what you upload, so a bitrate far above their recommendation mostly makes the upload slower; a bitrate far below it shows up as blocky motion and soft detail.

Match the shape to where the video plays and keep the frame rate you shot at. The video aspect ratio and resolution chart answers questions like what ratio 1080×1920 is, and 24 vs 30 vs 60 fps explains which frame rate suits film, talking heads and fast motion. If you work with broadcast or 29.97 fps footage, read drop-frame vs non-drop-frame timecode. Changing the frame rate after the fact rarely helps: converting 30 fps to 60 fps adds duplicate or invented frames, and converting down can make motion stutter, so decide before you record.

Plan on about 150 words per minute of speech, then time the script aloud. Words per minute for a video script has a chart from 15 seconds to 10 minutes, and average speaking rate gives the pace for talks, podcasts and audiobooks. For speeches, see how many words are in a 5-minute speech and how long a 1,000-word speech takes. Watching faster? How long a video is at 1.5x speed has the chart. Numbers, names and pauses for on-screen moments add time, so a script that looks right on paper often runs long when read.