Bitrate
/ˈbɪtreɪt/ · noun · compression
Bitrate is how much data a media file uses per second. Higher bitrate means better quality and a bigger file.
In more detail
Bitrate is the number of bits used to store each second of audio or video. It is the main setting behind the trade between quality and file size.
Images don't have a bitrate. The closest idea is the quality setting. More data keeps more detail and makes a larger file.
What bitrate means for file size and quality
Audio bitrate is usually given in kilobits per second, or kbps. Video bitrate is usually given in megabits per second, or Mbps. A five minute song at 320 kbps holds about twice as much data as the same song at 160 kbps. So the file is about twice as large.
Constant bitrate, or CBR, uses the same amount of data every second. Variable bitrate, or VBR, gives simple parts less data and busy parts more. VBR usually sounds or looks better at a similar file size. The codec, resolution, frame rate and source quality also change how good a given bitrate looks or sounds.
How to choose a bitrate
Pick a bitrate for where the file will be used. Don't just pick the highest number. Speech stays clear at a much lower audio bitrate than dense music. A small phone video needs far less data than 4K footage with fast motion and fine detail.
A higher bitrate can't bring back detail the source already lost. Start from the best original you have. Test a short clip first. Then compare it on the device or site where people will actually play it.
Key points
- A higher bitrate usually means a bigger file and can mean better quality.
- Variable bitrate spends more data on complex parts and less on simple ones.
- The codec, resolution, frame rate and source decide how much bitrate is enough.