Library & files
Variable bitrate
Variable bitrate spends more data on complex passages and less on simple ones, so quality stays even and file size varies. Constant bitrate spends the same everywhere, so size is predictable and quality is not.
In practice
Buy whatever the store sells. Variable bitrate is fine on modern players and the old seeking objection has aged out.
Do not go looking for constant-bitrate copies of tracks you already own, and do not re-encode to "fix" a variable file — that is a second lossy pass for no gain. The one place the distinction still shows up is very old hardware and some poorly written third-party tools, which can misreport the length of a variable file. If a track shows the wrong duration in a browser but plays correctly, that is what you are looking at.
VBR
Even quality, varying size
CBR
Even size, varying quality
Duration
The only symptom left
Where these come from: How the two encoding modes behave and where the seeking objection came from — established encoder behaviour, not catalog figures. For what we can measure, see what the number actually means.
Why it matters
For listening, variable wins on efficiency — the same perceived quality in a smaller file, because a quiet intro does not need the same data as a full drop. For DJing, constant has one specific advantage: it is trivially seekable, because any position in the file maps to a fixed offset.
That mattered a great deal in the era of hardware that scrubbed by arithmetic, and it matters much less now. Modern players index the file on analysis, so seeking is exact either way, and the old advice to avoid variable bitrate entirely is largely a leftover.
Frequently asked
Is VBR bad for DJing?+
Not on current hardware. Players index the file when they analyse it, so seeking is exact. The objection dates from equipment that calculated position arithmetically.
Why does a track show the wrong length?+
Usually a variable-bitrate file with a missing or wrong header, read by a tool that estimated duration from the average rate. It plays correctly; only the reported length is wrong.
Should I convert VBR files to CBR?+
No. Re-encoding a lossy file is a second lossy pass, so you lose quality to solve a problem modern players do not have.
Related terms
Bit rate
Bit rate is how much data one second of audio uses, in kilobits per second. It decides the file size, and on a lossy format it decides how much of the original recording survives the encoding.
Lossy compression
Lossy compression shrinks a file by discarding audio a listener is unlikely to notice. What it removes is gone permanently, and encoding an already-lossy file removes more on top.
Joint stereo
Joint stereo encodes what the two channels share once and only the difference separately, rather than encoding each channel in full. At normal bitrates it buys quality; at very low ones it can narrow the stereo image.
Ogg and Opus
Ogg is an open container, usually holding Vorbis audio; Opus is a newer open codec that outperforms both at low bitrates. Both are lossy, both are free of licensing, and neither is standard in DJ software.
Explore: Audio quality checker · Bitrate · Lossy compression · All DJ terms