L

latency
Of a filter, the amount of time it takes the filter to process a sample.
letterbox
Video display format in which the video is sized as large as possible inside the display window, without any cropping or stretching.
locked audio
A digital video format in which the number of audio samples in a frame follows a specific distribution. For example, in NTSC 48-kHz locked audio, frame 1 contains 1600 samples and frames 2–5 each contain 1602 samples. Unlocked audio allows the number of samples to vary, although the average must equal the stated sample rate.
lookahead
Using data from later in the stream to process the current data. (For example, using the next key frame to calculate a delta frame.)
LTC
Linear Timecode (formerly known as Longitudinal Timecode). Timecode is stored on a separate audio track and is one video frame time in duration.