Change the PTS (presentation timestamp) of the input frames.

asetpts works on audio frames, setpts on video frames.

Accept in input an expression evaluated through the eval API, which can contain the following constants:

FRAME_RATE

frame rate, only defined for constant frame-rate video

PTS

the presentation timestamp in input

N

the count of the input frame, starting from 0.

NB_CONSUMED_SAMPLES

the number of consumed samples, not including the current frame (only audio)

NB_SAMPLES

the number of samples in the current frame (only audio)

SAMPLE_RATE

audio sample rate

STARTPTS

the PTS of the first frame

STARTT

the time in seconds of the first frame

INTERLACED

tell if the current frame is interlaced

T

the time in seconds of the current frame

TB

the time base

POS

original position in the file of the frame, or undefined if undefined for the current frame

PREV_INPTS

previous input PTS

PREV_INT

previous input time in seconds

PREV_OUTPTS

previous output PTS

PREV_OUTT

previous output time in seconds

RTCTIME

wallclock (RTC) time in microseconds. This is deprecated, use time(0) instead.

RTCSTART

wallclock (RTC) time at the start of the movie in microseconds