@end example
@item -dframes @var{number} (@emph{output})
-Set the number of data frames to record. This is an alias for @code{-frames:d}.
+Set the number of data frames to output. This is an alias for @code{-frames:d}.
@item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
Stop writing to the stream after @var{framecount} frames.
@table @option
@item -vframes @var{number} (@emph{output})
-Set the number of video frames to record. This is an alias for @code{-frames:v}.
+Set the number of video frames to output. This is an alias for @code{-frames:v}.
@item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
Set frame rate (Hz value, fraction or abbreviation).
@table @option
@item -aframes @var{number} (@emph{output})
-Set the number of audio frames to record. This is an alias for @code{-frames:a}.
+Set the number of audio frames to output. This is an alias for @code{-frames:a}.
@item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
Set the audio sampling frequency. For output streams it is set by
default to the frequency of the corresponding input stream. For input
is enabled) the output timestamps may mismatch with the input
timestamps even when this option is selected.
+@item -start_at_zero
+When used with @option{copyts}, shift input timestamps so they start at zero.
+
+This means that using e.g. @code{-ss 50} will make output timestamps start at
+50 seconds, regardless of what timestamp the input file started at.
+
@item -copytb @var{mode}
Specify how to set the encoder timebase when stream copying. @var{mode} is an
integer numeric value, and can assume one of the following values: