@item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
@item -force_key_frames[:@var{stream_specifier}] expr:@var{expr} (@emph{output,per-stream})
-Force key frames at the specified timestamps, more precisely at the first
-frames after each specified time.
+@item -force_key_frames[:@var{stream_specifier}] source (@emph{output,per-stream})
-If the argument is prefixed with @code{expr:}, the string @var{expr}
-is interpreted like an expression and is evaluated for each frame. A
-key frame is forced in case the evaluation is non-zero.
+@var{force_key_frames} can take arguments of the following form:
+
+@table @option
+
+@item @var{time}[,@var{time}...]
+If the argument consists of timestamps, ffmpeg will round the specified times to the nearest
+output timestamp as per the encoder time base and force a keyframe at the first frame having
+timestamp equal or greater than the computed timestamp. Note that if the encoder time base is too
+coarse, then the keyframes may be forced on frames with timestamps lower than the specified time.
+The default encoder time base is the inverse of the output framerate but may be set otherwise
+via @code{-enc_time_base}.
If one of the times is "@code{chapters}[@var{delta}]", it is expanded into
the time of the beginning of all chapters in the file, shifted by
-force_key_frames 0:05:00,chapters-0.1
@end example
+@item expr:@var{expr}
+If the argument is prefixed with @code{expr:}, the string @var{expr}
+is interpreted like an expression and is evaluated for each frame. A
+key frame is forced in case the evaluation is non-zero.
+
The expression in @var{expr} can contain the following constants:
@table @option
@item n
-force_key_frames expr:if(isnan(prev_forced_t),gte(t,13),gte(t,prev_forced_t+5))
@end example
+@item source
+If the argument is @code{source}, ffmpeg will force a key frame if
+the current frame being encoded is marked as a key frame in its source.
+
+@end table
+
Note that forcing too many keyframes is very harmful for the lookahead
algorithms of certain encoders: using fixed-GOP options or similar
would be more efficient.
extension.
@end table
+@item vulkan
+If @var{device} is an integer, it selects the device by its index in a
+system-dependent list of devices. If @var{device} is any other string, it
+selects the first device with a name containing that string as a substring.
+
+The following options are recognized:
+@table @option
+@item debug
+If set to 1, enables the validation layer, if installed.
+@item linear_images
+If set to 1, images allocated by the hwcontext will be linear and locally mappable.
+@item instance_extensions
+A plus separated list of additional instance extensions to enable.
+@item device_extensions
+A plus separated list of additional device extensions to enable.
+@end table
+
+Examples:
+@table @emph
+@item -init_hw_device vulkan:1
+Choose the second device on the system.
+
+@item -init_hw_device vulkan:RADV
+Choose the first device with a name containing the string @emph{RADV}.
+
+@item -init_hw_device vulkan:0,instance_extensions=VK_KHR_wayland_surface+VK_KHR_xcb_surface
+Choose the first device and enable the Wayland and XCB instance extensions.
+@end table
+
@end table
@item -init_hw_device @var{type}[=@var{name}]@@@var{source}
Show benchmarking information during the encode.
Shows real, system and user time used in various steps (audio/video encode/decode).
@item -timelimit @var{duration} (@emph{global})
-Exit after ffmpeg has been running for @var{duration} seconds.
+Exit after ffmpeg has been running for @var{duration} seconds in CPU user time.
@item -dump (@emph{global})
Dump each input packet to stderr.
@item -hex (@emph{global})
By default @command{ffmpeg} attempts to read the input(s) as fast as possible.
This option will slow down the reading of the input(s) to the native frame rate
of the input(s). It is useful for real-time output (e.g. live streaming).
-@item -loop_output @var{number_of_times}
-Repeatedly loop output for formats that support looping such as animated GIF
-(0 will loop the output infinitely).
-This option is deprecated, use -loop.
@item -vsync @var{parameter}
Video sync method.
For compatibility reasons old values can be specified as numbers.
Finish encoding when the shortest input stream ends.
@item -dts_delta_threshold
Timestamp discontinuity delta threshold.
-@item -muxdelay @var{seconds} (@emph{input})
+@item -dts_error_threshold @var{seconds}
+Timestamp error delta threshold. This threshold use to discard crazy/damaged
+timestamps and the default is 30 hours which is arbitrarily picked and quite
+conservative.
+@item -muxdelay @var{seconds} (@emph{output})
Set the maximum demux-decode delay.
-@item -muxpreload @var{seconds} (@emph{input})
+@item -muxpreload @var{seconds} (@emph{output})
Set the initial demux-decode delay.
@item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
Assign a new stream-id value to an output stream. This option should be
@table @option
@item empty_output
No packets were passed to the muxer, the output is empty.
+@item empty_output_stream
+No packets were passed to the muxer in some of the output streams.
@end table
@item -xerror (@emph{global})
projects / ffmpeg / blobdiff