DragonFly On-Line Manual Pages

FFPROBE(1) FFPROBE(1)

NAME
ffprobe - ffprobe media prober

SYNOPSIS
ffprobe [options] [input_file]

DESCRIPTION
ffprobe gathers information from multimedia streams and prints it in
human- and machine-readable fashion.

For example it can be used to check the format of the container used by
a multimedia stream and the format and type of each media stream
contained in it.

If a filename is specified in input, ffprobe will try to open and probe
the file content. If the file cannot be opened or recognized as a
multimedia file, a positive exit code is returned.

ffprobe may be employed both as a standalone application or in
combination with a textual filter, which may perform more sophisticated
processing, e.g. statistical processing or plotting.

Options are used to list some of the formats supported by ffprobe or
for specifying which information to display, and for setting how
ffprobe will show it.

ffprobe output is designed to be easily parsable by a textual filter,
and consists of one or more sections of the form:

[SECTION]
key1=val1
...
keyN=valN
[/SECTION]

Metadata tags stored in the container or in the streams are recognized
and printed in the corresponding "FORMAT" or "STREAM" section, and are
prefixed by the string "TAG:".

OPTIONS
All the numerical options, if not specified otherwise, accept in input
a string representing a number, which may contain one of the
International System number postfixes, for example 'K', 'M', 'G'. If
'i' is appended after the postfix, powers of 2 are used instead of
powers of 10. The 'B' postfix multiplies the value for 8, and can be
appended after another postfix or used alone. This allows using for
example 'KB', 'MiB', 'G' and 'B' as postfix.

Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing with
"no" the option name, for example using "-nofoo" in the commandline
will set to false the boolean option with name "foo".

Generic options
These options are shared amongst the ff* tools.

-L Show license.

-h, -?, -help, --help
Show help.

-version
Show version.

-formats
Show available formats.

The fields preceding the format names have the following meanings:

D Decoding available

E Encoding available

-codecs
Show available codecs.

The fields preceding the codec names have the following meanings:

D Decoding available

E Encoding available

V/A/S
Video/audio/subtitle codec

S Codec supports slices

D Codec supports direct rendering

T Codec can handle input truncated at random locations instead of
only at frame boundaries

-bsfs
Show available bitstream filters.

-protocols
Show available protocols.

-filters
Show available libavfilter filters.

-pix_fmts
Show available pixel formats.

-loglevel loglevel
Set the logging level used by the library. loglevel is a number or
a string containing one of the following values:

quiet
panic
fatal
error
warning
info
verbose
debug

By default the program logs to stderr, if coloring is supported by
the terminal, colors are used to mark errors and warnings. Log
coloring can be disabled setting the environment variable
FFMPEG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting the
environment variable FFMPEG_FORCE_COLOR. The use of the
environment variable NO_COLOR is deprecated and will be dropped in
a following FFmpeg version.

Main options
-f format
Force format to use.

-unit
Show the unit of the displayed values.

-prefix
Use SI prefixes for the displayed values. Unless the
"-byte_binary_prefix" option is used all the prefixes are decimal.

-byte_binary_prefix
Force the use of binary prefixes for byte values.

-sexagesimal
Use sexagesimal format HH:MM:SS.MICROSECONDS for time values.

-pretty
Prettify the format of the displayed values, it corresponds to the
options "-unit -prefix -byte_binary_prefix -sexagesimal".

-show_format
Show information about the container format of the input multimedia
stream.

All the container format information is printed within a section
with name "FORMAT".

-show_packets
Show information about each packet contained in the input
multimedia stream.

The information for each single packet is printed within a
dedicated section with name "PACKET".

-show_streams
Show information about each media stream contained in the input
multimedia stream.

Each media stream information is printed within a dedicated section
with name "STREAM".

-i input_file
Read input_file.

DECODERS
Decoders are configured elements in FFmpeg which allow the decoding of
multimedia streams.

When you configure your FFmpeg build, all the supported native decoders
are enabled by default. Decoders requiring an external library must be
enabled manually via the corresponding "--enable-lib" option. You can
list all available decoders using the configure option
"--list-decoders".

You can disable all the decoders with the configure option
"--disable-decoders" and selectively enable / disable single decoders
with the options "--enable-decoder=DECODER" /
"--disable-decoder=DECODER".

The option "-codecs" of the ff* tools will display the list of enabled
decoders.

VIDEO DECODERS
A description of some of the currently available video decoders
follows.

rawvideo
Rawvideo decoder.

This decoder decodes rawvideo streams.

Options

top top_field_first
Specify the assumed field type of the input video.

-1 the video is assumed to be progressive (default)

0 bottom-field-first is assumed

1 top-field-first is assumed

DEMUXERS
Demuxers are configured elements in FFmpeg which allow to read the
multimedia streams from a particular type of file.

When you configure your FFmpeg build, all the supported demuxers are
enabled by default. You can list all available ones using the configure
option "--list-demuxers".

You can disable all the demuxers using the configure option
"--disable-demuxers", and selectively enable a single demuxer with the
option "--enable-demuxer=DEMUXER", or disable it with the option
"--disable-demuxer=DEMUXER".

The option "-formats" of the ff* tools will display the list of enabled
demuxers.

The description of some of the currently available demuxers follows.

image2
Image file demuxer.

This demuxer reads from a list of image files specified by a pattern.

The pattern may contain the string "%d" or "%0Nd", which specifies the
position of the characters representing a sequential number in each
filename matched by the pattern. If the form "%d0Nd" is used, the
string representing the number in each filename is 0-padded and N is
the total number of 0-padded digits representing the number. The
literal character '%' can be specified in the pattern with the string
"%%".

If the pattern contains "%d" or "%0Nd", the first filename of the file
list specified by the pattern must contain a number inclusively
contained between 0 and 4, all the following numbers must be
sequential. This limitation may be hopefully fixed.

The pattern may contain a suffix which is used to automatically
determine the format of the images contained in the files.

For example the pattern "img-%03d.bmp" will match a sequence of
filenames of the form img-001.bmp, img-002.bmp, ..., img-010.bmp, etc.;
the pattern "i%%m%%g-%d.jpg" will match a sequence of filenames of the
form i%m%g-1.jpg, i%m%g-2.jpg, ..., i%m%g-10.jpg, etc.

The size, the pixel format, and the format of each image must be the
same for all the files in the sequence.

The following example shows how to use ffmpeg for creating a video from
the images in the file sequence img-001.jpeg, img-002.jpeg, ...,
assuming an input framerate of 10 frames per second:

ffmpeg -r 10 -f image2 -i 'img-%03d.jpeg' out.avi

Note that the pattern must not necessarily contain "%d" or "%0Nd", for
example to convert a single image file img.jpeg you can employ the
command:

ffmpeg -f image2 -i img.jpeg img.png

applehttp
Apple HTTP Live Streaming demuxer.

This demuxer presents all AVStreams from all variant streams. The id
field is set to the bitrate variant index number. By setting the
discard flags on AVStreams (by pressing 'a' or 'v' in ffplay), the
caller can decide which variant streams to actually receive. The total
bitrate of the variant that the stream belongs to is available in a
metadata key named "variant_bitrate".

PROTOCOLS
Protocols are configured elements in FFmpeg which allow to access
resources which require the use of a particular protocol.

When you configure your FFmpeg build, all the supported protocols are
enabled by default. You can list all available ones using the configure
option "--list-protocols".

You can disable all the protocols using the configure option
"--disable-protocols", and selectively enable a protocol using the
option "--enable-protocol=PROTOCOL", or you can disable a particular
protocol using the option "--disable-protocol=PROTOCOL".

The option "-protocols" of the ff* tools will display the list of
supported protocols.

A description of the currently available protocols follows.

applehttp
Read Apple HTTP Live Streaming compliant segmented stream as a uniform
one. The M3U8 playlists describing the segments can be remote HTTP
resources or local files, accessed using the standard file protocol.
HTTP is default, specific protocol can be declared by specifying
"+proto" after the applehttp URI scheme name, where proto is either
"file" or "http".

applehttp://host/path/to/remote/resource.m3u8
applehttp+http://host/path/to/remote/resource.m3u8
applehttp+file://path/to/local/resource.m3u8

concat
Physical concatenation protocol.

Allow to read and seek from many resource in sequence as if they were a
unique resource.

A URL accepted by this protocol has the syntax:

concat:<URL1>|<URL2>|...|<URLN>

where URL1, URL2, ..., URLN are the urls of the resource to be
concatenated, each one possibly specifying a distinct protocol.

For example to read a sequence of files split1.mpeg, split2.mpeg,
split3.mpeg with ffplay use the command:

ffplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg

Note that you may need to escape the character "|" which is special for
many shells.

file
File access protocol.

Allow to read from or read to a file.

For example to read from a file input.mpeg with ffmpeg use the command:

ffmpeg -i file:input.mpeg output.mpeg

The ff* tools default to the file protocol, that is a resource
specified with the name "FILE.mpeg" is interpreted as the URL
"file:FILE.mpeg".

gopher
Gopher protocol.

http
HTTP (Hyper Text Transfer Protocol).

mmst
MMS (Microsoft Media Server) protocol over TCP.

mmsh
MMS (Microsoft Media Server) protocol over HTTP.

The required syntax is:

mmsh://<server>[:<port>][/<app>][/<playpath>]

md5
MD5 output protocol.

Computes the MD5 hash of the data to be written, and on close writes
this to the designated output or stdout if none is specified. It can be
used to test muxers without writing an actual file.

Some examples follow.

# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
ffmpeg -i input.flv -f avi -y md5:output.avi.md5

# Write the MD5 hash of the encoded AVI file to stdout.
ffmpeg -i input.flv -f avi -y md5:

Note that some formats (typically MOV) require the output protocol to
be seekable, so they will fail with the MD5 output protocol.

pipe
UNIX pipe access protocol.

Allow to read and write from UNIX pipes.

The accepted syntax is:

pipe:[<number>]

number is the number corresponding to the file descriptor of the pipe
(e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number is not
specified, by default the stdout file descriptor will be used for
writing, stdin for reading.

For example to read from stdin with ffmpeg:

cat test.wav | ffmpeg -i pipe:0
# ...this is the same as...
cat test.wav | ffmpeg -i pipe:

For writing to stdout with ffmpeg:

ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
# ...this is the same as...
ffmpeg -i test.wav -f avi pipe: | cat > test.avi

Note that some formats (typically MOV), require the output protocol to
be seekable, so they will fail with the pipe output protocol.

rtmp
Real-Time Messaging Protocol.

The Real-Time Messaging Protocol (RTMP) is used for streaming
multimedia content across a TCP/IP network.

The required syntax is:

rtmp://<server>[:<port>][/<app>][/<playpath>]

The accepted parameters are:

server
The address of the RTMP server.

port
The number of the TCP port to use (by default is 1935).

app It is the name of the application to access. It usually corresponds
to the path where the application is installed on the RTMP server
(e.g. /ondemand/, /flash/live/, etc.).

playpath
It is the path or name of the resource to play with reference to
the application specified in app, may be prefixed by "mp4:".

For example to read with ffplay a multimedia resource named "sample"
from the application "vod" from an RTMP server "myserver":

ffplay rtmp://myserver/vod/sample

rtmp, rtmpe, rtmps, rtmpt, rtmpte
Real-Time Messaging Protocol and its variants supported through
librtmp.

Requires the presence of the librtmp headers and library during
configuration. You need to explicitely configure the build with
"--enable-librtmp". If enabled this will replace the native RTMP
protocol.

This protocol provides most client functions and a few server functions
needed to support RTMP, RTMP tunneled in HTTP (RTMPT), encrypted RTMP
(RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled variants of these
encrypted types (RTMPTE, RTMPTS).

The required syntax is:

<rtmp_proto>://<server>[:<port>][/<app>][/<playpath>] <options>

where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
server, port, app and playpath have the same meaning as specified for
the RTMP native protocol. options contains a list of space-separated
options of the form key=val.

See the librtmp manual page (man 3 librtmp) for more information.

For example, to stream a file in real-time to an RTMP server using
ffmpeg:

ffmpeg -re -i myfile -f flv rtmp://myserver/live/mystream

To play the same stream using ffplay:

ffplay "rtmp://myserver/live/mystream live=1"

rtp
Real-Time Protocol.

rtsp
RTSP is not technically a protocol handler in libavformat, it is a
demuxer and muxer. The demuxer supports both normal RTSP (with data
transferred over RTP; this is used by e.g. Apple and Microsoft) and
Real-RTSP (with data transferred over RDT).

The muxer can be used to send a stream using RTSP ANNOUNCE to a server
supporting it (currently Darwin Streaming Server and Mischa
Spiegelmock's RTSP server, <http://github.com/revmischa/rtsp-server>).

The required syntax for a RTSP url is:

rtsp://<hostname>[:<port>]/<path>[?<options>]

options is a "&"-separated list. The following options are supported:

udp Use UDP as lower transport protocol.

tcp Use TCP (interleaving within the RTSP control channel) as lower
transport protocol.

multicast
Use UDP multicast as lower transport protocol.

http
Use HTTP tunneling as lower transport protocol, which is useful for
passing proxies.

filter_src
Accept packets only from negotiated peer address and port.

Multiple lower transport protocols may be specified, in that case they
are tried one at a time (if the setup of one fails, the next one is
tried). For the muxer, only the "tcp" and "udp" options are supported.

When receiving data over UDP, the demuxer tries to reorder received
packets (since they may arrive out of order, or packets may get lost
totally). In order for this to be enabled, a maximum delay must be
specified in the "max_delay" field of AVFormatContext.

When watching multi-bitrate Real-RTSP streams with ffplay, the streams
to display can be chosen with "-vst" n and "-ast" n for video and audio
respectively, and can be switched on the fly by pressing "v" and "a".

Example command lines:

To watch a stream over UDP, with a max reordering delay of 0.5 seconds:

ffplay -max_delay 500000 rtsp://server/video.mp4?udp

To watch a stream tunneled over HTTP:

ffplay rtsp://server/video.mp4?http

To send a stream in realtime to a RTSP server, for others to watch:

ffmpeg -re -i <input> -f rtsp -muxdelay 0.1 rtsp://server/live.sdp

sap
Session Announcement Protocol (RFC 2974). This is not technically a
protocol handler in libavformat, it is a muxer and demuxer. It is used
for signalling of RTP streams, by announcing the SDP for the streams
regularly on a separate port.

Muxer

The syntax for a SAP url given to the muxer is:

sap://<destination>[:<port>][?<options>]

The RTP packets are sent to destination on port port, or to port 5004
if no port is specified. options is a "&"-separated list. The
following options are supported:

announce_addr=address
Specify the destination IP address for sending the announcements
to. If omitted, the announcements are sent to the commonly used
SAP announcement multicast address 224.2.127.254 (sap.mcast.net),
or ff0e::2:7ffe if destination is an IPv6 address.

announce_port=port
Specify the port to send the announcements on, defaults to 9875 if
not specified.

ttl=ttl
Specify the time to live value for the announcements and RTP
packets, defaults to 255.

same_port=0|1
If set to 1, send all RTP streams on the same port pair. If zero
(the default), all streams are sent on unique ports, with each
stream on a port 2 numbers higher than the previous. VLC/Live555
requires this to be set to 1, to be able to receive the stream.
The RTP stack in libavformat for receiving requires all streams to
be sent on unique ports.

Example command lines follow.

To broadcast a stream on the local subnet, for watching in VLC:

ffmpeg -re -i <input> -f sap sap://224.0.0.255?same_port=1

Similarly, for watching in ffplay:

ffmpeg -re -i <input> -f sap sap://224.0.0.255

And for watching in ffplay, over IPv6:

ffmpeg -re -i <input> -f sap sap://[ff0e::1:2:3:4]

Demuxer

The syntax for a SAP url given to the demuxer is:

sap://[<address>][:<port>]

address is the multicast address to listen for announcements on, if
omitted, the default 224.2.127.254 (sap.mcast.net) is used. port is the
port that is listened on, 9875 if omitted.

The demuxers listens for announcements on the given address and port.
Once an announcement is received, it tries to receive that particular
stream.

Example command lines follow.

To play back the first stream announced on the normal SAP multicast
address:

ffplay sap://

To play back the first stream announced on one the default IPv6 SAP
multicast address:

ffplay sap://[ff0e::2:7ffe]

tcp
Trasmission Control Protocol.

The required syntax for a TCP url is:

tcp://<hostname>:<port>[?<options>]

listen
Listen for an incoming connection

ffmpeg -i <input> -f <format> tcp://<hostname>:<port>?listen
ffplay tcp://<hostname>:<port>

udp
User Datagram Protocol.

The required syntax for a UDP url is:

udp://<hostname>:<port>[?<options>]

options contains a list of &-seperated options of the form key=val.
Follow the list of supported options.

buffer_size=size
set the UDP buffer size in bytes

localport=port
override the local UDP port to bind with

pkt_size=size
set the size in bytes of UDP packets

reuse=1|0
explicitly allow or disallow reusing UDP sockets

ttl=ttl
set the time to live value (for multicast only)

connect=1|0
Initialize the UDP socket with "connect()". In this case, the
destination address can't be changed with ff_udp_set_remote_url
later. If the destination address isn't known at the start, this
option can be specified in ff_udp_set_remote_url, too. This allows
finding out the source address for the packets with getsockname,
and makes writes return with AVERROR(ECONNREFUSED) if "destination
unreachable" is received. For receiving, this gives the benefit of
only receiving packets from the specified peer address/port.

Some usage examples of the udp protocol with ffmpeg follow.

To stream over UDP to a remote endpoint:

ffmpeg -i <input> -f <format> udp://<hostname>:<port>

To stream in mpegts format over UDP using 188 sized UDP packets, using
a large input buffer:

ffmpeg -i <input> -f mpegts udp://<hostname>:<port>?pkt_size=188&buffer_size=65535

To receive over UDP from a remote endpoint:

ffmpeg -i udp://[<multicast-address>]:<port>

INPUT DEVICES
Input devices are configured elements in FFmpeg which allow to access
the data coming from a multimedia device attached to your system.

When you configure your FFmpeg build, all the supported input devices
are enabled by default. You can list all available ones using the
configure option "--list-indevs".

You can disable all the input devices using the configure option
"--disable-indevs", and selectively enable an input device using the
option "--enable-indev=INDEV", or you can disable a particular input
device using the option "--disable-indev=INDEV".

The option "-formats" of the ff* tools will display the list of
supported input devices (amongst the demuxers).

A description of the currently available input devices follows.

alsa
ALSA (Advanced Linux Sound Architecture) input device.

To enable this input device during configuration you need libasound
installed on your system.

This device allows capturing from an ALSA device. The name of the
device to capture has to be an ALSA card identifier.

An ALSA identifier has the syntax:

hw:<CARD>[,<DEV>[,<SUBDEV>]]

where the DEV and SUBDEV components are optional.

The three arguments (in order: CARD,DEV,SUBDEV) specify card number or
identifier, device number and subdevice number (-1 means any).

To see the list of cards currently recognized by your system check the
files /proc/asound/cards and /proc/asound/devices.

For example to capture with ffmpeg from an ALSA device with card id 0,
you may run the command:

ffmpeg -f alsa -i hw:0 alsaout.wav

For more information see:
<http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html>

bktr
BSD video input device.

dv1394
Linux DV 1394 input device.

fbdev
Linux framebuffer input device.

The Linux framebuffer is a graphic hardware-independent abstraction
layer to show graphics on a computer monitor, typically on the console.
It is accessed through a file device node, usually /dev/fb0.

For more detailed information read the file
Documentation/fb/framebuffer.txt included in the Linux source tree.

To record from the framebuffer device /dev/fb0 with ffmpeg:

ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi

You can take a single screenshot image with the command:

ffmpeg -f fbdev -vframes 1 -r 1 -i /dev/fb0 screenshot.jpeg

See also <http://linux-fbdev.sourceforge.net/>, and fbset(1).

jack
JACK input device.

To enable this input device during configuration you need libjack
installed on your system.

A JACK input device creates one or more JACK writable clients, one for
each audio channel, with name client_name:input_N, where client_name is
the name provided by the application, and N is a number which
identifies the channel. Each writable client will send the acquired
data to the FFmpeg input device.

Once you have created one or more JACK readable clients, you need to
connect them to one or more JACK writable clients.

To connect or disconnect JACK clients you can use the jack_connect and
jack_disconnect programs, or do it through a graphical interface, for
example with qjackctl.

To list the JACK clients and their properties you can invoke the
command jack_lsp.

Follows an example which shows how to capture a JACK readable client
with ffmpeg.

# Create a JACK writable client with name "ffmpeg".
$ ffmpeg -f jack -i ffmpeg -y out.wav

# Start the sample jack_metro readable client.
$ jack_metro -b 120 -d 0.2 -f 4000

# List the current JACK clients.
$ jack_lsp -c
system:capture_1
system:capture_2
system:playback_1
system:playback_2
ffmpeg:input_1
metro:120_bpm

# Connect metro to the ffmpeg writable client.
$ jack_connect metro:120_bpm ffmpeg:input_1

For more information read: <http://jackaudio.org/>

libdc1394
IIDC1394 input device, based on libdc1394 and libraw1394.

oss
Open Sound System input device.

The filename to provide to the input device is the device node
representing the OSS input device, and is usually set to /dev/dsp.

For example to grab from /dev/dsp using ffmpeg use the command:

ffmpeg -f oss -i /dev/dsp /tmp/oss.wav

For more information about OSS see:
<http://manuals.opensound.com/usersguide/dsp.html>

sndio
sndio input device.

To enable this input device during configuration you need libsndio
installed on your system.

The filename to provide to the input device is the device node
representing the sndio input device, and is usually set to /dev/audio0.

For example to grab from /dev/audio0 using ffmpeg use the command:

ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav

video4linux and video4linux2
Video4Linux and Video4Linux2 input video devices.

The name of the device to grab is a file device node, usually Linux
systems tend to automatically create such nodes when the device (e.g.
an USB webcam) is plugged into the system, and has a name of the kind
/dev/videoN, where N is a number associated to the device.

Video4Linux and Video4Linux2 devices only support a limited set of
widthxheight sizes and framerates. You can check which are supported
for example with the command dov4l for Video4Linux devices and the
command v4l-info for Video4Linux2 devices.

If the size for the device is set to 0x0, the input device will try to
autodetect the size to use. Only for the video4linux2 device, if the
frame rate is set to 0/0 the input device will use the frame rate value
already set in the driver.

Video4Linux support is deprecated since Linux 2.6.30, and will be
dropped in later versions.

Follow some usage examples of the video4linux devices with the ff*
tools.

# Grab and show the input of a video4linux device, frame rate is set
# to the default of 25/1.
ffplay -s 320x240 -f video4linux /dev/video0

# Grab and show the input of a video4linux2 device, autoadjust size.
ffplay -f video4linux2 /dev/video0

# Grab and record the input of a video4linux2 device, autoadjust size,
# frame rate value defaults to 0/0 so it is read from the video4linux2
# driver.
ffmpeg -f video4linux2 -i /dev/video0 out.mpeg

vfwcap
VfW (Video for Windows) capture input device.

The filename passed as input is the capture driver number, ranging from
0 to 9. You may use "list" as filename to print a list of drivers. Any
other filename will be interpreted as device number 0.

x11grab
X11 video input device.

This device allows to capture a region of an X11 display.

The filename passed as input has the syntax:

[<hostname>]:<display_number>.<screen_number>[+<x_offset>,<y_offset>]

hostname:display_number.screen_number specifies the X11 display name of
the screen to grab from. hostname can be ommitted, and defaults to
"localhost". The environment variable DISPLAY contains the default
display name.

x_offset and y_offset specify the offsets of the grabbed area with
respect to the top-left border of the X11 screen. They default to 0.

Check the X11 documentation (e.g. man X) for more detailed information.

Use the dpyinfo program for getting basic information about the
properties of your X11 display (e.g. grep for "name" or "dimensions").

For example to grab from :0.0 using ffmpeg:

ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg

# Grab at position 10,20.
ffmpeg -f x11grab -25 -s cif -i :0.0+10,20 out.mpg

SEE ALSO
ffmpeg(1), ffplay(1), ffserver(1) and the FFmpeg HTML documentation

AUTHORS
The FFmpeg developers

2016-02-17 FFPROBE(1)