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# 1. Synopsis

The generic syntax is:

    ffprobe [options] [‘input_file’]

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# 2. 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:".

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# 3. 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".

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## 3.1 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 `NO_COLOR`.

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## 3.2 Main options

‘`-convert_tags`’

  Convert the tag names in the format container to the generic FFmpeg tag names.

‘`-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".

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# 4. 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.

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## 4.1 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.

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## 4.2 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".

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## 4.3 gopher

Gopher protocol.

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## 4.4 http

HTTP (Hyper Text Transfer Protocol).

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## 4.5 mmst

MMS (Microsoft Media Server) protocol over TCP.

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## 4.6 mmsh

MMS (Microsoft Media Server) protocol over HTTP.

The required syntax is:

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

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## 4.7 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.

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## 4.8 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.

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## 4.9 rtmp

Real-Time Messaging Protocol.

The Real-Time Messaging Protocol (RTMP) is used for streaming multime‐ dia 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

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## 4.10 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"

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## 4.11 rtp

Real-Time Protocol.

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## 4.12 tcp

Trasmission Control Protocol.

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## 4.13 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)

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

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# 5. 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.

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## 5.1 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

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## 5.2 bktr

BSD video input device.

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## 5.3 dv1394

Linux DV 1394 input device.

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## 5.4 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/

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## 5.5 libdc1394

IIDC1394 input device, based on libdc1394 and libraw1394.

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## 5.6 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

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## 5.7 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.

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.
    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.
    ffmpeg -f video4linux2 -i /dev/video0 out.mpeg

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## 5.8 vfwcap

VfW (Video for Windows) capture input device.

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## 5.9 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

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