Hu Chunming / FFNvDecoder

  All the numerical options, if not specified otherwise, accept a string
  representing a number as input, which may be followed by one of the SI
  unit prefixes, for example: 'K', 'M', or 'G'.
  
  If 'i' is appended to the SI unit prefix, the complete prefix will be
  interpreted as a unit prefix for binary multiples, which are based on
  powers of 1024 instead of powers of 1000. Appending 'B' to the SI unit
  prefix multiplies the value by 8. This allows using, for example:
  'KB', 'MiB', 'G' and 'B' as number suffixes.
  
  Options which do not take arguments are boolean options, and set the
  corresponding value to true. They can be set to false by prefixing
  the option name with "no". For example using "-nofoo"
  will set the boolean option with name "foo" to false.
  
  @anchor{Stream specifiers}
  @section Stream specifiers
  Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
  are used to precisely specify which stream(s) a given option belongs to.
  
  A stream specifier is a string generally appended to the option name and
  separated from it by a colon. E.g. @code{-codec:a:1 ac3} contains the
  @code{a:1} stream specifier, which matches the second audio stream. Therefore, it
  would select the ac3 codec for the second audio stream.
  
  A stream specifier can match several streams, so that the option is applied to all
  of them. E.g. the stream specifier in @code{-b:a 128k} matches all audio
  streams.
  
  An empty stream specifier matches all streams. For example, @code{-codec copy}
  or @code{-codec: copy} would copy all the streams without reencoding.
  
  Possible forms of stream specifiers are:
  @table @option
  @item @var{stream_index}
  Matches the stream with this index. E.g. @code{-threads:1 4} would set the
  thread count for the second stream to 4. If @var{stream_index} is used as an
  additional stream specifier (see below), then it selects stream number
  @var{stream_index} from the matching streams. Stream numbering is based on the
  order of the streams as detected by libavformat except when a program ID is
  also specified. In this case it is based on the ordering of the streams in the
  program.
  @item @var{stream_type}[:@var{additional_stream_specifier}]
  @var{stream_type} is one of following: 'v' or 'V' for video, 'a' for audio, 's'
  for subtitle, 'd' for data, and 't' for attachments. 'v' matches all video
  streams, 'V' only matches video streams which are not attached pictures, video
  thumbnails or cover arts. If @var{additional_stream_specifier} is used, then
  it matches streams which both have this type and match the
  @var{additional_stream_specifier}. Otherwise, it matches all streams of the
  specified type.
  @item p:@var{program_id}[:@var{additional_stream_specifier}]
  Matches streams which are in the program with the id @var{program_id}. If
  @var{additional_stream_specifier} is used, then it matches streams which both
  are part of the program and match the @var{additional_stream_specifier}.
  
  @item #@var{stream_id} or i:@var{stream_id}
  Match the stream by stream id (e.g. PID in MPEG-TS container).
  @item m:@var{key}[:@var{value}]
  Matches streams with the metadata tag @var{key} having the specified value. If
  @var{value} is not given, matches streams that contain the given tag with any
  value.
  @item u
  Matches streams with usable configuration, the codec must be defined and the
  essential information such as video dimension or audio sample rate must be present.
  
  Note that in @command{ffmpeg}, matching by metadata will only work properly for
  input files.
  @end table
  
  @section Generic options
  
  These options are shared amongst the ff* tools.
  
  @table @option
  
  @item -L
  Show license.
  
  @item -h, -?, -help, --help [@var{arg}]
  Show help. An optional parameter may be specified to print help about a specific
  item. If no argument is specified, only basic (non advanced) tool
  options are shown.
  
  Possible values of @var{arg} are:
  @table @option
  @item long
  Print advanced tool options in addition to the basic tool options.
  
  @item full
  Print complete list of options, including shared and private options
  for encoders, decoders, demuxers, muxers, filters, etc.
  
  @item decoder=@var{decoder_name}
  Print detailed information about the decoder named @var{decoder_name}. Use the
  @option{-decoders} option to get a list of all decoders.
  
  @item encoder=@var{encoder_name}
  Print detailed information about the encoder named @var{encoder_name}. Use the
  @option{-encoders} option to get a list of all encoders.
  
  @item demuxer=@var{demuxer_name}
  Print detailed information about the demuxer named @var{demuxer_name}. Use the
  @option{-formats} option to get a list of all demuxers and muxers.
  
  @item muxer=@var{muxer_name}
  Print detailed information about the muxer named @var{muxer_name}. Use the
  @option{-formats} option to get a list of all muxers and demuxers.
  
  @item filter=@var{filter_name}
  Print detailed information about the filter name @var{filter_name}. Use the
  @option{-filters} option to get a list of all filters.
  
  @item bsf=@var{bitstream_filter_name}
  Print detailed information about the bitstream filter name @var{bitstream_filter_name}.
  Use the @option{-bsfs} option to get a list of all bitstream filters.
  @end table
  
  @item -version
  Show version.
  
  @item -formats
  Show available formats (including devices).
  
  @item -demuxers
  Show available demuxers.
  
  @item -muxers
  Show available muxers.
  
  @item -devices
  Show available devices.
  
  @item -codecs
  Show all codecs known to libavcodec.
  
  Note that the term 'codec' is used throughout this documentation as a shortcut
  for what is more correctly called a media bitstream format.
  
  @item -decoders
  Show available decoders.
  
  @item -encoders
  Show all available encoders.
  
  @item -bsfs
  Show available bitstream filters.
  
  @item -protocols
  Show available protocols.
  
  @item -filters
  Show available libavfilter filters.
  
  @item -pix_fmts
  Show available pixel formats.
  
  @item -sample_fmts
  Show available sample formats.
  
  @item -layouts
  Show channel names and standard channel layouts.
  
  @item -colors
  Show recognized color names.
  
  @item -sources @var{device}[,@var{opt1}=@var{val1}[,@var{opt2}=@var{val2}]...]
  Show autodetected sources of the input device.
  Some devices may provide system-dependent source names that cannot be autodetected.
  The returned list cannot be assumed to be always complete.
  @example
  ffmpeg -sources pulse,server=192.168.0.4
  @end example
  
  @item -sinks @var{device}[,@var{opt1}=@var{val1}[,@var{opt2}=@var{val2}]...]
  Show autodetected sinks of the output device.
  Some devices may provide system-dependent sink names that cannot be autodetected.
  The returned list cannot be assumed to be always complete.
  @example
  ffmpeg -sinks pulse,server=192.168.0.4
  @end example
  
  @item -loglevel [@var{flags}+]@var{loglevel} | -v [@var{flags}+]@var{loglevel}
  Set logging level and flags used by the library.
  
  The optional @var{flags} prefix can consist of the following values:
  @table @samp
  @item repeat
  Indicates that repeated log output should not be compressed to the first line
  and the "Last message repeated n times" line will be omitted.
  @item level
  Indicates that log output should add a @code{[level]} prefix to each message
  line. This can be used as an alternative to log coloring, e.g. when dumping the
  log to file.
  @end table
  Flags can also be used alone by adding a '+'/'-' prefix to set/reset a single
  flag without affecting other @var{flags} or changing @var{loglevel}. When
  setting both @var{flags} and @var{loglevel}, a '+' separator is expected
  between the last @var{flags} value and before @var{loglevel}.
  
  @var{loglevel} is a string or a number containing one of the following values:
  @table @samp
  @item quiet, -8
  Show nothing at all; be silent.
  @item panic, 0
  Only show fatal errors which could lead the process to crash, such as
  an assertion failure. This is not currently used for anything.
  @item fatal, 8
  Only show fatal errors. These are errors after which the process absolutely
  cannot continue.
  @item error, 16
  Show all errors, including ones which can be recovered from.
  @item warning, 24
  Show all warnings and errors. Any message related to possibly
  incorrect or unexpected events will be shown.
  @item info, 32
  Show informative messages during processing. This is in addition to
  warnings and errors. This is the default value.
  @item verbose, 40
  Same as @code{info}, except more verbose.
  @item debug, 48
  Show everything, including debugging information.
  @item trace, 56
  @end table
  
  For example to enable repeated log output, add the @code{level} prefix, and set
  @var{loglevel} to @code{verbose}:
  @example
  ffmpeg -loglevel repeat+level+verbose -i input output
  @end example
  Another example that enables repeated log output without affecting current
  state of @code{level} prefix flag or @var{loglevel}:
  @example
  ffmpeg [...] -loglevel +repeat
  @end example
  
  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
  @env{AV_LOG_FORCE_NOCOLOR} or @env{NO_COLOR}, or can be forced setting
  the environment variable @env{AV_LOG_FORCE_COLOR}.
  The use of the environment variable @env{NO_COLOR} is deprecated and
  will be dropped in a future FFmpeg version.
  
  @item -report
  Dump full command line and console output to a file named
  @code{@var{program}-@var{YYYYMMDD}-@var{HHMMSS}.log} in the current
  directory.
  This file can be useful for bug reports.
  It also implies @code{-loglevel debug}.
  
  Setting the environment variable @env{FFREPORT} to any value has the
  same effect. If the value is a ':'-separated key=value sequence, these
  options will affect the report; option values must be escaped if they
  contain special characters or the options delimiter ':' (see the
  ``Quoting and escaping'' section in the ffmpeg-utils manual).
  
  The following options are recognized:
  @table @option
  @item file
  set the file name to use for the report; @code{%p} is expanded to the name
  of the program, @code{%t} is expanded to a timestamp, @code{%%} is expanded
  to a plain @code{%}
  @item level
  set the log verbosity level using a numerical value (see @code{-loglevel}).
  @end table
  
  For example, to output a report to a file named @file{ffreport.log}
  using a log level of @code{32} (alias for log level @code{info}):
  
  @example
  FFREPORT=file=ffreport.log:level=32 ffmpeg -i input output
  @end example
  
  Errors in parsing the environment variable are not fatal, and will not
  appear in the report.
  
  @item -hide_banner
  Suppress printing banner.
  
  All FFmpeg tools will normally show a copyright notice, build options
  and library versions. This option can be used to suppress printing
  this information.
  
  @item -cpuflags flags (@emph{global})
  Allows setting and clearing cpu flags. This option is intended
  for testing. Do not use it unless you know what you're doing.
  @example
  ffmpeg -cpuflags -sse+mmx ...
  ffmpeg -cpuflags mmx ...
  ffmpeg -cpuflags 0 ...
  @end example
  Possible flags for this option are:
  @table @samp
  @item x86
  @table @samp
  @item mmx
  @item mmxext
  @item sse
  @item sse2
  @item sse2slow
  @item sse3
  @item sse3slow
  @item ssse3
  @item atom
  @item sse4.1
  @item sse4.2
  @item avx
  @item avx2
  @item xop
  @item fma3
  @item fma4
  @item 3dnow
  @item 3dnowext
  @item bmi1
  @item bmi2
  @item cmov
  @end table
  @item ARM
  @table @samp
  @item armv5te
  @item armv6
  @item armv6t2
  @item vfp
  @item vfpv3
  @item neon
  @item setend
  @end table
  @item AArch64
  @table @samp
  @item armv8
  @item vfp
  @item neon
  @end table
  @item PowerPC
  @table @samp
  @item altivec
  @end table
  @item Specific Processors
  @table @samp
  @item pentium2
  @item pentium3
  @item pentium4
  @item k6
  @item k62
  @item athlon
  @item athlonxp
  @item k8
  @end table
  @end table
  @end table
  
  @section AVOptions
  
  These options are provided directly by the libavformat, libavdevice and
  libavcodec libraries. To see the list of available AVOptions, use the
  @option{-help} option. They are separated into two categories:
  @table @option
  @item generic
  These options can be set for any container, codec or device. Generic options
  are listed under AVFormatContext options for containers/devices and under
  AVCodecContext options for codecs.
  @item private
  These options are specific to the given container, device or codec. Private
  options are listed under their corresponding containers/devices/codecs.
  @end table
  
  For example to write an ID3v2.3 header instead of a default ID3v2.4 to
  an MP3 file, use the @option{id3v2_version} private option of the MP3
  muxer:
  @example
  ffmpeg -i input.flac -id3v2_version 3 out.mp3
  @end example
  
  All codec AVOptions are per-stream, and thus a stream specifier
  should be attached to them:
  @example
  ffmpeg -i multichannel.mxf -map 0:v:0 -map 0:a:0 -map 0:a:0 -c:a:0 ac3 -b:a:0 640k -ac:a:1 2 -c:a:1 aac -b:2 128k out.mp4
  @end example
  
  In the above example, a multichannel audio stream is mapped twice for output.
  The first instance is encoded with codec ac3 and bitrate 640k.
  The second instance is downmixed to 2 channels and encoded with codec aac. A bitrate of 128k is specified for it using
  absolute index of the output stream.
  
  Note: the @option{-nooption} syntax cannot be used for boolean
  AVOptions, use @option{-option 0}/@option{-option 1}.
  
  Note: the old undocumented way of specifying per-stream AVOptions by
  prepending v/a/s to the options name is now obsolete and will be
  removed soon.