ffmpeg的命令行-h内容非常非常多。
如需查看全部内容执行
ffmpeg -h full


如需观看特定topic的下的分支,比如想看ffmpeg demux的hls 帮助手册
执行如下
ffmpeg  -h demuxer=hls
结果如下:
Demuxer hls [Apple HTTP Live Streaming]:
hls demuxer AVOptions:
  -live_start_index          .D....... segment index to start live streams at (negative values are from the end) (from INT_MIN to INT_MAX) (default -3)
  -allowed_extensions      .D....... List of file extensions that hls is allowed to access (default "3gp,aac,avi,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav")
  -max_reload                .D....... Maximum number of times a insufficient list is attempted to be reloaded (from 0 to INT_MAX) (default 1000)
  -http_persistent       .D....... Use persistent HTTP connections (default true)
  -http_multiple         .D....... Use multiple HTTP connections for fetching segments (default auto)


比如我想看下 muxer 的 hls
执行
 ffmpeg -h muxer=hls

结果如下:

Muxer hls [Apple HTTP Live Streaming]:
    Common extensions: m3u8.
    Default video codec: h264.
    Default audio codec: aac.
    Default subtitle codec: webvtt.
hls muxer AVOptions:
  -start_number            E........ set first number in the sequence (from 0 to I64_MAX) (default 0)
  -hls_time                E........ set segment length in seconds (from 0 to FLT_MAX) (default 2)
  -hls_init_time           E........ set segment length in seconds at init list (from 0 to FLT_MAX) (default 0)
  -hls_list_size             E........ set maximum number of playlist entries (from 0 to INT_MAX) (default 5)
  -hls_delete_threshold         E........ set number of unreferenced segments to keep before deleting (from 1 to INT_MAX) (default 1)
  -hls_ts_options         E........ set hls mpegts list of options for the container format used for hls
  -hls_vtt_options        E........ set hls vtt list of options for the container format used for hls
  -hls_wrap                  E........ set number after which the index wraps (will be deprecated) (from 0 to INT_MAX) (default 0)
  -hls_allow_cache           E........ explicitly set whether the client MAY (1) or MUST NOT (0) cache media segments (from INT_MIN to INT_MAX) (default -1)
  -hls_base_url           E........ url to prepend to each playlist entry
  -hls_segment_filename      E........ filename template for segment files
  -hls_segment_size          E........ maximum size per segment file, (in bytes) (from 0 to INT_MAX) (default 0)
  -hls_key_info_file      E........ file with key URI and key file path
  -hls_enc               E........ enable AES128 encryption support (default false)
  -hls_enc_key            E........ hex-coded 16 byte key to encrypt the segments
  -hls_enc_key_url        E........ url to access the key to decrypt the segments
  -hls_enc_iv             E........ hex-coded 16 byte initialization vector
  -hls_subtitle_path      E........ set path of hls subtitles
  -hls_segment_type          E........ set hls segment files type (from 0 to 1) (default mpegts)
     mpegts                       E........ make segment file to mpegts files in m3u8
     fmp4                         E........ make segment file to fragment mp4 files in m3u8
  -hls_fmp4_init_filename      E........ set fragment mp4 file init filename (default "init.mp4")
  -hls_flags               E........ set flags affecting HLS playlist and media file generation (default 0)
     single_file                  E........ generate a single media file indexed with byte ranges
     temp_file                    E........ write segment to temporary file and rename when complete
     delete_segments              E........ delete segment files that are no longer part of the playlist
     round_durations              E........ round durations in m3u8 to whole numbers
     discont_start                E........ start the playlist with a discontinuity tag
     omit_endlist                 E........ Do not append an endlist when ending stream
     split_by_time                E........ split the hls segment by time which user set by hls_time
     append_list                  E........ append the new segments into old hls segment list
     program_date_time              E........ add EXT-X-PROGRAM-DATE-TIME
     second_level_segment_index              E........ include segment index in segment filenames when use_localtime
     second_level_segment_duration              E........ include segment duration in segment filenames when use_localtime
     second_level_segment_size              E........ include segment size in segment filenames when use_localtime
     periodic_rekey               E........ reload keyinfo file periodically for re-keying
     independent_segments              E........ add EXT-X-INDEPENDENT-SEGMENTS, whenever applicable
  -use_localtime         E........ set filename expansion with strftime at segment creation(will be deprecated ) (default false)
  -strftime              E........ set filename expansion with strftime at segment creation (default false)
  -use_localtime_mkdir     E........ create last directory component in strftime-generated filename(will be deprecated) (default false)
  -strftime_mkdir        E........ create last directory component in strftime-generated filename (default false)
  -hls_playlist_type         E........ set the HLS playlist type (from 0 to 2) (default 0)
     event                        E........ EVENT playlist
     vod                          E........ VOD playlist
  -method                 E........ set the HTTP method(default: PUT)
  -hls_start_number_source         E........ set source of first number in sequence (from 0 to 2) (default generic)
     generic                      E........ start_number value (default)
     epoch                        E........ seconds since epoch
     datetime                     E........ current datetime as YYYYMMDDhhmmss
  -http_user_agent        E........ override User-Agent field in HTTP header
  -var_stream_map         E........ Variant stream map string
  -cc_stream_map          E........ Closed captions stream map string
  -master_pl_name         E........ Create HLS master playlist with this name
  -master_pl_publish_rate         E........ Publish master play list every after this many segment intervals (from 0 to UINT32_MAX) (default 0)
  -http_persistent       E........ Use persistent HTTP connections (default false)
  -timeout              E........ set timeout for socket I/O operations (default -0.000001)
  -ignore_io_errors      E........ Ignore IO errors for stable long-duration runs with network output (default false)


12-02 17:26