##1.帮助调试信息
-L 显示 license.
-h, -?, -help, --help [arg]
arg可能值:
long
full
decoder=decoder_name
encoder=encoder_name
demuxer=demuxer_name
muxer=muxer_name
filter=filter_name
-formats
-devices
-codecs
-decoders
-encoders
-bsfs
-protocols
-filters
-pix_fmts
-sample_fmts
-layouts
-colors
-sources device[,opt1=val1[,opt2=val2]…]
-sinks device[,opt1=val1[,opt2=val2]…]
-loglevel [repeat+]loglevel | -v [repeat+]loglevel
‘quiet, -8’
‘panic, 0’
‘fatal, 8’
‘error, 16’
‘warning, 24’
‘info, 32’
‘verbose, 40’
‘debug, 48’
‘trace, 56’
-report
-hide_banner
##2.选择输入流
###2.1.默认规则
当一个输入中