Main options:
-L show license
-h show help
-formats show available formats, codecs, protocols, ...
-f fmt force format
-img img_fmt force image format
-i filename input file name
-y overwrite output files
-t duration set the recording time
-title string set the title
-author string set the author
-copyright string set the copyright
-comment string set the comment
-v verbose control amount of logging
-hq activate high quality settings

Video options:
-b bitrate set video bitrate (in kbit/s)
-r rate set frame rate (Hz value, fraction or abbreviation)
-s size set frame size (WxH or abbreviation)
-aspect aspect set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
-croptop size set top crop band size (in pixels)
-cropbottom size set bottom crop band size (in pixels)
-cropleft size set left crop band size (in pixels)
-cropright size set right crop band size (in pixels)
-vn disable video
-bt tolerance set video bitrate tolerance (in kbit/s)
-maxrate bitrate set max video bitrate tolerance (in kbit/s)
-minrate bitrate set min video bitrate tolerance (in kbit/s)
-bufsize size set ratecontrol buffere size (in kbit)
-vcodec codec force video codec ('copy' to copy stream)
-sameq use same video quality as source (implies VBR)
-pass n select the pass number (1 or 2)
-passlogfile file select two pass log file name

Advanced Video options:
-pix_fmt format set pixel format
-g gop_size set the group of picture size
-intra use only intra frames
-qscale q use fixed video quantiser scale (VBR)
-qmin q min video quantiser scale (VBR)
-qmax q max video quantiser scale (VBR)
-mbqmin q min macroblock quantiser scale (VBR)
-mbqmax q max macroblock quantiser scale (VBR)
-qdiff q max difference between the quantiser scale (VBR)
-qblur blur video quantiser scale blur (VBR)
-qcomp compression video quantiser scale compression (VBR)
-rc_init_cplx complexity initial complexity for 1-pass encoding
-b_qfactor factor qp factor between p and b frames
-i_qfactor factor qp factor between p and i frames
-b_qoffset offset qp offset between p and b frames
-i_qoffset offset qp offset between p and i frames
-rc_eq equation set rate control equation
-rc_override override rate control override for specific intervals
-me method set motion estimation method
-dct_algo algo set dct algo
-idct_algo algo set idct algo
-er n set error resilience
-ec bit_mask set error concealment
-bf frames use 'frames' B frames
-mbd mode macroblock decision
-4mv use four motion vector by macroblock (only MPEG-4)
-part use data partitioning (only MPEG-4)
-bug param workaround not auto detected encoder bugs
-strict strictness how strictly to follow the standarts
-deinterlace deinterlace pictures
-psnr calculate PSNR of compressed frames
-vstats dump video coding statistics to file
-vhook module insert video processing module
-aic enable Advanced intra coding (h263+)
-umv enable Unlimited Motion Vector (h263+)

Audio options:
-ab bitrate set audio bitrate (in kbit/s)
-ar rate set audio sampling rate (in Hz)
-ac channels set number of audio channels
-an disable audio
-acodec codec force audio codec ('copy' to copy stream)

Audio/Video grab options:
-vd device set video grab device
-vc channel set video grab channel (DV1394 only)
-tvstd standard set television standard (NTSC, PAL (SECAM))
-dv1394 set DV1394 grab
-ad device set audio device

Advanced options:
-map file:stream set input stream mapping
-debug print specific debug info
-benchmark add timings for benchmarking
-hex dump each input packet
-bitexact only use bit exact algorithms (for codec testing)
-re read input at native frame rate
-loop loop (current only works with images)
-ps size set packet size in bits