3 @c man begin CODEC OPTIONS
5 libavcodec provides some generic global options, which can be set on
6 all the encoders and decoders. In addition each codec may support
7 so-called private options, which are specific for a given codec.
9 Sometimes, a global option may only affect a specific kind of codec,
10 and may be unsensical or ignored by another, so you need to be aware
11 of the meaning of the specified options. Also some options are
12 meant only for decoding or encoding.
14 Options may be set by specifying -@var{option} @var{value} in the
15 FFmpeg tools, or by setting the value explicitly in the
16 @code{AVCodecContext} options or using the @file{libavutil/opt.h} API
19 The list of supported options follow:
22 @item b @var{integer} (@emph{encoding,audio,video})
23 Set bitrate in bits/s. Default value is 200K.
25 @item ab @var{integer} (@emph{encoding,audio})
26 Set audio bitrate (in bits/s). Default value is 128K.
28 @item bt @var{integer} (@emph{encoding,video})
29 Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate
30 tolerance specifies how far ratecontrol is willing to deviate from the
31 target average bitrate value. This is not related to min/max
32 bitrate. Lowering tolerance too much has an adverse effect on quality.
34 @item flags @var{flags} (@emph{decoding/encoding,audio,video,subtitles})
40 Use four motion vector by macroblock (mpeg4).
42 Use 1/4 pel motion compensation.
50 Always try a mb with mv=<0,0>.
54 Use internal 2pass ratecontrol in first pass mode.
56 Use internal 2pass ratecontrol in second pass mode.
58 Only decode/encode grayscale.
62 Set error[?] variables during encoding.
66 Normalize adaptive quantization.
72 Place global headers in extradata instead of every keyframe.
74 Use only bitexact stuff (except (I)DCT).
76 Apply H263 advanced intra coding / mpeg4 ac prediction.
78 Deprecated, use mpegvideo private options instead.
80 Deprecated, use mpegvideo private options instead.
82 Apply interlaced motion estimation.
87 @item me_method @var{integer} (@emph{encoding,video})
88 Set motion estimation method.
93 zero motion estimation (fastest)
95 full motion estimation (slowest)
97 EPZS motion estimation (default)
99 esa motion estimation (alias for full)
101 tesa motion estimation
103 dia motion estimation (alias for epzs)
105 log motion estimation
107 phods motion estimation
111 hex motion estimation
113 umh motion estimation
115 iter motion estimation
118 @item extradata_size @var{integer}
121 @item time_base @var{rational number}
124 It is the fundamental unit of time (in seconds) in terms of which
125 frame timestamps are represented. For fixed-fps content, timebase
126 should be @code{1 / frame_rate} and timestamp increments should be
129 @item g @var{integer} (@emph{encoding,video})
130 Set the group of picture size. Default value is 12.
132 @item ar @var{integer} (@emph{decoding/encoding,audio})
133 Set audio sampling rate (in Hz).
135 @item ac @var{integer} (@emph{decoding/encoding,audio})
136 Set number of audio channels.
138 @item cutoff @var{integer} (@emph{encoding,audio})
139 Set cutoff bandwidth.
141 @item frame_size @var{integer} (@emph{encoding,audio})
142 Set audio frame size.
144 Each submitted frame except the last must contain exactly frame_size
145 samples per channel. May be 0 when the codec has
146 CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is not
147 restricted. It is set by some decoders to indicate constant frame
150 @item frame_number @var{integer}
151 Set the frame number.
153 @item delay @var{integer}
155 @item qcomp @var{float} (@emph{encoding,video})
156 Set video quantizer scale compression (VBR). It is used as a constant
157 in the ratecontrol equation. Recommended range for default rc_eq:
160 @item qblur @var{float} (@emph{encoding,video})
161 Set video quantizer scale blur (VBR).
163 @item qmin @var{integer} (@emph{encoding,video})
164 Set min video quantizer scale (VBR). Must be included between -1 and
165 69, default value is 2.
167 @item qmax @var{integer} (@emph{encoding,video})
168 Set max video quantizer scale (VBR). Must be included between -1 and
169 1024, default value is 31.
171 @item qdiff @var{integer} (@emph{encoding,video})
172 Set max difference between the quantizer scale (VBR).
174 @item bf @var{integer} (@emph{encoding,video})
175 Set max number of B frames between non-B-frames.
177 Must be an integer between -1 and 16. 0 means that B-frames are
178 disabled. If a value of -1 is used, it will choose an automatic value
179 depending on the encoder.
183 @item b_qfactor @var{float} (@emph{encoding,video})
184 Set qp factor between P and B frames.
186 @item rc_strategy @var{integer} (@emph{encoding,video})
187 Set ratecontrol method.
189 @item b_strategy @var{integer} (@emph{encoding,video})
190 Set strategy to choose between I/P/B-frames.
192 @item ps @var{integer} (@emph{encoding,video})
193 Set RTP payload size in bytes.
195 @item mv_bits @var{integer}
196 @item header_bits @var{integer}
197 @item i_tex_bits @var{integer}
198 @item p_tex_bits @var{integer}
199 @item i_count @var{integer}
200 @item p_count @var{integer}
201 @item skip_count @var{integer}
202 @item misc_bits @var{integer}
203 @item frame_bits @var{integer}
204 @item codec_tag @var{integer}
205 @item bug @var{flags} (@emph{decoding,video})
206 Workaround not auto detected encoder bugs.
213 some old lavc generated msmpeg4v3 files (no autodetection)
215 Xvid interlacing bug (autodetected if fourcc==XVIX)
217 (autodetected if fourcc==UMP4)
219 padding bug (autodetected)
223 illegal vlc bug (autodetected per fourcc)
227 old standard qpel (autodetected per fourcc/version)
230 @item direct_blocksize
231 direct-qpel-blocksize bug (autodetected per fourcc/version)
233 edge padding bug (autodetected per fourcc/version)
239 Workaround various bugs in microsoft broken decoders.
244 @item lelim @var{integer} (@emph{encoding,video})
245 Set single coefficient elimination threshold for luminance (negative
246 values also consider DC coefficient).
248 @item celim @var{integer} (@emph{encoding,video})
249 Set single coefficient elimination threshold for chrominance (negative
250 values also consider dc coefficient)
252 @item strict @var{integer} (@emph{decoding/encoding,audio,video})
253 Specify how strictly to follow the standards.
258 strictly conform to a older more strict version of the spec or reference software
260 strictly conform to all the things in the spec no matter what consequences
264 allow unofficial extensions
266 allow non standardized experimental things, experimental
267 (unfinished/work in progress/not well tested) decoders and encoders.
268 Note: experimental decoders can pose a security risk, do not use this for
269 decoding untrusted input.
272 @item b_qoffset @var{float} (@emph{encoding,video})
273 Set QP offset between P and B frames.
275 @item err_detect @var{flags} (@emph{decoding,audio,video})
276 Set error detection flags.
283 detect bitstream specification deviations
285 detect improper bitstream length
287 abort decoding on minor error detection
289 consider things that violate the spec and have not been seen in the wild as errors
291 consider all spec non compliancies as errors
293 consider things that a sane encoder should not do as an error
296 @item has_b_frames @var{integer}
298 @item block_align @var{integer}
300 @item mpeg_quant @var{integer} (@emph{encoding,video})
301 Use MPEG quantizers instead of H.263.
303 @item qsquish @var{float} (@emph{encoding,video})
304 How to keep quantizer between qmin and qmax (0 = clip, 1 = use
305 differentiable function).
307 @item rc_qmod_amp @var{float} (@emph{encoding,video})
308 Set experimental quantizer modulation.
310 @item rc_qmod_freq @var{integer} (@emph{encoding,video})
311 Set experimental quantizer modulation.
313 @item rc_override_count @var{integer}
315 @item rc_eq @var{string} (@emph{encoding,video})
316 Set rate control equation. When computing the expression, besides the
317 standard functions defined in the section 'Expression Evaluation', the
318 following functions are available: bits2qp(bits), qp2bits(qp). Also
319 the following constants are available: iTex pTex tex mv fCode iCount
320 mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex
323 @item maxrate @var{integer} (@emph{encoding,audio,video})
324 Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
326 @item minrate @var{integer} (@emph{encoding,audio,video})
327 Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR
328 encode. It is of little use elsewise.
330 @item bufsize @var{integer} (@emph{encoding,audio,video})
331 Set ratecontrol buffer size (in bits).
333 @item rc_buf_aggressivity @var{float} (@emph{encoding,video})
336 @item i_qfactor @var{float} (@emph{encoding,video})
337 Set QP factor between P and I frames.
339 @item i_qoffset @var{float} (@emph{encoding,video})
340 Set QP offset between P and I frames.
342 @item rc_init_cplx @var{float} (@emph{encoding,video})
343 Set initial complexity for 1-pass encoding.
345 @item dct @var{integer} (@emph{encoding,video})
351 autoselect a good one (default)
361 floating point AAN DCT
364 @item lumi_mask @var{float} (@emph{encoding,video})
365 Compress bright areas stronger than medium ones.
367 @item tcplx_mask @var{float} (@emph{encoding,video})
368 Set temporal complexity masking.
370 @item scplx_mask @var{float} (@emph{encoding,video})
371 Set spatial complexity masking.
373 @item p_mask @var{float} (@emph{encoding,video})
376 @item dark_mask @var{float} (@emph{encoding,video})
377 Compress dark areas stronger than medium ones.
379 @item idct @var{integer} (@emph{decoding/encoding,video})
380 Select IDCT implementation.
413 floating point AAN IDCT
416 @item slice_count @var{integer}
418 @item ec @var{flags} (@emph{decoding,video})
419 Set error concealment strategy.
424 iterative motion vector (MV) search (slow)
426 use strong deblock filter for damaged MBs
429 @item bits_per_coded_sample @var{integer}
431 @item pred @var{integer} (@emph{encoding,video})
432 Set prediction method.
444 @item aspect @var{rational number} (@emph{encoding,video})
445 Set sample aspect ratio.
447 @item debug @var{flags} (@emph{decoding/encoding,audio,video,subtitles})
448 Print specific debug info.
461 per-block quantization parameter (QP)
475 memory management control operations (H.264)
479 visualize quantization parameter (QP), lower QP are tinted greener
481 visualize block types
483 picture buffer allocations
488 @item vismv @var{integer} (@emph{decoding,video})
489 Visualize motion vectors (MVs).
494 forward predicted MVs of P-frames
496 forward predicted MVs of B-frames
498 backward predicted MVs of B-frames
501 @item cmp @var{integer} (@emph{encoding,video})
502 Set full pel me compare function.
507 sum of absolute differences, fast (default)
509 sum of squared errors
511 sum of absolute Hadamard transformed differences
513 sum of absolute DCT transformed differences
515 sum of squared quantization errors (avoid, low quality)
517 number of bits needed for the block
519 rate distortion optimal, slow
523 sum of absolute vertical differences
525 sum of squared vertical differences
527 noise preserving sum of squared differences
529 5/3 wavelet, only used in snow
531 9/7 wavelet, only used in snow
538 @item subcmp @var{integer} (@emph{encoding,video})
539 Set sub pel me compare function.
544 sum of absolute differences, fast (default)
546 sum of squared errors
548 sum of absolute Hadamard transformed differences
550 sum of absolute DCT transformed differences
552 sum of squared quantization errors (avoid, low quality)
554 number of bits needed for the block
556 rate distortion optimal, slow
560 sum of absolute vertical differences
562 sum of squared vertical differences
564 noise preserving sum of squared differences
566 5/3 wavelet, only used in snow
568 9/7 wavelet, only used in snow
575 @item mbcmp @var{integer} (@emph{encoding,video})
576 Set macroblock compare function.
581 sum of absolute differences, fast (default)
583 sum of squared errors
585 sum of absolute Hadamard transformed differences
587 sum of absolute DCT transformed differences
589 sum of squared quantization errors (avoid, low quality)
591 number of bits needed for the block
593 rate distortion optimal, slow
597 sum of absolute vertical differences
599 sum of squared vertical differences
601 noise preserving sum of squared differences
603 5/3 wavelet, only used in snow
605 9/7 wavelet, only used in snow
612 @item ildctcmp @var{integer} (@emph{encoding,video})
613 Set interlaced dct compare function.
618 sum of absolute differences, fast (default)
620 sum of squared errors
622 sum of absolute Hadamard transformed differences
624 sum of absolute DCT transformed differences
626 sum of squared quantization errors (avoid, low quality)
628 number of bits needed for the block
630 rate distortion optimal, slow
634 sum of absolute vertical differences
636 sum of squared vertical differences
638 noise preserving sum of squared differences
640 5/3 wavelet, only used in snow
642 9/7 wavelet, only used in snow
649 @item dia_size @var{integer} (@emph{encoding,video})
650 Set diamond type & size for motion estimation.
652 @item last_pred @var{integer} (@emph{encoding,video})
653 Set amount of motion predictors from the previous frame.
655 @item preme @var{integer} (@emph{encoding,video})
656 Set pre motion estimation.
658 @item precmp @var{integer} (@emph{encoding,video})
659 Set pre motion estimation compare function.
664 sum of absolute differences, fast (default)
666 sum of squared errors
668 sum of absolute Hadamard transformed differences
670 sum of absolute DCT transformed differences
672 sum of squared quantization errors (avoid, low quality)
674 number of bits needed for the block
676 rate distortion optimal, slow
680 sum of absolute vertical differences
682 sum of squared vertical differences
684 noise preserving sum of squared differences
686 5/3 wavelet, only used in snow
688 9/7 wavelet, only used in snow
695 @item pre_dia_size @var{integer} (@emph{encoding,video})
696 Set diamond type & size for motion estimation pre-pass.
698 @item subq @var{integer} (@emph{encoding,video})
699 Set sub pel motion estimation quality.
701 @item dtg_active_format @var{integer}
703 @item me_range @var{integer} (@emph{encoding,video})
704 Set limit motion vectors range (1023 for DivX player).
706 @item ibias @var{integer} (@emph{encoding,video})
707 Set intra quant bias.
709 @item pbias @var{integer} (@emph{encoding,video})
710 Set inter quant bias.
712 @item color_table_id @var{integer}
714 @item global_quality @var{integer} (@emph{encoding,audio,video})
716 @item coder @var{integer} (@emph{encoding,video})
721 variable length coder / huffman coder
732 @item context @var{integer} (@emph{encoding,video})
735 @item slice_flags @var{integer}
737 @item xvmc_acceleration @var{integer}
739 @item mbd @var{integer} (@emph{encoding,video})
740 Set macroblock decision algorithm (high quality mode).
749 use best rate distortion
752 @item stream_codec_tag @var{integer}
754 @item sc_threshold @var{integer} (@emph{encoding,video})
755 Set scene change threshold.
757 @item lmin @var{integer} (@emph{encoding,video})
758 Set min lagrange factor (VBR).
760 @item lmax @var{integer} (@emph{encoding,video})
761 Set max lagrange factor (VBR).
763 @item nr @var{integer} (@emph{encoding,video})
766 @item rc_init_occupancy @var{integer} (@emph{encoding,video})
767 Set number of bits which should be loaded into the rc buffer before
770 @item flags2 @var{flags} (@emph{decoding/encoding,audio,video})
775 Allow non spec compliant speedup tricks.
777 Deprecated, use mpegvideo private options instead.
779 Skip bitstream encoding.
781 Ignore cropping information from sps.
783 Place global headers at every keyframe instead of in extradata.
785 Frame data might be split into multiple chunks.
787 Show all frames before the first keyframe.
789 Deprecated, use mpegvideo private options instead.
792 @item error @var{integer} (@emph{encoding,video})
794 @item qns @var{integer} (@emph{encoding,video})
795 Deprecated, use mpegvideo private options instead.
797 @item threads @var{integer} (@emph{decoding/encoding,video})
802 detect a good number of threads
805 @item me_threshold @var{integer} (@emph{encoding,video})
806 Set motion estimation threshold.
808 @item mb_threshold @var{integer} (@emph{encoding,video})
809 Set macroblock threshold.
811 @item dc @var{integer} (@emph{encoding,video})
812 Set intra_dc_precision.
814 @item nssew @var{integer} (@emph{encoding,video})
817 @item skip_top @var{integer} (@emph{decoding,video})
818 Set number of macroblock rows at the top which are skipped.
820 @item skip_bottom @var{integer} (@emph{decoding,video})
821 Set number of macroblock rows at the bottom which are skipped.
823 @item profile @var{integer} (@emph{encoding,audio,video})
861 @item level @var{integer} (@emph{encoding,audio,video})
869 @item lowres @var{integer} (@emph{decoding,audio,video})
870 Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.
872 @item skip_threshold @var{integer} (@emph{encoding,video})
873 Set frame skip threshold.
875 @item skip_factor @var{integer} (@emph{encoding,video})
876 Set frame skip factor.
878 @item skip_exp @var{integer} (@emph{encoding,video})
879 Set frame skip exponent.
881 @item skipcmp @var{integer} (@emph{encoding,video})
882 Set frame skip compare function.
887 sum of absolute differences, fast (default)
889 sum of squared errors
891 sum of absolute Hadamard transformed differences
893 sum of absolute DCT transformed differences
895 sum of squared quantization errors (avoid, low quality)
897 number of bits needed for the block
899 rate distortion optimal, slow
903 sum of absolute vertical differences
905 sum of squared vertical differences
907 noise preserving sum of squared differences
909 5/3 wavelet, only used in snow
911 9/7 wavelet, only used in snow
918 @item border_mask @var{float} (@emph{encoding,video})
919 Increase the quantizer for macroblocks close to borders.
921 @item mblmin @var{integer} (@emph{encoding,video})
922 Set min macroblock lagrange factor (VBR).
924 @item mblmax @var{integer} (@emph{encoding,video})
925 Set max macroblock lagrange factor (VBR).
927 @item mepc @var{integer} (@emph{encoding,video})
928 Set motion estimation bitrate penalty compensation (1.0 = 256).
930 @item skip_loop_filter @var{integer} (@emph{decoding,video})
931 @item skip_idct @var{integer} (@emph{decoding,video})
932 @item skip_frame @var{integer} (@emph{decoding,video})
934 Make decoder discard processing depending on the frame type selected
937 @option{skip_loop_filter} skips frame loop filtering, @option{skip_idct}
938 skips frame IDCT/dequantization, @option{skip_frame} skips decoding.
946 Discard useless frames like 0-sized frames.
949 Discard all non-reference frames.
952 Discard all bidirectional frames.
955 Discard all frames excepts keyframes.
961 Default value is @samp{default}.
963 @item bidir_refine @var{integer} (@emph{encoding,video})
964 Refine the two motion vectors used in bidirectional macroblocks.
966 @item brd_scale @var{integer} (@emph{encoding,video})
967 Downscale frames for dynamic B-frame decision.
969 @item keyint_min @var{integer} (@emph{encoding,video})
970 Set minimum interval between IDR-frames.
972 @item refs @var{integer} (@emph{encoding,video})
973 Set reference frames to consider for motion compensation.
975 @item chromaoffset @var{integer} (@emph{encoding,video})
976 Set chroma qp offset from luma.
978 @item trellis @var{integer} (@emph{encoding,audio,video})
979 Set rate-distortion optimal quantization.
981 @item sc_factor @var{integer} (@emph{encoding,video})
982 Set value multiplied by qscale for each frame and added to
985 @item mv0_threshold @var{integer} (@emph{encoding,video})
986 @item b_sensitivity @var{integer} (@emph{encoding,video})
987 Adjust sensitivity of b_frame_strategy 1.
989 @item compression_level @var{integer} (@emph{encoding,audio,video})
990 @item min_prediction_order @var{integer} (@emph{encoding,audio})
991 @item max_prediction_order @var{integer} (@emph{encoding,audio})
992 @item timecode_frame_start @var{integer} (@emph{encoding,video})
993 Set GOP timecode frame start number, in non drop frame format.
995 @item request_channels @var{integer} (@emph{decoding,audio})
996 Set desired number of audio channels.
998 @item bits_per_raw_sample @var{integer}
999 @item channel_layout @var{integer} (@emph{decoding/encoding,audio})
1004 @item request_channel_layout @var{integer} (@emph{decoding,audio})
1009 @item rc_max_vbv_use @var{float} (@emph{encoding,video})
1010 @item rc_min_vbv_use @var{float} (@emph{encoding,video})
1011 @item ticks_per_frame @var{integer} (@emph{decoding/encoding,audio,video})
1012 @item color_primaries @var{integer} (@emph{decoding/encoding,video})
1013 @item color_trc @var{integer} (@emph{decoding/encoding,video})
1014 @item colorspace @var{integer} (@emph{decoding/encoding,video})
1015 @item color_range @var{integer} (@emph{decoding/encoding,video})
1016 @item chroma_sample_location @var{integer} (@emph{decoding/encoding,video})
1018 @item log_level_offset @var{integer}
1019 Set the log level offset.
1021 @item slices @var{integer} (@emph{encoding,video})
1022 Number of slices, used in parallelized encoding.
1024 @item thread_type @var{flags} (@emph{decoding/encoding,video})
1025 Select multithreading type.
1034 @item audio_service_type @var{integer} (@emph{encoding,audio})
1035 Set audio service type.
1059 @item request_sample_fmt @var{sample_fmt} (@emph{decoding,audio})
1060 Set sample format audio decoders should prefer. Default value is
1063 @item pkt_timebase @var{rational number}
1065 @item sub_charenc @var{encoding} (@emph{decoding,subtitles})
1066 Set the input subtitles character encoding.
1068 @item field_order @var{field_order} (@emph{video})
1069 Set/override the field order of the video.
1075 Interlaced video, top field coded and displayed first
1077 Interlaced video, bottom field coded and displayed first
1079 Interlaced video, top coded first, bottom displayed first
1081 Interlaced video, bottom coded first, top displayed first
1084 @item skip_alpha @var{integer} (@emph{decoding,video})
1085 Set to 1 to disable processing alpha (transparency). This works like the
1086 @samp{gray} flag in the @option{flags} option which skips chroma information
1087 instead of alpha. Default is 0.
1090 @c man end CODEC OPTIONS
1092 @include decoders.texi
1093 @include encoders.texi