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 ignore decoding errors, and continue decoding.
290 This is useful if you want to analyze the content of a video and thus want
291 everything to be decoded no matter what. This option will not result in a video
292 that is pleasing to watch in case of errors.
294 consider things that violate the spec and have not been seen in the wild as errors
296 consider all spec non compliancies as errors
298 consider things that a sane encoder should not do as an error
301 @item has_b_frames @var{integer}
303 @item block_align @var{integer}
305 @item mpeg_quant @var{integer} (@emph{encoding,video})
306 Use MPEG quantizers instead of H.263.
308 @item qsquish @var{float} (@emph{encoding,video})
309 How to keep quantizer between qmin and qmax (0 = clip, 1 = use
310 differentiable function).
312 @item rc_qmod_amp @var{float} (@emph{encoding,video})
313 Set experimental quantizer modulation.
315 @item rc_qmod_freq @var{integer} (@emph{encoding,video})
316 Set experimental quantizer modulation.
318 @item rc_override_count @var{integer}
320 @item rc_eq @var{string} (@emph{encoding,video})
321 Set rate control equation. When computing the expression, besides the
322 standard functions defined in the section 'Expression Evaluation', the
323 following functions are available: bits2qp(bits), qp2bits(qp). Also
324 the following constants are available: iTex pTex tex mv fCode iCount
325 mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex
328 @item maxrate @var{integer} (@emph{encoding,audio,video})
329 Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
331 @item minrate @var{integer} (@emph{encoding,audio,video})
332 Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR
333 encode. It is of little use elsewise.
335 @item bufsize @var{integer} (@emph{encoding,audio,video})
336 Set ratecontrol buffer size (in bits).
338 @item rc_buf_aggressivity @var{float} (@emph{encoding,video})
341 @item i_qfactor @var{float} (@emph{encoding,video})
342 Set QP factor between P and I frames.
344 @item i_qoffset @var{float} (@emph{encoding,video})
345 Set QP offset between P and I frames.
347 @item rc_init_cplx @var{float} (@emph{encoding,video})
348 Set initial complexity for 1-pass encoding.
350 @item dct @var{integer} (@emph{encoding,video})
356 autoselect a good one (default)
366 floating point AAN DCT
369 @item lumi_mask @var{float} (@emph{encoding,video})
370 Compress bright areas stronger than medium ones.
372 @item tcplx_mask @var{float} (@emph{encoding,video})
373 Set temporal complexity masking.
375 @item scplx_mask @var{float} (@emph{encoding,video})
376 Set spatial complexity masking.
378 @item p_mask @var{float} (@emph{encoding,video})
381 @item dark_mask @var{float} (@emph{encoding,video})
382 Compress dark areas stronger than medium ones.
384 @item idct @var{integer} (@emph{decoding/encoding,video})
385 Select IDCT implementation.
418 floating point AAN IDCT
421 @item slice_count @var{integer}
423 @item ec @var{flags} (@emph{decoding,video})
424 Set error concealment strategy.
429 iterative motion vector (MV) search (slow)
431 use strong deblock filter for damaged MBs
433 favor predicting from the previous frame instead of the current
436 @item bits_per_coded_sample @var{integer}
438 @item pred @var{integer} (@emph{encoding,video})
439 Set prediction method.
451 @item aspect @var{rational number} (@emph{encoding,video})
452 Set sample aspect ratio.
454 @item debug @var{flags} (@emph{decoding/encoding,audio,video,subtitles})
455 Print specific debug info.
468 per-block quantization parameter (QP)
482 memory management control operations (H.264)
486 visualize quantization parameter (QP), lower QP are tinted greener
488 visualize block types
490 picture buffer allocations
495 @item vismv @var{integer} (@emph{decoding,video})
496 Visualize motion vectors (MVs).
501 forward predicted MVs of P-frames
503 forward predicted MVs of B-frames
505 backward predicted MVs of B-frames
508 @item cmp @var{integer} (@emph{encoding,video})
509 Set full pel me compare function.
514 sum of absolute differences, fast (default)
516 sum of squared errors
518 sum of absolute Hadamard transformed differences
520 sum of absolute DCT transformed differences
522 sum of squared quantization errors (avoid, low quality)
524 number of bits needed for the block
526 rate distortion optimal, slow
530 sum of absolute vertical differences
532 sum of squared vertical differences
534 noise preserving sum of squared differences
536 5/3 wavelet, only used in snow
538 9/7 wavelet, only used in snow
545 @item subcmp @var{integer} (@emph{encoding,video})
546 Set sub pel me compare function.
551 sum of absolute differences, fast (default)
553 sum of squared errors
555 sum of absolute Hadamard transformed differences
557 sum of absolute DCT transformed differences
559 sum of squared quantization errors (avoid, low quality)
561 number of bits needed for the block
563 rate distortion optimal, slow
567 sum of absolute vertical differences
569 sum of squared vertical differences
571 noise preserving sum of squared differences
573 5/3 wavelet, only used in snow
575 9/7 wavelet, only used in snow
582 @item mbcmp @var{integer} (@emph{encoding,video})
583 Set macroblock compare function.
588 sum of absolute differences, fast (default)
590 sum of squared errors
592 sum of absolute Hadamard transformed differences
594 sum of absolute DCT transformed differences
596 sum of squared quantization errors (avoid, low quality)
598 number of bits needed for the block
600 rate distortion optimal, slow
604 sum of absolute vertical differences
606 sum of squared vertical differences
608 noise preserving sum of squared differences
610 5/3 wavelet, only used in snow
612 9/7 wavelet, only used in snow
619 @item ildctcmp @var{integer} (@emph{encoding,video})
620 Set interlaced dct compare function.
625 sum of absolute differences, fast (default)
627 sum of squared errors
629 sum of absolute Hadamard transformed differences
631 sum of absolute DCT transformed differences
633 sum of squared quantization errors (avoid, low quality)
635 number of bits needed for the block
637 rate distortion optimal, slow
641 sum of absolute vertical differences
643 sum of squared vertical differences
645 noise preserving sum of squared differences
647 5/3 wavelet, only used in snow
649 9/7 wavelet, only used in snow
656 @item dia_size @var{integer} (@emph{encoding,video})
657 Set diamond type & size for motion estimation.
659 @item last_pred @var{integer} (@emph{encoding,video})
660 Set amount of motion predictors from the previous frame.
662 @item preme @var{integer} (@emph{encoding,video})
663 Set pre motion estimation.
665 @item precmp @var{integer} (@emph{encoding,video})
666 Set pre motion estimation compare function.
671 sum of absolute differences, fast (default)
673 sum of squared errors
675 sum of absolute Hadamard transformed differences
677 sum of absolute DCT transformed differences
679 sum of squared quantization errors (avoid, low quality)
681 number of bits needed for the block
683 rate distortion optimal, slow
687 sum of absolute vertical differences
689 sum of squared vertical differences
691 noise preserving sum of squared differences
693 5/3 wavelet, only used in snow
695 9/7 wavelet, only used in snow
702 @item pre_dia_size @var{integer} (@emph{encoding,video})
703 Set diamond type & size for motion estimation pre-pass.
705 @item subq @var{integer} (@emph{encoding,video})
706 Set sub pel motion estimation quality.
708 @item dtg_active_format @var{integer}
710 @item me_range @var{integer} (@emph{encoding,video})
711 Set limit motion vectors range (1023 for DivX player).
713 @item ibias @var{integer} (@emph{encoding,video})
714 Set intra quant bias.
716 @item pbias @var{integer} (@emph{encoding,video})
717 Set inter quant bias.
719 @item color_table_id @var{integer}
721 @item global_quality @var{integer} (@emph{encoding,audio,video})
723 @item coder @var{integer} (@emph{encoding,video})
728 variable length coder / huffman coder
739 @item context @var{integer} (@emph{encoding,video})
742 @item slice_flags @var{integer}
744 @item xvmc_acceleration @var{integer}
746 @item mbd @var{integer} (@emph{encoding,video})
747 Set macroblock decision algorithm (high quality mode).
756 use best rate distortion
759 @item stream_codec_tag @var{integer}
761 @item sc_threshold @var{integer} (@emph{encoding,video})
762 Set scene change threshold.
764 @item lmin @var{integer} (@emph{encoding,video})
765 Set min lagrange factor (VBR).
767 @item lmax @var{integer} (@emph{encoding,video})
768 Set max lagrange factor (VBR).
770 @item nr @var{integer} (@emph{encoding,video})
773 @item rc_init_occupancy @var{integer} (@emph{encoding,video})
774 Set number of bits which should be loaded into the rc buffer before
777 @item flags2 @var{flags} (@emph{decoding/encoding,audio,video})
782 Allow non spec compliant speedup tricks.
784 Deprecated, use mpegvideo private options instead.
786 Skip bitstream encoding.
788 Ignore cropping information from sps.
790 Place global headers at every keyframe instead of in extradata.
792 Frame data might be split into multiple chunks.
794 Show all frames before the first keyframe.
796 Deprecated, use mpegvideo private options instead.
799 @item error @var{integer} (@emph{encoding,video})
801 @item qns @var{integer} (@emph{encoding,video})
802 Deprecated, use mpegvideo private options instead.
804 @item threads @var{integer} (@emph{decoding/encoding,video})
809 detect a good number of threads
812 @item me_threshold @var{integer} (@emph{encoding,video})
813 Set motion estimation threshold.
815 @item mb_threshold @var{integer} (@emph{encoding,video})
816 Set macroblock threshold.
818 @item dc @var{integer} (@emph{encoding,video})
819 Set intra_dc_precision.
821 @item nssew @var{integer} (@emph{encoding,video})
824 @item skip_top @var{integer} (@emph{decoding,video})
825 Set number of macroblock rows at the top which are skipped.
827 @item skip_bottom @var{integer} (@emph{decoding,video})
828 Set number of macroblock rows at the bottom which are skipped.
830 @item profile @var{integer} (@emph{encoding,audio,video})
868 @item level @var{integer} (@emph{encoding,audio,video})
876 @item lowres @var{integer} (@emph{decoding,audio,video})
877 Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.
879 @item skip_threshold @var{integer} (@emph{encoding,video})
880 Set frame skip threshold.
882 @item skip_factor @var{integer} (@emph{encoding,video})
883 Set frame skip factor.
885 @item skip_exp @var{integer} (@emph{encoding,video})
886 Set frame skip exponent.
887 Negative values behave identical to the corresponding positive ones, except
888 that the score is normalized.
889 Positive values exist primarily for compatibility reasons and are not so useful.
891 @item skipcmp @var{integer} (@emph{encoding,video})
892 Set frame skip compare function.
897 sum of absolute differences, fast (default)
899 sum of squared errors
901 sum of absolute Hadamard transformed differences
903 sum of absolute DCT transformed differences
905 sum of squared quantization errors (avoid, low quality)
907 number of bits needed for the block
909 rate distortion optimal, slow
913 sum of absolute vertical differences
915 sum of squared vertical differences
917 noise preserving sum of squared differences
919 5/3 wavelet, only used in snow
921 9/7 wavelet, only used in snow
928 @item border_mask @var{float} (@emph{encoding,video})
929 Increase the quantizer for macroblocks close to borders.
931 @item mblmin @var{integer} (@emph{encoding,video})
932 Set min macroblock lagrange factor (VBR).
934 @item mblmax @var{integer} (@emph{encoding,video})
935 Set max macroblock lagrange factor (VBR).
937 @item mepc @var{integer} (@emph{encoding,video})
938 Set motion estimation bitrate penalty compensation (1.0 = 256).
940 @item skip_loop_filter @var{integer} (@emph{decoding,video})
941 @item skip_idct @var{integer} (@emph{decoding,video})
942 @item skip_frame @var{integer} (@emph{decoding,video})
944 Make decoder discard processing depending on the frame type selected
947 @option{skip_loop_filter} skips frame loop filtering, @option{skip_idct}
948 skips frame IDCT/dequantization, @option{skip_frame} skips decoding.
956 Discard useless frames like 0-sized frames.
959 Discard all non-reference frames.
962 Discard all bidirectional frames.
965 Discard all frames excepts keyframes.
971 Default value is @samp{default}.
973 @item bidir_refine @var{integer} (@emph{encoding,video})
974 Refine the two motion vectors used in bidirectional macroblocks.
976 @item brd_scale @var{integer} (@emph{encoding,video})
977 Downscale frames for dynamic B-frame decision.
979 @item keyint_min @var{integer} (@emph{encoding,video})
980 Set minimum interval between IDR-frames.
982 @item refs @var{integer} (@emph{encoding,video})
983 Set reference frames to consider for motion compensation.
985 @item chromaoffset @var{integer} (@emph{encoding,video})
986 Set chroma qp offset from luma.
988 @item trellis @var{integer} (@emph{encoding,audio,video})
989 Set rate-distortion optimal quantization.
991 @item sc_factor @var{integer} (@emph{encoding,video})
992 Set value multiplied by qscale for each frame and added to
995 @item mv0_threshold @var{integer} (@emph{encoding,video})
996 @item b_sensitivity @var{integer} (@emph{encoding,video})
997 Adjust sensitivity of b_frame_strategy 1.
999 @item compression_level @var{integer} (@emph{encoding,audio,video})
1000 @item min_prediction_order @var{integer} (@emph{encoding,audio})
1001 @item max_prediction_order @var{integer} (@emph{encoding,audio})
1002 @item timecode_frame_start @var{integer} (@emph{encoding,video})
1003 Set GOP timecode frame start number, in non drop frame format.
1005 @item request_channels @var{integer} (@emph{decoding,audio})
1006 Set desired number of audio channels.
1008 @item bits_per_raw_sample @var{integer}
1009 @item channel_layout @var{integer} (@emph{decoding/encoding,audio})
1014 @item request_channel_layout @var{integer} (@emph{decoding,audio})
1019 @item rc_max_vbv_use @var{float} (@emph{encoding,video})
1020 @item rc_min_vbv_use @var{float} (@emph{encoding,video})
1021 @item ticks_per_frame @var{integer} (@emph{decoding/encoding,audio,video})
1022 @item color_primaries @var{integer} (@emph{decoding/encoding,video})
1023 @item color_trc @var{integer} (@emph{decoding/encoding,video})
1024 @item colorspace @var{integer} (@emph{decoding/encoding,video})
1025 @item color_range @var{integer} (@emph{decoding/encoding,video})
1026 @item chroma_sample_location @var{integer} (@emph{decoding/encoding,video})
1028 @item log_level_offset @var{integer}
1029 Set the log level offset.
1031 @item slices @var{integer} (@emph{encoding,video})
1032 Number of slices, used in parallelized encoding.
1034 @item thread_type @var{flags} (@emph{decoding/encoding,video})
1035 Select multithreading type.
1044 @item audio_service_type @var{integer} (@emph{encoding,audio})
1045 Set audio service type.
1069 @item request_sample_fmt @var{sample_fmt} (@emph{decoding,audio})
1070 Set sample format audio decoders should prefer. Default value is
1073 @item pkt_timebase @var{rational number}
1075 @item sub_charenc @var{encoding} (@emph{decoding,subtitles})
1076 Set the input subtitles character encoding.
1078 @item field_order @var{field_order} (@emph{video})
1079 Set/override the field order of the video.
1085 Interlaced video, top field coded and displayed first
1087 Interlaced video, bottom field coded and displayed first
1089 Interlaced video, top coded first, bottom displayed first
1091 Interlaced video, bottom coded first, top displayed first
1094 @item skip_alpha @var{integer} (@emph{decoding,video})
1095 Set to 1 to disable processing alpha (transparency). This works like the
1096 @samp{gray} flag in the @option{flags} option which skips chroma information
1097 instead of alpha. Default is 0.
1100 @c man end CODEC OPTIONS
1102 @ifclear config-writeonly
1103 @include decoders.texi
1105 @ifclear config-readonly
1106 @include encoders.texi