mencoder
xvidenc (-xvidencopts)
There are three modes available: constant bitrate (CBR), fixed quantiz-
er and two pass.
pass=<1|2>
Specify the pass in two pass mode.
turbo (two pass only)
Dramatically speeds up pass one using faster algorithms and dis-
abling CPU-intensive options. This will probably reduce global
PSNR a little bit and change individual frame type and PSNR a
little bit more.
bitrate=<value> (CBR or two pass mode)
Sets the bitrate to be used in kbits/second if <16000 or in
bits/second if >16000. If <value> is negative, XviD will use
its absolute value as the target size (in kBytes) of the video
and compute the associated bitrate automagically (default: 687
kbits/s).
fixed_quant=<1-31>
Switch to fixed quantizer mode and specify the quantizer to be
used.
zones=<zone0>[/<zone1>[/...]] (CBR or two pass mode)
User specified quality for specific parts (ending, credits,
...). Each zone is <start-frame>,<mode>,<value> where <mode>
may be
q Constant quantizer override, where value=<2.0-31.0> rep-
resents the quantizer value.
w Ratecontrol weight override, where value=<0.01-2.00>
represents the quality correction in %.
EXAMPLE:
zones=90000,q,20
Encodes all frames starting with frame 90000 at constant
quantizer 20.
zones=0,w,0.1/10001,w,1.0/90000,q,20
Encode frames 0-10000 at 10% bitrate, encode frames
90000 up to the end at constant quantizer 20. Note that
the second zone is needed to delimit the first zone, as
without it everything up until frame 89999 would be en-
coded at 10% bitrate.
me_quality=<0-6>
This option controls the motion estimation subsystem. The high-
er the value, the more precise the estimation should be (de-
fault: 6). The more precise the motion estimation is, the more
bits can be saved. Precision is gained at the expense of CPU
time so decrease this setting if you need realtime encoding.
(no)interlacing
Encode the fields of interlaced video material. Turn this op-
tion on for interlaced content.
NOTE: Should you rescale the video, you would need an interlace-
aware resizer, which you can activate with -vf
scale=<width>:<height>:1.
4mv
Use 4 motion vectors per macroblock. This might give better
compression, but slows down encoding.
WARNING: As of XviD-1.0.x, this option is no longer available
separately, and its functionality is included in the me_quality
option. When me_quality > 4, 4mv is activated.
rc_reaction_delay_factor=<value>
This parameter controls the number of frames the CBR rate con-
troller will wait before reacting to bitrate changes and compen-
sating for them to obtain a constant bitrate over an averaging
range of frames.
rc_averaging_period=<value>
Real CBR is hard to achieve. Depending on the video material,
bitrate can be variable, and hard to predict. Therefore XviD
uses an averaging period for which it guarantees a given amount
of bits (minus a small variation). This settings expresses the
"number of frames" for which XviD averages bitrate and tries to
achieve CBR.
rc_buffer=<value>
size of the rate control buffer
quant_range=<1-31>-<1-31>[/<1-31>-<1-31>]
CBR mode: min & max quantizer for all frames (default: 2-31)
two pass mode: min & max quantizer for I/P-frames (default:
2-31/2-31)
WARNING: As of XviD-1.0.x, this option is replaced by the
[min|max]_[i|p|b]quant options.
min_key_interval=<value> (two pass only)
minimum interval between keyframes (default: 0)
max_key_interval=<value>
maximum interval between keyframes (default: 10*fps)
mpeg_quant
Use MPEG quantizers instead of H.263. For high bitrates, you
will find that MPEG quantization preserves more detail. For low
bitrates, the smoothing of H.263 will give you less block noise.
When using custom matrices, MPEG must be used.
WARNING: As of XviD-1.0.x, this option is replaced by the
quant_type option.
mod_quant
Decide whether to use MPEG or H.263 quantizers on a frame-by-
frame basis (two pass mode only).
WARNING: This will generate an illegal bitstream, and most like-
ly not be decodable by any MPEG-4 decoder besides libavcodec or
XviD.
WARNING: As of XviD-1.0.x, this option is no longer available.
keyframe_boost=<0-1000> (two pass mode only)
Shift some bits from the pool for other frame types to intra
frames, thus improving keyframe quality. This amount is an ex-
tra percentage, so a value of 10 will give your keyframes 10%
more bits than normal (default: 0).
kfthreshold=<value> (two pass mode only)
Works together with kfreduction. Determines the minimum dis-
tance below which you consider that two frames are considered
consecutive and treated differently according to kfreduction
(default: 10).
kfreduction=<0-100> (two pass mode only)
The above two settings can be used to adjust the size of
keyframes that you consider too close to the first (in a row).
kfthreshold sets the range in which keyframes are reduced, and
kfreduction determines the bitrate reduction they get. The last
I-frame will get treated normally (default: 30).
divx5bvop
Generate DivX5 compatible B-frames (default: on). This seems to
be mandatory only for old versions of DivX's decoder.
WARNING: As of XviD-1.0.x, this option is replaced by the
closed_gop option.
(no)greyscale
Make XviD discard chroma planes so the encoded video is
greyscale only. Note that this does not speed up encoding, it
just prevents chroma data from being written in the last stage
of encoding.
debug
Save per-frame statistics in ./xvid.dbg. (This is not the two
pass control file.)
The following options are only available with the latest stable releas-
es of XviD 1.0.x (api4).
(no)packed
This option is meant to solve frame-order issues when encoding
to container formats like AVI that cannot cope with out-of-order
frames. In practice, most decoders (both software and hardware)
are able to deal with frame-order themselves, and may get con-
fused when this option is turned on, so you can safely leave if
off, unless you really know what you are doing.
WARNING: This will generate an illegal bitstream, and will not
be decodable by ISO-MPEG-4 decoders except DivX/libavcodec/XviD.
WARNING: This will also store a fake DivX version in the file so
the bug autodetection of some decoders might be confused.
max_bframes=<0-4>
Maximum number of B-frames to put between I/P-frames (default:
2).
bquant_ratio=<0-1000>
quantizer ratio between B- and non-B-frames, 150=1.50 (default:
150)
bquant_offset=<-1000-1000>
quantizer offset between B- and non-B-frames, 100=1.00 (default:
100)
bf_threshold=<-255-255>
This setting allows you to specify what priority to place on the
use of B-frames. The higher the value, the higher the probabil-
ity of B-frames being used (default: 0). Do not forget that B-
frames usually have a higher quantizer, and therefore aggressive
production of B-frames may cause worse visual quality.
(no)closed_gop
This option tells XviD to close every GOP (Group Of Pictures
bounded by two I-frames), which makes GOPs independent from each
other. This just implies that the last frame of the GOP is ei-
ther a P-frame or a N-frame but not a B-frame. It is usually a
good idea to turn this option on (default: on).
frame_drop_ratio=<0-100> (max_bframes=0 only)
This setting allows the creation of variable framerate video
streams. The value of the setting specifies a threshold under
which, if the difference of the following frame to the previous
frame is below or equal to this threshold, a frame gets not cod-
ed (a so called n-vop is placed in the stream). On playback,
when reaching an n-vop the previous frame will be displayed.
WARNING: Playing with this setting may result in a jerky video,
so use it at your own risks!
(no)qpel
MPEG-4 uses a half pixel precision for its motion search by de-
fault. The standard proposes a mode where encoders are allowed
to use quarter pixel precision. This option usually results in
a sharper image. Unfortunately it has a great impact on bitrate
and sometimes the higher bitrate use will prevent it from giving
a better image quality at a fixed bitrate. It is better to test
with and without this option and see whether it is worth acti-
vating.
(no)gmc
Enable Global Motion Compensation, which makes XviD generate
special frames (GMC-frames) which are well suited for Pan/Zoom/
Rotating images. Whether or not the use of this option will
save bits is highly dependent on the source material.
(no)trellis
Trellis Quantization is a kind of adaptive quantization method
that saves bits by modifying quantized coefficients to make them
more compressible by the entropy encoder. Its impact on quality
is good, and if VHQ uses too much CPU for you, this setting can
be a good alternative to save a few bits (and gain quality at
fixed bitrate) at a lesser cost than with VHQ (default: on).
(no)cartoon
Activate this if your encoded sequence is an anime/cartoon. It
modifies some XviD internal thresholds so XviD takes better de-
cisions on frame types and motion vectors for flat looking car-
toons.
quant_type=<h263|mpeg>
Sets the type of quantizer to use. For high bitrates, you will
find that MPEG quantization preserves more detail. For low bi-
trates, the smoothing of H.263 will give you less block noise.
When using custom matrices, MPEG quantization must be used.
(no)chroma_me
The usual motion estimation algorithm uses only the luminance
information to find the best motion vector. However for some
video material, using the chroma planes can help find better
vectors. This setting toggles the use of chroma planes for mo-
tion estimation (default: on).
(no)chroma_opt
Enable a chroma optimizer prefilter. It will do some extra mag-
ic on color information to minimize the stepped-stairs effect on
edges. It will improve quality at the cost of encoding speed.
It reduces PSNR by nature, as the mathematical deviation to the
original picture will get bigger, but the subjective image qual-
ity will raise. Since it works with color information, you
might want to turn it off when encoding in greyscale.
(no)hq_ac
Activates high-quality prediction of AC coefficients for intra
frames from neighbor blocks (default: on).
vhq=<0-4>
The motion search algorithm is based on a search in the usual
color domain and tries to find a motion vector that minimizes
the difference between the reference frame and the encoded
frame. With this setting activated, XviD will also use the fre-
quency domain (DCT) to search for a motion vector that minimizes
not only the spatial difference but also the encoding length of
the block. Fastest to slowest:
0 off
1 mode decision (inter/intra MB) (default)
2 limited search
3 medium search
4 wide search
(no)lumi_mask
Adaptive quantization allows the macroblock quantizers to vary
inside each frame. This is a 'psychosensory' setting that is
supposed to make use of the fact that the human eye tends to no-
tice fewer details in very bright and very dark parts of the
picture. It compresses those areas more strongly than medium
ones, which will save bits that can be spent again on other
frames, raising overall subjective quality and possibly reducing
PSNR.
min_iquant=<0-31>
minimum I-frame quantizer (default: 2)
max_iquant=<0-31>
maximum I-frame quantizer (default: 31)
min_pquant=<0-31>
minimum P-frame quantizer (default: 2)
max_pquant=<0-31>
maximum P-frame quantizer (default: 31)
min_bquant=<0-31>
minimum B-frame quantizer (default: 2)
max_bquant=<0-31>
maximum B-frame quantizer (default: 31)
quant_intra_matrix=<filename>
Load a custom intra matrix file. You can build such a file with
xvid4conf's matrix editor.
quant_inter_matrix=<filename>
Load a custom inter matrix file. You can build such a file with
xvid4conf's matrix editor.
curve_compression_high=<0-100>
This setting allows XviD to take a certain percentage of bits
away from high bitrate scenes and give them back to the bit
reservoir. You could also use this if you have a clip with so
many bits allocated to high-bitrate scenes that the low(er)-bi-
trate scenes start to look bad (default: 0).
curve_compression_low=<0-100>
This setting allows XviD to give a certain percentage of extra
bits to the low bitrate scenes, taking a few bits from the en-
tire clip. This might come in handy if you have a few low-bi-
trate scenes that are still blocky (default: 0).
overflow_control_strength=<0-100>
During pass one of two pass encoding, a scaled bitrate curve is
computed. The difference between that expected curve and the
result obtained during encoding is called overflow. Obviously,
the two pass rate controller tries to compensate for that over-
flow, distributing it over the next frames. This setting con-
trols how much of the overflow is distributed every time there
is a new frame. Low values allow lazy overflow control, big
rate bursts are compensated for more slowly (could lead to lack
of precision for small clips). Higher values will make changes
in bit redistribution more abrupt, possibly too abrupt if you
set it too high, creating artifacts (default: 5).
NOTE: This setting impacts quality a lot, play with it careful-
ly!
max_overflow_improvement=<0-100>
During the frame bit allocation, overflow control may increase
the frame size. This parameter specifies the maximum percentage
by which the overflow control is allowed to increase the frame
size, compared to the ideal curve allocation (default: 5).
max_overflow_degradation=<0-100>
During the frame bit allocation, overflow control may decrease
the frame size. This parameter specifies the maximum percentage
by which the overflow control is allowed to decrease the frame
size, compared to the ideal curve allocation (default: 5).
container_frame_overhead=<0...>
Specifies a frame average overhead per frame, in bytes. Most of
the time users express their target bitrate for video w/o taking
care of the video container overhead. This small but (mostly)
constant overhead can cause the target file size to be exceeded.
XviD allows users to set the amount of overhead per frame the
container generates (give only an average per frame). 0 has a
special meaning, it lets XviD use its own default values (de-
fault: 24 - AVI average overhead).
profile=<profile_name>
Restricts options and VBV (peak bitrate over a short period) ac-
cording to the Simple, Advanced Simple and DivX profiles. The
resulting videos should be playable on standalone players adher-
ing to these profile specifications.
unrestricted
no restrictions (default)
sp0
simple profile at level 0
sp1
simple profile at level 1
sp2
simple profile at level 2
sp3
simple profile at level 3
asp0
advanced simple profile at level 0
asp1
advanced simple profile at level 1
asp2
advanced simple profile at level 2
asp3
advanced simple profile at level 3
asp4
advanced simple profile at level 4
asp5
advanced simple profile at level 5
dxnhandheld
DXN handheld profile
dxnportntsc
DXN portable NTSC profile
dxnportpal
DXN portable PAL profile
dxnhtntsc
DXN home theater NTSC profile
dxnhtpal
DXN home theater PAL profile
dxnhdtv
DXN HDTV profile
NOTE: These profiles should be used in conjunction with an ap-
propriate -ffourcc. Generally DX50 is applicable, as some play-
ers do not recognize XviD but most recognize DivX.
par=<mode>
Specifies the Pixel Aspect Ratio mode (not to be confused with
DAR, the Display Aspect Ratio). PAR is the ratio of the width
and height of a single pixel. So both are related like this:
DAR = PAR * (width/height).
MPEG-4 defines 5 pixel aspect ratios and one extended one, giv-
ing the opportunity to specify a specific pixel aspect ratio. 5
standard modes can be specified:
vga11
It is the usual PAR for PC content. Pixels are a square
unit.
pal43
PAL standard 4:3 PAR. Pixels are rectangles.
pal169
same as above
ntsc43
same as above
ntsc169
same as above (Do not forget to give the exact ratio.)
ext
Allows you to specify your own pixel aspect ratio with
par_width and par_height.
NOTE: In general, setting aspect and autoaspect options is
enough.
par_width=<1-255> (par=ext only)
Specifies the width of the custom pixel aspect ratio.
par_height=<1-255> (par=ext only)
Specifies the height of the custom pixel aspect ratio.
aspect=<x/y | f (float value)>
Store movie aspect internally, just like MPEG files. Much nicer
solution than rescaling, because quality is not decreased.
MPlayer and a few others players will play these files correct-
ly, others will display them with the wrong aspect. The aspect
parameter can be given as a ratio or a floating point number.
(no)autoaspect
Same as the aspect option, but automatically computes aspect,
taking into account all the adjustments (crop/expand/scale/etc.)
made in the filter chain.
psnr
Print the PSNR (peak signal to noise ratio) for the whole video
after encoding and store the per frame PSNR in a file with a
name like 'psnr_hhmmss.log' in the current directory. Returned
values are in dB (decibel), the higher the better.
The following option is only available in XviD 1.1.x.
bvhq=<0|1>
This setting allows vector candidates for B-frames to be used
for the encoding chosen using a rate distortion optimized opera-
tor, which is what is done for P-frames by the vhq option. This
produces nicer-looking B-frames while incurring almost no per-
formance penalty (default: 1).
The following option is only available in the CVS version of XviD.
threads=<0-n>
Create n threads to run the motion estimation (default: 0). The
maximum number of threads that can be used is the picture height
divided by 16.
