see also :
mplex - mp2enc - lavplay - lav2yuv - lav2wav - yuvscaler - yuvdenoise - y4mdenoise
add an example, a script, a trick and tips
videorate ! ffmpegcolorspace ! mpeg2enc ! \
udpsink host=$1 port=$VIDEO_UDP_PORT sync=false
mpeg2enc -f2 -b 10000 -n n -q 4 -H -o "$OutputFile".mpg stream.yuv
if [[ $? != 0 ]]; then
echo "mpeg2enc did not
finish properly! Exiting..."
did not finish properly! Exiting..."
heavily enhanced derivative of the MPEG Software Simulation
Group’s MPEG-2 reference encoder. It accepts streams
in a simple planar YUV format "YUV4MPEG" produced
by the lav2yuv and related filters (e.g.
yuvscaler(1)) from the mjpegtools(1) package.
An output plug-in to the mpeg2dec(1) MPEG decoder is
available to permit its use in transcoding applications. The
encoder currently fully supports the generation of
elementary MPEG-1, progressive and interlaced frame MPEG-2
streams. Field encoded MPEG-2 is also possible but is not
currently maintained or supported.
purposes this elementary stream output will need to be
multiplexed with one or more audio streams into a
program/systems stream using the mplex(1) tool.
although this manual page aims to explain how mpeg2enc can
be used effectively it is not intended as an introduction to
MPEG-1/2 video which is a fairly complex topic in its own
right. The MPEG video format is a somewhat baroque standard
with many many options, not all of which necessarily easy to
explain or even particular useful in the context of a
practical information for novices can be found in the
mjpeg-HOWTO document that should have been installed with
mjpegtools(1) package. Further information and useful
supporting software can be found on the mjpegtools
function letters adjusting the selected profile
N.b. If the profile you have selected sets particular values for
these parameters it will over-ride these adjustment flags. In
particular, there is almost nothing that can be adjusted
for the standard VCD and SVCD profiles.
The bitrate of the output video stream in kBits/sec. The default
is exactly the bitrate required for VCD streams. If variable
bitrate (VBR) mode has been selected (see the -q option) this is
the maximum bitrate of the stream. NOTE: By default
MPEG-2 streams (-f 3, 4, 5, 8 and 9 are VBR. Use the
--cbr option for generating CBR (Constant Bit Rate)
Specify which of the rate control algorithms to use. Default is
The maximum video buffer usage required to decode the stream in
KBytes. The default is 46KB the (tiny) size specified for VCD.
The size to use for SVCD is the (more reasonable) 230KB. If you
are encoding for a half-decent software decoder it makes sense to
push this up to 500K or more.
Set the target size for (S)VCD still images in KB.
This flag forces the encoder to generate a "sequence header" at
the start of every group-of-pictures. This is needed by some
player hardware to support fast forward/rewind/random access
functions but is a waste of bits otherwise.
The SVCD MPEG-2 profile demands that special "Scan OFfset" which
are (in effect) pointers to the place on the final SVCD disk
where the video for 0.5 and around 5-10 seconds behind and ahead
in the stream is located. The intended use of this information is
to support"Fast forward/Rewind" functions. Unfortunately, at the
time mpeg2enc encodes the video it doesn’t know where the
video is going to finally end up. So special dummy "Scan OFfset"
values are written which are intended to be filled in during the
creation of the SVCD image. Currently the GNU vcdimager tool
handles this task. However, in some circumstances the dummy
offsets can cause problems. This flags stops mpeg2enc generating
In the official SVCD standards the field in the MPEG-2 header
information that passes on the encoders "recommended" horizontal
resolution to decode the stream to is supposed to take the values
540 (for 4:3 sequences) or 720 (for 16:9 sequences). In practice
many players don’t work unless the value is 480. This flag,
forces mpeg2enc to follow the official standard. It is worth
trying if 16:9 sequences play at 4:3 aspect ratio.
This flag deactivates all constraints for the maximum video
samplerate or video resolution. Its purpose is to allow the
encoding of unusual resolutions of MPEG-video (e.g. 2200 x 576,
160 degrees FOV VR-theatre MPEG movies), but should be used with
care: It can possible circumvent a number of other security
checks, and untested settings can cause mpeg2enc to crash in this
mode. -l|--level h|high|m|main
This flag allows the MPEG-2 implementation level against which
the coding parameters are checked to be set. You may need to set
this to ’high’ if you’re encoding HDTV
This flag deactivates the use of the ’alternate’
macroblock scan pattern for MPEG2 encoding. Normally this pattern
is used but a few elderly software decoders had bugs relating to
this feature. You should never need to use this flag.
MPEG-2 supports a special motion estimation mode (DPME, Dual
Prime Motion Estimation) for I/P-frame only streams that can
somewhat improve compression. A number of players (both hardware
and software) do not support this mode. Those players may or may
not be MPEG-2 compliant depending if DPME is an option or not in
the MPEG-2 specs. If you need to generate content for such
players (e.g. Ogle or Apple’s DVD player application) you
should NOT turn on dualprime-mpeg2! Surprisingly at least one
hardware/set-top player is known to be allergic to DPME being
This flag overrides the field-order specified in the interlacing
tag of the input stream header. (If you need this option, it
indicates a problem in the capturing/encoding process where the
temporal order of the two fields in each frame has been
mislabeled. The effect of this is weird "juddering" when playing
back the stream on a TV. Check the mjpeg-howto for more
information about interlacing problems.)
general function letters
Set verbosity level to num. 0 = warnings and errors only, 1 =
information as well, 2=really verbose.
default | hi-res | file=inputfile | help
Specify which quantisation matrices to use instead of the
defaults (which can be specified by using "-K default"). Using
"-K hi-res" is identical to using the -H option. The value kvcd
uses the Kvcd.Net matrices from http://www.kvcd.net/; the value
tmpgenc invokes the TMPGEnc matrices from
http://www.tmpgenc.net/e_main.html. On average (this depends on
the source material), the tmpgenc tables reduce the average
bitrate by about 10% and the kvcd tables reduce bitrate by about
16% (compared to the default tables).
Specify when a special ’unit coefficient elimination’
algorithm should be applied to the encoded picture blocks.
Basically, this procedure forces blocks of a type that
don’t carry much information but are expensive to encode to
be simply skipped. The larger the number the more potentially
visible this skipping is likely to be but the more compression is
boosted. A negative value means that all coefficients are zeroed,
positive means only texture but not base intensity coefficients
are zeroed. Values of around 10 or -10 seem to work well with
high quality source material. For noisier material it might be
worth trying 20 or -20.
Specify how many bi-directionally (B type) difference-encoded
frames should be encoded between reference (I or P) frames. The
default is 0 except for VCD encoding where it is 2 B frames as
required by the standard. Experts differ on how much using B
frames improves compression. In practice unless you have really
clean material they tend to be fairly useless and sometimes even
harmful. Encoding is significantly faster and uses less memory if
no B frames are encoded and compression is rarely more than
Display a synopsis of the command syntax.
option letters controlling video parameters
Force the input stream to be treated as NTSC|PAL|SECAM regardless
of what the stream header might suggest. Basically this just sets
the defaults for a bunch of other options.
Set the frame-rate of the output-stream. By default, this value
is inferred from the input header. Currently only the standard
MPEG rates are supported. Eventually more-or-less arbitrary rates
will be possible.
0 - illegal
1 - 24000.0/1001.0 (NTSC 3:2 pulldown converted FILM)
2 - 24.0 (NATIVE FILM)
3 - 25.0 (PAL/SECAM VIDEO / converted FILM)
4 - 30000.0/1001.0 (NTSC VIDEO)
5 - 30.0
6 - 50.0 (PAL FIELD RATE)
7 - 60000.0/1001.0 (NTSC FIELD RATE)
8 - 60.0
Set the playback aspect ratio code of the encoded video. By
default, this value is inferred from the input header.
1 - 1 - 1:1 display
2 - 2 - 4:3 display
3 - 3 - 16:9 display
4 - 4 - 2.21:1 display
For MPEG-2 the specified aspect ratios are used directly. For
MPEG-1 mpeg2enc infers the MPEG-1 pixel aspect code from the
video norm specified and the specified playback aspect ratio.
These set the display-horizontal-size and display-vertical-size
hints in the MPEG-2. By default these are simply the encode frame
dimensions. However, if they are set to different values the
player gets a hint that the appropriate ’black bars’
or cropping/scaling should be performed. The main use for these
parameters is to set a display-vertical-size of 1080 for HDTV
1080i or 1080p material. Here, since the frame height has to be a
multiple of 16, the encoded frame height is forced to be 1088,
even though HDTV standards specify only 1080 lines of picture
content. Standards committees ... love’ em.
Setting -p only makes sense for 24frame/sec Movie source
material. It sets flags in the output stream that tell the
decoder to play the movie as NTSC 60field/sec video using "3:2
pulldown". This is vastly more efficient than encoding as
60field/sec video. The classic application is to transcode a
PAL-encoded movie (24fps played too fast at 25 fps!) into NTSC
(see the -f flag).
option letters for chunking the output stream
This flag allows the target size of individual sequences in the
final multiplexed stream to be set in MBytes. If set mpeg2enc
keeps track of how large the eventual stream is getting and
inserts a sequence split (actually: sequence end / sequence
start) into the output stream each time it reaches the specified
limit. The multiplexer mplex(1) can recognise these splits
and start a new multiplexed output file each time it encounters
one. In this way it is easy to automatically ensure each
component sequence file can be burnt onto a CD-R and still be
played as a stand-alone MPEG sequence. For the SVCD and VCD
profiles the default target sequence length is 700M bytes. For
other profiles the default is that sequence length is unlimited.
Since mpeg2enc can’t read minds it cannot know in advance
what other material will be multiplexed with the output video
stream. Thus to get its calculations of where to insert split
point right it needs to be told the combined data-rate of the
other material that is eventually to be multiplexed with the
video. This flag allows this rate to be specified in K bits/sec.
A good rule of thumb is to use the total rate of all the other
streams plus 1% of the total rate including video.
Force the use of Constant Bit Rate encoding. Less than optimal
(and inefficient in almost all cases) but some folks insist on
it. NOTE: this disables (overrides) the use of the
It is an error to use this option and not specify a bitrate using
-b since a constant bitrate of 0 makes no sense.
This flag allows you to define chapter points within the mpeg
stream. This is most useful when generating DVD video. Each
chapter point is specified by frame number, with the first frame
being number 0. Every chapter point defined will end up at the
beginning of a closed GOP as an I frame.
option letters for controlling compression and speed
MPEG encoding is a task that can be split over a small number of
CPU’s quite efficiently. Mpeg2enc can be internally set to
split major processing tasks between a number of concurrent
threads. This flag adjusts the multi-threading to the optimum to
utilise the specified number of CPU’s.
It should be noted that even with 1 CPU present some
multi-threading is performed: frame input takes place in parallel
with encoding. The default -M value is 1. This allows good
performance to be achieved when when a seperate machine is being
used for pre-processing (decoding from MJPEG, scaling, denoising
etc) with the final result pipe to mpeg2enc (e.g. using rsh or
Setting -M 0 disables all multithreading. This is sometimes
useful for debugging or to achieve maximum CPU efficiency on a
shared machine. Setting -M 3 on a dual-CPU machine will produce
slightly faster results than -M 2 at the price of slightly less
CPU efficiency. This is useful if nothing else needs to be done
on the encoding machine. In practice there is little point
setting -M greater than 4 even if the CPU’s are available
due to the fairly coarse-grained parallelism used. Indeed there
is a hardcoded limit of 4 worker threads.
The default has been changed to be 0 instead of 1 to avoid the
crash at end of encoding:
INFO: [mpeg2enc] Signaling last frame = 499
mpeg2enc: seqencoder.cc:433: void SeqEncoder::EncodeStream():
Assertion ’pass1coded.size() == 0’ failed.
Minimum quantisation of the output stream. Quantisation controls
the precision with which image information is encoded. The lower
the number the higher the quality but the greater the required
data-rate. NOTE: on IA32 systems it is possible to cause
artifacting by setting the value too low (3 or less) due to
arithmetic overflow/truncation in the DCT/iDCT routines. If this
option is set a variable bitrate stream is produced. This
is more efficient but variable bitrate MPEG-1 cannot be played by
some hardware decoders and is rejected by some DVD authoring
packages. If you intend to use a software decoder you’d be
insane not to use variable bitrate.
If this option is set without a maximum bitrate being specified
then quantisation is fixed at the specified value. It should be
noted that not specifying a bitrate is probably an error and may
produce unexpected results.
For MPEG-2 streams a default of 8 is used if -q is not
explicitly given. To force constant bitrate streams use
--cbr and -b NOT -q!
Set the sequence picture structure and block encoding type for
MPEG-2 streams. By default, this value is inferred from the
interlacing tag of the input stream. Setting 0 encodes
frame-by-frame with support for interlaced video turned off, and
specifies that progressive chroma subsampling has been used.
Setting 1 encodes frame-by-frame with interlace-adapted motion
compensation and block encoding, and specifies that interlaced
chroma subsampling has been used. Setting 2 encodes interlaced
material field-by-field, which will produce more accurate results
for highly textured interlaced material with lots of motion, at
the expense of generally less efficiency.
This setting should match the interlaced-ness of the input
stream, otherwise chroma artifacts may be generated when the MPEG
stream is played back.
These flags set the minimum and maximum group-of-picture (GOP)
size for the output MPEG stream. The default values depend on the
For MPEG-1 (for example VCD) the default is a fixed GOP size of
12 (-g and -G are both set to 12).
For MPEG-2 the default value of -G (max) is set according to the
video system: -G 15 for 625 line (PAL) and 18 for 525 line
(NTSC). If -g (min) has not been specified then the minimum GOP
size is set to be one half of the maximum (-G).
To force a fixed GOP size specify both -g and -G with the same
If the minimum and maximum GOP sizes are not identical
then mpeg2enc will start a new GOP if more than 60% of the
macroblocks in a P or B frame are Intra encoded. This ensure big
changes of image coincide with a fully-encoded I-frame by
starting a new GOP. This can help prevent transient "blockiness".
Reasonable minimum GOP sizes are 6 or 9. If a minimum is not
specified but a maximum is given then the minimum will be set to
one half the maximum. A larger GOP size can help reduce the
bitrate required for a given quality. However, this really only
applies to high-quality source material with little
noise (e.g. digital video). For broadcast material there is
little point setting GOP size much beyond 21 or 24. Even with
good source material diminishing returns set in quite rapidly.
Also it must be noted that specific MPEG-2 formats (such as for
DVD) are constrained in the maximum allowable GOP size.
Note: mpeg2enc is currently hard-wired to produce 2 B frames
between each I/P frame unless the GOP size forces less. This is
reasonable for medium to high bitrates (>= 1Mbps) but probably
sub-optimal for low-bitrate encoding.
Setting this flag causes the encoder to generate only "closed"
GOPs (Groups of Pictures) that can be decoded without reference
to their predecessor. This is useful for streams that are
supposed to be used in multi-angle DVD’s and applications
where more easily edittable MPEG is required.
This flag forces the GOP size selection to choose sizes that
ensure 2 B frames appear between adjacent I/P frames. Several
common MPEG-1 decoders can’t handle streams where less than
2 B-frames appear between I/P frames.
This flag sets the amount quantisation is reduced for blocks
containing large amounts of sharp image detail. Large values
produces efficient use of bits but may cause visible artifacting
around detailed sections. With noisy source material this option
may cause a "swimming" effect on textured backgrounds as the
noise cause the quantisation of blocks to be boosted at random.
The default is 0.0 (off). See also the -X option.
Luma variance below which quantisation boost (-Q) is activated.
This flag sets the motion estimation search radius. For most
purposes the default (16) should be just fine. For
high-resolution MPEG-2 and active scenes it may be worth bumping
it up. However, this will make encoding significantly slower.
There is little point reducing the radius. Speed gains are not
huge and the impact on quality can be marked.
These options control how radical the encoder is in throwing away
apparently poor candidate estimates during motion estimation. A
setting of 1 means very few blocks are discarded early which
makes for slow encoding but quality as good as it gets. A setting
of 4 makes for fast encoding but can impact quality. The -4 flag
controls discarding during the initial 4*4 sub-sampled search
stage, the -2 flag controls discarding during the secondary 2*2
These flags are useful as the speed quality trade-off is markedly
different depending on which CPU you have. On modern machines the
impact on speed is around a factor 2 on older machines a factor
3. The impact on quality is around 10% quantisation (0.2 of a bit
of precision in encoding textures). For most purposes the default
settings will be fine. However on P-III Katmai etc -4 2 -2 1
gives a good near-optimum quality setting with reasonably speed.
Setting this flag adjusts the way texture detail is quantised to
reduce the precision with which of high-frequency information
encoded. This is very useful for mildly noisy sources. If
you have really noisy material the filtering tools available in
mjpegtools are a much better bet. The specified number must be in
the range 0.0 to 2.0 gives the maxium quantisation boost. A
useful number to use would be 1.5 or 1.0.
Setting this flag makes the encoder encode as much high-frequency
information as possible. This is a good setting for maximising
quality at VCD resolution with good quality low-noise source
material. It can also help with "swimmy" material if you can
spare the bitrate!
Specifies the precision of the DC component. The default is 9.
Most commercial DVDs use 10. Using 9 instead saves a few bits.
Using 10 might help to avoid looking larger areas of nearly the
same color blocky. A value of 11 is only valid at the next MPEG-2
profile/level so it’s not a currently meaningful value to
selecting the mpeg profile
Set the MPEG profile to use. The MPEG standards support a vast
number of options. In practice, different applications of the
MPEG format place additional constraints of the form the MPEG
stream. Setting this flag selects the kind of stream to produce.
- Generic MPEG1.
A basic MPEG-1 profile that lets most parameters
be adjusted for particular applications using the other
Typical applications would be to produce a variable bitrate
stream with big buffers and a high data-rate software
on a computer.
- Standard VCD.
An MPEG1 profile exactly to the VCD2.0 specification. Flag
settings that would result in a non-standard stream structure are
- User VCD.
As for profile 2 but bitrate and video buffer size can be set to
non-standard values. Frame size may also be non-standard.
Bit-rate and buffer sizes default to those for standard VCD.
- Generic MPEG2.
A basic MPEG-2 profile that lets most parameters be adjusted for
particular applications using the other flags. Typical
applications would be to produce a MPEG-2 stream with big buffers
and long GOP’s for software playback on a computer.
- Standard SVCD.
An MPEG-2 profile exactly to the SVCD2.0 specification. Flag
settings that would result in a non-standard stream structure are
- Non-standard SVCD.
As for profile 4 but bitrate, video buffer size, GOP sizes and
structure can be set to non-standard values. Frame size may also
be non-standard. Bit-rate and buffer sizes default to those for
- VCD Stills sequence.
Encodes the special style of MPEG stream used for still images on
VCDs. To use this profile you must set the target size you wish
to compress the images to using the -T flag. Reasonable values
are around 35KB for standard resolution stills (352 wide) and
120KB for high resolution stills (704 wide).
- SVCD Stills sequence.
Encodes the special style of MPEG stream used for still images on
SVCDs. Both standard (480 wide) and high resolution (704 wide)
images are supported. As with VCD stills you select how big each
compressed still should be using the -T flag.
- DVD MPEG-2 for ’dvdauthor’
This version adds special dummy navigation packets into the
output stream that the dvdauthor tool fills in to make a proper
.VOB for authoring. Bit-rate defaults to 7500kbps, buffer sizes
to the maximum permitted by the DVD specification.
- DVD MPEG-2.
Just a very basic implementation. Useful with DXR2 board and
similar hardware that can decode MPEG-2 only if it is presented
in a DVD like form. Bit-rate defaults to 7500kbps, buffer sizes
to the maximum permitted by the DVD specification.
- ATSC 480i
- ATSC 480p
- ATSC 720p
- ATSC 1080i
sse- 3d-now!- mmx !
sse- 3d-now - mmx
mpeg2enc makes extensive use of these SIMD instruction set
extension on x86 family CPU’s. The routines used are
determined dynamically at run-time. It should be noted that using
SSE requires operating system support. Old 2.2.x Linux kernels
(unless patched ones like RedHat) do not have this and so SSE,
although physically present, won’t be activated.
There should be
an option to force GOP sizes that permit 2 B frames between
I/P frames. Some decoders (even software) can’t handle
the case where I/P frames come back to back or with only 1 B
frame between them.
There needs to
be a facility for writing dummy user-data fields so that the
multiplexer/imager can insert forward/backward pointers when
muxing/imaging an SVCD.
mp2enc , lavrec, lavplay ,
lav2yuv , lav2wav , yuvscaler ,
yuvdenoise , y4mdenoise ,
This man page
was written by Andrew Stevens. If you have questions,
remarks, problems or you just want to contact the
developers, the main mailing list for the MJPEG-tools is:
For more info,
see our website at