transcode(1)
NAME
transcode - LINUX video stream processing tool
SYNOPSIS
transcode -i name [-o name] [-y vmod,amod]
[-w vbitrate [ ,vkeyframes [ ,vcrispness ] ]]
[-a atrack [ ,vtrack ]]
[-b abitrate [ ,is_vbr [ ,quality [ ,mode ] ] ]]
[-M demuxer_mode] [-F codec_string] [other options]
QUICK SUMMARY
transcode supports a huge range of options, as described in detail in further section. Only one option is mandatory: -i name, for supplying the input main (video) source. All other options are discretionary and they can be skipped. Most commonly needed options are -o, -y, -w, -a, -b, -M, -F and a fair number of transcode session needs a little more than those. See section below for full description of all transcode options. To inspect the properties of a module, such as their parameters or the help text, use the tcmodinfo tool.
DESCRIPTION
transcode is a linux text-console utility for video stream processing, running on a platform that supports shared libraries and threads. It supports a huge range of options, as described in detail in further section. Only one option is mandatory: -i name, for supplying the input main (video) source. All other options are discretionary and they can be skipped. Most commonly needed options are -o, -y, -w, -a, -b, -M, -F and a fair number of transcode session needs a little more than those. See section below for full description of all transcode options. Decoding and encoding is done by loading modules that are responsible for feeding transcode with raw video/audio streams (import modules) and encoding the frames (export modules). It supports elementary video and audio frame transformations, including de-interlacing or fast resizing of video frames and loading of external filters. A number of modules are included to enable import of DVDs on-the-fly, MPEG elementary (ES) or program streams (VOB), MPEG video, Digital Video (DV), YUV4MPEG streams, NuppelVideo file format, AVI based codecs and raw or compressed (pass-through) video frames and export modules for writing DivX;-), XviD, DivX 4.xx/5.xx or uncompressed AVI and raw files with MPEG, AC3 (pass-through) or PCM audio. Additional export modules to write single frames (PPM) or YUV4MPEG streams are available, as well as an interface import module to the avifile library. Its modular concept is intended to provide flexibility and easy user extensibility to include other video/audio codecs or filetypes. A set of tools is included to demux (tcdemux), extract (tcextract) and decode (tcdecode) the sources into raw video/audio streams for import, probing (tcprobe) and scanning (tcscan) your sources and to enable post-processing of AVI files, fixing AVI file header information (avifix), merging multiple files (avimerge), splitting large AVI files (avisplit) to fit on a CD and avisync to correct AV-offsyncs.
OPTIONS
-A
use AC3 as internal audio codec [off]. Only pass-through supported.
-B n[,m[,M]]
resize to height-n*M rows [,width-m*M] columns [off,32]. M must be
one of 8, 16 or 32. It makes no difference which M you use. You
might look at the fast flag of the -Z option if you don not want to
calculate n and m yourself.
-C mode
enable anti-aliasing mode (1-3) [off].
1
de-interlace effects only
2
resize effects only
3
process full frame (slow)
-D num
sync video start with audio frame num [0].
-E r[,b[,c]]
audio output samplerate [Hz], bits per sample and channels [as
input]. The option "-J resample" must be provided for export
modules not capable of re-sampling. Samplerate and bits per sample
can be specified as 0 to mean "same as input"; this allows
converting from stereo to mono while leaving the other parameters
alone (-E 0,0,1).
-F codec_string
encoder parameter strings [module dependent]. The -F parameter has
different meanings for different export modules. Those meanings are
documented in transcode_export(1) manual page.
-G val
Gamma correction (0.0-10.0) [off]. A value of 1.0 does not change
anything. A value lower than 1.0 will make the picture "brighter",
a value above 1.0 will make it "darker".
-H n
auto-probe n MB of source (0=disable) default [1]. Use a higher
value than the default to detect all subtitles in the VOB.
-I mode
enable de-interlacing mode (1-5) [off].
1
"interpolate scanlines" linear interpolation (takes the average
of the surronding even rows to determine the odd rows), and
copies the even rows as is.
2
"handled by encoder" tells the encoding code to handle the fact
that the frames are interlaced. Most codecs do not handle this.
3
"zoom to full frame" drops to to half size, then zooms out.
This can cause excessive blurring which is not always unwanted.
On the other hand results are quite good.
4
"drop field / half height" drop every other field and keep half
height.
5
"interpolate scanlines / blend frames" linear blend (similar to
-vop pp=lb in mplayer) this, like linear blend calculates the
odd rows as the average of the surrounding even rows, and also
calculates the even rows as an average of the original even
rows and also calculates the even rows as an average of the
original odd rows and averages the calculated and original
rows. Something like avg (avg(row1,row3), avg(row2, row4))
-J filter1[,filter2[,...]]
apply external filter plugins [off]. The avalaible import modules
and their options are documented into the transcode_filter(1)
manual page. Note: You can specify more than one -J argument. The
order of filter arguments specify in which order the filters are
applied. Note also, for transcode internally it makes no difference
whether you do "-J filter1 -J filter2" or "-J filter1,filter2". Use
tcmodinfo -i NAME to get more information about the filter_NAME.
Not all filters support this but most of them do. Some of the
filter plugins have additional documentation in the docs/
directory.
-L n
seek to VOB stream offset nx2kB default [0]. This option is usually
calculated automatically when giving --nav_seek and -c.
-K
enable black/white by removing colors mode (grayscale) [off].
Please note this does not necessarily lead to a smaller image /
better compression. For YUV mode, this is done by emptying the
chroma planes, for RGB mode a weightend grayscale value is
computed.
-M mode
demuxer PES AV sync modes (0-4) [1].
Overview
The demuxer takes care that the right video frames go together
with the right audio frame. This can sometimes be a complex
task and transcode tries to aid you as much as possible.
WARNING: It does make a difference if you (the user) specifies
a demuxer to use or if transcode resp. tcprobe(1) chooses the
one which it thinks is right for your material. This is done on
purpose to avoid mystic side-effects. So think twice, wether
you specify a demuxer or let transcode choose one or you might
end up with an off-sync result.
0
Pass-through. Do not mess with the stream, switch off any
synchronization/demuxing process.
1
PTS only (default). Synchronize video and audio by inspecting
PTS/DTS time stamps of audio and video. Preferred mode for PAL
VOB streams and DVDs.
2
NTSC VOB stream synchronization feature. This mode generates
synchronization information for transcode by analyzing the
frame display time.
3
(like -M 1): sync AV at initial PTS, but invokes
"-D/--av_fine_ms" options internally based on "tcprobe" PTS
analysis. PTS stands for Presentation Time Stamp.
4
(like -M 2): initial PTS / enforce frame rate, with additional
frame rate enforcement (for NTSC).
-N format
select export format. Default is mp3 for audio, and
module-dependant format for video. This option has two different
behaviours and accepts two different set of options, as side-effect
of ongoing export module transition. For old-style modules (current
default, as found in 1.0.x series), argument is audio format ID has
hexadecimal value: see below for a list of recognized IDs. Default
id, so default format for audio exported track, is MP3 (0x55). If
you are using, the transcodes the new-style encode/multiplex
modules (still under development, see the encode and multiplex
directories), argument is a comma-separated pair of export format
names. Use tcmodinfo tool to check out what new-style export module
support what formats.
Available format for old-style behaviour are:
0x1
PCM uncompressed audio
0x50
MPEG layer-2 aka MP2
0x55
MPEG layer-3 aka MP3. Also have a look at --lame_preset if you
intend to do VBR audio.
0x2000
AC3 audio
0xfffe
OGG/Vorbis audio
-O
skip flushing of buffers at encoder stop [off, do flushing at each
stop].
-P flag
pass-through flag (0=off|1=V|2=A|3=A+V) [0]. Pass-through for flag
!= 1 is broken and not a trivial thing to fix.
You can pass-through DV video, AVI files and MPEG2 video. When
doing MPEG2 pass-through (together with the -y raw module), you can
give a requantization factor by using -w (for example -w 1.5), this
will make the MPEG2 stream smaller.
The pass-through mode is useful for reconstruction of a broken
index of an AVI file. The -x ffmpeg import-module analyzes the
compressed bitstream and can detect a keyframe for DIV3, MPEG4
(DivX, XviD, ..) and other formats. It then sets an internal flag
which the export module will respect when writing the frame out.
-Q n[,m]
encoding[,decoding] quality (0=fastest-5=best) [5,5].
-R n[,f1[,f2]]
enable multi-pass encoding (0-3) [0,divx4.log,pcm.log].
0 Constant bitrate (CBR) encoding. [default]
The codec tries to achieve constant bitrate output. This means,
each encoded frame is mostly the same size. This type of
encoding can help in maintaining constant filling of hardware
buffer on set top players or smooth streaming over networks. By
the way, Constant bitrate is often obtained sacrifying quality
during high motion scenes.
1 Variable bitrate encoding: First pass.
In this mode, the codec analyses the complete sequence in order
to collect data that can improve the distribution of bits in a
second VBR pass. The collected data is written to second sub
argument (default: divx4.log). This data is codec dependant and
cannot be used across codecs. It is strongly advised to use the
same codec settings for the VBR analysis pass and the VBR
encoding pass if you want predictable results.
The video output of the first pass is not of much use and can
grow very large. Its a good idea to not save the video output
to a file but directly to /dev/null. Usually the bitrate is
ignored during first pass.
Disabling audio export makes sense too, so use -y codec,null.
It is not recommended to disable the audio import because
transcode might drop video frames to keep audio and video in
sync. This is not possible when the audio import is disabled.
It may lead to the fact that the codec will see a different
sequence of frames which effectively renders the log file
invalid.
2 Variable bitrate encoding: Second pass.
The first pass allowed the codec collecting data about the
complete sequence. During the second pass, the codec will use
that data in order to find an efficient bit distribution that
respects both the desired bitrate and the natural bitrate curve
shape. This ensures a good compromise between quality and
desired bitrate.
Make sure you activate both sound and video encoding during
this pass.
3 Constant quantizer encoding.
The quantizer is the "compression level" of the picture. The
lower the quantizer is, the higher is the quality of the
picture. This mode can help in making sure the sequence is
encoded at constant quality, but no prediction can be made on
the final bitrate. When using this mode, the -w option changes
its meaning, it now takes the quantizer ranging from 1 to 31.
Note that constant quantizer encoding is not supported with
some codecs (notably mpeg1/2/4 with -y ffmpeg).
-S unit[,s1-s2]
process program stream unit[,s1-s2] sequences [0,all]. This option
is a bit redundant to --psu*. This option lets you specify which
units you want to have decoded or skipped. At a program stream unit
boundary, all (internal) mpeg timers are reset to 0. tcprobe will
tell you how many units are in one file.
-T t[,c[,a]]
select DVD title[,chapter[,angle]] [1,1,1]. Only a single chapter
is transcoded. Use -T 1,-1 to trancode all chapters in a row. You
can even specify chapter ranges.
-U base
process DVD in chapter mode to base-ch%02d.avi [off].
-V format
select video layout / colour space for internal processing.
Possible values for this options are: yuv420p (default), yuv422p,
rgb24
yuv420p is default because it is most codecs internal format so
there is no need for conversions. Some modules may not support it
though: use rgb in that case.
rgb24 is the old (pre-0.6.13) transcode internal format. Most
codecs do not support this format natively and have to convert it
to/from YUV first, so only use this option if youre really sure or
you want to use a module that doesnt support YUV.
yuv422p is an experimental feature and a developers playground. Not
many import, export and filter modules support this colorspace. A
4:2:2 colorspace offers much more quality than the consumer
oriented 4:2:0 colorspaces like I420/YV12. Most equipment in film
and video post-production uses YUV422. YUV422 doubles the precision
for chroma (color difference) information in the image.
All internal transformations are supported in YUV422 mode
(clipping, flipping, zooming, etc).
-W n,m[,nav_file]
autosplit and process part n of m (VOB only) [off]
-X n[,m,[M]]
resize to height+n*M rows [,width+m*M] columns [off,32]. M must be
one of 8, 16 or 32. It makes no difference which M you use. You
might look at the fast flag of the -Z option if you do not want to
calculate n and m yourself.
-Y top[,left[,bottom[,right]]]
select (encoder) frame region by clipping border. Negative values
add a border [off].
-Z widthxheight[,fast|interlaced]
resize to width columns, height rows with filtering
[off,notfast,notinterlaced]. If fast is given, transcode will
calculate the parameters for -X and/or -B. The file fast can only
be used when the import and export geometry of an image is a
multiple of 8.
In fast mode, a faster but less precise resizing algorithm will be
used resulting in a slightly less good quality. Beside this (small)
drawback, it is worth a try.
If interlaced is given, transcode will assume the frame is
interlaced when resizing, and resize each field independently. This
will give better results on interlaced video, but is incompatible
with fast mode. Also, the height (both old and new) must be a
multiple of 4.
It is also possible to omit width OR height. In this case,
transcode will calculate the missing value using the import aspect
ratio. The new value will be aligned to be a multiple of 8. Using
an additional fast or interlaced is also possible.
Examples (assume input is a 16:9 coded file at 720x576):
-Z 576x328 uses filtered zoom.
-Z 576x328,fast uses fast zoom.
-Z 576x,fast guess 328 and do fast zoom.
-Z x328,interlaced guess 576 and do interlaced zoom.
If you also set --export_prof, you can use just "fast" to indicate
that fast resizing is wanted (likewise with "interlaced").
-a ach[,vch]
extract audio[,video] track for encoding.
-b b[,v,[q,[m]]]
audio encoder bitrate kBits/s[,vbr[,quality[,mode]]] [128,0,5,0]
The mode parameter specifies which modus lame should use for
encoding. Available modes are:
0
Joint Stereo (default)
1
Full stereo
2
Mono
-c f1-f2[,f3-f4[, ... ] ]
encode only frames f1-f2 [and f3-f4]. Default is to encode all
available frames. Use this and youll get statistics about
remaining encoding time. The f[N] parameters may also be timecodes
in the HH:MM:SS.FRAME format. Example:
-c 500-0:5:01,:10:20-1:18:02.1
Will encode only from frame 500 to 5 minutes and 1 second and from
10 min, 20 sec to 1 hour, 18 min, 2 sec and one frame.
Note that transcode starts counting frames at 0 and excludes the
last frame specified. That means that "-c 0-100" will encoded 100
frames starting at frame 0 up to frame 99
-d
swap bytes in audio stream [off]. In most cases, DVD PCM audio
tracks require swapping of audio bytes
-e r[,b[,c]]
PCM audio stream parameter. Sample rate [Hz], bits per sample and
number of channels [48000,16,2]. Normally this is autodetected.
-f rate[,frc]
import video frame rate[,frc] [25.000,0]. If frc (frame rate code)
is specified, transcode will calculate the precise frames per
second internally. Valid values for frc are:
1
23.976 (24000/1001.0)
2
24
3
25
4
29.970 (30000/1001.0)
5
30
6
50
7
59.940 (2 * 29.970)
8
60
9
1
10
5
11
10
12
12
13
15
-g WidthxHeight
video stream frame size [720x576].
-h
print out usage information.
-i name
input file/directory/device/mountpoint/host name, default is
[/dev/zero].
-j top[,left[,bottom[,right]]]
select frame region by clipping border. Negative values add a
border [off].
-k
swap red/blue (Cb/Cr) in video frame [off]. Use if people have blue
faces.
-l
mirror video frame [off].
-m file
write audio stream to separate file [off].
-n 0xnn
import audio format id [0x2000]. Normally, this is autodetected.
-o file
output file name, default is [/dev/null].
-p file
read audio stream from separate file [off].
-q debuglevel
possible values for debuglevel:
0
QUIET
1
INFO
2
DEBUG
4
STATS
8
WATCH
16
FLIST
32
VIDCORE
64
SYNC
128
COUNTER
256
PRIVATE
-r n[,m]
reduce video height/width by n[,m] [off]. Example: -r 2 will
rescale the framesize of a 720x576 file to 360x288.
-s gain,[center,[front,[rear]]]
increase volume of audio stream by gain,[center,front,rear] default
[off,1,1,1].
-t n,base
split output to base%03d.avi with n frames [off].
-u m[,n]
use m framebuffer[,n threads] for AV processing [10,1].
-v
print version.
-w b[,k[,c]]
encoder bitrate[,keyframes[,crispness]] [(6000 for MPEG 1/2, 1800
for others),250,100].
--video_max_bitrate b
Use b as maximal bitrate (kbps) when encoding variable bitrate
streams.
-x vmod[,amod]
video[,audio] import modules [auto,auto]. If omitted, transcode
will probefor appropriate import modules. The avalaible import
modules and their options are documented into the
transcode_import(1) manual page.
-y vmod[,amod[,mmod]]
video[,audio[,multiplex]] export modules [null]. If omitted,
transcode will encode to the null module. If a multiplex module is
given, transcode will use the new-style encode/multiplex modules
(still under development, see the encode and multiplex
directories); if no multiplex module is given, the traditional
export modules will be used. The avalaible export, encoder and
multiplexor modules and their options are documented into the
transcode_export(1) manual page.
--accel type
enforce experimental IA32 acceleration for type [autodetect]. type
may be one of
C
No acceleration
ia32asm
plain x86 assembly
mmx
MMX instruction set
3dnow
3DNow! instruction set
sse
SSE instruction set
sse2
SSE2 instruction set
--avi_limit N
split/rotate output AVI file after N MB [2048].
--avi_comments F
Read AVI header comments from file F [off]. The AVI file format
supports so-called tomb-stone data. It can be used to write
annotations into the AVI file.
See the file docs/avi_comments.txt for a sample input file with all
tags. When the file is read, empty lines and lines starting with
# are ignored. The syntax is: "TAG<space>STRING". The order of
the tags does not matter. If a tag has no string following it, it
is ignored. That means, you can use the file docs/avi_comments.txt
as input and only fill out the fields you want.
A very simple example is:
----------------snip----------------
INAM My 1st Birthday
ISBJ My first steps!
IART My proud family
----------------snip----------------
Keep in mind that there is no endless space in the AVI header, most
likely its around 1000 bytes.
--zoom_filter string
use filter string for video resampling -Z [Lanczos3] The following
filters are available:
Bell
Box
Lanczos3 (default)
Mitchell
Hermite
B_spline
Triangle
--cluster_percentage
use percentage mode for cluster encoding -W> [off]
--cluster_chunks a-b
process chunk range instead of selected chunk [off]
--export_asr C
set export aspect ratio code C [as input] Valid codes for C are:
1
1:1
2
4:3
3
16:9
4
2.21:1
--export_prof S
WARNING: this option will be renamed as --export_profile in future
releases.
Select an export profile {vcd, svcd, xvcd, dvd}
[-pal|-ntsc|-secam]. Default is no profile.
If you set this meta option to one of the values below, transcode
will adjust some internal paramaters as well as geometry and
clipping. If no export modules are specified, mpeg2enc for video
and mp2enc for audio are used when compiled with mjpegtools
support.
Valid values for S are e.g. vcd, vcd-pal, vcd-ntsc, svcd, svcd-pal,
...
xvcd profile is equal to svcd except that it allows for up to 9000
Kbps video bitrate (default is 5000) and arbitrary audio
samplerate.
When one of the above is used, transcode will calculate the needed
clipping and resizing values for you based on the import and export
aspect ratio. This is especially handy if you want to encode a 16:9
DVD into a 4:3 SVCD for example. Transcode internally then sets
--pre_clip to add the black bars ("letterboxing").
If you use "vcd" instead of "vcd-pal" or "vcd-ntsc", transcode will
make an educated guess if PAL or NTSC vcd is wanted. The same is
true for the other profiles. When the input file has no aspect
ratio information at all, transcode guesses it based on the import
frame sizes. You can set the import aspect ratio by giving
--import_asr CODE.
Examples (assume input is a 16:9 coded file at 720x576 (PAL)):
--export_prof svcd clip top/bot -96; resizes to 480x576
--export_prof vcd-ntsc clip top/bot -96; resizes to 352x240
This enables simpilified commandlines where transcode tries to set
sensible values for mpeg export. When you dont specify an export
module with -y, mpeg2enc will be used.
transcode -i vob/ --export_prof svcd -Z fast -o test
The ffmpeg export module `-y ffmpeg does support profiles as well.
The module tries to be smart and sets internal ffmpeg parameters
which are otherwise quite tricky to find out. Usage is similar to
the above.
transcode -i vob/ --export_prof dvd -y ffmpeg -o test -m test.ac3
tcmplex -m d -i test.m2v -p test.ac3 -o test.mpg
--export_par C[,N]
set export pixel aspect ratio to C[,N]. To encode anamorphic
material, transcode can encode the target pixel aspect ratio into
the file. This is NOT the actual aspect ratio of the image, but
only the amount by which every single pixel is stretched when
played with an aspect ratio aware application, like mplayer.
To encode at non standard aspect ratios, set both C and N. E.g. to
make every pixel twice as high as its wide (e.g. to scale back to
normal size after deinterlacing by dropping every second line).
If C and N are specified, the value set for C does give the pixel
aspect ratio of the width and N the one for the height. If only C
is specified, the table below applies.
Valid codes for C are
1
1:1 No stretching
2
12:11 5:4 image to 4:3 (ex: 720x576 -> 768x576)
3
10:11 3:2 image to 4:3 (ex: 720x480 -> 640x480)
4
16:11 5:4 image to 16:9 (ex: 720x576 -> 1024x576)
5
40:33 3:2 image to 16:9 (ex: 720x480 -> 872x480)
--import_asr C
set import aspect ratio code C [autoprobed]
Valid codes for C are
1
1:1
2
4:3
3
16:9
4
2.21:1
--keep_asr
try to keep aspect ratio (only with -Z) [off]
The --keep_asr options changes the meaning of -Z. It tries to fit
the video into a framesize specified by -Z by keeping the original
aspect ratio.
+----------------+ +---480-----+
| | | black |
|720x306 = 2.35:1| -> -Z 480x480 --keep_asr ->|-----------4
| | | 480x204 8
+----------------+ |-----------0
| black |
+-----------+
Consider --keep_asr a wrapper for calculating -Y options and -Z
options.
--mplayer_probe
use external mplayer binary to probe stream, reset default import
modules as mplayer ones [off]. Default is to use internal probing
code. Using this option without mplayer import modules (-x mplayer)
can lead to unpredictable and possibly wrong results.
--quantizers min,max
set encoder min/max quantizer. This is meaningfull only for video
codecs of MPEG family. For other kind of codecs, this options is
harmless. [2,31]
--divx_rc p,rp,rr
divx encoder rate control parameter [2000,10,20]
--divx_vbv_prof N
divx5 encoder VBV profile (0=free-5=hiqhq) [3]. Sets a predefined
profile for the Video Bitrate Verifier. If N is set to zero, no
profile is applied and the user specified values from --divx_vbv
are used.
Valid profiles
0
Free/No profile ( Use supplied values )
1
Handheld ( 320, 16, 3072 )
2
Portable ( 1920, 64, 12288 )
3
Home Theatre ( 10000, 192, 36864 )
4
High Definition ( 20000, 384, 73728 )
--divx_vbv br,sz,oc
divx5 encoder VBV params (bitrate,size,occup.) [10000,192,36864]
These parameters are normally set through the profile parameter
--divx_vbv_prof. Do not mess with theses value unless you are
absolutely sure of what you are doing. Transcode internally
multiplicates vbv_bitrate with 400, vbv_size with 16384 and
vbv_occupancy with 64 to ensure the supplied values are multiples
of what the encoder library wants.
--export_fps rate[,frc]
set export frame rate (and code) [as input].Valid values for frc
are
frc rate
1
23.976 (24000/1001.0)
2
24
3
25
4
29.970 (30000/1001.0)
5
30
6
50
7
59.940 (2 * 29.970)
8
60
9
1
10
5
11
10
12
12
13
15
--export_frc F
set export frame rate code F [as input]. Obsolete, use
--export_fps 0,F
--hard_fps
disable smooth dropping (for variable fps clips) [off]. See
/docs/framerate.txt for more information.
--pulldown
set MPEG 3:2 pulldown flags on export [off]
--antialias_para w,b
center pixel weight, xy-bias [0.333,0.500]
--no_audio_adjust
disable internal audio frame sample adjustment [off]
--no_bitreservoir
disable lame bitreservoir for MP3 encoding [off]
--config_dir dir
Assume config files are in this dir. This only affects the -y
ffmpeg and -y xvid4 modules. It gives the path where the modules
search for their configuration.
--lame_preset name[,fast]
use lame preset with name [off]. Lame features some built-in
presets. Those presets are designed to provide the highest possible
quality. They have for the most part been subject to and tuned via
rigorous listening tests to verify and achieve this objective.
These are continually updated to coincide with the latest
developments that occur and as a result should provide you with
nearly the best quality currently possible from LAME. Any of those
VBR presets can also be used in fast mode, using the new vbr
algorithm. This mode is faster, but its quality could be a little
lower. To enable the fast mode, append ",fast"
<N kbps>
Using this preset will usually give you good quality at a
specified bitrate. Depending on the bitrate entered, this
preset will determine the optimal settings for that particular
situation. While this approach works, it is not nearly as
flexible as VBR, and usually will not reach the same quality
level as VBR at higher bitrates. ABR.
medium
This preset should provide near transparency to most people on
most music. The resulting bitrate should be in the 150-180kbps
range, according to music complexity. VBR.
standard
This preset should generally be transparent to most people on
most music and is already quite high in quality. The resulting
bitrate should be in the 170-210kbps range, according to music
complexity. VBR.
extreme
If you have extremely good hearing and similar equipment, this
preset will provide slightly higher quality than the "standard"
mode. The resulting bitrate should be in the 200-240kbps range,
according to music complexity. VBR.
insane
This preset will usually be overkill for most people and most
situations, but if you must have the absolute highest quality
with no regard to filesize, this is the way to go. This preset
is the highest preset quality available. 320kbps CBR.
(taken from http://www.mp3dev.org/mp3/doc/html/presets.html)[1]
--av_fine_ms t
AV fine-tuning shift t in millisecs [autodetect] also see -D.
--nav_seek file
use VOB or AVI navigation file [off]. Generate a nav file with
tcdemux -W >nav_log for VOB files or with aviindex(1) for AVI
files.
--psu_mode
process VOB in PSU, -o is a filemask incl. %d [off]. PSU means
Program Stream Unit and this mode is useful for (mostly) NTSC DVDs
which have several program stream units.
--psu_chunks a-b
process only selected units a-b for PSU mode [all]
--no_split
encode to single file in chapter/psu/directory mode [off]. If you
dont give this option, youll end up with several files in one of
the above mentioned modes. It is still possible to merge them with
avimerge(1).
--multi_input
(EXPERIMENTAL) enable multiple input mode: intelligently join input
files in import. The inputs can be expressed using standard POSIX
globbing. While theorically all input modules are supported, it is
safe to use this only when dealing with constant-sized audio (PCM)
and intra-frame only video codecs (es: MJPEG). To be safe, use this
mode with im, ffmpeg and raw import modules.
--pre_clip t[,l[,b[,r]]]
select initial frame region by clipping border [off]
--post_clip t[,l[,b[,r]]]
select final frame region by clipping border [off]
--a52_drc_off
disable liba52 dynamic range compression [enabled]. If you dont
specify this option, liba52 will provide the default behaviour,
which is to apply the full dynamic range compression as specified
in the A/52 stream. This basically makes the loud sounds softer,
and the soft sounds louder, so you can more easily listen to the
stream in a noisy environment without disturbing anyone.
If you let it enabled this this will totally disable the dynamic
range compression and provide a playback more adapted to a movie
theater or a listening room.
--a52_demux
demux AC3/A52 to separate channels [off]
--a52_dolby_off
disable liba52 dolby surround [enabled]. Selects whether the output
is plain stereo (if the option is set) or if it is Dolby Pro Logic
- also called Dolby surround or 3:1 - downmix (if the option is not
used).
--log_no_color
disable colored log messages. By default transcode use colors in
log messages in order to easily distinguish message classes. That
behaviour can be problematic if output of transcode is a file or a
pipe, so this option came handful.
--dir_mode base
process directory contents to base-%03d.avi [off]
--frame_interval N
select only every Nth frame to be exported [1]
--encode_fields C
enable field based encoding (if supported) [off]. This option takes
an argument if given to denote the order of fields. If the option
is not given, it defaults to progressive (do not assume the picture
is interlaced)
Valid codes for C are:
p
progressive (default)
t
top-field first
b
bottom-field first
--dv_yuy2_mode, --dv_yv12_mode
Indicates that libdv decodes Digital Video frames in YUY2 (packed)
or YV12 (planar) mode, respectively. Normally transcode figures out
the correct mode automatically, but if you try to transcode PAL DV
files and the results look strange, try one of these options.
--write_pid file
write pid of signal thread to file [off]. Enables you to terminate
transcode cleanly by sending a SIGINT (2) to the pid in file.
Please note file will be overwritten. Usage example
$ transcode ... --write_pid /tmp/transcode.pid &
$ kill -2 `cat /tmp/transcode.pid`
--nice N
set niceness to N [off]. The option --nice which renices transcode
to the given positive or negative value. -10 sets a high priority;
+10 a low priority. This might be useful for cluster mode.
--progress_meter N
select type of progress meter [1]. Selects the type of progress
message printed by transcode:
0
no progress meter
1
standard progress meter
2
raw progress data (written to standard output)
Scripts that need progress data should use type 2, since the format
of type 1 is subject to change without notice.
--progress_rate N
print progress every N frames [1]. Controls how frequently the
status message is printed (every N frames).
--socket FILE
Open a socket to accept commands while running. See tcmodinfo(1)
and /docs/filter-socket.txt for more information about the
protocol.
ENVIRONMENT
TRANSCODE_LOG_NO_COLOR
if set, forces the colored logging off for all the tools of
transcode suite.
NOTES
*
Most source material parameter are auto-detected.
*
Clipping region options are expanded symmetrically. Examples:
-j 80 will be expanded to -j 80,0,80,0
-j 80,8 will be expanded to -j 80,8,80,8
-j 80,8,10 will be expanded to -j 80,8,10,8
*
maximum image size is 1920x1088.
*
The video frame operations ordering is fixed: "-j -I -X -B -Z -Y -r
-z -l -k -K -G -C" (executed from left to right).
*
Shrinking the image with -B is not possible if the image
width/height is not a multiple of 8, 16 or 32.
*
Expanding the image with -X is not possible if the image
width/height is not a multiple of 8, 16 or 32.
*
The final frame width/height should be a multiple of 8. (to avoid
encoding problems with some codecs)
1.
Reducing the video height/width by 2,4,8 Option -r factor can
be used to shrink the video image by a constant factor, this
factor can be 2,4 or 8.
2.
Clipping and changing the aspect ratio transcode uses 3 steps
to produce the input image for the export modules
1.
Clipping of the input image.
2.
Changing the aspect ratio of the 1) output.
3.
Clipping of the 2) output.
*
Bits per pixel (bits/pixel) is a value transcode calculates and
prints when starting up. It is mainly useful when encoding to MPEG4
(xvid, divx, etc). Youll see line like
[transcode] V: bits/pixel | 0.237
Simplified said, bits/pixel quantifies how good an encode will be.
Although this value depends heavily on the used input material, as
a general rule of thump it can be said that values greater or close
to 0.2 will result in good encodes, encodes with values less than
0.15 will have noticeable artifacts.
Bits per pixel depends on the resolution, bitrate and frames per
second. If you have a low value ( < 0.15), you might want to raise
the bitrate or encode at a lower resolution. The exact formula is
bitrate*1000
bpp = ------------------
width*height*fps
*
AC3 / Multiple channels
When you do import an audio stream which has more then two audio
channels - this is usually the case for AC3 audio - transcode will
automagically downmix to two channels (stereo). Youll see line
like
[transcode] A: downmix | 5 channels -> 2 channels
This is done, because most encoders and audio filters can not
handle more than 2 channels correctly. The PCM internal
representation does not support more than two channels, audio will
be downmixed to stereo No downmix will happen, if you use AC3 as
the internal audio codec or use audio pass-through.
EXAMPLES
The following command will read its input from the DVD drive (I assume
/dev/dvd is a symbolic link to the actual DVD device) and produce a
splitted divx4 movie according to the chapter information on the DVD
medium. The output files will be named my_movie-ch00.avi,
my_movie-ch01.avi ...
transcode -i /dev/dvd/ -x dvd -j 16,0 -B 5,0 -Y 40,8 -s 4.47 -U my_movie -y xvid -w 1618
Option -j 16,0 will be expanded to -j 16,0,16,0 and results in 16 rows
from the top and the bottom of the image to be cut off. This may be
usefull if the source consists of black top and bottom bars.
Option -B 5,0 tells transcode to shrink the resulting image by 5*32=160
rows in height.
Option -Y 40,8 will be expanded to -Y 40,8,40,8 and tells transcode to
...
Option -s 4.47 tells transcode to increase audio volume by a factor
4.47.
Option -U my_movie tells transcode to operate in chapter mode and
produce output to files named my_movie-ch00.avi, my_movie-ch01.avi....
You can either merge the files afterwards with avimerge or add the
option --no_split to the command line.
Option -y xvid tells transcode to use the export module export_xvid.so
which in turn uses the XviD encoder to encode the video.
Option -w 1618 tells transcode to set the encoder bitrate to 1618 which
is lower than the default of 1800 and results in smaller files with the
loss of visual quality.
Lets assume that you have an NTSC DVD (720x480) and you want to make an
NTSC-SVCD
The frame size of the DVD movie is 720x480 @ 16:9. For the purpose
of frame resizing, the width 720 is not relavant (that is, it will
not be used in the following reasoning). It is not needed because
the original frame size is really defined by the frame height and
aspect ratio. The _final result_ should be 640x480, encoded as
480x480 @ 4:3 (the height 480 multiplied by the aspect ratio 4:3
gives the width 640). This same frame size (640x480) can also be
encoded as 640x360 @ 16:9 (the height 360 by the aspect ratio 16:9
gives the width 640).
As the _original video_ has aspect ratio 16:9, first we resize to
640x360, keeping that aspect ratio. But the aspect ratio has to be
changed to 4:3. To find the frame size in the new aspect ratio the
height 360 is multiplied by the new aspect ratio, giving the width
480. This is accomplished with the transcode options "--export_asr
2 -Z 480x360,fast".
To avoid stretching the video height in this change (because the
new aspect ratio is less than the original), black borders should
be added at the top and bottom of the video, bringing the frame to
the desired 480x480 @ 4:3 size. The transcode option for this is
"-Y -60,0,-60,0".
If for some reason (maybe a subtitle filter) the black borders (of
height 60 each) should be added before resizing the frame and
changing the aspect ratio to 4:3. One reason for that would be the
need of running a _pre_ filter after adding the black borders. Then
the options "-j" or "--pre_clip" can be used instead of "-Y". In
this case the black border height has to be recalculated by
applying the aspect ratio 4:3 to the value alreadyfound: 60 * (4/3)
= 80. The transcode options "-j -80,0,-80,0" or "--pre_clip
-80,0,-80,0" are then used instead of "-Y -60,0,-60,0", and "-Z
480x360,fast" is replaced by "-Z 480x480,fast".
AUTHORS
Written by Thomas Oestreich <[email protected]>, Tilmann Bitterberg and the Transcode-Team See the AUTHORS file for details.
SEE ALSO
transcode_export(1) , transcode_filter(1) , transcode_import(1) , avifix(1) , avisync(1) , avimerge(1) , avisplit(1) , tcprobe(1) , tcscan(1) , tccat(1) , tcdemux(1) , tcextract(1) , tcdecode(1) , tcmodinfo(1) , tcxmlcheck(1) , transcode(1)
WWW
Frequently asked questions (FAQ) at
http://www.transcoding.org/cgi-bin/transcode?Transcode_FAQ [1] Example
transcode sessions at
http://www.transcoding.org/cgi-bin/transcode?Command_Examples [1]
BUGS
Yes, there are bugs in transcode! Do your part and report them
immediately.
For details, see
http://www.transcoding.org/cgi-bin/transcode?Reporting_Problems [1]
NOTES
1. http://www.mp3dev.org/mp3/doc/html/presets.html)
a
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