mjpegtools.1

来自「Motion JPEG编解码器源代码」· 1 代码 · 共 2,296 行 · 第 1/5 页

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You can decode mpeg2 streams with the patched mpeg2dec version which 
creates yuv streams. You can pipe that into any other mjpegtools program. 
Or you use a mpeg2dec version directly from the libmpeg2  project and use 
the output mode pgmpipe. With the \fBpgmtoy4m\fP program from the 
mjpegtools you can convert that pgm output back to yuv.

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If you ask yourself why there is a patched version and pgmtoy4m.
The answer is that the patch for yuv output was sent several
times to the libmpeg2 developers but was never included.
Now we have two ways around that problem. Decoding looks like this:

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\fB> mpeg2dec -s -o pgmpipe ANYTS.VOB \(br pgmtoy4m -i t -a 10:11 -r 30000:1001 \(br mpeg2enc -f 8 newvideo.m2v\fP

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You can decode the audio as described in the 
\fBTranscoding of existing MPEG-2\fP Section.

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.SH Other things to know


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If you have Transport Streams from your DVB card, or os Satelite Receiver
you might want to demultiplex or cut them. A nice tool for that is 
\fBProject X\fP available from: 

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You can process the streams afterwards as you would do with any mpeg movie
or demultiplexed audio video. So the \fBTranscoding of existing MPEG-2\fP
section of this document will be of interest.Checking if recording was successful


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You can use lavplay or glav. \fBIMPORTANT: NEVER\fP try to run xawtv
and lavplay or glav with hardware playback, it will not work. For
software playback it works fine.

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\fB>lavplay -p S record.avi\fP

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You should see the recorded video and hear the sound. But the decoding
of the video is done by the CPU which will place a heavy load on the system.
The advantage of this method is you don't need xawtv.

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The better way:

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\fB>lavplay -p H record.avi\fP

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The video is decoded and played by the hardware. The system load is
now very low. This will play it back on-screen using the hardware rather than
software decoding.

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You might also try:

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\fB> lavply -p C record.avi\fP

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Which will play it back using the hardware but to the video output of
the card.

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\fB> glav record.avi\fP

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Does the same as lavplay but you have an nice GUI. The options for
glav and lavplay are nearly the same. Using no option SW playback is used.

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Using hardware playback a signal for the Composite and SVHS OUT is
generated so you can view the movie on your TV.

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\fB> lav2yuv test.eli \(br yuvplay\fP

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Is a other way to get the video without sound. You can use yuvplay
once in the encoding command. When you use yuvplay in the encoding
command you see the changes made by filters and scaling. You can also
use it for slow-motion debugging.

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\fBNOTE:\fP After loading the driver's you have to start xawtv to
set up some things lavplay and glav do not, but they are needed for
HW-Playback. Don't forget to close xawtv !!

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\fBNOTE2:\fP Do not try to send glav an lavplay into background, wont work
correct !!!

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\fBNOTE3:\fP SECAM playback is now (12.3.2001) only in monochrome, but the
recording and encoding is done right.

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\fBNOTE4:\fPBad cables may reduce the quality of the image. Normally
you can't see this but when there is text you might notice a small
shadow. When you see this you should change the cable.

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\fBComing soon:\fP There is a tool which makes recoding videos very simple:
Linux Studio. You can download it at:

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Edit the video


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.SH Edit with glav


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Most tasks can be easily done by glav. Like deleting parts of the video,
cut paste and copy parts of the videos.

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glav button description

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The modifications should be saved because glav does not destructively edit
the video. This means that the original video is left untouched
and the modifications are kept in an extra \(rqEdit List\(rq file
readable with a text editor. These files can be used as an input to the other
lavtools programs such as lav2wav, lav2yuv, lavtrans.

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If you want to cut off the beginning and the end of the stream mark the
beginning and the and, and use the \(rqsave select\(rq button. The
edit list file is than used as input for the lavtools. If you want to split
a recorded video to some smaller parts simply select the parts and 
then save each part to a different listfile.

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You can see all changes to the video and sound NOW and you do not need to
recalculate anything.

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If you want to get a \&"destructive\&" version of your edited video use:

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\fB> lavtrans -o short_version.avi -f a editlist.eli\fP

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.nr ll +1
.nr t\n(ll 2
.if \n(ll>1 .RS
.IP "-o"
.nr bi 1

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specifies the output name
.IP "-f a"
.nr bi 1

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specifies the output format (AVI for example)
.IP "editlist.eli"
.nr bi 1

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is the list file where the modifications are described.
You generate the list file with the \&"save all\&" or \(rqsave select\(rq
buttons in glav.
.if \n(ll>1 .RE
.nr ll -1

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.SH Unify videos


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\fB> lavtrans -o stream.qt -f q record_1.avi record_2.avi ... record_n.avi\fP

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.nr ll +1
.nr t\n(ll 2
.if \n(ll>1 .RS
.IP "-o"
.nr bi 1

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specifies the outputfile name
.IP "-f q"
.nr bi 1

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specifies the output format, quicktime in this case
.if \n(ll>1 .RE
.nr ll -1

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This is usually not needed. Keep in your mind that there is the 2GB
file-size-limit on 32Bit systems with an older glibc.

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.SH Separate sound


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\fB> lavtrans -o sound.wav -f w stream.avi\fP

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Creates a wav file with the sound of the stream.avi
Maybe needed if you want to remove noise or if you want
to convert it to another sound format.

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Another way to split the sound is:

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\fB> lav2wav editlist.eli >sound.wav\fP

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.SH Separate images


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\fB>mkdir jpg; lavtrans -o jpg/image%05d.jpg -f i stream.avi\fP

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First create the directory \(rqjpg\(rq\&. Then lavtrans will create
single JPG images in the jpg directory from the stream.avi file. The
files will be named: image00000.jpg, image00001.jpg ....

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The jpg images created contain the whole picture. But if you have recorded 
at full size the images are stored interlaced. Usually the picture viewers
show only the first field in the jpg file.

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If you want to have the image in a single file you can use that version

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\fB> lav2yuv -f 1 stream.avi \(br y4mtoppm -L >file.pnm\fP

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If you want to split the fields into single files use that:

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\fB>  lav2yuv -f 5 ../stream.avi \(br y4mtoppm \(br
pnmsplit - image%d.pnm\fP

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Maybe interesting if you need sample images and do not want to play
around with grabbing a single image.

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.SH Creating movie transitions


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Thanks to Philipp Zabel's lavpipe, we can now make simple transitions
between movies or combine multiple layers of movies.

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Philipp wrote this HOWTO on how to make transitions:

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Let's assume simple this scene: We have two input videos intro.avi
and epilogue.mov and want to make intro.avi transition into epilogue.mov with a
duration of one second (that is 25 frames for PAL or 30 frames for NTSC).

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Intro.avi and epiloque.mov have to be of the same format (the same
frame rate and resolution). In this example they
are both 352x288 PAL files. intro.avi contains 250 frames and
epilogue.mov is 1000 frames long.

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Therefore our output file will contain: 

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.nr ll +1
.nr t\n(ll 2
.if \n(ll>1 .RS
.IP ""
.nr bi 1

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the first 225 frames of intro.avi
.IP ""
.nr bi 1

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a 25 frame transition containing the last 25 frames of intro.avi and
the first 25 frames of epilogue.mov
.IP ""
.nr bi 1

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the last 975 frames of epilogue.mov
.if \n(ll>1 .RE
.nr ll -1

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We could get the last 25 frames of intro.avi by calling:

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\fB>lav2yuv -o 225 -f 25 intro.avi\fP

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\fB-o 255\fP, the offset, tells lav2yuv to begin with frame # 225 and
\fB -f 25\fP makes it output 25 frames from there on.

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Another possibility is:

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\fB> lav2yuv -o -25 intro.avi\fP

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Since negative offsets are counted from the end.

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And the first 25 frames of epilogue.mov:

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\fB> lav2yuv -f 25 epilogue.mov\fP

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\fB-o\fP defaults to an offset of zero

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But we need to combine the two streams with lavpipe. So the call would be:

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\fB> lavpipe \(rqlav2yuv -o 255 -f 25 intro.avi\(rq \(rqlav2yuv -f 25 epilogue.mov\(rq \fP

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The output of this is a raw yuv stream that can be fed into 
transist.flt.

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transist.flt needs to be informed about the duration of the transition and
the opacity of the second stream at the beginning and at the end of the
transition:

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.nr ll +1
.nr t\n(ll 2
.if \n(ll>1 .RS
.IP "-o num"
.nr bi 1

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opacity of second input at the beginning [0-255]
.IP "-O num"
.nr bi 1

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opacity of second input at the end [0-255]
.IP "-d num"
.nr bi 1

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duration of transition in frames
.if \n(ll>1 .RE
.nr ll -1

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An opacity of 0 means that the second stream is fully transparent
(only stream one visible), at 255 stream two is fully opaque.

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In our case the correct call (transition from stream 1 to stream 2)
would be:

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\fB> transist.flt -o 0 -O 255 -d 25\fP

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The -s and -n parameters equate to the -o and -f parameters of lav2yuv
and are only needed if anybody wants to render only a portion of the  
transition for whatever reason. Please note that this only affects the
weighting calculations - none of the input is really skipped.  If you
use the skip parameter (-s 30, for example) you also need to skip the first
30 frames in lav2yuv (-o 30) in order to get the expected result. If you
didn't understand this send an email to the authors or simply ignore
-s and -n. The whole procedure will eventually be automated.

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Now we want to compress the yuv stream with yuv2lav:

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\fB> yuv2lav -f a -q 80 -o transition.avi\fP

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Reads the yuv stream from stdin and outputs an avi file (-f a) with
compressed jpeg frames of quality 80.

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Now we have the whole command for creating a transition:

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\fB> ypipe \(rqlav2yuv -o 255 -f 25 intro.avi\(rq \(rqlav2yuv
-f 25 epilogue.mov\(rq \(br transist.flt -o 0 -O 255 -d 25 \(br yuv2lav -f a -q 80 -o transition.avi\fP

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The resulting video can be written as a LAV Edit List, a plain text file
containing the following lines:

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.DS
.sp 
.ft RR
.nf
LAV Edit List
PAL
3
intro.avi
transition.avi
epilogue.mov
0 0 224
1 0 24
2 25 999
.DE
.fi 
.ec
.ft P
.sp

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This file can be fed into glav or lavplay, or you can pipe it into 
mpeg2enc with lav2yuv or combine the whole stuff into one single mjpeg
file with lavtrans or lav2yuv\(bryuv2lav.

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Converting the stream to MPEG or DIVx videos


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