[MPlayer-DOCS] CVS: main/DOCS/xml/en documentation.xml, 1.22, 1.23 mencoder.xml, 1.38, 1.39 video.xml, 1.77, 1.78
Diego Biurrun CVS
syncmail at mplayerhq.hu
Sat Mar 19 17:55:28 CET 2005
CVS change done by Diego Biurrun CVS
Update of /cvsroot/mplayer/main/DOCS/xml/en
In directory mail:/var2/tmp/cvs-serv24774/DOCS/xml/en
Modified Files:
documentation.xml mencoder.xml video.xml
Log Message:
precise framerate values everywhere
patch by Corey Hickey <bugfood-ml at fatooh dot org>
Index: documentation.xml
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/xml/en/documentation.xml,v
retrieving revision 1.22
retrieving revision 1.23
diff -u -r1.22 -r1.23
--- documentation.xml 7 Jan 2005 22:33:01 -0000 1.22
+++ documentation.xml 19 Mar 2005 16:55:25 -0000 1.23
@@ -141,7 +141,7 @@
</simpara></listitem>
<listitem><simpara>
FPS correction with <option>-ofps</option> option (useful when encoding
- 29.97 fps VOB to 24 fps AVI)
+ 30000/1001 fps VOB to 24000/1001 fps AVI)
</simpara></listitem>
<listitem><simpara>
Using our very powerful filter system (crop, expand, flip, postprocess,
Index: mencoder.xml
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/xml/en/mencoder.xml,v
retrieving revision 1.38
retrieving revision 1.39
diff -u -r1.38 -r1.39
--- mencoder.xml 25 Feb 2005 23:25:57 -0000 1.38
+++ mencoder.xml 19 Mar 2005 16:55:25 -0000 1.39
@@ -718,12 +718,12 @@
<title>Interlacing and Telecine</title>
<para>
- Almost all movies are shot at 24 fps. Because NTSC is 29.97 fps, some
+ Almost all movies are shot at 24 fps. Because NTSC is 30000/1001 fps, some
processing must be done to this 24 fps video to make it run at the correct
NTSC framerate. The process is called 3:2 pulldown, commonly referred to
as telecine (because pulldown is often applied during the telecine
process), and, naively described, it works by slowing the film down to
- 23.976 fps, and repeating every fourth frame.
+ 24000/1001 fps, and repeating every fourth frame.
</para>
<para>
@@ -746,7 +746,7 @@
<para>
For movies shot at 24 fps, the video on the NTSC DVD is either telecined
- 29.97 fps, or else it is progressive 24 fps and intended to be telecined
+ 30000/1001, or else it is progressive 24000/1001 fps and intended to be telecined
on-the-fly by a DVD player. On the other hand, TV series are usually
only interlaced, not telecined. This is not a hard rule: some TV series
are interlaced (such as Buffy the Vampire Slayer) whereas some are a
@@ -810,7 +810,7 @@
of Secrets (widescreen edition, of course), and you want to rip this DVD
so that you can add it to your Home Theatre PC. This is a region 1 DVD,
so it's NTSC. The example below will still apply to PAL, except you'll
- omit <option>-ofps 23.976</option> (because the output framerate is the
+ omit <option>-ofps 24000/1001</option> (because the output framerate is the
same as the input framerate), and of course the crop dimensions will be
different.
</para>
@@ -819,7 +819,7 @@
After running <option>mplayer dvd://1</option>, we follow the process
detailed in the section <link linkend="menc-feat-telecine">How to deal
with telecine and interlacing in NTSC DVDs</link> and discover that it's
- 24 fps progressive video, which means that we needn't use an inverse
+ 24000/1001 fps progressive video, which means that we needn't use an inverse
telecine filter, such as <option>pullup</option> or
<option>filmdint</option>.
</para>
@@ -888,13 +888,13 @@
<para>
We're now ready to do the two pass encode. Pass one:
- <screen>mencoder dvd://1 -ofps 23.976 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
+ <screen>mencoder dvd://1 -ofps 24000/1001 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=2400:v4mv:mbd=2:trell:cmp=3:subcmp=3:mbcmp=3:autoaspect:vpass=1 \
-o Harry_Potter_2.avi</screen>
And pass two is the same, except that we specify <option>vpass=2</option>:
- <screen>mencoder dvd://1 -ofps 23.976 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
+ <screen>mencoder dvd://1 -ofps 24000/1001 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=2400:v4mv:mbd=2:trell:cmp=3:subcmp=3:mbcmp=3:autoaspect:vpass=2 \
-o Harry_Potter_2.avi</screen>
</para>
@@ -943,8 +943,10 @@
<sect1 id="menc-feat-telecine">
<title>How to deal with telecine and interlacing within NTSC DVDs</title>
-<formalpara>
+<sect2 id="menc-feat-telecine-intro">
<title>Introduction</title>
+<formalpara>
+<title>What is telecine?</title>
<para>
I suggest you visit this page if you don't understand much of what
is written in this document:
@@ -953,48 +955,80 @@
description of what telecine is.
</para></formalpara>
+<formalpara>
+<title>A note about the numbers.</title>
+<para>
+ Many documents, including the guide linked above, refer to the fields
+ per second value of NTSC video as 59.94 and the corresponding frames
+ per second values as 29.97 (for telecined and interlaced) and 23.976
+ (for progressive). For simplicity, some documents even round these
+ numbers to 60, 30, and 24.
+</para></formalpara>
+
<para>
- For technical reasons pertaining to the limitations of early
- television hardware, all video intended to be displayed on an NTSC
- television set must be 59.94 fields per second. Made-for-TV movies
- and shows are often filmed directly at 59.94 fields per second, but
- the majority of cinema is filmed at 24 or 23.976 frames per
+ Strictly speaking, all those numbers are approximations. Black and
+ white NTSC video was exactly 60 fields per second, but 60000/1001
+ was later chosen to accomodate color data while remaining compatible
+ with contemporary black and white televisions. Digital NTSC video
+ (such as on a DVD) is also 60000/1001 fields per second. From this,
+ interlaced and telecined video are derived to be 30000/1001 frames
+ per second; progressive video is 24000/1001 frames per second.
+</para>
+
+<para>
+ Older versions of the <application>MEncoder</application> documentation
+ and many archived mailing list posts refer to 59.94, 29.97, and 23.976.
+ All <application>MEncoder</application> documentation has been updated
+ to use the fractional values, and you should use them too.
+</para>
+
+<para>
+ <option>-ofps 23.976</option> is incorrect.
+ <option>-ofps 24000/1001</option> should be used instead.
+</para>
+
+<formalpara>
+<title>How telecine is used.</title>
+<para>
+ All video intended to be displayed on an NTSC
+ television set must be 60000/1001 fields per second. Made-for-TV movies
+ and shows are often filmed directly at 60000/1001 fields per second, but
+ the majority of cinema is filmed at 24 or 24000/1001 frames per
second. When cinematic movie DVDs are mastered, the video is then
converted for television using a process called telecine.
-</para>
+</para></formalpara>
<para>
- On a DVD, the video is never actually stored as 59.94 fields per
- second. For video that was originally 59.94, each pair of fields is
- combined to form a frame, resulting in 29.97 frames per
+ On a DVD, the video is never actually stored as 60000/1001 fields per
+ second. For video that was originally 60000/1001, each pair of fields is
+ combined to form a frame, resulting in 30000/1001 frames per
second. Hardware DVD players then read a flag embedded in the video
stream to determine whether the odd- or even-numbered lines should
form the first field.
</para>
<para>
- Usually, 23.976 frames per second content stays as it is when
+ Usually, 24000/1001 frames per second content stays as it is when
encoded for a DVD, and the DVD player must perform telecining
on-the-fly. Sometimes, however, the video is telecined
<emphasis>before</emphasis> being stored on the DVD; even though it
- was originally 23.976 frames per second, it becomes 59.94 fields per
- second, and is stored on the disk as 29.97 frames per second.
+ was originally 24000/1001 frames per second, it becomes 60000/1001 fields per
+ second. When it is stored on the DVD, pairs of fields are combined to form
+ 30000/1001 frames per second.
</para>
<para>
- When looking at individual frames formed from 59.94 fields per
+ When looking at individual frames formed from 60000/10001 fields per
second video, telecined or otherwise, interlacing is clearly visible
wherever there is any motion, because one field (say, the
- even-numbered lines) represents a moment in time 1/59.94th of a
- second later than the other. Playing interlaced video on a computer
+ even-numbered lines) represents a moment in time 1/(60000/1001)
+ seconds later than the other. Playing interlaced video on a computer
looks ugly both because the monitor is higher resolution and because
the video is shown frame-after-frame instead of field-after-field.
</para>
-<para>
-Notes:
-</para>
<itemizedlist>
+<title>Notes:</title>
<listitem><para>
This section only applies to NTSC DVDs, and not PAL.
</para></listitem>
@@ -1011,6 +1045,7 @@
<link linkend="menc-feat-telecine-footnotes">[1]</link>
</para></listitem>
</itemizedlist>
+</sect2>
<sect2 id="menc-feat-telecine-ident">
<title>How to tell what type of video you have</title>
@@ -1018,7 +1053,7 @@
<sect3 id="menc-feat-telecine-ident-progressive">
<title>Progressive</title>
<para>
- Progressive video was originally filmed at 23.976 fps, and stored
+ Progressive video was originally filmed at 24000/1001 fps, and stored
on the DVD without alteration.
</para>
@@ -1027,10 +1062,10 @@
<application>MPlayer</application> will print the following line as
soon as the movie begins to play:
- <screen> demux_mpg: 24fps progressive NTSC content detected, switching framerate.</screen>
+ <screen> demux_mpg: 24000/1001 fps progressive NTSC content detected, switching framerate.</screen>
From this point forward, demux_mpg should never say it finds
- "30fps NTSC content."
+ "30000/1001 fps NTSC content."
</para>
<para>
@@ -1063,7 +1098,7 @@
<sect3 id="menc-feat-telecine-ident-telecined">
<title>Telecined</title>
<para>
- Telecined video was originally filmed at 23.976, but was telecined
+ Telecined video was originally filmed at 24000/1001, but was telecined
<emphasis>before</emphasis> it was written to the DVD.
</para>
@@ -1100,7 +1135,7 @@
<para>
Sometimes telecined video on DVDs is referred to as
- "hard-telecine". Since hard-telecine is already 59.94 fields
+ "hard-telecine". Since hard-telecine is already 60000/1001 fields
per second, the DVD player plays the video without any manipulation.
</para>
</sect3>
@@ -1108,10 +1143,10 @@
<sect3 id="menc-feat-telecine-ident-interlaced">
<title>Interlaced</title>
<para>
- Interlaced video was originally filmed at 59.94 fields per second,
- and stored on the DVD as 29.97 frames per second. The interlacing effect
+ Interlaced video was originally filmed at 60000/1001 fields per second,
+ and stored on the DVD as 30000/1001 frames per second. The interlacing effect
(often called "combing") is a result of combining pairs of
- fields into frames. Each field is supposed to be 1/59.94 seconds apart,
+ fields into frames. Each field is supposed to be 1/(60000/1001) seconds apart,
and when they are displayed simultaneously the difference is apparent.
</para>
@@ -1130,18 +1165,18 @@
<title>Mixed progressive and telecine</title>
<para>
All of a "mixed progressive and telecine" video was originally
- 23.976 frames per second, but some parts of it ended up being telecined.
+ 24000/1001 frames per second, but some parts of it ended up being telecined.
</para>
<para>
When <application>MPlayer</application> plays this category, it will
- (often repeatedly) switch back and forth between "30fps NTSC"
- and "24fps progressive NTSC". Watch the bottom of
+ (often repeatedly) switch back and forth between "30000/1001 fps NTSC"
+ and "24000/1001 fps progressive NTSC". Watch the bottom of
<application>MPlayer</application>'s output to see these messages.
</para>
<para>
- You should check the "30fps NTSC" sections to make sure
+ You should check the "30000/1001 fps NTSC" sections to make sure
they are actually telecine, and not just interlaced.
</para>
</sect3>
@@ -1155,7 +1190,7 @@
<para>
This category looks just like "mixed progressive and telecine",
- until you examine the 30fps sections and see that they don't have the
+ until you examine the 30000/1001 fps sections and see that they don't have the
telecine pattern.
</para>
</sect3>
@@ -1175,12 +1210,12 @@
<para>
Progressive video requires no special filtering to encode. The only
parameter you need to be sure to use is
- <option>-ofps 23.976</option>. Otherwise, <application>MEncoder</application>
- will try to encode at 29.97 fps and duplicate frames.
+ <option>-ofps 24000/1001</option>. Otherwise, <application>MEncoder</application>
+ will try to encode at 30000/1001 fps and will duplicate frames.
</para>
<para>
- <screen>mencoder dvd://1 -nosound -ovc lavc -ofps 23.976</screen>
+ <screen>mencoder dvd://1 -nosound -ovc lavc -ofps 24000/1001</screen>
</para>
<para>
@@ -1196,7 +1231,7 @@
<sect3 id="menc-feat-telecine-encode-telecined">
<title>Telecined</title>
<para>
- Telecine can be reversed to retrieve the original 23.976 content,
+ Telecine can be reversed to retrieve the original 24000/1001 content,
using a process called inverse-telecine.
<application>MPlayer</application> contains several filters to
accomplish this; the best filter, <option>pullup</option>, is described
@@ -1251,7 +1286,7 @@
<application>MEncoder G2</application>, but that isn't here yet. You
might experience crahes. Anyway, the purpose of <option> -vf
tfields</option> is to create a full frame out of each field, which
- makes the framerate 59.94. The advantage of this approach is that no
+ makes the framerate 60000/1001. The advantage of this approach is that no
data is ever lost; however, since each frame comes from only one
field, the missing lines have to be interpolated somehow. There are
no very good methods of generating the missing data, and so the
@@ -1268,14 +1303,14 @@
<option>-fps</option> and <option>-ofps</option> to be twice the
framerate of your original source.
- <screen>mencoder dvd://1 -nosound -vf tfields=2 -ovc lavc -fps 59.94 -ofps 59.94</screen>
+ <screen>mencoder dvd://1 -nosound -vf tfields=2 -ovc lavc -fps 60000/1001 -ofps 60000/1001</screen>
</para></listitem>
<listitem><para>
If you plan on downscaling dramatically, you can extract and encode
only one of the two fields. Of course, you'll lose half the vertical
resolution, but if you plan on downscaling to at most 1/2 of the
original, the loss won't matter much. The result will be a
- progressive 29.97 frames per second file. The procedure is to use
+ progressive 30000/1001 frames per second file. The procedure is to use
<option>-vf field</option>, then crop
<link linkend="menc-feat-telecine-footnotes">[1]</link> and scale
appropriately. Remember that you'll have to adjust the scale to
@@ -1296,8 +1331,8 @@
rescaling; unless you really know what you're doing,
inverse-telecine before cropping, too
<link linkend="menc-feat-telecine-footnotes">[1]</link>.
- <option>-ofps 23.976</option> is needed here because the output video
- will be 23.976 frames per second.
+ <option>-ofps 24000/1001</option> is needed here because the output video
+ will be 24000/1001 frames per second.
</para>
<itemizedlist>
@@ -1311,7 +1346,7 @@
accurate method available for encoding both telecine and
"mixed progressive and telecine".
- <screen>mencoder dvd://1 -nosound -vf pullup,softskip -ovc lavc -ofps 23.976</screen>
+ <screen>mencoder dvd://1 -nosound -vf pullup,softskip -ovc lavc -ofps 24000/1001</screen>
</para>
@@ -1324,9 +1359,9 @@
a video and makes the entire file telecined. If we follow
softpulldown with either <option>detc</option> or
<option>ivtc</option>, the final result will be entirely
- progressive. <option>-ofps 23.976</option> is needed.
+ progressive. <option>-ofps 24000/1001</option> is needed.
- <screen>mencoder dvd://1 -nosound -vf softpulldown,ivtc=1 -ovc lavc -ofps 23.976</screen>
+ <screen>mencoder dvd://1 -nosound -vf softpulldown,ivtc=1 -ovc lavc -ofps 24000/1001</screen>
</para>
</listitem>
@@ -1363,10 +1398,10 @@
<para>
This option should definitely not be used if you want to eventually
display the video on an interlaced device (with a TV card, for
- example). If you have interlaced frames in a 23.976 frames per
+ example). If you have interlaced frames in a 24000/1001 frames per
second video, they will be telecined along with the progressive
frames. Half of the interlaced "frames" will be displayed for three
- fields' duration (3/59.94 seconds), resulting in a flicking
+ fields' duration (3/(60000/1001) seconds), resulting in a flicking
"jump back in time" effect that looks quite bad. If you
even attempt this, you <emphasis role="bold">must</emphasis> use a
deinterlacing filter like <option>lb</option> or
@@ -1377,9 +1412,9 @@
It may also be a bad idea for progressive display, too. It will drop
pairs of consecutive interlaced fields, resulting in a discontinuity
that can be more visible than with the second method, which shows
- some progressive frames twice. 29.97 frames per second interlaced
+ some progressive frames twice. 30000/1001 frames per second interlaced
video is already a bit choppy because it really should be shown at
- 59.94 fields per second, so the duplicate frames don't stand out as
+ 60000/1001 fields per second, so the duplicate frames don't stand out as
much.
</para>
Index: video.xml
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/xml/en/video.xml,v
retrieving revision 1.77
retrieving revision 1.78
diff -u -r1.77 -r1.78
--- video.xml 5 Feb 2005 12:55:12 -0000 1.77
+++ video.xml 19 Mar 2005 16:55:25 -0000 1.78
@@ -2082,10 +2082,10 @@
that you use that unless you have problems with it. See the man page for further
info about <option>-vf lavc/fame</option>.
Using lavc is highly recommended. Currently there is no way of setting the fps
-of the em8300 which means that it is fixed to 29.97fps. Because of this it is
+of the em8300 which means that it is fixed to 30000/1001 fps. Because of this it is
highly recommended that you use <option>-vf lavc=<replaceable>quality</replaceable>:25</option>
-especially if you are using prebuffering. Then why 25 and not 29.97? Well, the
-thing is that when you use 29.97 the picture becomes a bit jumpy. The reason for
+especially if you are using prebuffering. Then why 25 and not 30000/1001? Well, the
+thing is that when you use 30000/1001 the picture becomes a bit jumpy. The reason for
this is unknown to us. If you set it to somewhere between 25 and 27 the picture
becomes stable. For now all we can do is accept this for a fact.
</para></listitem>
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