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<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>14.2.聽How to deal with telecine and interlacing within NTSC DVDs</title><link rel="stylesheet" href="default.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.73.2"><link rel="start" href="index.html" title="MPlayer - The Movie Player"><link rel="up" href="encoding-guide.html" title="Chapter聽14.聽Encoding with MEncoder"><link rel="prev" href="menc-feat-dvd-mpeg4.html" title='14.1.聽Making a high quality MPEG-4 ("DivX") rip of a DVD movie'><link rel="next" href="menc-feat-enc-libavcodec.html" title="14.3.聽Encoding with the libavcodec codec family"><link rel="preface" href="howtoread.html" title="How to read this documentation"><link rel="chapter" href="intro.html" title="Chapter聽1.聽Introduction"><link rel="chapter" href="install.html" title="Chapter聽2.聽Installation"><link rel="chapter" href="usage.html" title="Chapter聽3.聽Usage"><link rel="chapter" href="cd-dvd.html" title="Chapter聽4.聽CD/DVD usage"><link rel="chapter" href="faq.html" title="Chapter聽5.聽Frequently Asked Questions"><link rel="chapter" href="containers.html" title="Chapter聽6.聽Containers"><link rel="chapter" href="codecs.html" title="Chapter聽7.聽Codecs"><link rel="chapter" href="video.html" title="Chapter聽8.聽Video output devices"><link rel="chapter" href="audio.html" title="Chapter聽9.聽Audio output devices"><link rel="chapter" href="tv.html" title="Chapter聽10.聽TV"><link rel="chapter" href="radio.html" title="Chapter聽11.聽Radio"><link rel="chapter" href="ports.html" title="Chapter聽12.聽Ports"><link rel="chapter" href="mencoder.html" title="Chapter聽13.聽Basic usage of MEncoder"><link rel="chapter" href="encoding-guide.html" title="Chapter聽14.聽Encoding with MEncoder"><link rel="appendix" href="bugreports.html" title="Appendix聽A.聽How to report bugs"><link rel="appendix" href="bugs.html" title="Appendix聽B.聽Known bugs"><link rel="appendix" href="skin.html" title="Appendix聽C.聽MPlayer skin format"><link rel="appendix" href="history.html" title="Appendix聽D.聽History"><link rel="subsection" href="menc-feat-telecine.html#menc-feat-telecine-intro" title="14.2.1.聽Introduction"><link rel="subsection" href="menc-feat-telecine.html#menc-feat-telecine-ident" title="14.2.2.聽How to tell what type of video you have"><link rel="subsection" href="menc-feat-telecine.html#menc-feat-telecine-encode" title="14.2.3.聽How to encode each category"><link rel="subsection" href="menc-feat-telecine.html#menc-feat-telecine-footnotes" title="14.2.4.聽Footnotes"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">14.2.聽How to deal with telecine and interlacing within NTSC DVDs</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="menc-feat-dvd-mpeg4.html">Prev</a>聽</td><th width="60%" align="center">Chapter聽14.聽Encoding with <span class="application">MEncoder</span></th><td width="20%" align="right">聽<a accesskey="n" href="menc-feat-enc-libavcodec.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="menc-feat-telecine"></a>14.2.聽How to deal with telecine and interlacing within NTSC DVDs</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="menc-feat-telecine-intro"></a>14.2.1.聽Introduction</h3></div></div></div><p><b>What is telecine?聽</b>
If you do not understand much of what is written in this document, read the
<a class="ulink" href="http://en.wikipedia.org/wiki/Telecine" target="_top">Wikipedia entry on telecine</a>.
It is an understandable and reasonably comprehensive
description of what telecine is.
</p><p><b>A note about the numbers.聽</b>
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.
</p><p>
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.
</p><p>
Older versions of the <span class="application">MEncoder</span> documentation
and many archived mailing list posts refer to 59.94, 29.97, and 23.976.
All <span class="application">MEncoder</span> documentation has been updated
to use the fractional values, and you should use them too.
</p><p>
<tt class="option">-ofps 23.976</tt> is incorrect.
<tt class="option">-ofps 24000/1001</tt> should be used instead.
</p><p><b>How telecine is used.聽</b>
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.
</p><p>
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.
</p><p>
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
<span class="emphasis"><em>before</em></span> being stored on the DVD; even though it
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.
</p><p>
When looking at individual frames formed from 60000/1001 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/(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.
</p><div class="itemizedlist"><p class="title"><b>Notes:</b></p><ul type="disc"><li><p>
This section only applies to NTSC DVDs, and not PAL.
</p></li><li><p>
The example <span class="application">MEncoder</span> lines throughout the
document are <span class="bold"><strong>not</strong></span> intended for
actual use. They are simply the bare minimum required to encode the
pertaining video category. How to make good DVD rips or fine-tune
<code class="systemitem">libavcodec</code> for maximal
quality is not within the scope of this document.
</p></li><li><p>
There are a couple footnotes specific to this guide, linked like this:
<a class="link" href="menc-feat-telecine.html#menc-feat-telecine-footnotes" title="14.2.4.聽Footnotes">[1]</a>
</p></li></ul></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="menc-feat-telecine-ident"></a>14.2.2.聽How to tell what type of video you have</h3></div></div></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-ident-progressive"></a>14.2.2.1.聽Progressive</h4></div></div></div><p>
Progressive video was originally filmed at 24000/1001 fps, and stored
on the DVD without alteration.
</p><p>
When you play a progressive DVD in <span class="application">MPlayer</span>,
<span class="application">MPlayer</span> will print the following line as
soon as the movie begins to play:
</p><pre class="screen">
demux_mpg: 24000/1001 fps progressive NTSC content detected, switching framerate.
</pre><p>
From this point forward, demux_mpg should never say it finds
"30000/1001 fps NTSC content."
</p><p>
When you watch progressive video, you should never see any
interlacing. Beware, however, because sometimes there is a tiny bit
of telecine mixed in where you would not expect. I have encountered TV
show DVDs that have one second of telecine at every scene change, or
at seemingly random places. I once watched a DVD that had a
progressive first half, and the second half was telecined. If you
want to be <span class="emphasis"><em>really</em></span> thorough, you can scan the
entire movie:
</p><pre class="screen">mplayer dvd://1 -nosound -vo null -benchmark</pre><p>
Using <tt class="option">-benchmark</tt> makes
<span class="application">MPlayer</span> play the movie as quickly as it
possibly can; still, depending on your hardware, it can take a
while. Every time demux_mpg reports a framerate change, the line
immediately above will show you the time at which the change
occurred.
</p><p>
Sometimes progressive video on DVDs is referred to as
"soft-telecine" because it is intended to
be telecined by the DVD player.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-ident-telecined"></a>14.2.2.2.聽Telecined</h4></div></div></div><p>
Telecined video was originally filmed at 24000/1001, but was telecined
<span class="emphasis"><em>before</em></span> it was written to the DVD.
</p><p>
<span class="application">MPlayer</span> does not (ever) report any
framerate changes when it plays telecined video.
</p><p>
Watching a telecined video, you will see interlacing artifacts that
seem to "blink": they repeatedly appear and disappear.
You can look closely at this by
</p><div class="orderedlist"><ol type="1"><li><pre class="screen">mplayer dvd://1</pre></li><li><p>
Seek to a part with motion.
</p></li><li><p>
Use the <span class="keycap"><b>.</b></span> key to step forward one frame at a time.
</p></li><li><p>
Look at the pattern of interlaced-looking and progressive-looking
frames. If the pattern you see is PPPII,PPPII,PPPII,... then the
video is telecined. If you see some other pattern, then the video
may have been telecined using some non-standard method;
<span class="application">MEncoder</span> cannot losslessly convert
non-standard telecine to progressive. If you do not see any
pattern at all, then it is most likely interlaced.
</p></li></ol></div><p>
</p><p>
Sometimes telecined video on DVDs is referred to as
"hard-telecine". Since hard-telecine is already 60000/1001 fields
per second, the DVD player plays the video without any manipulation.
</p><p>
Another way to tell if your source is telecined or not is to play
the source with the <tt class="option">-vf pullup</tt> and <tt class="option">-v</tt>
command line options to see how <tt class="option">pullup</tt> matches frames.
If the source is telecined, you should see on the console a 3:2 pattern
with <code class="systemitem">0+.1.+2</code> and <code class="systemitem">0++1</code>
alternating.
This technique has the advantage that you do not need to watch the
source to identify it, which could be useful if you wish to automate
the encoding procedure, or to carry out said procedure remotely via
a slow connection.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-ident-interlaced"></a>14.2.2.3.聽Interlaced</h4></div></div></div><p>
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/(60000/1001) seconds apart,
and when they are displayed simultaneously the difference is apparent.
</p><p>
As with telecined video, <span class="application">MPlayer</span> should
not ever report any framerate changes when playing interlaced content.
</p><p>
When you view an interlaced video closely by frame-stepping with the
<span class="keycap"><b>.</b></span> key, you will see that every single frame is interlaced.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-ident-mixedpt"></a>14.2.2.4.聽Mixed progressive and telecine</h4></div></div></div><p>
All of a "mixed progressive and telecine" video was originally
24000/1001 frames per second, but some parts of it ended up being telecined.
</p><p>
When <span class="application">MPlayer</span> plays this category, it will
(often repeatedly) switch back and forth between "30000/1001 fps NTSC"
and "24000/1001 fps progressive NTSC". Watch the bottom of
<span class="application">MPlayer</span>'s output to see these messages.
</p><p>
You should check the "30000/1001 fps NTSC" sections to make sure
they are actually telecine, and not just interlaced.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-ident-mixedpi"></a>14.2.2.5.聽Mixed progressive and interlaced</h4></div></div></div><p>
In "mixed progressive and interlaced" content, progressive
and interlaced video have been spliced together.
</p><p>
This category looks just like "mixed progressive and telecine",
until you examine the 30000/1001 fps sections and see that they do not have the
telecine pattern.
</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="menc-feat-telecine-encode"></a>14.2.3.聽How to encode each category</h3></div></div></div><p>
As I mentioned in the beginning, example <span class="application">MEncoder</span>
lines below are <span class="bold"><strong>not</strong></span> meant to actually be used;
they only demonstrate the minimum parameters to properly encode each category.
</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-encode-progressive"></a>14.2.3.1.聽Progressive</h4></div></div></div><p>
Progressive video requires no special filtering to encode. The only
parameter you need to be sure to use is <tt class="option">-ofps 24000/1001</tt>.
Otherwise, <span class="application">MEncoder</span>
will try to encode at 30000/1001 fps and will duplicate frames.
</p><p>
</p><pre class="screen">mencoder dvd://1 -oac copy -ovc lavc -ofps 24000/1001</pre><p>
</p><p>
It is often the case, however, that a video that looks progressive
actually has very short parts of telecine mixed in. Unless you are
sure, it is safest to treat the video as
<a class="link" href="menc-feat-telecine.html#menc-feat-telecine-encode-mixedpt" title="14.2.3.4.聽Mixed progressive and telecine">mixed progressive and telecine</a>.
The performance loss is small
<a class="link" href="menc-feat-telecine.html#menc-feat-telecine-footnotes" title="14.2.4.聽Footnotes">[3]</a>.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-encode-telecined"></a>14.2.3.2.聽Telecined</h4></div></div></div><p>
Telecine can be reversed to retrieve the original 24000/1001 content,
using a process called inverse-telecine.
<span class="application">MPlayer</span> contains several filters to
accomplish this; the best filter, <tt class="option">pullup</tt>, is described
in the <a class="link" href="menc-feat-telecine.html#menc-feat-telecine-encode-mixedpt" title="14.2.3.4.聽Mixed progressive and telecine">mixed
progressive and telecine</a> section.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="menc-feat-telecine-encode-interlaced"></a>14.2.3.3.聽Interlaced</h4></div></div></div><p>
For most practical cases it is not possible to retrieve a complete
progressive video from interlaced content. The only way to do so
without losing half of the vertical resolution is to double the
framerate and try to "guess" what ought to make up the
corresponding lines for each field (this has drawbacks - see method 3).
</p><div class="orderedlist"><ol type="1"><li><p>
Encode the video in interlaced form. Normally, interlacing wreaks
havoc with the encoder's ability to compress well, but
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