CVS change done by Guillaume Poirier CVS
Update of /cvsroot/mplayer/main/DOCS/xml/en
In directory mail:/var2/tmp/cvs-serv26323/en
Modified Files:
encoding-guide.xml
Log Message:
Moves the "audio" section just before the "muxing" section. + fixes suggested by Jeff
Index: encoding-guide.xml
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/xml/en/encoding-guide.xml,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- encoding-guide.xml 24 Jul 2005 20:53:54 -0000 1.2
+++ encoding-guide.xml 24 Jul 2005 21:37:24 -0000 1.3
@@ -972,7 +972,7 @@
change the bitrate as well!.
</para>
<para>
- Bitrate does <emphasis role="bold">not</emphasis> scale proportional
+ Bitrate does <emphasis role="bold">not</emphasis> scale proportionally
to resolution.
That is to say, a 320x240 file at 200 kbit/sec will not be the same
quality as the same movie at 640x480 and 800 kbit/sec!
@@ -1010,7 +1010,7 @@
rigor.
Further, given that movies vary greatly with regard to noise, detail,
degree of motion, etc., it's futile to make general recommendations
- for bits per length-of-diagonal (the analogue of bits per pixel,
+ for bits per length-of-diagonal (the analog of bits per pixel,
using the square root).
</para>
<para>
@@ -1082,70 +1082,39 @@
</sect2>
-<sect2 id="menc-feat-dvd-mpeg4-audio">
-<title>Audio</title>
+<sect2 id="menc-feat-dvd-mpeg4-filtering">
+<title>Filtering</title>
<para>
- Audio is a much simpler problem to solve: if you care about quality, just
- leave it as is.
- Even AC3 5.1 streams are at most 448Kbit/s, and they are worth every bit.
- You might be tempted to transcode the audio to high quality Vorbis, but
- just because you do not have an A/V receiver for AC3 pass-through today
- does not mean you will not have one tomorrow. Future-proof your DVD rips by
- preserving the AC3 stream.
- You can keep the AC3 stream either by copying it directly into the video
- stream <link linkend="menc-feat-mpeg4">during the encoding</link>.
- You can also extract the AC3 stream in order to mux it into containers such
- as NUT or Matroska.
- <screen>mplayer <replaceable>source_file.vob</replaceable> -aid 129 -dumpaudio -dumpfile <replaceable>sound.ac3</replaceable></screen>
- will dump into the file <replaceable>sound.ac3</replaceable> the
- audio track number 129 from the file
- <replaceable>source_file.vob</replaceable> (NB: DVD VOB files
- usually use a different audio numbering,
- which means that the VOB audio track 129 is the 2nd audio track of the file).
+ In general, you want to do as little filtering as possible to the movie
+ in order to remain close to the original DVD source. Cropping is often
+ necessary (as described above), but avoid to scale the video. Although
+ scaling down is sometimes preferred to using higher quantizers, we want
+ to avoid both these things: remember that we decided from the start to
+ trade bits for quality.
</para>
<para>
- But sometimes you truly have no choice but to further compress the
- sound so that more bits can be spent on the video.
- Most people choose to compress audio with either MP3 or Vorbis audio
- codecs.
- While the latter is a very space-efficient codec, MP3 is better supported
- by hardware players, although this trend is changing.
+ Also, do not adjust gamma, contrast, brightness, etc. What looks good
+ on your display may not look good on others. These adjustments should
+ be done on playback only.
</para>
<para>
- First of all, you will have to convert the DVD sound into a WAV file that the
- audio codec can use as input.
- For example:
- <screen>mplayer <replaceable>source_file.vob</replaceable> -ao pcm:file=<replaceable>destination_sound.wav</replaceable> -vc dummy -aid 1 -vo null</screen>
- will dump the second audio track from the file
- <replaceable>source_file.vob</replaceable> into the file
- <replaceable>destination_sound.wav</replaceable>.
- You may want to normalize the sound before encoding, as DVD audio tracks
- are commonly recorded at low volumes.
- You can use the tool <application>normalize</application> for instance,
- which is available in most distributions.
- If you are using Windows, a tool such as <application>BeSweet</application>
- can do the same job.
- You will compress in either Vorbis or MP3.
- For example:
- <screen>oggenc -q1 <replaceable>destination_sound.wav</replaceable></screen>
- will encode <replaceable>destination_sound.wav</replaceable> with
- the encoding quality 1, which is roughly equivalent to 80Kb/s, and
- is the minimum quality at which you should encode if you care about
- quality.
- Please note that MEncoder currently cannot mux Vorbis audio tracks
- into the output file because it only supports AVI and MPEG
- containers as an output, each of which may lead to audio/video
- playback synchronization problems with some players when the AVI file
- contain VBR audio streams such as Vorbis.
- Do not worry, this document will show you how you can do that with third
- party programs.
+ One thing you might want to do, however, is pass the video through a
+ very light denoise filter, such as <option>-vf hqdn3d=2:1:2</option>.
+ Again, it is a matter of putting those bits to better use: why waste them
+ encoding noise when you can just add that noise back in during playback?
+ Increasing the parameters for <option>hqdn3d</option> will further
+ improve compressibility, but if you increase the values too much, you
+ risk degrading the image visibily. The suggested values above
+ (<option>2:1:2</option>) are quite conservative; you should feel free to
+ experiment with higher values and observe the results for yourself.
</para>
</sect2>
+
<sect2 id="menc-feat-dvd-mpeg4-interlacing">
<title>Interlacing and Telecine</title>
@@ -1254,34 +1223,67 @@
</para>
</sect2>
-<sect2 id="menc-feat-dvd-mpeg4-filtering">
-<title>Filtering</title>
+
+<sect2 id="menc-feat-dvd-mpeg4-audio">
+<title>Audio</title>
<para>
- In general, you want to do as little filtering as possible to the movie
- in order to remain close to the original DVD source. Cropping is often
- necessary (as described above), but do not scale the video. Although
- scaling down is sometimes preferred to using higher quantizers, we want
- to avoid both these things: remember that we decided from the start to
- trade bits for quality.
+ Audio is a much simpler problem to solve: if you care about quality, just
+ leave it as is.
+ Even AC3 5.1 streams are at most 448Kbit/s, and they are worth every bit.
+ You might be tempted to transcode the audio to high quality Vorbis, but
+ just because you do not have an A/V receiver for AC3 pass-through today
+ does not mean you will not have one tomorrow. Future-proof your DVD rips by
+ preserving the AC3 stream.
+ You can keep the AC3 stream either by copying it directly into the video
+ stream <link linkend="menc-feat-mpeg4">during the encoding</link>.
+ You can also extract the AC3 stream in order to mux it into containers such
+ as NUT or Matroska.
+ <screen>mplayer <replaceable>source_file.vob</replaceable> -aid 129 -dumpaudio -dumpfile <replaceable>sound.ac3</replaceable></screen>
+ will dump into the file <replaceable>sound.ac3</replaceable> the
+ audio track number 129 from the file
+ <replaceable>source_file.vob</replaceable> (NB: DVD VOB files
+ usually use a different audio numbering,
+ which means that the VOB audio track 129 is the 2nd audio track of the file).
</para>
<para>
- Also, do not adjust gamma, contrast, brightness, etc. What looks good
- on your display may not look good on others. These adjustments should
- be done on playback only.
+ But sometimes you truly have no choice but to further compress the
+ sound so that more bits can be spent on the video.
+ Most people choose to compress audio with either MP3 or Vorbis audio
+ codecs.
+ While the latter is a very space-efficient codec, MP3 is better supported
+ by hardware players, although this trend is changing.
</para>
<para>
- One thing you might want to do, however, is pass the video through a
- very light denoise filter, such as <option>-vf hqdn3d=2:1:2</option>.
- Again, it is a matter of putting those bits to better use: why waste them
- encoding noise when you can just add that noise back in during playback?
- Increasing the parameters for <option>hqdn3d</option> will further
- improve compressibility, but if you increase the values too much, you
- risk degrading the image visibily. The suggested values above
- (<option>2:1:2</option>) are quite conservative; you should feel free to
- experiment with higher values and observe the results for yourself.
+ First of all, you will have to convert the DVD sound into a WAV file that the
+ audio codec can use as input.
+ For example:
+ <screen>mplayer <replaceable>source_file.vob</replaceable> -ao pcm:file=<replaceable>destination_sound.wav</replaceable> -vc dummy -aid 1 -vo null</screen>
+ will dump the second audio track from the file
+ <replaceable>source_file.vob</replaceable> into the file
+ <replaceable>destination_sound.wav</replaceable>.
+ You may want to normalize the sound before encoding, as DVD audio tracks
+ are commonly recorded at low volumes.
+ You can use the tool <application>normalize</application> for instance,
+ which is available in most distributions.
+ If you are using Windows, a tool such as <application>BeSweet</application>
+ can do the same job.
+ You will compress in either Vorbis or MP3.
+ For example:
+ <screen>oggenc -q1 <replaceable>destination_sound.wav</replaceable></screen>
+ will encode <replaceable>destination_sound.wav</replaceable> with
+ the encoding quality 1, which is roughly equivalent to 80Kb/s, and
+ is the minimum quality at which you should encode if you care about
+ quality.
+ Please note that MEncoder currently cannot mux Vorbis audio tracks
+ into the output file because it only supports AVI and MPEG
+ containers as an output, each of which may lead to audio/video
+ playback synchronization problems with some players when the AVI file
+ contain VBR audio streams such as Vorbis.
+ Do not worry, this document will show you how you can do that with third
+ party programs.
</para>
</sect2>
