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misc fixes
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@15035 b3059339-0415-0410-9bf9-f77b7e298cf2
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@ -521,7 +521,7 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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<title>Making a high quality MPEG-4 ("DivX") rip of a DVD movie</title>
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<para>
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One frequently asked question is "How do I make highest quality rip for
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One frequently asked question is "How do I make the highest quality rip for
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a given size?". Another question is "How do I make the highest quality DVD
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rip possible? I don't care about file size, I just want the best quality."
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</para>
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@ -552,8 +552,9 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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<para>
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If this seems to be too much for you, you should probably use one of the
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many fine front-ends that are listed on our
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<ulink url="http://mplayerhq.hu/homepage/design7/projects.html">related projects page</ulink>.
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many fine frontends that are listed in the
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<ulink url="http://mplayerhq.hu/homepage/design7/projects.html#mencoder_frontends">MEncoder section</ulink>
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of our related projects page.
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That way, you should be able to achieve high quality rips without too much
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thinking, because most of those tools are designed to take clever decisions
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for you.
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@ -592,8 +593,8 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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low enough bitrate that <systemitem class="library">libavcodec</systemitem>
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is forced to use a higher quantizer, then you're almost certainly ruining
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the quality of your video.
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In order to avoid that, you should probably down scale your video, according
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to the method which will be gone over later on that guide.
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In order to avoid that, you should probably downscale your video, according
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to the method described later on in this guide.
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In general, you should avoid CBR altogether if you care about quality.
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</para>
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@ -660,7 +661,7 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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those</link> first.
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You can compute the bitrate with the following equation:
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bitrate = (target_size_in_Mbytes - sound_size_in_Mbytes) * 1024 * 1024 / length_in_secs * 8 / 1000
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For instance, to squeeze a two-hour movie into a 702Mbytes CD, with 60Mbytes
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For instance, to squeeze a two-hour movie onto a 702MB CD, with 60MB
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of audio track, the video bitrate will have to be
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(702 - 60) * 1024 * 1024 / (120*60) * 8 / 1000 = 740kbps.
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</para>
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@ -751,20 +752,20 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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there's a limited total number of bits that you can spend; therefore it's
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necessary to find a good tradeoff between compressibility and quality.
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The CQ depends both on the bitrate and the movie resolution.
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In order to raise the CQ, typically you'd down scale the movie given that the
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In order to raise the CQ, typically you'd downscale the movie given that the
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bitrate is computed in function of the target size and the length of the
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movie, which are constant.
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A CQ below 0.18 usually ends up in a very blocky picture, because there
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aren't enough bits to code the information of each macroblock (MPEG4, like
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many other codecs, groups pixels by blocks of several pixels to compress the
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image; if there aren't enough bits, the edge of those blocks are
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image; if there aren't enough bits, the edges of those blocks are
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visible).
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It's therefore wise to take a CQ ranging from 0.20 to 0.22 for a 1 CD rip,
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and 0.26-0.28 for 2 CDs.
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Please thake note that the CQ is just an indicative figure, as depending on
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the encoded content, a CQ of 0.18 may look just fine for a Bergman, contrary
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to a movie such as The Matrix, which contains many high-motion scenes.
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On the other hand, it's worthless to raise CQ as higher than 0.30 as you'd
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On the other hand, it's worthless to raise CQ higher than 0.30 as you'd
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be wasting bits without any noticeable quality gain.
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</para>
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@ -777,7 +778,7 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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Audio is a much simpler problem to solve: if you care about quality, just
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leave it as is.
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Even AC3 5.1 streams are at most 448Kbit/s, and they're worth every bit.
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You might be tempted to transcode the audio to high quality Ogg Vorbis, but
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You might be tempted to transcode the audio to high quality Vorbis, but
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just because you don't have an A/V receiver for AC3 pass-through today
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doesn't mean you won't have one tomorrow. Future-proof your DVD rips by
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preserving the AC3 stream.
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@ -788,13 +789,13 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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<screen>mplayer source_file.vob -aid 129 -dumpaudio -dumpfile sound.ac3</screen>
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will dump into the file sound.ac3 the audio track number 129 from the file
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source_file.vob (NB: DVD VOB files usually use a different audio numbering,
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which means that the VOB audio track 128 is the 2nd audio track of the file).
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which means that the VOB audio track 129 is the 2nd audio track of the file).
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</para>
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<para>
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But sometimes you truly have no choice but to further compress the
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sound so that more bits can be spent on the video.
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Most people choose to compress audio with either MP3 or Ogg Vorbis audio
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Most people choose to compress audio with either MP3 or Vorbis audio
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codecs.
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While the latter is a very space-efficient codec, MP3 is better supported
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by hardware players, although this trend is changing.
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@ -813,13 +814,13 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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which is available in most distributions.
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If you're using Windows, a tool such as <application>BeSweet</application>
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can do the same job.
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You will compress in either Ogg Vorbis or MP3.
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You will compress in either Vorbis or MP3.
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For example:
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<screen>oggenc -q1 destination_sound.wav</screen>
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will encode destination_sound.wav with the encoding quality 1, which is
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roughly equivalent to 80Kb/s, and is the minimum quality at which you
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should encode if you care about quality.
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Please note that MEncoder currently can't currently mux Ogg Vorbis files
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Please note that MEncoder currently cannot mux Ogg Vorbis files
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into a video stream because it can only create AVI and MPEG files.
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Don't worry, this document will show you how you can do that with third
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party programs.
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@ -921,14 +922,14 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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Ideally, you'd probably want to be able to just tell the encoder to switch
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into "high quality" mode and move on.
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That would probably be nice, but unfortunately hard to implement as different
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encoding options yield different qualities depending on the source material.
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encoding options yield different quality results depending on the source material.
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That's because compression depends on the visual properties of the video
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in question.
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For example, anime and live action have very different properties and
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thus require different options to obtain optimum encoding.
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The good news is that some options should never be left out, like
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<option>mbd=2</option>, <option>trell</option>, and <option>v4mv</option>.
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See below a for detailed description of common encoding options.
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See below for a detailed description of common encoding options.
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</para>
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@ -1018,25 +1019,25 @@ vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
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when the change in a block is less than the threshold you specify, and in
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such a case, to just encode the block as "no change".
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This saves bits and perhaps speeds up encoding. vlelim=-4 and vcelim=9
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seem to be good for live movies, but seem not to help in with anime;
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seem to be good for live movies, but seem not to help with anime;
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when encoding animation, you should probably leave them unchanged.
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</para></listitem>
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<listitem><para>
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<emphasis role="bold">qpel</emphasis>: Quarter pixel motion estimation.
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MPEG-4 uses a half pixel precision for its motion search by default,
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MPEG-4 uses half pixel precision for its motion search by default,
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therefore this option comes with an overhead as more information will be
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stored in the encoded file.
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The compression gain/loss depends on the movie, but it's usually not very
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effective on anime.
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qpel always incurs a significant cost in CPU time needed to decode (+20% in
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qpel always incurs a significant cost in CPU decode time (+20% in
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practice).
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</para></listitem>
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<listitem><para>
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<emphasis role="bold">psnr</emphasis>: doesn't affect the actual encoding,
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but writes a log file giving the type/size/quality of each frame, and
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prints a sumary of PSNR (Peak Signal to Noise Ratio) at the end.
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prints a summary of PSNR (Peak Signal to Noise Ratio) at the end.
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</para></listitem>
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</itemizedlist>
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