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Diffstat (limited to 'DOCS/xml')
| -rw-r--r-- | DOCS/xml/en/encoding-guide.xml | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/DOCS/xml/en/encoding-guide.xml b/DOCS/xml/en/encoding-guide.xml index 6c418a6d05..b54c401171 100644 --- a/DOCS/xml/en/encoding-guide.xml +++ b/DOCS/xml/en/encoding-guide.xml @@ -1288,6 +1288,48 @@ Note the <option>ilmv</option> and <option>ildct</option> options. </sect2> +<sect2 id="menc-feat-dvd-mpeg4-av-sync"> +<title>Notes on Audio/Video synchronization</title> +<para> +<application>MEncoder</application>'s audio/video synchronization +algorithms were designed with the intention of recovering files with +broken sync. +However they seem to cause unnecessary skipping and duplication of +frames, and possibly slight A/V desync, when used with proper input. +It is therefore recommended that you switch to basic A/V sync with +the <option>-mc 0</option> option, or put this in your +<systemitem>~/.mplayer/mencoder</systemitem> config file, as long as +you are only working with good sources (DVD, TV capture, high quality +MPEG-4 rips, etc) and not broken ASF/RM/MOV files. +</para> +<para> +If you want to further guard against strange frame skips and +duplication, you can use both <option>-mc 0</option> and +<option>-noskip</option>. +This will prevent <emphasis>all</emphasis> A/V sync, and copy frames +one-to-one, so you cannot use it if you will be using any filters that +unpredictably add or drop frames, or if your input file has variable +framerate! +Therefore, using <option>-noskip</option> is not in general recommended. +</para> +<para> +The so-called "three-pass" encoding which <application>MEncoder</application> +supports has been reported to cause A/V desync. +This will definitely happen if it is used in conjunction with certain +filters, therefore, it is now recommended <emphasis>not</emphasis> to +use three-pass mode. +This feature is only left for compatibility purposes and for expert +users who understand when it is safe to use and when it is not. +If you have never heard of three-pass mode before, forget that we +even mentioned it! +</para> +<para> +There have also been reports of A/V desync when encoding from stdin +with <application>MEncoder</application>. +Do not do this! Always use a file or CD/DVD/etc device as input. +</para> +</sect2> + <sect2 id="menc-feat-dvd-mpeg4-audio"> <title>Audio</title> |