[MPlayer-users] Conversion from avi to mpeg2 summary

[Giacomo Comes]

On Mon, Jun 27, 2005 at 05:23:31PM +0200, Guillaume POIRIER wrote:
> Hej,
> 
> On 6/27/05, Giacomo Comes <comes at naic.edu> wrote:
> > On Mon, Jun 27, 2005 at 03:09:12PM +0200, Nico Sabbi wrote:
> > > Guillaume POIRIER wrote:
> [...]
> > > format=xsvcd.
> > > In order to make the gop structure svcd compliant the keyint should be
> > > 15 for pal and 18 for ntsc, although very often much longer gops play
> > > correctly
> > > (I always used 25 without problems).
> > > Please, mention also that the resulting file
> > > - is an extended svcd (that's why it's called xsvcd), mainly because it
> > > doesn't
> > > contain scan offsets
> > > - it should be passed to vcdimager to generate the svcd image
> > >
> > 
> > There should be a mention that PAL requires -ofps 25 and NTSC -ofps 30000/1001.
> 
> Fixed
> 
> 
> > It it also necessary very often -vf harddup.
> 
> Is it safe to add it all the time?

Yes.

Giacomo

> 
> 
> > There is no mention about the fact that the audio should be mp2:
> > -oac toolame -toolameopts br=224
> > or
> > -oac lavc -lavcopts acodec=mp2:abitrate=224
> 
> Fixed already :-)
> 
> 
> > Question. Is -af lavcresample=44100 necessary? My experience shows that just -srate 44100
> > is enough (althouth I always use it with -af-adv force=1).
> 
> I don't know, I've never tested it. What's the advantage of your
> command line (with -af-adv force =1 on)? Better quality?
> 
> 
> Here is the updated FAQ entry (I'm starting to wonder if this should
> still be in the FAQ or would rather go into the encoding guide):
> 
> 
> <qandaentry>
> <question><para>
> How can I create SVCDs?
> </para></question>
> <answer><para>
> Newer version of MEncoder can directly generate MPEG-2 files that can be
> used as a base to create a SVCD and are likely to be played out of the
> box on all platforms (for example to share a video from a digital
> camcorder with your computer illiterate friends).
> <screen>
> mencoder -of mpeg -ovc toolame -toolameopts br=224 -lavcopts \
> vcodec=mpeg2video:mbd=2:keyint=25:vrc_buf_size=917:vrc_minrate=600:vbitrate=2500:vrc_maxrate=2500
> \
> -oac lavc -af lavcresample=44100 -srate 44100 -mpegopts format=xsvcd \
> -vf harddup -ofps 25 \
> <replaceable>in.avi</replaceable> -o <replaceable>xsvcd.mpg</replaceable>
> </screen>
> This will convert the input file <replaceable>in.avi</replaceable> into
> the output file <replaceable>xsvcd.mpg</replaceable>, converting the
> audio with <systemitem class="library">toolame</systemitem> at 224kbps
> and the video with <systemitem class="library">libavcodec</systemitem>.
> </para><para>
> Please note that in order to make the GOP structure SVCD compliant the
> <option>keyint</option> option should be 15 for PAL and 18 for NTSC,
> although very often files with much longer GOPs play correctly (25 should
> never lead to any problem).
> Also, even though leaving out <option>-ofps</option> should work in most
> cases PAL requires <option>-ofps</option> 25 and NTSC
> <option>-ofps</option> 30000/1001.
> </para><para>
> As far as the audio is concerned, svcd only support MPEG-1 layer II audio,
> therefore you have to use either
> <systemitem class="library">toolame</systemitem>,
> <systemitem class="library">twolame</systemitem>, or as a last resort
> <systemitem class="library">libavcodec</systemitem>'s MPEG-1 layer II
> encoder (as its quality is far from being as good as the former two
> libraries).
> Both <systemitem class="library">toolame</systemitem> and
> <systemitem class="library">twolame</systemitem> follow the same syntax,
> so you depending on which one you managed to install, the example only
> requires a small chance, but if you need to use
> <systemitem class="library">libavcodec</systemitem>'s MPEG-1 layer II
> encoder, replace
> <screen>
> -oac toolame -toolameopts br=224
> </screen>
> by
> <screen>
> -oac lavc -lavcopts acodec=mp2:abitrate=224
> </screen>
> </para><para>
> The resulting file <replaceable>xsvcd.mpg</replaceable> is an extended SVCD
> (that's why it's called xsvcd), mainly because it doesn't contain scan
> offsets, so if you need to generate a SVCD image out of it, you should
> pass it to
> <ulink url="http://www.gnu.org/software/vcdimager/vcdimager.html">vcdimager</ulink>.
> </para></answer>
> </qandaentry>