[mythtv-users] custom mytharchive recording profile

[Mark J. Small]

I've been playing a bit with mytharchive, and have been pretty happy with the 
results.  However, I'm trying to make a custom recording profile, and would 
like a few more details.

I've copied ffmpeg_dvd_ntsc.xml in to .mythtv/MythArchive/

I've added the following profile in the hopes of creating a good 3 hour/dvd 
option.  It's basically a copy of the EP profile, except for the bitrate 
and -b options.  These are the averages of the SP and the EP values.


    <profile>
        <name>RP</name>
        <description>Mark's custom play profile giving approx. 3 hour of video 
on a single layer DVD</description>
        <bitrate>1563.35</bitrate>
        <passes>1</passes>
        <parameter name="-v"      value="1"/>
        <parameter name="-i"      value="%inputfile"/>
        <parameter name="-r"      value="ntsc"/>
        <parameter name="-target" value="dvd"/>
        <parameter name="-b"      value="3557k"/>
        <parameter name="-s"      value="352x480"/>
        <parameter name="-acodec" value="ac3"/>
        <parameter name="-ab"     value="192k"/>
        <parameter name="-ac"     value="2"/>
        <parameter name="-copyts" value=""/>
        <parameter name="-aspect" value="%aspect"/>
        <parameter name=""        value="%outputfile"/>
    </profile>


When I try to select 3 hours of video using these options, I get a DVD size of 
4679 Mb, just a little too big.  Can I just drop the bitrate and the -b by 5 
percent and cross my fingers?  What is the relationship between the two?

I understand that the -b parameter is the video bitrate passed to ffmpeg, but 
what is the bitrate at the top used for?  Why is it so much lower?

Mark