<br><br><div><span class="gmail_quote">On 4/9/07, <b class="gmail_sendername">Rod Smith</b> <<a href="mailto:mythtv@rodsbooks.com">mythtv@rodsbooks.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On Monday 09 April 2007 17:38, Chris Weiland wrote:<br>> I'm trying to archive a few of my recordings to DVD using Mytharchive,<br>> which worked beautifully, except that the audio was out of sync by about<br>> 3-5 seconds.
<br><br>This is a serious problem with every tool I've tried to make DVDs, although<br>it's worse with some tools and source files than with others. That said, a<br>3-5 second sync problem is pretty awful. The usual pattern for me is that the
<br>audio sync starts out OK but slowly drifts over the course of the recording.<br><br>In any event, I've had better luck using mencoder to create MPEG-2 files from<br>MPEG-4 and non-Myth sources than using MythArchive's tools (namely ffmpeg). I
<br>still use MythArchive to create the DVD, but not to transcode into MPEG-2<br>format. Here's the command I use:<br><br>mencoder -vf kerndeint,softskip,scale=720:480,harddup -ofps 30000/1001 -aspect<br>${aspect} -ovc lavc -lavcopts
<br>vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9600:vbitrate=${vbitrate}:keyint=18:turbo:trell:dc=10:autoaspect=1 -oac<br>lavc -lavcopts acodec=ac3:abitrate=192 -of mpeg -o ${dest} ${src}<br><br>Note that's one big long line; it'll be split across multiple lines by the
<br>e-mail transfer. Replace ${aspect} by the source's aspect ratio (1.3333 or<br>1.7777), ${vbitrate} by your desired bitrate (such as 4771000 to fit two<br>hours on a 4GB DVD), ${dest} by the destination filename, and ${src} by the
<br>source filename. Of course, I've got this in a script, myself. I'm not yet<br>100% satisfied with my parameters; I'm still fiddling with them, but it's a<br>slow process. It's also possible to add a crop option to crop the
<br>letterboxing off of letterboxed NTSC source material.<br><br>Once I've transcoded a recording, I use MythArchive with the "always<br>transcode" option DISABLED and the "don't re-encode" quality setting; the
<br>whole point of using mencoder is to bypass the buggy ffmpeg step.<br><br>Nine times out of ten, the DVDs I get from this process have better audio sync<br>than they do if I'd used MythArchive with its ffmpeg transcoding. I also get
<br>better deinterlacing (due to the kerndeint option) -- MythArchive/ffmpeg<br>tends to produce hideous interlacing artifacts. I still have occasional<br>problems with this approach, but they're less common and usually less severe
<br>than what MythArchive/ffmpeg produces.<br><br>All of this applies to material that wasn't originally in MPEG-2 form or that<br>needs processing to reduce its size or otherwise modify it. As I've got two<br>tuners with hardware MPEG-2 encoders, when I know I'll be making a DVD from
<br>material obtained from them, I prefer to set the recording bitrate<br>appropriately and then use MythArchive with the "always transcode" option<br>disabled and the quality set to "don't re-encode". When I do this, though,
<br>I'm sure to set the recording resolution to a DVD-compatible one (typically<br>720x480).<br><br>> The wiki<br>> article also suggests setting "Always use Transcode", which was on in both<br>> tries.
<br><br>I disagree that this is a good idea, at least in my experience. Maybe it helps<br>with source files recorded with certain hardware and/or software, but not<br>with the files I've used.<br><br>FWIW, I've run across a few instances where my MPEG-2 hardware encoder
<br>produces audio that's about 100-200ms out of sync when played by MythTV, but<br>when transcoded with mencoder and a DVD created, the audio sync is much<br>better. Thus, I try not to judge the audio sync until I've got a DVD image on
<br>disk (see below).<br><br>> Other than that, I don't really know what to make of it. I don't really<br>> want to mess around with it until I know what to do because each try takes<br>> about 2 hours to burn, plus the disk.
<br><br>Try "burning" to an .iso image rather than directly to disc. You can then move<br>the .iso file to your Myth Video directory to test it. If it's good, you can<br>then burn that image to disc:<br><br>
growisofs -dvd-compat -Z /dev/dvd=mythburn.iso<br><br>Replace mythburn.iso with the source filename, if you change it or need to<br>refer to it by its complete pathname. If you were to do this blindly, it<br>wouldn't take much longer than telling MythArchive to burn the disc directly.
<br>If you find a problem, though, it'll be quicker and easier to correct when<br>you do it this way, and you won't waste a disc in the process.<br><br>As an alternative to all of this, you could try creating a MythTV native
<br>backup rather than a conventional DVD. This will be quicker and will preserve<br>the files in their original form, so if audio sync is correct when you play<br>the recording normally, it should be OK in the DVD you burn, too. The trouble
<br>is that the DVD won't be playable on a standard DVD player; you'll need a<br>computer capable of playing the files that MythTV records. (It doesn't<br>necessarily have to be a MythTV system itself, though.)
<br><br>--<br>Rod Smith<br><a href="http://www.rodsbooks.com">http://www.rodsbooks.com</a><br>_______________________________________________<br>mythtv-users mailing list<br><a href="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org
</a><br><a href="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users">http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</a><br></blockquote></div><br>Whoa, thanks for the detailed replay. I'll have to give this a shot. However, it would be nice to be able to do this from my remote control -
i.e. through mythtv's menus.<br>