[mythtv-users] Transcoding/editing recordings to 720p/AC3 .mkv/.avi format

Another Sillyname anothersname at googlemail.com
Tue Sep 1 14:20:05 UTC 2009


2009/9/1 Bob Sully <rcs at malibyte.net>:
> Hi all -
>
> I've been having problems trying to transcode recordings.
>
> Forgive me if these questions are overly simplistic, but I've been all
> over Google and haven't found an easy answer.  I have two different types
> of files I'm trying to transcode - in both cases I'd like to wind up with
> 720p .mkv or .avi files with AC3 5.1 audio, at approximately 700MB per
> ~40-45 minute "1 hour" episode after the commercials are cut out.  I don't
> want to have to download torrents to get these, since I have the
> high-quality source recordings already saved on my Myth backend.
>
> (1) Regular Myth recordings.  Currently, I do NOT have auto-transcoding
> enabled, but I do have commflagging set.  I still have to edit and set up
> a precise cutlist - after which I wind up with an .mpg file (no longer
> .nuv).  Mythtranscode wants to do DVD-resolution and .ps files - neither
> of those are what I'm looking for.  Problem is, nothing else knows about
> the cutlist, so I have to do the same edits in avidemux - which does a
> great job with the video but b0rks the audio completely (for example, it
> usually cuts video correctly but doesn't always edit out the corresponding
> audio, so when I do get audio at all after the save, it's out of sync - or
> I get pops and hums, and that's all the sound I get).  I think I must have
> the wrong output settings (currently using x264/AC3/MKV - please tell me
> if these are wrong).  Can Mythnuv2mkv handle an .mpg with a cutlist as the
> input file?  If so, what are the command-line options I need to use?
>
> (2) HD-PVR recordings which I've recorded via a little bash script (will
> share if anyone's interested - changes channel on the Motorola 6200 STB,
> starts/stops recording at preset times); I'm running 0.21-fixes with JYA's
> VDPAU backports, so can't yet record from the HD-PVR within Myth.  These
> recordings are at 720p resolution from the STB with 5.1 AC3 sound.  Same
> problem with avidemux - I can edit out commercials from the video, but it
> doesn't cut the audio correctly.
>
> I know there must be a way to do these edits and wind up with the
> decent-quality 720p/AC3 .mkv and .avi files I'm looking for.
>
> Can anyone please enlighten me/send me a pointer?
>
> Thanks in advance!
> Bob
> --
> ________________________________________
> Bob Sully - Simi Valley, California, USA
> http://www.malibyte.net
> http://www.malibyte.com
>
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>
Hi Bob

I'm currently using Mencoder to turn BBC HD 1080i AC3 material into
720p H264 AC3 saves, like you there wasn't a lot on info out there.

Try running the following as a two pass on one of your files and see
what you get (you MUST run the second pass in the directory where you
ran the first pass).

mencoder -noskip -oac lavc -lavcopts acodec=ac3 -ovc lavc -lavcopts
vcodec=mpeg4:vbitrate=1800:vqmin=2:vqmax=31:mbd=2:vpass=1 -vf
scale=1280:720 -ss 1:32:0 -endpos 41:10:00 -o /dev/null
/path/to/original/file/for/transcode

mencoder -noskip -oac lavc -lavcopts acodec=ac3 -ovc lavc -lavcopts
vcodec=mpeg4:vbitrate=1800:vqmin=2:vqmax=31:mbd=2:vpass=2 -vf
scale=1280:720 -ss 1:32:0 -endpos 41:10:00 -o
/path/to/file/you/want/to/create/itsname
/path/to/original/file/for/transcode

The -ss value is the start position of where you want to begin the transcode

The -endpos value is the LENGTH (It's not the actual end position)

Both the above is MM:SS:FS (i.e. Minutes:Seconds:Tenths of Seconds)

Good Luck


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