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

[Bob Sully]

Another Sillyname wrote:
> 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
>>
>> _______________________________________________
>> mythtv-users mailing list
>> mythtv-users at mythtv.org
>> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>>
> 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
>

OK...tried this again, starting to get somewhere.  It aborted before
because of a mistake I made in not specifying the start time as 00:00:00.

Anyway, the file appears to have too many glitches for mencoder to handle,
despite the fact that it's simply a recording with a cutlist (plays fine
within Myth), copied directly from my Myth recording directory.  It was
recorded via an HDHR.

Here's the relevant stuff:

----------------------------------------
<snip>

Warning! FPS changed 47.952 -> 59.940  (-11.988010) [7]  V:-0.012 [1789:224]
Pos:1645.8s  98741f (61%) 56.43fps Trem:  18min 643mb  A-V:0.007 [1789:224]]
demux_mpg: 24000/1001fps progressive NTSC content detected, switching
framerate.
Pos:1646.5s  98782f (61%) 56.43fps Trem:  18min 643mb  A-V:0.034 [1789:223]
Skipping frame!
Pos:1646.7s  98794f (61%) 56.43fps Trem:  18min 644mb  A-V:0.028 [1789:224]
demux_mpg: 30000/1001fps NTSC content detected, switching framerate.
Warning! FPS changed 47.952 -> 59.940  (-11.988010) [7]  V:0.029 [1789:224]
Pos:1647.1s  98822f (61%) 56.43fps Trem:  18min 644mb  A-V:0.023 [1789:224]
Too many audio packets in the buffer: (4096 in 31457280 bytes).
Maybe you are playing a non-interleaved stream/file or the codec failed?
For AVI files, try to force non-interleaved mode with the -ni option.

Too many audio packets in the buffer: (4096 in 31457280 bytes).
Maybe you are playing a non-interleaved stream/file or the codec failed?
For AVI files, try to force non-interleaved mode with the -ni option.

Flushing video frames.
Writing index...
Writing header...
ODML: Aspect information not (yet?) available or unspecified, not writing
vprp header.

Video stream: 1789.651 kbit/s  (223706 B/s)  size: 368473192 bytes 
1647.129 secs  98822 frames

Audio stream:  224.000 kbit/s  (28000 B/s)  size: 46134144 bytes  1647.648
secs
------------------------------------------


Thanks for any more help you can provide.
Bob
-- 
________________________________________
Bob Sully - Simi Valley, California, USA
http://www.malibyte.net
http://www.malibyte.com