[mythtv-users] converting home movies via mythtv?

[Stephen Worthington]

On Wed, 20 Dec 2017 18:03:58 +0000, you wrote:

>i’ve been putting off this task, but maybe it’s time.  I have a bunch of home movies that originally were on tape and were converted to DVD years ago.  I then copied the DVDs to my NAS for safe keeping.  But they are hard to work with in that DVD format. lots of .VOB files and DVD menu files, etc.  If I could convert these to mp4 (h.264) files they would be better for storing online in a safe place.  
>
>Any thoughts on the best way to do this.  Are some of the Job’s in Mythtv good for this??
>
>Jim A

If you want to preserve the quality of the videos, it is a very bad
idea to re-encode them.  Every time you re-compress a video in a
different (or the same) format, you lose information, reducing the
quality available.  Try taking a little video file and recompressing
it multiple times with H.264.  After 10 recompressions, there will be
nothing viewable left.  The best idea to make DVDs easier to work with
is just to rip the DVDs to a single .mpg file.  That removes all the
menus and extraneous bits, but leaves you with untouched video and
audio data.  I have not done that on Linux - I normally use the old
Windows software DVDDecrypter for that.  Even if a DVD is not
encrypted and does not need DVDDecrypter's decrypting capabilities, it
has all the right options for extracting the VOB files and making them
into one big .mpg file.  It can be a bit hard to find on the net now,
but there are still sites that have copies of it.

However, if your DVDs where mastered in a simple manner where there is
only one set of split *.VOB files, as usually happens with home made
DVDs, then all you need to do to extract a single .mpg file from them
is to copy and concatenate them, which can be done with the cat
command.  When DVDs are mastered, any VOB file that is over 1 Gibyte
gets split into several just under 1 Gibyte files (each of the same
size), plus one smaller file at the end.  The splitting is done by
just splitting the file, so only the first of these VOB files will
have the headers needed to make it a valid MPEG2 container file.  If
you play the first file, it will play properly, due to having the
headers.  If you play one of the other split files, it will have
problems at the start - frames will not play properly until a valid I
frame is found.  If you use a video file splitter to split video
files, each of the split files will have correct headers at the front
and will play all the frames properly, but that is not how DVDs work.
The splitting on DVDs only splits the files, so that no file is larger
than allowed for a DVD disk format.  DVD players, on reaching the end
of one of the split files, simply read on at the start of the next
split file, effectively concatenating the files, so they do not need
new headers on each split file.

The method suggested by Simon of concatenating the files and then
running them through ffmpeg is overly complicated.  There is no need
for ffmpeg, and they way he is using it may cause problems with the
resulting file as it may not copy all the streams properly.  Instead,
just use cat on its own and send the result to a .mpg file.  That will
create a valid MPEG2 format file with all the streams intact.

Here is the directory listing for a typical fairly simple commercially
mastered DVD I have:

total 4387474
dr-xr-xr-x 2 nobody nogroup       2640 Aug 18  2005 ./
dr-xr-xr-x 5 nobody nogroup        184 Aug 18  2005 ../
-r--r--r-- 1 nobody nogroup      24576 Aug 18  2005 VIDEO_TS.BUP
-r--r--r-- 1 nobody nogroup      24576 Aug 18  2005 VIDEO_TS.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VIDEO_TS.VOB
-r--r--r-- 1 nobody nogroup      65536 Aug 18  2005 VTS_01_0.BUP
-r--r--r-- 1 nobody nogroup      65536 Aug 18  2005 VTS_01_0.IFO
-r--r--r-- 1 nobody nogroup   65245184 Aug 18  2005 VTS_01_0.VOB
-r--r--r-- 1 nobody nogroup 1073565696 Aug 18  2005 VTS_01_1.VOB
-r--r--r-- 1 nobody nogroup 1073565696 Aug 18  2005 VTS_01_2.VOB
-r--r--r-- 1 nobody nogroup 1073565696 Aug 18  2005 VTS_01_3.VOB
-r--r--r-- 1 nobody nogroup  295804928 Aug 18  2005 VTS_01_4.VOB
-r--r--r-- 1 nobody nogroup      22528 Aug 18  2005 VTS_02_0.BUP
-r--r--r-- 1 nobody nogroup      22528 Aug 18  2005 VTS_02_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_02_0.VOB
-r--r--r-- 1 nobody nogroup   55328768 Aug 18  2005 VTS_02_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_03_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_03_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_03_0.VOB
-r--r--r-- 1 nobody nogroup  126056448 Aug 18  2005 VTS_03_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_04_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_04_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_04_0.VOB
-r--r--r-- 1 nobody nogroup    9746432 Aug 18  2005 VTS_04_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_05_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_05_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_05_0.VOB
-r--r--r-- 1 nobody nogroup   73205760 Aug 18  2005 VTS_05_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_06_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_06_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_06_0.VOB
-r--r--r-- 1 nobody nogroup   91582464 Aug 18  2005 VTS_06_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_07_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_07_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_07_0.VOB
-r--r--r-- 1 nobody nogroup   89047040 Aug 18  2005 VTS_07_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_08_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_08_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_08_0.VOB
-r--r--r-- 1 nobody nogroup  126375936 Aug 18  2005 VTS_08_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_09_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_09_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_09_0.VOB
-r--r--r-- 1 nobody nogroup   56381440 Aug 18  2005 VTS_09_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_10_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_10_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_10_0.VOB
-r--r--r-- 1 nobody nogroup   70985728 Aug 18  2005 VTS_10_1.VOB
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_11_0.BUP
-r--r--r-- 1 nobody nogroup      18432 Aug 18  2005 VTS_11_0.IFO
-r--r--r-- 1 nobody nogroup     116736 Aug 18  2005 VTS_11_0.VOB
-r--r--r-- 1 nobody nogroup  210468864 Aug 18  2005 VTS_11_1.VOB

In this you can see that it has one main set of split VOB files,
VTS_01_1.VOB, VTS_01_2.VOB, VTS_01_3.VOB and VTS_01_4.VOB.  The
VTS_01_1.VOB file is not part of the split files - it is mastered as a
separate video that gets played before the main split files.  It is
likely the usual copyright and FBI warnings and that sort of thing.
The other VOB files eg VTS_02_1.VOB will likely be trailers for other
movies and that sort of thing.  On a home mastered DVD, they will not
normally be present.  I have this DVD mounted on /media/cdrom, so to
convert it to a single valid MPEG2 .mpg file, I would do this:

cd /media
cat /media/cdrom/VTS_02_1.VOB /media/cdrom/VTS_02_2.VOB
/media/cdrom/VTS_02_3.VOB /media/cdrom/VTS_02_4.VOB >mydvd.mpg

(The above command is all on one line - it will likely get wrapped by
the email software)