[mythtv-users] Transcoding to mp4 to reduce file size

Sat Nov 10 20:07:58 UTC 2007

On Nov 10, 2007 10:48 AM, jedi <jedi at mishnet.org> wrote:

> On Sat, Nov 10, 2007 at 09:48:55AM -0500, Don Jerman wrote:
> > On Nov 10, 2007 9:37 AM, Chris Isip <cmisipster at gmail.com> wrote:
> > >
> > >
> > >
> > >
> > > On Nov 9, 2007 7:16 PM, Dan Wilson <dwilson at dslextreme.com> wrote:
> > > >
> > > >
> > > >
> > > > On 11/9/2007 at 6:31 PM Chris Isip wrote:
> > > >
> > > > > I'm hitting the limits of my file storage.  I was wondering if
> there is
> > > > > a
> > > > > way that I can transcode the mpeg2 programs to mpeg4 and still let
> the
> > > > > videos be viewable in mythtv "Watch Recordings".
> > > > >
> > > > > Thanks
> > > > > Chris
> > > > >
> > > >
> > > > I use the internal transcoding available in myth to convert mpeg2
> into
> > > mpeg4.  I get about 50% reduction in size, bringing an hour of SD tv
> down to
> > > about 1 GB.
> > > >
> > > > HTH,
> > > >
> > > > Dan.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > mythtv-users mailing list
> > > > mythtv-users at mythtv.org
> > > > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> > >
> > > I was looking more towards a reduction  in size from 1.43  GB to 200
> MB for
> > > a 1 hour SD show.  I found a ffmpeg formula for transoding to ipod
> touch and
> > > it did just that.  The quality was acceptable for playback fullscreen
> on my
> > > TV as well , but mythtv will not play it ( I tried renaming the
> transcoded
> > > file to the original filename).
> > >
> > > Has anybody used ffmpeg or mencoder to achieve this.  I'm not really
> sure
> > > what myth thinks the video should be before it can play it.  Theres
> probably
> > > going to be some database edits as well.
> > >
> > > Thanks
> > > Chris
> > >
> > >
> > > _______________________________________________
> > > mythtv-users mailing list
> > > mythtv-users at mythtv.org
> > > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> > >
> > >
> >
> > You can configure your transcoding profile to shrink the video size,
> > which will do what you're looking for. It'll also lose some quality,
> > but there you go, tradeoffs.  480x480 should cut the size in about
> > half without changing the quality much on a SD TV.  After that you'll
> > start to see the degradation accelerate.
>
>  I would not recommend altering the resolution, just reducing the bitrate.
>
>  I start out at 6000-9000 mpeg2 and go to 1200 mpeg4. Quality loss is
> neglible. I have more complaints about my video source than my transcoder.
> (which is pretty standard for Tivo with "compression" btw)
>
>  A lot of these issues are not unique to MythTV.
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>

I am going to try the built in transcoder mythtranscode.  Looking at the
mythtv docs though it states that  choosing to manually transcode will use
the profile in the transcoder column in the recorded table in the database.
I queried one recording :

-----------------+-----------------+----------+--------+---------------+------------+-------------+-------------+-------------------------+---------------------+---------------------+-----------+---------+-----------+------------+---------+
| chanid | starttime           | endtime             | title         |
subtitle |
description
| bookmark | editing | cutlist | hostname | category | autoexpire |
commflagged | recgroup    | recordid | seriesid | programid      |
lastmodified        | filesize   | stars | previouslyshown | originalairdate
| preserve | findid | deletepending | transcoder | timestretch | recpriority
| basename              | progstart           | progend             |
playgroup | profile | duplicate | transcoded | watched |
+--------+---------------------+---------------------+---------------+----------+---------------------------------------------------------------------------------------------------------------------+----------+---------+---------+----------+----------+------------+-------------+-------------+----------+----------+----------------+---------------------+------------+-------+-----------------+-----------------+----------+--------+---------------+------------+-------------+-------------+-------------------------+---------------------+---------------------+-----------+---------+-----------+------------+---------+
|   1030 | 2007-11-10 02:00:00 | 2007-11-10 04:00:00 | The Medallion
|          | Killed by a villain's henchmen, a Hong Kong detective (Jackie
Chan) comes back to life with supernatural abilities. |        0 |       0
|       0 | mymythtv | Action  |        100 |           0 | Suggest-TVW
|     2986 |          | MV001189610000 | 2007-11-10 04:00:01 | 3067487580
|   0.5 |               1 | 2007-11-10      |        0 |      0
|             0 |          0 |           1 |         -91 |
1030_20071110020000.mpg | 2007-11-10 02:00:00 | 2007-11-10 04:00:00 |
Default   | Default |         1 |          0 |       0 |
+--------+---------------------+---------------------+---------------+----------+---------------------------------------------------------------------------------------------------------------------+----------+---------+---------+----------+----------+------------+-------------+-------------+----------+----------+----------------+---------------------+------------+-------+-----------------+-----------------+----------+--------+---------------+------------+-------------+-------------+-------------------------+---------------------+---------------------+-----------+---------+-----------+------------+---------+
1 row in set (0.00 sec)

It seems the transcoder column has a value of 0.  I thought it was supposed
to have an id value corresponding to the transcode profiles.  Does this mean
that I must do all my transcode of current recordings via the command line?
I assume the format for the command is :

 nice -n 19 mythtranscode --infile  /mnt/VIDEO/2042_20070103012900.mpg
--profile 22

I am running it now.  Does this take care of any necessary database changes?
Can I run mythtranscode from a frontend with the mpeg2 file nfs mounted? (
so I dont overburden the backend cpu)

Thanks
Chris
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mythtv.org/pipermail/mythtv-users/attachments/20071110/5f89af35/attachment-0001.htm 