[mythtv-users] How to transcode to SD within mythtv - system too slow to play HD

A. F. Cano afc at shibaya.lonestar.org
Sat Dec 14 23:22:21 UTC 2013


On Tue, Dec 10, 2013 at 06:52:07PM -0600, Raymond Wagner wrote:
> On 12/10/13 19:42, I originally wrote:
> > Interestingly, when I tried to transcode manually with the command you 
> > gave below, mythffmpeg was not installed.  I installed it via aptitude.
> > We'll see if this has any effect next time I record a show.

Update: I recorded another show after mythffmpeg was installed and it
was recorded in HD (720) which is probably the format the show was
transmitted in.

> FFmpeg is a library and transcoding application.  MythTV uses the
> library for video decoding and encoding, and ships with an internal fork
> of the library. Mythffmpeg is a copy of that application built using
> MythTV's internal version of that library, convenient as it provides a
> stable target for users wanting to distribute transcoding scripts to others.

Thanks for the clarification, I'm slowly learning mythtv.

> ...
> The original aspect ratio is 1920x1080 (1088), so half would be 960x540
> (544). You need you resolution to be in multiples of 16. It's possible
> ffmpeg was automatically padding to meet that requirement.

Yea, I found that out as soon as I played the transcoded file with
mplayer and it said it was adjusting the x and y.

> > One other question.  I deleted a test recording from within myth.  It
> > says that deleting the show from the list does not remove the file.
> > Is there a way to manually remove recordings completely? the mpg file,
> > the data that gets stored in the database, etc...  I'm aware that there
> > is some expiration time, but since the disk is not full, myth is
> > apparently not removing shows.
> 
> With the default settings, deletion should be performed at the next pass
> of the auto-expirer, which should be no longer than 15 minutes. Was this
> an original recording, or one you had transcoded? If the latter, is it
> possible there was a permissions issue?

I probably have a permissions issue.  I can start the backend by doing
this: "mythbackend&" as a regular user under my normal login but starting
it via "/etc/init.d/mythtv-backend start" fails.  I'll dig into this
later.  It is not a (video) file permission issue.  Both the transcoded
ones and the original HD ones have the same permissions.  I double-checked.

About the transcoded files: I can play them with mplayer, but when I try
it from within myth, I get a message (that unfortunately I didn't save)
that said something like "waited too long" for something and the
playback fails after a few seconds.  This is after a did a manual
mythcommflag on the transcoded file, as pointed out in another
sub-thread.  The original HD files work fine, although they're
unwatchable due to cpu load.

Augustine



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