[mythtv-users] Is the MythTV .nuv format non-standard ... oram Imissing something?

[Alan Snyder]

You don't want --fifosync in mythtranscode.  It's
meant only for when you
need separate processes to read the audio and video.  

If the audio gets read faster than the video,
mythtranscode without
--fifosync is forced to buffer the video and since
it's raw video, it will
rapidly fill your virtual memory.  --fifosync makes
the process reading the
audio wait until the corresponding video is read, and
vice-versa.  

With one process reading both, this isn't necessary. 
Furthermore, with one
process reading both, if that process, for example,
wants to read a few
video frames ahead of the audio for whavever reason
(filtering, details of
the compression algorithm, whatever), you have a
problem.  mythtranscode
would refuse to provide the video until the audio
reads caught up, but the
program would sit there waiting for the read on the
video fifo to complete.
What you have is a deadlock.

Bottom line - use --fifosync if separate processes
read the audio and video.
Leave it off if one process reads both.

Looking at what I posted, I see that I didn't specify
a video rate in
mencoder.  The default might be pretty low.  There's a
complete man page for
mencoder.

> -----Original Message-----
> From: mythtv-users-bounces at mythtv.org 
> [mailto:mythtv-users-bounces at mythtv.org] On Behalf
Of Garett Harnish
> Sent: Thursday, September 11, 2003 1:53 PM
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] Is the MythTV .nuv
format 
> non-standard ... oram Imissing something?
> 
> 
> Alan Snyder wrote:
> 
> 
> 
> > The mencoder patch is for version 0.90 and
mencoder is at 0.91 now.
> 
> >  
> 
> > But the new mencoder (1.0pre1) will properly
process mythtranscode
> 
> > output through named pipes.  See my post from a
few days ago for the
> 
> > commands that worked for me.
> 
> 
> 
> 
> 
> Excellent, that would be the message that you sent
Monday 
> night entitled 
> 
> "mythtranscode to avi works with mencoder 1.0pre1",
correct?  
>  So then 
> 
> where would I find some documentation on using
Mythtranscode 
> ... I was 
> 
> able to get myth running last week, but I have no
idea how to 
> use it to 
> 
> its fullest yet.  My guess on using mythtranscode
(for the recording 
> 
> 1040_20030901201500_20030901210000.nuv) would be
something like this:
> 
> 
> 
> mythtranscode -p Default -c 1040 -s
2003-09-01-20-15-00 -f  fifodir  
> 
> --fifosync &
> 
> mencoder -audiofile fifodir/audout -audio-demuxer 20
-rawaudio 
> 
> rate=32000 -rawvideo on:w=480:h=480:fps=29.97 -vf
scale=640:480 -ovc 
> 
> lavc -oac mp3lame -o out.avi fifodir/vidout
> 
> 
> 
> Is this correct?   Does anyone have any
documentation on using 
> 
> Mythtranscode ... all I can find is some vague
mention of 
> trancoding in 
> 
> the FAQ (which sounds fairly cool, cutting out
commercials 
> and all ... 
> 
> though I have a feeling it isn't quite a easy as it
sounds).
> 
> 
> 
> Thanks.
> 
> 
> 
> --
> 
> Garett
> 
> 
> 
> _______________________________________________
> 
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> 
> mythtv-users at mythtv.org
> 
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