[mythtv-users] How small can I get my captures?

Ray Olszewski ray at comarre.com
Fri Jun 13 15:47:59 EDT 2003


At 05:28 PM 6/13/2003 -0400, John Klimek wrote:
>I'm running off of very limited space and I was wondering how small I could
>get my captures.  Typically VCD's (compressed in MPEG1 or MPEG2) are only
>700-800mb and have over an hours worth of audio/video.

Preliminary comment: if compression is not being done realtime, it can be 
done with multipass encoding, which can do a better job of optimizing the 
size-quality tradeoff. Myth necessarily captures in realtime so lacks this 
option.

>MythTV (using RTjpeg [I think thats what its called]) creates HUGE files.  A
>30 minute show took up nearly 1.5 GB of space.  Thats insane.
>
>So, two questions really:
>
>1)  Does MythTV have any other codecs to compress the size?

Yes. Somewhere in Setup (my Myth box is not running at the moment so I have 
to work from memory here) is a place where you can choose between RTJPEG 
(big files, low CPU load) and a modified MPEG-4 (smaller files, heavier CPU 
load) for a capture profile. Change it for both the "default" and "live TV' 
profiles.

>What else can I
>do to shrink the file sizes?

A. Specify a smaller capture size. Try 320x240 ... these are at least 
passable ... actually, to my eye, they look just fine on a 25" TV set (just 
tried this today ... much nicer than a 19" computer screen).

B. Specify a smaller bitrate for capture. Also somewhere in Setup, perhaps 
called "quality", probably in the profiles.

>2)  I tried using a Samba-mounted drive to save a capture.  The samba drive
>had TONS of room but after about 30 minutes my mythbackend server crashed
>out saying something about exceeding the maximum file size.

Dunno what your Samba drive is. Many filesystem types have 2 GB file 
limits. Could be smbfs is one of them. (I saw it when accessing vidcaps on 
a Linux host from a Win98 system ... the limtiation here was in either 
Win98 or SMB, not ext2.)

>Jeremy Oddo (INCREDIBLY helpful guy) said that Samba had a limit to file
>transfers.
>
>Is there any other way to store these files over a network drive?  or can I
>compress my files more?

Try nfs mounts.





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