[mythtv-users] Reducing resolution/bitrate of recordings?

Nick Rout nick.rout at gmail.com
Sat Nov 3 07:18:20 UTC 2012

On Sat, Nov 3, 2012 at 8:08 PM, Lee Maisel <maisel at lobo.net> wrote:

> Nick Rout wrote:
>> On Sat, Nov 3, 2012 at 7:28 PM, Lee Maisel <maisel at lobo.net <mailto:
>> maisel at lobo.net>> wrote:
>>     I'm trying to get some performance gains.   Currently, there are
>>     some artifacts/sound pauses (annoying)  Not surprising when
>>     multiple recordings are going, and they are typically 8GB in size.
>>     I read in the optimization wiki a mention of reducing the
>>     recording sizes, but there was no instruction as how to do so!
>>     I assume that by doing this, I would:
>>     reduce disk usage
>>     decrease network traffic
>>     reduce CPU processing
>>     Setup is as follows:
>>     Mythbuntu Mythtv 0.25 Fe/Be
>>     4GB ram
>>     3TB separate disk for recordings (USB unfortunately, but that's
>>     another story, bios won't see correct drive size if installed as SATA)
>>     3 HD Homerun tuners (giving me 6 inputs)
>>     Nvidia HDMI output for video and audio
>>     I have looked and looked at the settings, and cannot for the life
>>     of me find out where in the heck to change the recording
>>     resolution/bitrate etc.
>> You can't. You have a digital tuner (albeit joined to your backend via a
>> network) and it records what the TV company sends.
>>  I Suspected as much.  Well that's a bummer.   Any ideas on what to do
> about the annoying audio issue?  It's not all the time, but when it
> happens, it's so irritating, nobody wants to continue the program.  It like
> blanks out (audio) every few seconds for a blip.
> I'm really really hoping it's a reception issue, which i'll remedy soon
> with dual antennas.
Could be a number of things, most likely one of the following is breaking
the stream:

*reception errors (check all cabling, signal levels, there are hdhr
utilities for measuring stuff like this)

*network bandwidth if you have a dodgy connection between the HDHRs and
your backend, but it would take a few simultaneous streams to max out a
100M network. (put HDHR on a separate network and separate video card,
chack all networking hardware including cables)

*disk IO when recording multiple streams, perhaps coupled with disk IO
required for the database writes associated with recording a number of
streams. (make sure mysql is on a separate disk to your recordings storage
groups, get mysql performance optimised (there is a mythtv wiki page) make
sure all disks are OK, defrag, blah blah)

I have probably missed some things.

> Lee
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