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

[John P DeVale]

Ray Olszewski wrote:

> At 09:58 AM 6/14/2003 -0500, John P DeVale wrote:
>
>>> [...]
>>> Have you tried using the MPEG4 option?  For me, with the default
>>> settings, this produces files approximately 400mb for 30 minutes / 
>>> 900mb
>>> for an hour.
>>
>> ARRGH!  This is *most* annoying.  For me the default MPEG4 settings 
>> produce files that are 3-4 GB per hour.  Does anyone know why this 
>> might be and how to fix it?
>
>
> Are you sure of this? That is, are you sure the relevant recording 
> profile is set for MPEG4 and not RTJPEG? Here, I'm using the default 
> bitrate settings, but 320x240 captures, and I'm seeing about 250-300 
> MB/hour for timed recordings (I don't at the moment have a "live" TV 
> buffer to check). This makes 900 MB/hr about right for the standard 
> 480x480 Myth settings. Your numbers are more consistent with usual 
> values for RTJPEG than MPEG4.
>
> If you are sure ... the usual reason for increased size of MPEG4 
> captures (in general; this is not specific to Myth) is a noisy TV 
> signal. I just cleaned up my signal here, and my vcr/avifile captures 
> dropped in size by about a third, with no settings changes.
>
> Here, the default bitrate is 2200 Kbps, or about 300 KBps, which works 
> out to  1.1 GB/hr, consistent with John's experience but not yours. 
> "Scale bitrate for frame size" is selected, with quality range 2 
> maximum, 15 minimum. Audio is MP3, quality 7. You might want to double 
> check that you and he (and I) really are using the same "default" values.
>
> BTW, my results are for the Debian prepacks of Myth 0.8.
>
>
>
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Well, I am certain that the files are too big -- beyond that, everything 
is up for grabs.  However, I went through all the configurations and 
verified that the settings were what they should be.  I made no changes 
to any of the settings, but the profiles list now shows LiveTV, Default, 
Transcode where previously it showed LiveTV, Movies, Transcode.  But 
everything is set identically, except LiveTV is set to 320x480 whereas 
everything else is set to 480x480.  Suddenly, the files that are 
generated are the size I would expect (~1gb/hour).  The codec settings 
were all 2200, scale bitrate, quality max2, min 15, audio mp3 q7.  It 
doesn't seem logical or likely to think it is a causal relationship, but 
the only difference between the setup is the things listed in the 
recording profiles list.  It is possible that the values were somehow 
corrupt and just going through them somehow reset things to right.  I 
don't know.

Thanks for the feedback, although the problem gone, I would hesitate to 
say it was *fixed*.

On a separate note, what did you do to clean up your signal?  Most of my 
channels are fairly clean, but a few a re atrocious.  I have complained 
to Time-Warner, but their primary response is to try and sell me digital 
cable rather than fixing their analog signal...

Thanks

John