[mythtv-users] Always use the HD PVR and retire my PVR 250, or continue to use both in same recording group

[belcampo]

James Orr wrote:
> 
> 
> On Fri, Jun 25, 2010 at 10:19 PM, John P Poet <jppoet at gmail.com 
> <mailto:jppoet at gmail.com>> wrote:
> 
>     On Fri, Jun 25, 2010 at 8:13 PM, Yeechang Lee <ylee at pobox.com
>     <mailto:ylee at pobox.com>> wrote:
>      > John P Poet <jppoet at gmail.com <mailto:jppoet at gmail.com>> says:
>      >> If the quality via the HD-PVR is lower, you probably have the
>      >> bitrate on the HD-PVR set too low.
>      >
>      > Speaking of bitrates, how optimal are the settings in the default
>      > HD-PVR recording profile? Is there room to tweak them, or are they
>      > about as good as VBR bitrates for the device can get?
> 
>     I am not even sure what the current defaults are.  I have been using
>     my HD-PVRs since before Myth had defaults for the HD-PVR :-)
> 
>     As far as what the defaults should be, that is a good question.  I
>     would assume most people using the HD-PVR are more concerned with
>     quality than file size.  Personally, I use max bitrate VBR by default,
>     and max bitrate CBR for "high quality" (e.g. sports events).
> 
> 
> That's actually a good idea, though I'd probably do it the other way 
> around (CBR for shows/movies and VBR for sports and maybe documentaries).
> 
> The defaults on the HD-PVR were ...
> 
> Low Avg - 4,500, Low Max - 6,000
> Med. Avg - 9,000, Med. Max - 11,000
> High Avg. - 13,500, High Max - 20,200
I partially agree, I/me/myself don't see any use for CBR, unless you 
have to fit some recording a finite-size, CD/DVD, device and are not 
able to calculate/educated-guess a reasonable avarage bitrate. Choosing 
CBR, which you have to do in front, it'll always be too much or too 
little, unless you can read the future, which none of us is able to, AFAIK.
VBR with quality settings as with x264/ffmpeg is the only setting, 
unless you have to 'fit it on a certain device' that makes sense to me.
The HD-PVR lacks such a setting AFAIK, so you'll have to make an 
educated guess of what would be the minimum-bitrate for the quality you 
want, and let the HD-PVR raise the bitrate to an available max of 
20Mb/s, by using VBR, if there is need for that.
By choosing CBR you are more or less 'limited' to 13.5Mb/s.
              video_bitrate_mode (menu) : min=0 max=1 default=1 value=1 
flags=update
                   video_bitrate (int)  : min=1000000 max=13500000 
step=100000 default=6500000 value=6500000
              video_peak_bitrate (int)  : min=1100000 max=20200000 
step=100000 default=9000000 value=9000000 flags=inactive

> 
> Quality vs. Filesize ... for stuff I watch right away I don't really 
> care about filesize, but I also have stuff that sits around unwatched 
> for a long time (I have some recordings almost a year old) and for those 
> I'd rather have smaller file sizes.
> 
> 
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> 
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