[mythtv-users] hdpvr and bitrate

[Richard Woelk]

Christopher Meredith wrote:
> On Mon, Nov 16, 2009 at 7:30 AM, Richard Woelk <richardwoelk at yahoo.ca> wrote:
>   
>> Marius Schrecker wrote:
>>     
>>>  Hi,
>>>
>>> The last quality issues with TV recordings from my hdpvr are solved after
>>> I turned the bitrate settings up to max 13500 - 22000 for all resolutions.
>>>
>>>
>>> Output quality looks subjectively AT LEAST  as good as direct output from
>>> stb to TV :-), using 720p over component, and s/pdif -> ac3. Any trace of
>>> jerkyness/jitter/frame corruption is gone.
>>>
>>> Obviously, the max setting is overkill, eating disk space, and stressing
>>> the bus unneccessarily (Even using VDPAU the cpu and fans are obviously
>>> woring harder than with the default settings, which I can't remember
>>> offhand).
>>>
>>> STB is spitting out 720p, although most content is SD/PAL.
>>>
>>>
>>>  What recording profiles are others using?
>>>
>>>
>>> Cheers!
>>>
>>>
>>> Marius
>>>
>>>
>>>       
>> Marius
>>   I just checked my recording profile. I use the max 13500 - 20200 for both
>> 720p and 1080i. I use 4500-7000 for SD
>> I have two HD-PVR1212s. #1 is hooked to a STB forced to 720p, and #2 is
>> forced to 1080i. This way I can choose the quality by schedule
>>
>> My tv shows take up about 2.6GB / hr for 720p, and 4.5GB/hr for 1080i.
>> My satellite receivers have a setting for 4x3 override for SD channels. I
>> set that to 480i (480p looks worse) and those recordings are about 700MB/hr
>>
>> My frontend has a Geforce 9500GT in it, so I use VDPAU most of the time. I
>> did try some trunk packages once and didn't notice VDPAU wasn't working. my
>> 3.16Ghz core2duo was doing 1080i playback with 70% of one core.
>>
>> When I was first testing, I had a Athlon 64 X2 as my frontend, I had to turn
>> the 720p bitrate down to half to get that to play smoothly. The quality
>> wasn't bad, but I upgraded pretty quick.
>>
>> If there is anything you want me to try, I could make some test recordings.
>>     
>
> I'm using the default profile for my HD-PVR and my STB is forcing
> 720p. One thing I want to confirm here is that I've been assuming that
> if I have a 720p display (1360x768) there's nothing to be gained from
> watching 1080 content, since it will essentially be scaled down to 720
> anyway. Is this correct?
That would be the case if you are getting a true 720p from your STB.
I know my satellite provider sends everything as 1080i, so having the 
STB downconvert to 720p is worse quality than having the TV or videocard 
do it


- Richard


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