[mythtv-users] OT: XBMC on Apple TV2 and iPad

[belcampo]

Raymond Wagner wrote:
> On 1/21/2011 17:45, belcampo wrote:
>> Raymond Wagner wrote:
>>> On 1/21/2011 15:41, Matt Emmott wrote:
>>>> It changes everything in that, you now have a small portable device 
>>>> with a great front end to all your media.
>>> This changes nothing, yet.  The published performance specs for the 
>>> A4 chip are hardware accelerated h.264 up to Main Level 3.1.  No 
>>> MPEG2, so that cuts out the bulk of digital TV.  No h.264 Level 4.1, 
>>> so that cuts out the rest of digital TV and output from an HDPVR.  
>>> Lack of that, and VC1, means no Bluray playback either.  From the 
>>> published information on the chip, it's still garbage requiring any 
>>> content be transcoded down to low quality specifically for that device.
>> Not LowQuality, but the same quality at a 'little higher' bitrate.
>> Main3.1 is as good as High3.1 with the same crf or qp settings.
> 
> High gets you some additional transforms, and slightly higher bitrate, 
> but that's not what I'm talking about.  I'm talking about the ATV2 only 
> officially supporting Level 3.1, but the rest of the hardware decoding 
> world doing 4.1.
> 
>> Bitrate is NOT = QUALITY
>> Better encoder produces same quality in less bits.
>> I've done several BluRay encodings with qp=24, between 16 - 26, most 
>> people perceive this setting 'almost as good' as the original. 
>> Resulting bitrates drop from 32-38Mb/s to 3-7Mb/s on average.
> 
> qp=24 is a pretty high setting.  Perceivable lossless for x264 is 
> generally considered to be somewhere around 18-20.  Some parts of some 
> 1080p content may look good at 7Mbps.  If you have a lot of film grain, 
> it's going to get averaged out into a blurry mess.  If you have smooth 
> gradients, they will get replaced by a single color field.  If you have 
> high motion, you're going to end up with all sorts of nasty blocking.  
I know all these arguments, do you have any material to proof these ? 
Side by side of course.
> It's nothing like 'almost as good',
I've done a lot of actual testing, believe my eyes more then the words 
of others.
> but then of course the average user 
> is happy with theater cams, and runs their nice 24" monitor at 1280x800 
> because 'everything is too small on screen'.
> 
> However this whole argument is irrelevant.  The key point of my post is 
> that the ATV2, as specified by the Apple website, will not handle any HD 
> content recorded by MythTV in its original form.  You will need to spend 
> vast amounts of time transcoding at a fraction of real time, to get your 
> content down to a form playable on the device.  Until the XBMC devs get 
> some real performance information about the real capabilities beyond of 
> the specs published by Apple, it is too early to plan anything.  They're 
> not going to do so until the code evolves beyond an unstable, 
> developmental branch (that's the answer they gave when I asked).
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