[mythtv-users] hdhr file troubles on atv2

[Raymond Wagner]

On 2/15/2011 13:30, belcampo wrote:
> Raymond Wagner wrote:
>> On 2/15/2011 11:23, belcampo wrote:
>>> belcampo wrote:
>>>> belcampo wrote:
>>>>> Raymond Wagner wrote:
>>>>>> On 2/14/2011 09:51, David Evans wrote:
>>>>>>> I picked up a atv2 about a week ago and I have been tinkering with it.
>>>>>>>     I have xbmc running on it and using the built in myth:// protocol I
>>>>>>> can play SD files without any trouble.  The issue that I am having is
>>>>>>> with files produced by the hdhr.  They will load up but I get a severe
>>>>>>> stutter with the audio and they are unwatchable.  I tried loading the
>>>>>>> files via a smb mount and I get constant buffering.
>>>>>>>
>>>>>>> I figured the solution would be to transcode the files down to a mpeg4
>>>>>>> format that should be easier for the ATV2 to play but I'm struggling
>>>>>>> with the settings of mythtranscode to get a file that plays cleanly.
>>>>>>> If I could get any insight it would be great.
>>>>>> The ATV2 does not support hardware acceleration of the MPEG2 output by a
>>>>>> digital tuner, nor the HD MPEG4 output by mythtranscode.  That means you
>>>>>> are relying on the woefully inadequate 1GHz ARM for software decoding.
>>>>>> Until XBMC has fully explored the VideoToolBox API and documented what
>>>>>> the device is actually capable of, rather than what Apple has restricted
>>>>>> the device to, the only authoritative reference on the decoding
>>>>>> performance of that device is on the Apple site.
>>>>> I do have one for 2 weeks and it can play BluRay as input-format.
>>>>> I use makemkv to get the BD in a matroska container which I then serve
>>>>> with minidlna to upnp to XBMC on the atv2, although it scales it down to
>>>>> 720p, but further it works very well.
>>>> Sorry I was too hasty, I had encoded them to 1080p but at a lower
>>>> bitrate with ffmpeg -crf 24, which resulted in visibly perfect,
>>>> according to mediainfo:
>>>> Overall bit rate                 : 6 143 Kbps
>>> Again too fast, I used -cqp 24
>>> instead of -crf 24
>> In case anyone wants to follow suit, a quantizer of 18 is considered
>> effectively lossless, and 20 or under good enough that most people will
>> not notice any artifacts on a moving image, only stills.  A quantizer of
>> 24 is considered 'medium quality' and will result in artifacts and
>> blurring visible by most people even during playback.  There is good
>> reason why Bluray video typically runs at upwards of 30Mbps, rather than 6.
> Bits ain't always Bit's. Gzip-slow does a better job then Gzip-fast on
> compressing a textfile.

Yes, quality is determined by the quantizer.  Lower quantizer means 
higher quality and more bits.  For my tastes, '24' just doesn't cut it.