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Re: Alternative to zbox for a frontend [ In reply to ]
On 13/09/2017 00:59, Peter Bennett wrote:
> On 09/12/2017 06:22 PM, Paul Gardiner wrote:
>> That's useful to know. I'll see if I can find the commit in the kodi
>> repo that added that feature for the pi.
>
> Before going too far down this road you may want to check whether the
> performance of the Raspberry Pi is sufficient for your critical eye. I
> suggest check what your TV scan rate is on the raspberry pi, then watch
> a 25 fps recording and a 24 fps recording and see if there is a
> difference on the raspberry pi MythTV.
>
> A quick internet search shows you can change the video mode. Modes are
> listed here:
> http://elinux.org/RPiconfig#Video_mode_options
>
> The tvservice command lets you see the mode and change it. You can also
> change it in config.txt. So you could see if changing it improves the
> playback of the respective recordings.

Turns out I was misinterpreting what I was seeing. tvservice seems to be
showing that the pi is picking up the 50Hz prefered mode of my tv. The
problem is performance. SD runs perfectly, but with 1080i25 content
frames are dropped - I'd guess about 1 in 4 or 5 because the result is
so much like running at the wrong frame rate. Strangely some 720p24
isn't quite perfect either although in that case it depends on the scene
and some parts are perfectly smooth (that's with the screen mode changed
to 24Hz).

I'm pretty sure I've applied every optimisation you list, besides trying
greater than 256MB gpu mem. Perhaps I need to get a Pi 3.
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Re: Alternative to zbox for a frontend [ In reply to ]
On 09/13/2017 10:21 AM, Paul Gardiner wrote:
> Turns out I was misinterpreting what I was seeing. tvservice seems to
> be showing that the pi is picking up the 50Hz prefered mode of my tv.
> The problem is performance. SD runs perfectly, but with 1080i25
> content frames are dropped - I'd guess about 1 in 4 or 5 because the
> result is so much like running at the wrong frame rate. Strangely some
> 720p24 isn't quite perfect either although in that case it depends on
> the scene and some parts are perfectly smooth (that's with the screen
> mode changed to 24Hz).
>
> I'm pretty sure I've applied every optimisation you list, besides
> trying greater than 256MB gpu mem. Perhaps I need to get a Pi 3.
You never said what version of MythTV you are using - the 0.27 version
for Raspberry Pi was an unofficial release and is missing many
optimizations, so hopefully you are on 0.28 or 29.

Verify the mpeg2 license (vcgencmd codec_enabled MPG2).
You could try running with -v playback to see if it is dropping frames
or there is some other problem.

Completely smooth video may not be achievable at this time. See ticket
at https://code.mythtv.org/trac/ticket/12907

I use it for 1080i and 1080p at 30 fps on a pi2. If it is not 100%
smooth all the time it does not worry me or my wife.

If you have done all of the performance steps I recommended, I don't
think that a Pi 3 will make that much of an improvement. Perhaps you
notice these things more than I do.

Peter
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Re: Alternative to zbox for a frontend [ In reply to ]
On 12/09/2017 23:49, jrh wrote:
> Returning to the original subject: A 2010 mac mini loaded with linux functions great as a front end. They are 2.4 ghz core2duo and nvidia geforce 320m graphics chipsets. They can also be had for around $200 used.
>
> I am currently using one now with lubuntu installed and the nvidia drivers installed.

That's a good possibility. I actually have one I'm not using. Might be a
bit noisy though because, while updating the disc to an SSD, I broke the
fan connector and had to rewire it to one of the USB sockets. :-)
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Re: Alternative to zbox for a frontend [ In reply to ]
On Mon, Sep 11, 2017 at 5:38 AM, Peter Bennett <cats22@comcast.net> wrote:

>
>
> On 09/10/2017 01:30 PM, Paul Gardiner wrote:
>
>> Oh astounding! From the wiki, it looks like I might get away with using
>> the pi 2 I was given as a present some time ago and for which until now I
>> never found a use.
>>
>
> Yes - Pi 2 works well. Just make sure to follow the wiki
> https://www.mythtv.org/wiki/Raspberry_Pi especially the "Performance"
> section for best results.
>

Pi/pi2/pi3 all have the same GPU, so graphics performance on GPU decoded
video will be the same.

The pi3 will give better software decoding, and is faster through GUI
screens. As a general statement a pi3 will software decode h265 up to 720p
(on kodi anyway, dunno about mfe for software decoding on pi)
Re: Alternative to zbox for a frontend [ In reply to ]
On 2017-09-13 11:54 PM, Nick Rout wrote:
>
> Pi/pi2/pi3 all have the same GPU, so graphics performance on GPU decoded
> video will be the same.
>

The Pi/pi2/pi3 might all have the same GPU, but the Pi3 runs the GPU at
a higher standard frequency (400 MHz versus 250 MHz) [1]. The GPU
frequency can be over-clocked, but may still end up being faster on the
Pi3. Hence the decoded video results may not be the same on Pi/pi2/pi3.

[1] https://en.wikipedia.org/wiki/Raspberry_Pi#Video

>
> The pi3 will give better software decoding, and is faster through GUI
> screens. As a general statement a pi3 will software decode h265 up to 720p
> (on kodi anyway, dunno about mfe for software decoding on pi)
>

RE: pi3 better software decoding. Agreed.
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Re: Alternative to zbox for a frontend [ In reply to ]
On 13/09/2017 16:16, Peter Bennett wrote:
>
> On 09/13/2017 10:21 AM, Paul Gardiner wrote:
>> Turns out I was misinterpreting what I was seeing. tvservice seems to
>> be showing that the pi is picking up the 50Hz prefered mode of my tv.
>> The problem is performance. SD runs perfectly, but with 1080i25
>> content frames are dropped - I'd guess about 1 in 4 or 5 because the
>> result is so much like running at the wrong frame rate. Strangely some
>> 720p24 isn't quite perfect either although in that case it depends on
>> the scene and some parts are perfectly smooth (that's with the screen
>> mode changed to 24Hz).
>>
>> I'm pretty sure I've applied every optimisation you list, besides
>> trying greater than 256MB gpu mem. Perhaps I need to get a Pi 3.
> You never said what version of MythTV you are using - the 0.27 version
> for Raspberry Pi was an unofficial release and is missing many
> optimizations, so hopefully you are on 0.28 or 29.

I'm usingh 0.28.

> Verify the mpeg2 license (vcgencmd codec_enabled MPG2).
> You could try running with -v playback to see if it is dropping frames
> or there is some other problem.

Yeah, that's enabled. I thought it must be: my first run was before my
license was delivered and playback was very lumpy.

> Completely smooth video may not be achievable at this time. See ticket
> at https://code.mythtv.org/trac/ticket/12907
>
> I use it for 1080i and 1080p at 30 fps on a pi2. If it is not 100%
> smooth all the time it does not worry me or my wife.

It's such a shame. It's so close. Most of the 1080i content we get here
isn't truly interlaced and the results for that are not quite perfect
but acceptable. True interlaced content though is noticeably less smooth
than on my zbox.

> If you have done all of the performance steps I recommended, I don't
> think that a Pi 3 will make that much of an improvement. Perhaps you
> notice these things more than I do.

I might give a pi 3 a try, given they're so cheap, but I think you are
corrrect. It looks like the pi 3, although faster with the default set
up, cannot be overclocked much past the pi 2.
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Re: Alternative to zbox for a frontend [ In reply to ]
On 14/09/2017 16:30, Curtis Gedak wrote:
> On 2017-09-13 11:54 PM, Nick Rout wrote:
>>
>> Pi/pi2/pi3 all have the same GPU, so graphics performance on GPU decoded
>> video will be the same.
>>
>
> The Pi/pi2/pi3 might all have the same GPU, but the Pi3 runs the GPU at
> a higher standard frequency (400 MHz versus 250 MHz) [1]. The GPU
> frequency can be over-clocked, but may still end up being faster on the
> Pi3. Hence the decoded video results may not be the same on Pi/pi2/pi3.
>
> [1] https://en.wikipedia.org/wiki/Raspberry_Pi#Video

Yes, but I'm overclocking the GPU on the pi 2 at 500Hz, and from what I
read the pi 3 cannot be taken any higher than that, maybe 550Hz.
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Re: Alternative to zbox for a frontend [ In reply to ]
On 12/09/2017 23:49, jrh wrote:
> Returning to the original subject: A 2010 mac mini loaded with linux functions great as a front end. They are 2.4 ghz core2duo and nvidia geforce 320m graphics chipsets. They can also be had for around $200 used.
>
> I am currently using one now with lubuntu installed and the nvidia drivers installed.

Is it possible to PXE network boot a mac mini? If so it might be trivial
for me to try out mine with the image I use for the zbox.

P.
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Re: Alternative to zbox for a frontend [ In reply to ]
> On Sep 19, 2017, at 8:47 AM, Paul Gardiner <lists@glidos.net> wrote:
>
> On 12/09/2017 23:49, jrh wrote:
>> Returning to the original subject: A 2010 mac mini loaded with linux functions great as a front end. They are 2.4 ghz core2duo and nvidia geforce 320m graphics chipsets. They can also be had for around $200 used.
>> I am currently using one now with lubuntu installed and the nvidia drivers installed.
>
> Is it possible to PXE network boot a mac mini? If so it might be trivial for me to try out mine with the image I use for the zbox.
>
> P.


I don’t know. You might see if Google has any info regarding PXE booting on Macs.
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Re: Alternative to zbox for a frontend [ In reply to ]
On 19/09/2017 15:48, jrh wrote:
>
>> On Sep 19, 2017, at 8:47 AM, Paul Gardiner <lists@glidos.net> wrote:
>>
>> On 12/09/2017 23:49, jrh wrote:
>>> Returning to the original subject: A 2010 mac mini loaded with linux functions great as a front end. They are 2.4 ghz core2duo and nvidia geforce 320m graphics chipsets. They can also be had for around $200 used.
>>> I am currently using one now with lubuntu installed and the nvidia drivers installed.
>>
>> Is it possible to PXE network boot a mac mini? If so it might be trivial for me to try out mine with the image I use for the zbox.
>
> I don’t know. You might see if Google has any info regarding PXE booting on Macs.

A quick google didn't turn up anything, but now on second attempt, iPXE
sounds like what I want. Put an iPXE image onto a USB stick and have it
boot to that.

P.
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