[mythtv-users] Intel i965 video buffers errors on frontend - Live TV?

faginbagin mythtv at hbuus.com
Tue Jul 11 17:47:04 UTC 2017


On 7/10/2017 6:06 AM, evade. wrote:
> On 07/07/17 18:22, faginbagin wrote:
>> On 7/6/2017 7:35 AM, evade at internode.on.net wrote:
>>> Hello,
>>> I'm having difficult problems with playback in the frontend version 
>>> 0.28.1-3 and would love some help please!
>>>
>>>
>  >> <snip>
>>>
>>> So I switched to VAAPI, despite it lacking deinterlacing.  I'm still 
>>> having playback problems with stuttering, especially with live TV.  
>>> My PC also has Intel HD audio (Realtek ALC892).
>>>
>>> Although playback works, when I enable debug logging I see multiple 
>>> occurrences of both:
>>>
>>> <date> <time> I  Player(0): Waiting for video buffers...
>>>
>>> and:
>>>
>>> <date> <time> I  Player(0): Video is 3.54437 frames ahead of audio,
>>>                          doubling video frame interval to slow down.
>>>
>>> Relevant devices:
>>> Intel H170M chipset, Intel i5-6500 CPU with HD Graphics 530
>>> Intel "HD Audio" (Realtek ALC892)
>  >
>>
>> I suggest trying an OpenGL playback profile. That's what I'm using on 
>> mythtv 0.27 with an i3-3220. My CPU with HD graphics 2500 should be 
>> far less capable than your i5-6500 with HD graphics 530. FWIW, I had 
>> to create a custom playback profile that I called "OpenGL Slimmer" 
>> because I needed to change the primary deinterlacer from Linear Blend 
>> (2X, HW) to Kernel and the fallback from Linear Blend (HW) to One 
>> field. Looks fine on a 32 inch TV in the bedroom. I would imagine your 
>> system can use a better deinterlacer.
>>
>> HTH,
>> Helen
>  >
> 
> Thanks for the fast response Helen!
> 
> Your answer was helpful as I didn't realise that 2D video playback could 
> be so taxing (I guess it's the deinterlacer?).
> 
> You gave me the idea to increase the minimum video memory to the 
> graphics card in the BIOS.  It's now 128 MiB, although that doesn't seem 
> to have changed anything.
> 
> 
> I've just replied to another post and explained that I purchased the i5 
> for my media PC because I hope to run two small VMs on it at the same 
> time. (They use different storage)
> I had hoped the GPU would easily be sufficient for 2D video playback at 
> 1080p and I'd really like to avoid software rendering.  Aren't the 
> OpenGL playback profiles using software?
> 
> 
> Hmm.  I just tried the high quality OpenGL playback profile and it has 
> the same problem with my buffer being 0% when I first change channel.  I 
> could skimp lower, but I will be watching this on our main 55 inch TV.
> 
> Any other ideas, please?
> 
> Thank you,
> evade.

I didn't realize your problems were while watching Live TV. Could it be 
that Live TV is the problem and not which playback profile you're using? 
MythTV's Live TV functionality has always had a bad reputation. If I 
were you, I would first use recordings to test and configure the optimal 
playback profile, and only after you've got that working to your 
satisfaction, test it with Live TV. And you may just have to accept the 
fact you've got to pause for a few seconds to get Live TV to work 
reasonably well.

To give you some points of comparison:
- My CPU is an i3-3220 (2 physical cores with hyper-threading)
- The MB has a B75 chipset
- I have changed the "Internal Graphics Memory Size" in the BIOS from 
the default 64M to the max 1024M.
- The machine has a single 8GB RAM stick.
- I have no SSDs, there's one HDD for the OS, database and 8GB swap 
(which I've never observed being used). One HDD for recordings and 2 for 
"Watch Videos" content.
- I have often had up to 4 simultaneous recordings, with commercial 
flagging jobs going, along with transcoding via Handbrake, and still had 
smooth playback of 1080i mpeg2 recordings.
- I don't see an issue with software rendering, what I care about are 
the results.

-  I don't have access to H.264 1080i content, but when I playback a 
1080i mpeg2 recording (nothing else going on) my Playback Data screen 
reads numbers like:
Storage to Buffer:	>1Gbps
Buffer to Decoder:	3.1 Mbps
Available Buffer:	99% of 4Mb
Video:          	1920x1080 at 29.97fps
Codec/Dec:        	MPEG-2 ffmpeg
CPUs:           	15% 13% 25% 15%
FPS:            	30.01+-0.00
A/V Sync:       	-0.05
Frames decoded/free:	29/1
Audio:          	AC3
Channels:       	6
Sample Rate:    	48 GHz

-When I playback a 1080p H.264 Bluray rip (nothing else going on), my 
Playback Data screen reads numbers like:
Storage to Buffer:	>1Gbps
Buffer to Decoder:	24.5 Mbps
Available Buffer:	99% of 4Mb
Video:          	1920x1080 at 23.98fps
Codec/Dec:        	H.264 ffmpeg
CPUs:           	10% 21% 16% 12%
FPS:            	23.80+-0.00
A/V Sync:       	-0.08
Frames decoded/free:	25/1
Audio:          	DTS
Channels:       	6
Sample Rate:    	48 GHz

You've got a 55 inch TV, so you'll probably notice artifacts I wouldn't 
on my 32 inch TV with OpenGL. Maybe VAAPI will help, maybe not. MythTV's 
OpenGL support provides more deinterlacing options than VAAPI and some 
are supposedly hardware based, so I suspect you can get better results 
with OpenGL.

HTH,
Helen


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