Framerate Mismatch (NZ)

Channels Apple TV
#1

Hi there.

I am posting this following on from our twitter discussion. I am having frame rate mismatch issues feeding a 25i stream into the channels software through ATV. The ATV output is set to 50hz and the TV is confirming a 50hz signal but I am getting non-smooth playback with a repeat frame with a consistent frequency. This only appears to affect the app via the ATV. When using the iPad or iPhone app the frame rate is smooth so I assume there is some conversion happing with the stream through the ATV/Channels software?

Specs are as follows: HomeRun CONNECT - DVB-T, ATV model 4 tvOS 11.0, Channels TV s/w v3.0.2

Any advice appreciated!

Thanks.

Rob.

1 Like
#2

Actually - on closer inspection (being a much smaller screen!) there is also a frame rate mismatch on the ipad/iphone too but its just a lot harder to see!

#3

I wonder if anyone else using DVB is seeing this issue?

cc @stoli412 @hippykiller2 @jat80 @jmdraper

#4

I run my Apple TV at 60Hz because most other apps look terrible in 50Hz. I have Channels deinterlacing set to Blend (30fps) as I find that does a better job than Linear (60fps). I still experience slight judder but it’s really only noticeable with things like news crawls.

If I do switch the Apple TV to 50Hz and set Channels deinterlacing to Linear (60fps), it plays perfectly smooth.

#5

The problem there also seems to be with the ATV is that there is no ‘auto’ frequency switching. In an ideal world the ATV would switch between 50/60 depending on what source is being played, so yes for a lot of content and apps the 60hz setting is what is correct, but when you are watching a 25fps signal then the ATV has to be set to 50hz to ensure smooth motion and frame rate. (Which obviously isn’t currently happening!) With the consistent frequency of the repeat frame it really does feel like there is some sort of frame rate conversion going on somewhere and not a smooth pass through of the signal.

#6

We have a ticket open with Apple asking for an api to let us automatically change the display refresh rate.

I wonder why you’re seeing different behavior than @stoli412, who said things are “perfectly smooth” when the ATV is put into 50hz mode.

Can you try the free apps InstaTV and VLC to compare?

#7

I use Plex and its smooth going though that. Will check out the others now and let you know!

#8

@robgordon000 Are you sure you have switched off all motion compensation and/or frame interpolation that your TV may be performing? I find those settings create far more issues than they’re worth. If you have the Apple TV set to 50Hz and Channels set to Linear deinterlacing, you shouldn’t have any frame rate issues with standard UK content.

I 100% agree that Apple need to add automatic framerate switching between 50, 60, and 24 Hz. I’m not holding my breath though :frowning:

#9

Yep - it’s set to linear. I have tried both and the blend option still has the stepping but just then looks like its been field stripped! Its a shame you can’t turn off deinterlacing completely and just pass an interlaced signal though to the TV and let the TV do the deinterlacing! I guess that’s a limitation of the ATV only having a progressive output?

#10

Oh yes. ALL options are turned off on the TV! Haha. That’s always the first thing I do with any new TV. Why people think these options make an image look better is beyond me!!

#11

I’m really at a loss then. 50Hz + Linear looks flawless on my TV. I actually wish I could leave it on 50Hz all the time, but Netflix and Plex just won’t display properly with it, so I compromise with 60Hz + Blend.

#12

So an update from this morning… I’ve put on the 11.1 update onto the ATV and playback is currently smooth! I don’t know if this can be directly attributed to the update or something else that has changed. Obviously that doesn’t change the iOS version but I assume the displays on those are stuck at a specific frequency?

I’m seeing the very occasional skipped frame on the ATV but certainly not consistent repeated or skipped frames like last night. This makes me happy as the TiVo service is due to stop here soon ( :sadface: ) and I need to find an alternative for terrestrial TV that works well and so far Channels is the best app available as a replacement!

2 Likes
#13

Ah, sounds like you hit the known performance issue in tvOS 11.0. See TvOS 11 Stuttering

That issue mostly only affects mpeg2 playback, but can also affect H264 users who are receiving interlaced video.

We are hoping tvOS 11.1 is released soon…

#14

I have a gen5 ATV arriving in the morning so will be interesting to see how it works on that. I assume it will come with tvOS 11.0 on… if it’s the same I will put the beta on and check. That should answer the question!

#15

The ATV4K is not affected because it is much more powerful.

1 Like
#16

I’m on the new Apple TV 4K, maybe that’s why I’m not seeing what you’re seeing.

1 Like
#17

I’ve been holding out for the 64gb and it’s been taking ages to get sent!

#18

4K ATV arrived and is working perfectly!

Last question I have now is when will you roll out the DVR functionality? That’s the missing part of the TiVo replacement!