Feature Request - Sync playback to display while passing-trough audio in Kodi 17

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larsete Offline
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Post: #1
Hi guys!

I was a really happy user in terms of video/audio quality/smoothness when using "Sync Audio to Display" at the same time as "Audio Passtrough", but this has changed in Kodi 17 to avoid dropping audio packets when both options are selected at the same time, as very well explained in this thread by FernetMenta; so this is not possible now.

I'm aware this could lead to even better quality with the correct setup/options, but for reasons also explained in that thread (Like ATMOS decoding or simply being able to know my setup is working fine just reading the AV display instead of checking all the time), I still prefer to be able to do both things at the same time, without giving up on having a correct A/V sync, and thus avoiding the video glitch every 40" if not perfectly in sync with the refresh rate.

I was perfectly fine with the old method dropping audio packets, as for me at least, was completely inaudible (on the contrary as the video glitch), But as FernetMenta said, it might be double implementing some better video sync when passtrough is also selected than coming back to this. I'm not the expert here, but I hope this all makes sense Smile

Thank you!!
Best.
(This post was last modified: 2017-03-04 21:10 by larsete.)
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HeresJohnny Offline
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Post: #2
When you publish your first version, l'll be willing to test it.
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larsete Offline
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Post: #3
Thank you for your reply HeresJohnny, but I thought this was the correct place for a "Feature Request" suggestion.

I don't think I'm being disrespectful. I'm completely aware is not something easy, I wish I could do it myself, but in fact, I'm not even asking for something new, as I'm saying I was already happy with the old method that has been removed. So I thought it would be good to let the community know my opinion (and also others), and just leaving it here as a suggestion, because I think more people would find it useful, but sorry if you felt my words weren't in a correct manner or place.

Best.
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HeresJohnny Offline
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Post: #4
Ah, a request. I didn't see that on Tapatalk. Good luck :-)
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witte200 Offline
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Post: #5
I completely agree with Larsete!

I know, allowing audio pass trough with "sync playback to display" makes no sense from a technical point of view, but I've never experienced issues with it in the past. And "adjust display to refresh rate" does not fix the micro stutters when the camera is panning in 24p videos, where "sync playback" to display does fix this.

As for disabling pass trough audio: I hear a noticeable difference from my Marantz A/V receiver when the audio is not in its original DTS/DTS HD format. PCM Multi channel does not give the same warmth and base during movies.

So please make it possible to enable "pass trough audio" and "sync playback to display" together in Kodi 17. Otherwise I will be forced to downgrade back to Kodi 16. And that's something I really don't want to do Sad

Thanks!

PS: I'm on the latest LibreELEC build installed on an AMD based HTPC.
(This post was last modified: 2017-03-15 19:09 by witte200.)
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Memphiz Offline
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Post: #6
Multichannel pcm sounding different then passthrough - that is a strange fact to me. Doesn't happen on my yamaha amp.

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host505 Offline
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Post: #7
If there is a difference, then some kind of dsp is being applied from the avr when passthrough, that can't be applied on pcm.
So, in a sence, multi-pcm is the real pasthrough from source to speakers.
But I guess any processing can be disabled on avr when passthrough, in which case the result should be the same.
(This post was last modified: 2017-03-15 23:00 by host505.)
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rr_7351 Offline
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Post: #8
I too vote for bringing the Sync Playback back.
I got excellent Atmos/DTS:X audio with KODI17 (15 and 16 were dropping out audio) but the movement is jerky. 15 and 16 have excellent movement but Atmos soundtracks are dropping audio every few seconds. All the other audio formats are playing fine most of the time. I did notice occasional clicks. I assume this was because of sync playback. But rather this than stutter video.
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voochi Offline
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Post: #9
(2017-03-04 21:03)larsete Wrote:  I'm aware this could lead to even better quality with the correct setup/options, but for reasons also explained in that thread (Like ATMOS decoding or simply being able to know my setup is working fine just reading the AV display instead of checking all the time), I still prefer to be able to do both things at the same time, without giving up on having a correct A/V sync, and thus avoiding the video glitch every 40" if not perfectly in sync with the refresh rate.

Lets say we are using passthrough and our video framerate is slightly out of whack with display refresh - causing a dupe frame every 40s in order to maintain sync.

Instead of doing it like clockwork every time the sync drifts by 42ms (or whatever the frametime is), would it be possible to intelligently delay this dupe until a black frame (scene transition) or a frame with no movement ? Then this glitch would be unnoticeable.
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forest Offline
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Post: #10
+1 for this (or a suitable replacement).

Use case:
  • Raspberry Pi 2 with TOSLINK board
  • Optical connection to 5.1 AC3/DTS decoder/amplifier
  • HDMI projector (Sony) w/ no sound capability

Optical passthrough is (AFAIK) my only option for 5.1 audio with this hardware.

Without "sync playback to display", video playback is periodically jittery on some content.

Therefore, I have both audio passthrough and sync playback to display enabled in Kodi 16 (LibreELEC 7). I'm using the "adjust PLL" method, as directed here and here. My audio hardware has no trouble with this. My projector has no trouble with this. My eyes and ears perceive a lovely A/V experience.

The fact that Kodi no longer supports both options (and apparently has no replacement option for this hardware setup) keeps me from upgrading to Kodi 17.
(This post was last modified: 2017-03-16 22:23 by forest.)
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Eisi2005 Online
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Post: #11
+1
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ezechiel1917 Offline
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Post: #12
+1

Kodi v17
24/30 video playback randomly stutters (passthrough on/off)
and audio quality is worse Sad (passthrough off)

Still happily on v16 because sync playback to display is just perfect there (with right modelines I never get any acutal dropped/duplicated audio packets during standard playback)
and like many people mentioned audio passthrough does indeed sound noticably better than LPCM (Onkyo).
+ passthrough works on Live TV without any issues.

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drdwridav Offline
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Post: #13
+1
17.1
My use is windows pc connected to ac3 decoder by spdif. Hdmi connection from pc to benq w1110/ht2050.
Adjust refresh rate is on start/stop, but unless sync playback to display is enabled playback is very jerky on movies. It's perfect with it enabled. Of course enabling stops me using passthrough so I only get 2 channel pcm to the decoder
(This post was last modified: 2017-04-02 10:29 by drdwridav.)
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larsete Offline
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Post: #14
(2017-04-02 10:29)drdwridav Wrote:  +1
17.1
My use is windows pc connected to ac3 decoder by spdif. Hdmi connection from pc to benq w1110/ht2050.
Adjust refresh rate is on start/stop, but unless sync playback to display is enabled playback is very jerky on movies. It's perfect with it enabled. Of course enabling stops me using passthrough so I only get 2 channel pcm to the decoder

In your case the lack of this option has a worst effect than in my case, that is just a matter of missing ATMOS (and the AV display thing Tongue), which I can live with; but I hope we will have this option again at some point in the future Smile

In any case, you are always doing a suberb job guys.
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rr_7351 Offline
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Post: #15
(2017-03-04 21:03)larsete Wrote:  I was perfectly fine with the old method dropping audio packets, as for me at least, was completely inaudible (on the contrary as the video glitch), But as FernetMenta said, it might be double implementing some better video sync when passtrough is also selected than coming back to this. I'm not the expert here, but I hope this all makes sense Smile
Did you perhaps try the 17.3 version? Any updates on that matter?
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