[Bug]: EAC3 7.1 make choppy video playback

[datiyo]

Problem description

I tried some mkv on Xiaomi TV under Fire OS and sometimes the video was choppy with Nova Video Player. With VLC/Kodi no issues.

It's only happenning when the video playback is with EAC3 7.1 audio.
https://youtu.be/9y4eVMpDG9g

I tried disable/mode 2/force passthrough...

I found a lot of old discussions about EAC3 7.1 on VLC like https://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3e9d676192fc6ef719a904f8a2d114efec03d7c1

Steps to reproduce the issue

I uploaded the sample AAC2.0 / DDP5.1 / DDP7.1
https://transfert.free.fr/uDNg7Ru

Your phone/tablet/androidTV model

Xiaomi Fire Smart TV F2 55

Operating system version

Android 9

Application version and app store

6.2.93 on Amazon appstore and 6.3.15 on Github

Additional system information

No response

Debug logs

No response

[Pentaphon]

@courville I also find that enabling Nova passthrough on 6.3.15 on my FireTV 4K stick 1st gen on a file with E-AC3 audio creates choppy playback. I always have to disable it.

[datiyo]

I tried on my phone (pixel 4a 5g) and same problem, when I choose EAC3 7.1 in any video it's super fast choppy and no audio.

[courville]

@datiyo, thx for sharing the sample and describing the issue: I can reproduce on my phone too.
What I found out based on the observation that on the android emulator (android tv api 31) that it was working, that when disabling on the phone the deactivate stereo downmix option, it starts working.
I thus think the issue is in the downmix code of avos. I will investigate.

[datiyo]

@courville

Thx

• I tried desactivate stereo ON on the phone and 7.1 audio is back and video is choppy (OFF was super fast choppy and no audio)
  Actually on my phone the video is always choppy with Nova even with AAC 2.0 and all setting combinaison. With Kodi it's ok.
  https://youtu.be/k6jFEzZV6ps

• I also did more tests on TV, passthrough always MODE 2 and android frame sync OFF

Force passthrough OFF
Force stereo OFF
AAC ok
5.1 ok
7.1 choppy video, audio ok

Force passthrough ON
Force stereo OFF
AAC ok
5.1 choppy video, audio ok
7.1 choppy video, audio ok

Force passthrough OFF
Force stereo ON
AAC ok
5.1 ok
7.1 super fast choppy video, no audio

Force passthrough ON
Force stereo ON
AAC ok
5.1 choppy video, audio ok
7.1 choppy video, audio ok

Deactivate stereo on the phone and force stereo on TV are the same option but reverse ?

[courville]

@datiyo thx for your testing.
Indeed there is a difference between what is experienced on tv and phone.
What I can see on my side is that when enabling @phhusson android frame sync the video plays smooth on the phone and without it does not. However smooth playback is only experienced when launching the video and slight stuttering is back always when switching audio tracks.

[datiyo]

@courville

On my phone I was on the Play Store version.
I updated now to the latest, and I have the same experience as you with android frame sync on the sample 👍

EDIT

I tried the sample again on TV and now it's good with android frame sync !! I don't understand because I tried this option (EDIT 3 : I tried at the beginning with a 24p sample and after I switched for the 60fps sample without new test with android frame sync ON that's why).

Passthrough always MODE 2 and android frame sync ON

Force passthrough OFF
Force stereo OFF
AAC ok
5.1 ok
7.1 ok

Force passthrough ON
Force stereo OFF
AAC ok
5.1 ok
7.1 ok

Force passthrough OFF
Force stereo ON
AAC ok
5.1 ok
7.1 video ok, no audio

Force passthrough ON
Force stereo ON
AAC ok
5.1 ok
7.1 ok

EDIT 2

Finally it's ok only with the sample, Star Wars full movie 7.1 is still stuttering even with Android Frame Sync ON 🤔

[datiyo]

@courville @phhusson

I created a all fps stutter test sample pack (thx Rantapossu on youtube) with 2.0 5.1 7.1 audio
https://mega.nz/file/fAY1WBCQ#1YGPdaAN_nNOAKG33xOQDtQEuRlG2yGQf8m-bY_BNVQ

• On TV, passthrough mode 2, force passthrough OFF, force stereo OFF

Android frame sync OFF

23.976   2.0 ok        5.1 ok        7.1 stutter
24       2.0 ok        5.1 ok        7.1 stutter
25       2.0 ok        5.1 ok        7.1 stutter
29.97    2.0 ok        5.1 ok        7.1 stutter
30       2.0 ok        5.1 ok        7.1 stutter
59.94    2.0 ok        5.1 ok        7.1 stutter
60       2.0 ok        5.1 ok        7.1 stutter

Android frame sync ON

23.976   2.0 stutter   5.1 stutter   7.1 stutter
24       2.0 ok        5.1 ok        7.1 ok
25       2.0 ok        5.1 ok        7.1 ok
29.97    2.0 stutter   5.1 stutter   7.1 stutter
30       2.0 ok        5.1 ok        7.1 ok
59.94    2.0 stutter   5.1 stutter   7.1 stutter
60       2.0 ok        5.1 ok        7.1 ok

• On Smartphone, passthrough OFF, force passthrough ON, disable stereo ON

Android frame sync OFF

23.976   5.1 stutter   7.1 stutter
24       5.1 stutter   7.1 stutter
25       5.1 stutter   7.1 stutter
29.97    5.1 stutter   7.1 stutter
30       5.1 stutter   7.1 stutter
59.94    5.1 stutter   7.1 stutter
60       5.1 stutter   7.1 stutter

Android frame sync ON

23.976   5.1 stutter   7.1 stutter
24       5.1 ok        7.1 ok
25       5.1 ok        7.1 ok
29.97    5.1 stutter   7.1 stutter
30       5.1 ok        7.1 ok
59.94    5.1 stutter   7.1 stutter
60       5.1 ok        7.1 ok

Android frame sync works great for 24 25 30 60 fps video and it's not working for 23.976 29.97 59.94 fps video
All movies are usually 23.976 fps that's why it was not good with.