[PROBLEM] Gapless playback not working anymore on FLAC

[A.T.E.]

Software
XBian version: since 2017.02.24; latest tried 2019.04.19
XBMC/Kodi version: 17, 18.1
Overclock settings: none

Hardware
Device type and model (e.g. Raspberry Pi Model A/B 256/512 MB, CuBox-i i4Pro, ...): RPi2
Power supply rating: the usual 5 Volt, 2 Ampère
SD card size and make/type: Toshiba Exceria SDHC UHS1 16GB, but it happens on other models
Network (Ethernet or wireless): Ethernet
Connected devices (TV, USB, network storage, ...): TV, NAS, Hifiberry DACplus

Log files
Link to logfile(s): https://trac.kodi.tv/ticket/17375#ticket

Problem description:

Since Kodi 17.0 (XBIAN 2017.02.24 on a Raspberry Pi 2) the FLAC playback experiences a very short, but audible, gap between tracks. As far as I can tell, the gap happens at the beginning of the subsequent track. It happens on FLAC, but not on on MP3.

As you can see from the link to the logfile, I had opened a ticket for the Kodi folks. Since then, I have tried a version of OSMC (2018.12-1 running Kodi 17.6), and that one is not experiencing the issue. This leads me to suspect that perhaps this is not an issue of the Kodi source code, but of how it is built into an executable.

Now, I took the chance of the new Kodi 18 to try to come back to Xbian, but again, to my disappointment, the issue is still there.

So, I have decided to try my luck here reporting the issue to you; perhaps you will be able to have a look at it and understand the root cause. As I am not sure of the origin of this issue, before going to github, I am posting it here.

FYI, the last Xbian version that I am aware not to be affected by this issue is 2017.02.17 (Kodi 16), whose .img I keep as a treasure on my computer. The problem is that add-ons evolve, and they gradually stop supporting Kodi 16...

How to reproduce:

It happens on FLAC, not MP3. So, you need two consecutive FLAC tracks without silence between them (such as on a live album).

[Nachteule]

@A.T.E.
Can you please provide two consecutive FLAC tracks without silence between them
Thanks

[A.T.E.]

(22nd Apr, 2019 09:31 PM)Nachteule Wrote:  @A.T.E.
Can you please provide two consecutive FLAC tracks without silence between them
Thanks

Hi, I am sharing these files: https://drive.google.com/open?id=1LuJ64225hiKx_3k3OPsJcnbD3FNytV3V

[Nachteule]

Got it, thanks

[Nachteule]

First quick test (RPi3B+, Kodi 18.2, Samba share, output via HDMI):

I can't recognize any gap between those 2 tracks

Will try it with my RPi2 + Hifiberry Amp+ tomorrow

[Nachteule]

Next test run:

Hardware and configuration:
- RPi2, no overclock
- rootfs on external usb disk
- Hifiberry AMP+
- Kernel 4.19.14+
- Kodi 18.1
- Audio output device ALSA Default (snd_rpi_hifiberry_amp Analog)
- Audio Setting: Cross fade between songs: Off
- Audio Setting: Visualisation: Shadertoy
- Cachiing: using defaults, nothing set in advancedsettings.xml
- No /etc/asound.conf file
- Flac files on Samba share

Result:
Absolutely no gap between tracks recognizable

[A.T.E.]

Thanks for devoting some of your time to this issue.
I am thinking that either you could not replicate the issue, either you could, but you did not notice the gap, which is in fact very very short.
Just in case it should be the latter, I have shared one more file, which is what I hear when I play those two FLACs on my system.
If you carefully listen (perhaps using a headset as the audio quality is not the best) to this audio file, which I recorded with my phone, you can feel (between seconds 14 and 15, actually more towards 15) the gap happening: https://drive.google.com/open?id=17Oz5-PYPmjQcmBtAleGNBuVvyj1bi2Cu
The two FLAC files were played locally (i.e.: they were on the local SD card), so that I would discard any possible SMB or network latency.
Also, later I have disabled the Hifiberry DAC+ by restoring the /boot/config.txt file to its original settings. I played the two files again through the HDMI output and I could feel the gap.
At that point, XBIAN was in its “vanilla” state (i.e.: no add-ons) except for the old Confluence skin.
If on the other hand you could not replicate the issue, the thing becomes more complicated. It can be my system, but other people reported the same issue, and also the thing is not happening on OSMC (which has received a major system and Kodi (18.2 RC1) update some days ago.

[Nachteule]

(27th Apr, 2019 08:05 PM)A.T.E. Wrote:  Thanks for devoting some of your time to this issue.
I am thinking that either you could not replicate the issue, either you could, but you did not notice the gap, which is in fact very very short.
Just in case it should be the latter, I have shared one more file, which is what I hear when I play those two FLACs on my system.
If you carefully listen (perhaps using a headset as the audio quality is not the best) to this audio file, which I recorded with my phone, you can feel (between seconds 14 and 15, actually more towards 15) the gap happening: https://drive.google.com/open?id=17Oz5-PYPmjQcmBtAleGNBuVvyj1bi2Cu
The two FLAC files were played locally (i.e.: they were on the local SD card), so that I would discard any possible SMB or network latency.
Also, later I have disabled the Hifiberry DAC+ by restoring the /boot/config.txt file to its original settings. I played the two files again through the HDMI output and I could feel the gap.
At that point, XBIAN was in its “vanilla” state (i.e.: no add-ons) except for the old Confluence skin.
If on the other hand you could not replicate the issue, the thing becomes more complicated. It can be my system, but other people reported the same issue, and also the thing is not happening on OSMC (which has received a major system and Kodi (18.2 RC1) update some days ago.

Thanks again for your sample file.

Yes, I can hear the gap in this file, but this gap is definitely not there when playing the two FLAC files. Checked even with Confluence skin, no gap recognisable

I've made a recording, you can check if you hear any gap in this sample