[S905X] - Noise when playing files with AAC 5.1 audio

    Device: Cooleme MB1 (S905X - 2GB/8GB)
    Build: kszaq's LE version 8.0.0b
    Set-up: TV box connected via HDMI to Onkyo TX-SR508 AVR

    Symptoms: when playing video files with AAC 5.1 audio, I get crackling noises from the rear speakers. Sometimes I get white noise from all speakers.
    It happens mainly with 1080p/23.976fps files. I had this problem with most Krypton releases (maybe with Jarvis as well but I can't be certain). All other audio formats work perfectly.

    Audio passthrough is enabled, using ALSA HDMI audio output.
    DSP processing is off

    Samples files: The "I Am Legend" trailers from this page: H.264 Demo Clips | H264info.com
    You may need to play the video a few times for the problem to appear.

    Oh well...I guess I have to learn to live with it. After restarting a video 2 or 3 times the sound clears up. Thanks anyway :)

    I was wondering if others have the same problem.

    I have tons of files with AAC audio, from 2.0 to 7.1 - but I never noticed any problems with playback. Passthrough should be irrelevant, as AAC needs to be decoded by the SoC. All I noticed is that with my 7.1 setup, with 5.1 AAC or FLAC audio the avr still indicates 7.1 input, and the rear speakers will stay silent. I know that this is a limitation of the amlogic hd multichannel hdmi audio.

    I will do some decoding tests with my S905X and see if I can reproduce your issue. My box in the home cinema still runs LE 7.

    Thanks for the info.

    It's a strange problem, indeed. You may start a movie and all will be well for 15-20 minutes and then the crackling begins. Other times the video starts with high distortion in all channels (white noise) and with a simple stop\play the problem goes away.

    I really can't remember whether I had this problem with Jarvis or not. I'll see if I have a spare microSD card for testing.

    Can definately confirm I have the exact same issue.

    I have multiple boxes running libreelec S905 and S905x. Those connected directly to tv with passthrough disabled no issues.

    Issue only occurs when plugged via hdmi into avr. All passthrough options enabled. I believe the S905x box converts multichannel aac to pcm (5.1 to 5.1 or 7.1 to 7.1) but occasionally this results in the loud white noise. Happens when initially playing/resuming a video after a pause. Only way to get rid of it is to stop video and play again... Sometimes 2 or 3 times and then the noise is gone. Very very annoying because the noise is often louder than the audio track and my Yamaha avr wakes everyone up til I stop it... Lol.

    Tried multiple builds and every setting I can see, sometimes disabling passthrough and reenabling it during play fixes it.

    Please note with passthrough disabled this does not occur.

    When u reduce your speaker/audio setting to 2ch, another option appears to transcode aac to ac3 but everytime I tried that my boxes would freeze.

    I just put up with the noise stopping and starting til it goes away. It's almost like an inserted noise that starts during the digital to analogue pcm conversion randomly for some reason. All other passthrough formats work flawlessly.

    Minimoe I feel your pain....

    This and the odd occasional lock up after reboot (very rare) are the only 2 problems I am encountering with my libreelec and s905/s905x boxes.

    Sent from my HTC 2PS6200 using Tapatalk

    I connected my S905x box to my avr yesterday and tried to reproduce the issue. Passthrough was enabled and I tested multiple different files with 5.1, 7.1 and 2.0 sac.

    I did not have any crackling or white noise.

    Quote from DATS2LS


    I just put up with the noise stopping and starting til it goes away. It's almost like an inserted noise that starts during the digital to analogue pcm conversion randomly for some reason. All other passthrough formats work flawlessly.

    Do have noise\distortion in 720p videos? Seems like the box is struggling with simultaneous 1080p and multuchannel AAC decoding.
    [hr]

    Quote from mmpp


    I connected my S905x box to my avr yesterday and tried to reproduce the issue. Passthrough was enabled and I tested multiple different files with 5.1, 7.1 and 2.0 sac.

    I did not have any crackling or white noise.

    Have you tasted the trailers in the OP?
    Those cause problems to me almost half the times I play them.

    Edited once, last by minimoe (February 27, 2017 at 4:17 PM).

    Have you tasted the trailers in the OP?
    Those cause problems to me almost half the times I play them.
    [/quote]

    Unfortunately most of my library is 1080p x265 5.1 aac. I will have a hunt through for some 720p x265 5.1 aac. Or I'll try the link u sent through later tonight after work.

    Sent from my HTC 2PS6200 using Tapatalk

    Edited once, last by DATS2LS (February 27, 2017 at 11:31 PM).

    You're right, there are not many 720p/AAC5.1 sample files.
    Don't waste your time, I'll post links when I find them :)

    (the links in the OP are 1080p )

    Edited once, last by minimoe (February 28, 2017 at 6:40 AM).

    Minimoe

    I just tested some 720p x265 5.1 aac files and found the problem occurs there also. I don't think it's an issue with the video component... Or total bitrate size being played. I think it's just the way kodi is initialising the 5.1 aac to pcm conversion that is introducing the noise randomly. When you hit play and there is no noise it plays quickly and smoothly, even when I hit the menu button, slight frame loss while the menu opens but the sound is smooth. It's like a hit and miss sometimes it just introduces the sound and keeps going with it until you hit stop.

    MMPP please note as mentioned this occurs randomly. And certainly not everytime I hit play. I would hazard a guess and say one out of 7 plays would produce the noise. Just for kicks I counted just then on the same 1080p 5.1 aac x265 file just now... It took 11 attempts for the sound to be heard.

    Minimoe is this about the same for you? Or do you find yours produces the sound more often?


    Sent from my HTC 2PS6200 using Tapatalk

    Edited once, last by DATS2LS (February 28, 2017 at 6:55 AM).

    First of all, thank you for the extensive testing :)

    I'd say one out of 7 plays is about right. Some files (like the samples in the OP) are worst than others. I haven't noticed any frame loss.
    I think the distortion is more frequent when there is music playing.

    I had volume amplification enabled (level 12) in the Audio & Subtitles Settings. I turned it off now, in case it causes distortion.

    Edit: nope, that didn't help.

    Edited once, last by minimoe (February 28, 2017 at 10:42 AM).

    In further testing, I could get noisy crackling output from all speakers with the "I am Legend" trailer linked above on my S905X. It happend about 1 in 6 times.

    None of my own files (tested 30+ files) triggered the noise, and I repeatedly tried with the "Simpsons Movie" trailer from the same site above, and also got no noise (started at least 15 times).

    Quote from mmpp


    In further testing, I could get noisy crackling output from all speakers with the "I am Legend" trailer linked above on my S905X. It happend about 1 in 6 times.

    None of my own files (tested 30+ files) triggered the noise, and I repeatedly tried with the "Simpsons Movie" trailer from the same site above, and also got no noise (started at least 15 times).


    Consider yourself lucky :)

    I see you're running 8.0.0c. I'll upgrade from "b" in case something changed and made the noise less frequent.

    Quote from minimoe


    Consider yourself lucky :)

    I see you're running 8.0.0c. I'll upgrade from "b" in case something changed and made the noise less frequent.


    I was running 8.0.0c also minimoe. No changes. About to upgrade to 8.0.0d but as Kszaq is unable to reproduce issue I don't see how we can get a fix...

    Sent from my HTC 2PS6200 using Tapatalk

    You're right, no changes with 8.0.0c.

    Well, all we can do is provide as much data as possible and then maybe Kszaq can fix it. My theory is that it has something to do with sound levels at the rear speakers. I hear it more when there is loud music or sound FX.

    I have the exact same random issue, although with FLAC surround audio and a Pioneer AVR. The rest of the details are identical.
    MakeMKV rip with HD surround tracks converted to FLAC. Infrequently but regularly blasts static through the rear channels (5.1 set up). Stopping and restarting often will fix the issue. Pausing allows but does not guarantee that it reappears.