Cracking / Popping audio - HDMI - LibreELEC (official): 9.95.1 (RK3399.arm)

  • Hello has anyone also experienced a slight popping/cracking of audio when playing video? I have tested multiple audio files, current version of LE and older versions. device is not the issue - confirmed.

  • I'm not sure which sample, on any video that I would not play, there are crackles in the sound output on hdmi, it is most clearly manifested in ishi's dialogues when music is playing.

  • Just tried it again with my rockpro64 and various sample rates: I really can't hear anything cracking. Can you verify it doesn't happen with older LE (vendor kernel based) release or android? if it happens there also: parts of HW might be broken (due to overclocking or something)

  • This is definitely not a hardware problem. I have a new SBC Rock Pi 4B, installed LibreELEC 9.2.6 on the EMMC module and 9.95.2 on the microSD card (by the way, when will LibreELEC 10 be able to boot from EMMC?), I compared rebooting between them, on 9.2.6 there is no such problem. Perhaps this is not a problem with all RK3399 SoCs, but only Rock Pi 4B on the new kernel.

  • by the way, when will LibreELEC 10 be able to boot from EMMC?

    If you're using a detachable emmc module, feel free to flash the image there - its working great witch rockpro64. (and upstream device tree for rockpi4 has emmc enabled as well)

    Perhaps this is not a problem with all RK3399 SoCs, but only Rock Pi 4B on the new kernel.

    Yeah, looks like. I can't hear any cracking on neither my RK3399 TV box nor on rockpro64. Its kind of hard to do some remote guesswork - can you upload a audio record to get a feeling, what is actually meant with "cracking" and also link to the stream which you played at that time?

  • The description sounds [sic] like the high-pitched pops that I heard on Amlogic until I ditched the experimental HDMI pass-through patches.

  • one another note.. since a few weeks ago audio has stopped working completly.. GUI sounds are no longer heard and the only way i have found to get audio working is to do "pulseaudio --start" as soon as i play the same audio file/s again, audio is working.. i have rebooted and also confirm that pulseaudio service is running using "ps aux | grep pulseaudio"


    Output:

    396 root 0:04 /usr/bin/pulseaudio --system --disallow-exit --exit-idle-time=-1 --disable-shm --enable-memfd --realtime


    its strange.. i remember the day it happened.. GUI audio sounds were popping and cracking.. when played video file during the movie audio died.. since then.. this is the only way i found to fix it.. I also upgraded to LibreELEC (official): 9.95.2 (RK3399.arm).. and issue is still there..

  • I compared vendor with mainline kernel for anyting which could belong to hdmi audio - all I could find, that could help was, that dmac clock is higher in vendor kernel.

    Mr.Tiptop  Mikhail

    Please take a spare SD card, flash the latest nightly (no update) on it and replace the device tree with the with this one: https://mega.nz/file/vHZ21D5R#…bzl2NgnAgXdUVYUJezmP6fPfo , where I increased that clock:


    Code
    scp rk3399-rock-pi-4a.dtb [email protected]<ip of device>:


    login via ssh:


    Code
    ssh <ip of device>

    move devicetree to flash partition:

    Code
    mount -o remount,rw /flash/
    mv /storage/rk3399-rock-pi-4a.dtb /flash/

    and

    Code
    reboot



    . It does make zero difference on my boards (never had audio issues with no bit-/or sample-rate) - but it might make a difference for rockpi4 (dram maybe slower). Do not enable passthough (this is experimental and will go away before final LE10 release) and don't touch any audio settings. If everything went OK

    Code
    cat /sys/kernel/debug/clk/clk_summary | grep dmac

    should look like that:


    Code
    aclk_dmac1_perilp       0        1        0   297000000          0     0  50000
    aclk_dmac0_perilp       1        2        0   297000000          0     0  50000


    Please check if it makes any difference for you for audio output.

  • lease take a spare SD card, flash the latest nightly (no update) on it and replace the device tree with the with this one: https://mega.nz/file/vHZ21D5R#…bzl2NgnAgXdUVYUJezmP6fPfo , where I increased that clock:

    I have a NanoPi M4. can you send me the dbt file for the M4 please?


    Current output:


    Code
    cat /sys/kernel/debug/clk/clk_summary | grep dmac
    aclk_dmac1_perilp       0        1        0   100000000          0     0  50000
    aclk_dmac0_perilp       1        2        0   100000000          0     0  50000
  • I could not boot from the EMMC module on the Rock Pi 4: Could not mount / flash / SYSTEM, as I understand it, you need to change the paths after uploading the image to the EMMC? I tried a new .dtb, it got better, but the problem did not go away completely, if you listen, there are occasional crackles. On the last nightlies, the Kodi interface on my TV began to turn purple-green, which is not on 9.95.2, apparently, the output signal for some reason switches to YCbCr.

  • I could not boot from the EMMC module on the Rock Pi 4: Could not mount / flash / SYSTEM, as I understand it, you need to change the paths after uploading the image to the EMMC?

    Nope. no paths have to be changed - but Rock pi4 needs special handling of emmc. It will be available from next nightlies - so presumably from tomorrow on. Please check and report back.


    For all other issues which seem to be Rockpi 4 related: radxa will send me a board - which might take some time to arrive.