Sound glitches in AAC sound from DVB-T2 stream

  • DM525, latest official firmware
    Here in Czech Republic I'm able to receive DVB-T2 stream with HEVC video and AAC audio.
    But audio quality is very poor both on HDMI and with S/PDIF. I have recorded audio from dream to WAV and also converted AAC to WAV (both files in attached ZIP). In audio from dream I found silent spaces - the source of poor audio quality.
    Both WAV files can be loaded to Audacity to compare both audio tracks.


    I'm ready to provide support to solve the problem.


    [Blockierte Grafik: https://i.snag.gy/nfXroM.jpg]

  • This messages I found in kernel log. Is it significant or not? No problem with signal strength.

    DM525 DVB-T2 + DVB-S2

    • Offizieller Beitrag

    Is the problem only present when you are watching live?


    Can you try to make a recording and look if the problem is also present on playback?



    Otherwise you can try the following:


    Connect to your stb via telnet / ssh / or serial terminal.


    And write:


    echo 6978 > /proc/stb/audio/pcr_offset_aache


    This should fix the issue.


    Please report if it works.


    After reboot you must set it again. When it works i can add it as default for next hardware driver snapshot.


    cu

  • Problem is only when watching "online". Playback of recordings and also the timeshift are OK.


    echo 6978 > /.... doesn't solve the problem (sure spaces before and after >, cat /proc/stb/audio/pcr_offset_aache gives me 00006978).


    Here in the Czech Republic we have only one DVB-T2 multiplex, all channels coded with h265+AAC and all channels has the same problem.


    I also tried FTA DVB-S radio coded with AAC and it worked fine. Unfortunately audio of Euronews English HD is coded back in MPEG. Can you suggest me a FTA station with AAC sound I could try? I know CZ DVB-T2 is quite far from you.

    DM525 DVB-T2 + DVB-S2

  • @Ghost Thank you for your support, but it's still the same


    Short recording can be downloaded from http://ge.tt/5F1y9rl2


    If it should be helpful for you, I can provide you a ssh/web access to my box.

    DM525 DVB-T2 + DVB-S2

  • The problem is still unresolved in 4.3.1r18. It's also discussed on czech forums, so it's not only my problem.
    If it will not be fixed, we are considering return the box in warranty period.

    DM525 DVB-T2 + DVB-S2

  • I have exactly the same problem with DM525 with DVB-T2 tuner here in Czech republic. The sound is husky, but only when watching online. Recorded streams sounds normal without any distortion.