discontinuity errors when playback during recording

  • I'm using rpi4 2 GB with tvh and a technotrend s2-4600 dvb card.

    power supply is good, no throttling, dvb card is attached to usb2 port.

    Recordings work quite good but if I start playback during the recording I get discontinuity errors in tvh log.

    Could this be improved?


    service log http://ix.io/2cAY

    dmesg http://ix.io/2cAZ

  • On a Pi3 it was possible to improve this by messing around with "vcgencmd arbiter set arm_uc" command, e.g.:

    # vcgencmd arbiter status

    # vcgencmd arbiter set arm_uc 12 0


    No idea it this is still valid for Pi4.

  • On a Pi3 it was possible to improve this by messing around with "vcgencmd arbiter set arm_uc" command, e.g.:

    # vcgencmd arbiter status

    # vcgencmd arbiter set arm_uc 12 0


    No idea it this is still valid for Pi4.

    Tried that, but didn't solve the issue.

    Also tried performance cpu governor with no improvement.

    Edited once, last by polo_joe ().

  • On a Pi3 it was possible to improve this by messing around with "vcgencmd arbiter set arm_uc" command, e.g.:

    # vcgencmd arbiter status

    # vcgencmd arbiter set arm_uc 12 0


    No idea it this is still valid for Pi4.

    Is there anything else I could try? I also tried to connect dvb card to usb3 with no improvement.

    I'm running now le 9.2.1 with latest firmware, eeprom and usb3 firmware.

  • Hi, I am getting this if I try to play back any existing recording, whilst a current recording is going, I never has this issue before the latest update, I am running an apollo lake NUC with a USB tuner

  • The changes between 9.2.0 and 9.2.2 are kinda minor, kernel is the same (5.1.16). It doesn't seem likely that 9.2.1/9.2.2 would introduce those kind of issues.

  • Today I tried to boot from usb ssd, I still get continuity counter errors in tvh if I playback an ongoing recording.

  • Today I tried to boot from usb ssd, I still get continuity counter errors in tvh if I playback an ongoing recording.

    Are you recording to this SSD?


    I saw this behaviour, but I haven't had time to look into it properly.


    I've just done a very quick test with an SD TV channel. I started recording, and then started playing the recording. No errors within about a minute.


    I record to a NAS which is connected to my raspberry pi 4 via a wired network.


    Also, I was doing the playback on a different system to the one on which TVH is running.


    I THINK when I saw these problems previously, that I was recording to the microSD card.


    If your TV tuner is USB, and your SSD is USB, could it be that recording from one USB device to another AND playing the file back from USB is simply too much? Sure, it shouldn't reach the theoretical bandwidth, but you never know.


    I guess it would be useful to know which scenarios cause the problem and which do not.

  • I guess it would be useful to know which scenarios cause the problem and which do not.


    I tried the following scenarios with no success


    le and recording on sdcard

    le on sdcard, recording on usb ssd

    le and recording on usb ssd

    le and recording on usb stick


    The issue only occurs with hd channels, sd are ok.

  • Is recording to network an option for you?


    Also, I checked the thread I posted when I was having issues, and I now remember that changing the TV signal booster was a significant factor.


    I can do some testing with HD channels another day, but I've got a recording running at the moment that I don't want to mess up!

  • I will try recording on network, signal strength shouldn't be the issue.

    I tried Generic build with same usb tuner and dvb cable with no problems.


    EDIT: Today I tried recording on network, if I start playback during recording I get discontinuity errors.

    Edited once, last by polo_joe ().

  • I switched my tuner to sundtek skytv 8 but with no improvement.

    After some hours of debugging with sundtek support I was told that rpi (graphics driver) is locking system when playback is started. That's why usb is blocked, dvb buffer runs dry and some data of livetv gets lost.


    Could this be improved somehow?