RPi2, DVB-C - Data errors / Continuity errors in stream. I don't know what to do more.

Jan Kowalski

Hi,

I'm using RPi2 with Tvh 4.2.4-6 on Raspbian Jessie last release. All working fine beside Data errors / Continuity errors in DVB-C stream. I was trying many configurations, two different USB-sticks but still is the same problem with errors.

1. Currently I'm using DVBSky T330 Stick. Before it was Geniatech T230c.

2. I have good cables and good connectors. Signal strength is -50 dBm, SNR 34 dB. All connections are grounded.

3. CPU on RPi (when recording stream) has about 8%. In config.txt Gpu_mem=192, gpu_freq=500

3. I was trying to disable EPG, initial scans, changing input buffer or status period amounts, disable wifi router, unplug all usb sticks and network cable etc. and nothing helps :( One hour of recording has about 50-60 data errors - amount is similar on HD or SD channels.

How can I fix this problem? Is this possible?

mpmc

You could try using "force_pid_filter_usage".

add:

"options dvb_usb force_pid_filter_usage=1" to /etc/modprobe.d/dvb.conf :)

Jan Kowalski

Thanks, but I don't have this file: /etc/modprobe.d/dvb.conf

Do I need to make this file?

One little thing - if I disable ALL EPG Grabber Modules in Configuration > Channel/EPG > EPG Grabber Modules, quantity of errors is much less, about 25 per hour.

Jan Kowalski

I made dvb.conf file in modprobe.d with "options dvb_usb force_pid_filter_usage=1" but it doesn't change situation :(

mpmc

This sounds like data overload on the single USB bus - not much you can do unless you use a separate backend with a separate Ethernet (giga preferred) & USB ports.

Jan Kowalski

Mark Clarkstone wrote:

> This sounds like data overload on the single USB bus - not much you can do unless you use a separate backend with a separate Ethernet (giga preferred) & USB ports.

What does it mean? Do I need powered USB hub or something like this?

mpmc

Jan Kowalski wrote:
> Mark Clarkstone wrote:
> > This sounds like data overload on the single USB bus - not much you can do unless you use a separate backend with a separate Ethernet (giga preferred) & USB ports.
>

> What does it mean? Do I need powered USB hub or something like this?

The Pi shares a single "USB" bus between it's USB Ports and Ethernet. "This" explains it better than I could.

Jan Kowalski

Just couple words:

1. Tvh shows bandwidth (in Status tab)
- for HD channels: 3500-6500 kb/s

- for SD channels: 2400-3500 kb/s

2. If I use etc/modprobe.d/dvb.conf with:
"options dvbusb force_pid_filter_usage=1"_
or

"options dvbusb_v2 force_pid_filter_usage=1"_

It won't show anything. check

sudo modinfo {dvb_usb,dvb_usb_v2} | less

Syslog show nothing about pid filtering options. But When I use

"options dvbusb_dvbsky force_pid_filter_usage=1_"

Syslog shows:

dvbusb_dvbsky: unknown parameter 'force_pid_filter_usage' ignored_

That's because that module doesn't support the option. :p

I think about buying other tuner: Hauppauge WinTV-Solo which provide DVB-C. Anyone knows that this tuner can handle "force_pid_filter_usage" ???

Jan Kowalski

Well, is that:

1. My dvb.conf file has:
options dvb_usb_v2 force_pid_filter_usage=1
options dvb_usb_v2 disable_rc_polling=1

options dvb_usb_dvbsky disable_rc=1

After reboot

<code>systool -v -m dvb_usb_v2</code>

Module = "dvb_usb_v2"

  Attributes:
    coresize            = "16424"
    initsize            = "0"
    initstate           = "live"
    refcnt              = "1"
    srcversion          = "B48D772FD4CD86C536DE815"
    taint               = ""
    uevent              = <store method only>
    version             = "2.0"

  Parameters:
    disable_rc_polling  = "1"
    force_pid_filter_usage= "1"

  Sections:
    .ARM.exidx          = "0x7f165ba0"
    .ARM.extab          = "0x7f165a20"
    .bss                = "0x7f165ec0"
    .gnu.linkonce.this_module= "0x7f165cc0"
    .note.gnu.build-id  = "0x7f16521c"
    .rodata             = "0x7f1652ac"
    .rodata.str1.4      = "0x7f1653a0"
    .strtab             = "0x7f16a020"
    .symtab             = "0x7f169000"
    .text               = "0x7f163000"
    __kcrctab           = "0x7f165288"
    __ksymtab_strings   = "0x7f1652d8"
    __ksymtab           = "0x7f165240"
    __mcount_loc        = "0x7f1659a0"
    __param             = "0x7f165978"

<code>systool -v -m dvb_usb_dvbsky</code>

Module = "dvb_usb_dvbsky"

  Attributes:
    coresize            = "10092"
    initsize            = "0"
    initstate           = "live"
    refcnt              = "1"
    srcversion          = "05A35D125162F5B71AA58C1"
    taint               = ""
    uevent              = <store method only>

  Parameters:
    adapter_nr          = "-1,-1,-1,-1,-1,-1,-1,-1"
    disable_rc          = "1"

  Sections:
    .ARM.exidx          = "0x7f175758"
    .ARM.exidx.exit.text= "0x7f175388"
    .ARM.exidx.init.text= "0x7f175374"
    .ARM.extab.exit.text= "0x7f17537c"
    .ARM.extab.init.text= "0x7f175368"
    .ARM.extab          = "0x7f175668"
    .bss                = "0x7f175d40"
    .data               = "0x7f1757f8"
    .exit.text          = "0x7f17516c"
    .gnu.linkonce.this_module= "0x7f175b40"
    .init.text          = "0x7f178000"
    .note.gnu.build-id  = "0x7f175188"
    .rodata             = "0x7f1751ac"
    .rodata.str1.4      = "0x7f175390"
    .strtab             = "0x7f178b0c"
    .symtab             = "0x7f17802c"
    .text               = "0x7f174000"
    __mcount_loc        = "0x7f175618"
    __param             = "0x7f1755f0"

<code>sudo modinfo {dvb_usb,dvb_usb_v2} | less</code>

filename:       /lib/modules/4.9.35-v7+/kernel/drivers/media/usb/dvb-usb/dvb-usb.ko
license:        GPL
description:    A library module containing commonly used USB and DVB function USB DVB devices
author:         Patrick Boettcher <patrick.boettcher@posteo.de>
version:        1.0
srcversion:     5052817F8F74754EDB57F76
depends:        rc-core,dvb-core
intree:         Y
vermagic:       4.9.35-v7+ SMP mod_unload modversions ARMv7 p2v8 
parm:           debug:set debugging level (1=info,xfer=2,pll=4,ts=8,err=16,rc=32,fw=64,mem=128,uxfer=256  (or-able)). (debugging is not enabled) (int)
parm:           disable_rc_polling:disable remote control polling (default: 0). (int)
parm:           force_pid_filter_usage:force all dvb-usb-devices to use a PID filter, if any (default: 0). (int)
filename:       /lib/modules/4.9.35-v7+/kernel/drivers/media/usb/dvb-usb-v2/dvb_usb_v2.ko
license:        GPL
description:    DVB USB common
author:         Antti Palosaari <crope@iki.fi>
author:         Patrick Boettcher <patrick.boettcher@posteo.de>
version:        2.0
srcversion:     B48D772FD4CD86C536DE815
depends:        rc-core,dvb-core
intree:         Y
vermagic:       4.9.35-v7+ SMP mod_unload modversions ARMv7 p2v8 
parm:           disable_rc_polling:disable remote control polling (default: 0) (int)
parm:           force_pid_filter_usage:force all DVB USB devices to use a PID filter, if any (default: 0) (int)

<code>ls -al /sys/module/dvb_usb_dvbsky/parameters/</code>

total 0 drwxr-xr-x 2 root root 0 Nov 7 20:54 . drwxr-xr-x 7 root root 0 Nov 7 20:42 .. -r--r--r-- 1 root root 4096 Nov 7 20:46 adapter_nr -rw-r--r-- 1 root root 4096 Nov 7 20:46 disable_rc

I wondering what means this (after command: systool -v -m dvb_usb_dvbsky):

Parameters: adapter_nr = "-1,-1,-1,-1,-1,-1,-1,-1"

Looks weird

mpmc

adapter_nr allows you to assign a custom adapter number. I believe -1 basically tells the driver to pick the next number available. Nothing to worry about.

Jan Kowalski

So, after disabling RC, and adding options dvb_usb_v2 force_pid_filter_usage=1, is still the same amount of errors, nothing change.

I wondering about two things:
1. Is my signal isn't too.... high. Is about -50 dBm, SNR 34 dB
2. Order RPi3.

mpmc

Check that the chipset isn't the same as the one you already have (I think they are).

Getting an RPi3 might not solve the problem either. Hell an Orange Pi zero might be worth a shot if you want something cheap that doesn't share usb buses with Ethernet!

---

If you really want to be sure that tvh is using filtering reduce "Maximum PIDs" (to something like 3) and uncheck "Allow all PIDs" in the tuner frontend options - you may need to change your view-level to expert to see them (in the tv adapters tab).

HTH

Jan Kowalski

I've got no option "Allow all PIDs" (Tvh HTS Tvheadend 4.2.4-6). Is only "Maximum PIDs". Set to 3 doesn't change situation.

mpmc

That's not very promising :(

The DVBSky T330 uses the silabs si216* chipset which I've actually used on a Pi 1 & it worked fine for DVB-T. Mainly because the max bit rate for T is a lot lower compared to C.

Only other thing I can suggest now is to change the power governor on the Pi to performance & see if that helps.

Jan Kowalski

Well, power governon is interesing. After few tests looks good.

I'm using this script to change the raspberry pi governor and let this setting persist through restarts:

https://github.com/DavidM42/rpi-cpu.gov

After installing and command: sudo rpi.gov I choose options "performance - locks the CPU at maximum frequency" and so far I noticed just overall 13 data erros in about 1,5 hours of FHD recording material. I will experiment with other options in cpu.gov

In other side probably I will buy OrangePi strictly for Tvh and DVB-C tuner.

mpmc

Jan Kowalski wrote:
> Well, power governon is interesing. After few tests looks good.
>
> I'm using this script to change the raspberry pi governor and let this setting persist through restarts:
> https://github.com/DavidM42/rpi-cpu.gov >
> After installing and command: sudo rpi.gov I choose options "performance - locks the CPU at maximum frequency" and so far I noticed just overall 13 data erros in about 1,5 hours of FHD recording material. I will experiment with other options in cpu.gov
>

>In other side probably I will buy OrangePi strictly for Tvh and DVB-C tuner.

Get one of the OPis with a H3, avoid the lite as it uses shared usb I believe. H2 CPUs tend to run a little hotter compared to H3 (I have an OPi PC H3 & a OPi zero H2+).

Look "here" to find the right board for you :)

Jan Kowalski

Thanks. I think about OP PC Plus to replace RPi2. Before I though about OP zero just for Tvh but like you said, H2 can be to hotter for tuner. Do you think OP PC Plus is good choice to replace RPi2?

mpmc

Jan Kowalski wrote:

> Thanks. I think about OP PC Plus to replace RPi2. Before I though about OP zero just for Tvh but like you said, H2 can be to hotter for tuner. Do you think OP PC Plus is good choice to replace RPi2?

Pick one that has at least stable "Armbian" (mainline if no desktop, or legacy otherwise). Don't forget about the USB bus issues.

Avoid any that use the XR819 wireless chip, if you plan to use wifi! See "here" for a list of issues!

Jan Kowalski

Well, after some research about OP, I will stay with RPi2.

I take risk and buy OP Zero strict for Tvh

Jan Kowalski

Today I tested OrangePi Zero.

Probably this would be good solution but.... kernel is now just 4.13 and is unable to have DVB-C drivers with this kernel version. Minimum for this 4.4.1 kernel is required.

But is also good news. I installed OSMC on RPi - version OSMC from january 2017 and is working GREAT! Is much quicker than Raspbian with Kodi and better than OpenELEC because I can install all software I want through apt-get install.

But the most important is that quantity of continuity errors is VERY SMALL even if I watching 720p movie from internet via Kodi and have Tvh recording (full HD stream) at the same time! I noticed about 4 errors per 1 hour. This is very promising because I think about upgrade to RPi3.