channel scanning segfaults on analog tuner of pchdtv5500

[thomas.epperson@…]

Mythtv version is mythtv-0.25.2+fixes.20120802.46cab93

I have experienced this segfault everytime I try to scan for channels on the analog tuner of my PCHDTV5500 card. I am using kubuntu-12.04 and am scanning on the v4l /dev/video0 card. Attached is a core dump of the program.

[thomas.epperson@…]

I'm attaching a backtrace from the core dump.

Program terminated with signal 11, Segmentation fault.
#0  0x00007f1879f2955c in TVRec::IsBusy(TunedInputInfo*, int) const () from /usr/lib/libmythtv-0.25.so.0
(gdb) bt
#0  0x00007f1879f2955c in TVRec::IsBusy(TunedInputInfo*, int) const () from /usr/lib/libmythtv-0.25.so.0
#1  0x00007f1879e9b48f in ?? () from /usr/lib/libmythtv-0.25.so.0
#2  0x00007f1879f87590 in ?? () from /usr/lib/libmythtv-0.25.so.0
#3  0x00007f1879f80e44 in ?? () from /usr/lib/libmythtv-0.25.so.0
#4  0x00007f1879f8041c in ?? () from /usr/lib/libmythtv-0.25.so.0
#5  0x00007f1879eb95ed in ?? () from /usr/lib/libmythtv-0.25.so.0
#6  0x00007f1879eb98c3 in ?? () from /usr/lib/libmythtv-0.25.so.0
#7  0x00007f1879ecac4e in ?? () from /usr/lib/libmythtv-0.25.so.0
#8  0x00007f1879ecb689 in ?? () from /usr/lib/libmythtv-0.25.so.0
#9  0x00007f187955ec27 in MThread::run() () from /usr/lib/libmythbase-0.25.so.0
#10 0x00007f18774d3fcb in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#11 0x00007f1871977e9a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#12 0x00007f1876c73cbd in clone () from /lib/x86_64-linux-gnu/libc.so.6
#13 0x0000000000000000 in ?? ()

[thomas.epperson@…]

Replying to thomas.epperson@…:

I didn't do that core dump with the right stuff installed. Looks like a null pointer to a TVRec object.

Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `mythtv-setup'.
Program terminated with signal 11, Segmentation fault.
#0  TVRec::IsBusy (this=0x0, busy_input=0x7f20b6dad150, time_buffer=5) at tv_rec.cpp:2403
2403        if (!channel)
(gdb) bt
#0  TVRec::IsBusy (this=0x0, busy_input=0x7f20b6dad150, time_buffer=5) at tv_rec.cpp:2403
#1  0x00007f212186a0cf in ChannelBase::IsInputAvailable (this=0x3863fe0, inputid=7, mplexid_restriction=@0x7f20b6dad45c: 0)
    at channelbase.cpp:522
#2  0x00007f2121956140 in V4LChannel::SwitchToInput (this=0x3863fe0, inputnum=7, setstarting=false) at v4lchannel.cpp:768
#3  0x00007f212194f9f4 in V4LChannel::Tune (this=0x3863fe0, frequency=55250000, inputname=...) at v4lchannel.cpp:504
#4  0x00007f212194efcc in V4LChannel::Tune (this=<optimized out>, tuning=..., inputname=...) at v4lchannel.cpp:479
#5  0x00007f212188808d in ChannelScanSM::Tune (this=0x38651d0, transport=...) at channelscan/channelscan_sm.cpp:1644
#6  0x00007f2121888363 in ChannelScanSM::ScanTransport (this=0x38651d0, transport=...) at channelscan/channelscan_sm.cpp:1675
#7  0x00007f21218996ee in ChannelScanSM::HandleActiveScan (this=0x38651d0) at channelscan/channelscan_sm.cpp:1586
#8  0x00007f212189a129 in ChannelScanSM::run (this=0x38651d0) at channelscan/channelscan_sm.cpp:1465
#9  0x00007f2120f7e377 in MThread::run (this=0x38141c0) at mthread.cpp:319
#10 0x00007f211eef3fcb in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#11 0x00007f211ab37e9a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#12 0x00007f211e693cbd in clone () from /lib/x86_64-linux-gnu/libc.so.6
#13 0x0000000000000000 in ?? ()

[thomas.epperson@…]

Here is part of the verbose output of mythtv-setup -v all

2012-10-27 23:39:04.825066 I  SetPage(Scanning)
2012-10-27 23:39:04.825117 I  SWiz: SetPage(): type(2) cardid(7) inputname(Television)
2012-10-27 23:39:04.827038 I  V4LChannel(/dev/video0): Device name 'pcHDTV HD5500 HDTV' driver 'cx8800'.
2012-10-27 23:39:04.827066 I  V4LChannel(/dev/video0): v4l2: 1 stream io: 0 std io: 1 async io: 0 tuner 1 sliced vbi 0
2012-10-27 23:39:04.847339 I  ChannelBase(7): Input #7: 'Television' schan(3) sourceid(3) ccid(7)
2012-10-27 23:39:04.847347 I  ChannelBase(7): Input #8: 'Composite1' schan(0) sourceid(4) ccid(7)
2012-10-27 23:39:04.847353 I  ChannelBase(7): Input #9: 'S-Video' schan(0) sourceid(4) ccid(7)
2012-10-27 23:39:04.847359 I  ChannelBase(7): Current Input #8: 'Composite1'
2012-10-27 23:39:04.847874 I  Global TVFormat Setting 'NTSC'
2012-10-27 23:39:04.847891 I  V4LChannel(/dev/video0): Input #7: 'Television' schan(3) tun() v4l1(Unknown) v4l2(NTSC)
2012-10-27 23:39:04.847898 I  V4LChannel(/dev/video0): Input #8: 'Composite1' schan(0) tun() v4l1(Unknown) v4l2(NTSC)
2012-10-27 23:39:04.847904 I  V4LChannel(/dev/video0): Input #9: 'S-Video' schan(0) tun() v4l1(Unknown) v4l2(NTSC)
2012-10-27 23:39:04.847913 I  V4LChannel(/dev/video0): SetFormat(Default) fmt(NTSC) input(8)
2012-10-27 23:39:04.847924 I  V4LChannel(/dev/video0): SetInputAndFormat(8, NTSC) (v4l v2) input_switch: 0 mode_switch: 1
2012-10-27 23:39:04.854043 I  ChScan: Scan()
2012-10-27 23:39:04.856357 I  ChScan: ScanTransports(analog, analog, us-bcast)
2012-10-27 23:39:04.856545 I  ChannelScanSM(/dev/video0): run -- begin
2012-10-27 23:39:04.856708 I  ChannelScanSM(/dev/video0): Looked up freq table (analog, analog, us-bcast) w/68 entries
2012-10-27 23:39:04.857264 I  ChannelScanSM(/dev/video0): Transport Scan Item 'us-bcast 2' #2

So it appears it is trying to scan for the composite instead of the television input. It tries to use this input regardless of which card I select from "Input connections"

[V4L : /dev/video0 ] (Television) -> analog_channels
[V4L : /dev/video0 ] (Composite1) -> other
[V4L : /dev/video0 ] (S-Video) -> other

[Raymond Wagner]

While any segfault should be fixed, the quick solution to your problem, as well as the proper install method, is to simply not scan analog. Pull a lineup from your Schedules Direct account.

[Stuart Morgan <smorgan@…>]

In 47d6ec82e54138b77e93674d279d650ef0f5d80d/mythtv:

Fix a segfault when using the Analogue Channel scanner. Fixes #11202