[mythtv-users] Channel scanner won't find a specific channel

[David Parker]

I do know that the signal strength dropped from 92% to 87% when it hit
QAM-256 channel 115 in the scan, then went back up on the next channel.
When I actually tune to the channel in Live TV mode, it shows a signal
strength of 91%.

mythffmpeg reports the following:

# mythffmpeg -i hd_test_1.dat
ffmpeg version 1.2.7 Copyright (c) 2000-2014 the FFmpeg developers
  built on Feb  2 2016 10:27:10 with gcc 4.9.2 (Debian 4.9.2-10)
  configuration: --prefix=/usr/local/mythtv-0.27-2255patch
  libavutil      52. 18.100 / 52. 18.100
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.104 / 54. 63.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 42.103 /  3. 42.103
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[mpeg2video @ 0x1372000] 0x0 is invalid
    Last message repeated 9 times
[mpegts @ 0x136fa20] Stream #0: not enough frames to estimate rate;
consider increasing probesize
[mpegts @ 0x136fa20] PES packet size mismatch
Input #0, mpegts, from 'hd_test_1.dat':
  Duration: 00:00:37.09, start: 13266.651322, bitrate: 15013 kb/s
Codec 0x20000 is not in the full list.
    Stream #0:0[0x0]: Data: unknown_codec, 18399 kb/s
    Stream #0:1[0x6f]: Video: mpeg2video (Main), yuv420p, 1280x720 [SAR 1:1
DAR 16:9], 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
    Stream #0:2[0x70]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s
At least one output file must be specified

And I got an error when I tried to run a conversion:

# mythffmpeg hd_test_1.dat
ffmpeg version 1.2.7 Copyright (c) 2000-2014 the FFmpeg developers
  built on Feb  2 2016 10:27:10 with gcc 4.9.2 (Debian 4.9.2-10)
  configuration: --prefix=/usr/local/mythtv-0.27-2255patch
  libavutil      52. 18.100 / 52. 18.100
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.104 / 54. 63.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 42.103 /  3. 42.103
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[NULL @ 0x2285a20] Unable to find a suitable output format for
'hd_test_1.dat'
hd_test_1.dat: Invalid argument

    - Dave

On Thu, Feb 4, 2016 at 3:21 PM, John Pilkington <J.Pilk at tesco.net> wrote:

> On 04/02/16 19:24, David Parker wrote:
>
>> Thanks for all the help so far.
>>
>> I now have the channel set up in MythTV and can see it, but there's a
>> new wrinkle.  The stream from this channel (and only this channel) seems
>> unstable, at least in MythTV.  In both recordings and live TV, the video
>> shakes slightly and the sound stutters.  The weird thing is, this
>> doesn't happen when I capture the raw stream and view in in mplayer:
>>
>> $ dvbv5-zap -c dvb_channel.conf -v -r "WFXV HD"
>> $ cat /dev/dvb/adapter0/dvr0 > hd_test_1.dat
>>
>> Viewing hd_test_1.dat in mplayer shows the video and audio are fine.
>> This issue seems to be isolated to MythTV, and/or the MPEG-2 compression
>> of the stream.  But it doesn't happen on any other channels.  Is there
>> something I'm missing here?
>>
>> Thanks!
>>
>>
> Perhaps myth is having to process other streams, like subtitles, or
> processing other stuff?  Do you have any indication of signal strengths for
> all the channels you see?
>
> 'mythffmpeg -i  hd_test_1.dat'  might help - and allow comparison with
> other channels.  You can also display some diagnostics via
> Menu > Playback > Playback Data
>
>
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