[mythtv-users] Radio recordings are zero bytes; TV is fine

Mike Holden mythtv at mikeholden.org
Wed Oct 22 00:57:24 UTC 2014


Richard Hulme wrote:
> On 21/10/14 01:20, Hika van den Hoven wrote:
>> Hoi Nicolas,
>>
>> Tuesday, October 21, 2014, 1:02:30 AM, you wrote:
>>
>>> Am 2014-10-21 00:16, schrieb mythtv-users-request at mythtv.org:
>>>> Message: 11
>>>> Date: Mon, 20 Oct 2014 20:39:36 +0100
>>>> From: Keith Edmunds <kae at midnighthax.com>
>>>> To: mythtv-users at mythtv.org
>>>> Subject: Re: [mythtv-users] Radio recordings are zero bytes; TV
>>>> is
>>>>        fine
>>>> Message-ID: <20141020203936.0caa8b83 at ws.the.cage>
>>>> Content-Type: text/plain; charset=US-ASCII
>>>>
>>>> I have the logs as requested.
>>>>
>>>> The FE log is at http://pastebin.com/XyTzL562 (ignore log before
>>>> 20:23:36
>>>> - sorry, I meant to trim it).
>>>>
>>>> The BE log is at http://pastebin.com/2ua5VuJG
>>>>
>>>> What was done: both the BE and FE were rebooted. On the FE, I
>>>> went to
>>>> "Watch TV", displayed the program guide, scrolled to BBC Radio
>>>> 4, and
>>>> tried to play it. MythTV crashed.
>>>>
>>>> I restarted MythTV and repeated the above. This time I had a
>>>> black
>>>> square,
>>>> the height of the screen, and after a while a dialog box that
>>>> said,
>>>> "Could
>>>> not read first 2048 bytes".
>>>>
>>>> Thanks,
>>>> Keith
>>> I tried this on my system as well and it did worked! Screen went
>>> black,
>>> but radio audio was played correctly!
>>> But I could not stop then... mythfrontend was unresponsive and I
>>> had to
>>> kill it (via -9 aka SIGKILL). Repeated this 2 times and it
>>> behaved
>>> identical all 3 times.
>>
>>> This is german dvb-t here with MythTV 0.27, no current updates, I
>>> assume (last update session is some weeks ago).
>>
>> As far as I know a digital radio feed is in essence the same as a
>> TV
>> feed, only with an empty video stream. So if Tv works, radio
>> should
>> work too. With Keith my suspicion is at the channel settings. It
>> seems
>> Mythtv doesn't get input. Why it locks with Nicolas I have no
>> idea.
>
> It's locking because of an issue with buffering.  In essence,
> there's
> enough data in the audio buffers to play happily but not quite as
> much
> as it would like to have and it gets a bit stuck in a loop (playing
> and
> adding data but never quite getting over the threshold).  Playback
> is
> fine in this loop but because it never leaves it, trying to exit
> playback causes another thread to wait forever for that loop to end.
>
> I'm not sure what exactly is causing it.  It's certainly got
> something
> to do with the overall bitrate (which is why it tends to only affect
> DVB
> radio) but it didn't use to happen and I haven't identified exactly
> what
> changed.
>
> One workaround is to pause playback for a few seconds and then
> restart.
>   That lets the audio buffer fill up a bit more and stops it getting
> stuck in the loop.
>
> Richard

This issue sounds similar to an issue that cropped up a couple of
years ago which affected many DVB-T radio users for a while. There
was a code fix to resolve it:

http://jhauser.dyndns.org:8080/archives/html//mythtv-users/2013-03/msg00202.html

http://jhauser.dyndns.org:8080/archives/html//mythtv-users/2013-01/msg00377.html
-- 
Mike Holden



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