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

[Richard Hulme]

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