[mythtv-users] Playback errors with DVB-T Radio programs

Mike Holden mythtv at mikeholden.org
Sun Jun 22 12:21:34 UTC 2008

DVB-T Freeview in UK includes several Radio channels, that transmit a
stream with audio channels but no video channels embedded within them.

These record fine, and can be played back via a variety of means (mplayer
standalone, and MVP client box connected to Myth BE). I can also rip them
to mp3 using the contrib script via ffmpeg and they then play fine in any
old mp3 player.

However when playing the program in myth FE (single box FE/BE, Fedora 8
with uptodate atrpms), I get a big problem.

Audio plays, but it comes in tiny spurts of a fraction of a second,
followed by several seconds of silence.

The FE log output is as follows:

2008-06-22 12:59:04.084 TV: Attempting to change from None to
2008-06-22 12:59:04.190 DPMS Deactivated
2008-06-22 12:59:04.410 AFD: codec MP3 has 2 channels
2008-06-22 12:59:04.410 AFD: Opened codec 0xa36a980, id(MP3) type(Audio)
2008-06-22 12:59:04.417 Opening audio device '/dev/dsp'. ch 2(2) sr 48000
2008-06-22 12:59:04.417 Opening OSS audio device '/dev/dsp'.
2008-06-22 12:59:04.642 VideoOutputXv: Desired video renderer 'xvmc-blit'
not available.
                        codec 'None' makes 'opengl,xv-blit,xshm,xlib,'
available, using 'opengl' instead.
2008-06-22 12:59:05.354 OSD Theme Dimensions W: 640 H: 480
2008-06-22 12:59:06.641 TV: Changing from None to WatchingPreRecorded
2008-06-22 12:59:06.647 Video timing method: USleep with busy wait
2008-06-22 12:59:06.648 Realtime priority would require SUID as root.
2008-06-22 12:59:09.145 NVP: Timed out waiting for free video buffers.
2008-06-22 12:59:11.161 NVP: Timed out waiting for free video buffers.
2008-06-22 12:59:13.182 NVP: Timed out waiting for free video buffers.
2008-06-22 12:59:16.400 NVP: Timed out waiting for free video buffers.
2008-06-22 12:59:51.986 TV: Attempting to change from WatchingPreRecorded
to None
2008-06-22 12:59:59.810 TV: Changing from WatchingPreRecorded to None
2008-06-22 13:00:00.233 DPMS Reactivated.

The NVP errors continue for as long as playback continues.

I don't see why we even __need__ video buffers for an audio-only recording
(or is this part of the problem?) :-)

Googling shows a known problem (in the Myth wiki) for nvidia and glx, but
seems to be only on live tv. LiveTv is fine for me, as is changing
channels, and playback of any other recording, but happens 100% of the
time when playing a radio recording. Various other threads thrown up my
Google also don't seem to apply here.

mplayer standalone produces the following diagnostics when playing the
file correctly:

[mike at tux2 mythtv]$ mplayer /multimedia/mythtv/radio/3708_20080621175500.mpg
MPlayer 1.0rc2-4.1.2 (C) 2000-2007 MPlayer Team
CPU: AMD Athlon(tm) XP 2000+ (Family: 6, Model: 6, Stepping: 2)
CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 0
Compiled with runtime CPU detection.
115 audio & 237 video codecs
Can't open joystick device /dev/input/js0: No such file or directory
Can't init input joystick
mplayer: could not open config files /home/mike/.lircrc and /etc/lircrc
mplayer: No such file or directory
Failed to read LIRC config file ~/.lircrc.

Playing /multimedia/mythtv/radio/3708_20080621175500.mpg.
TS file format detected.
Opening audio decoder: [mp3lib] MPEG layer-2, layer-3
AUDIO: 48000 Hz, 2 ch, s16le, 160.0 kbit/10.42% (ratio: 20000->192000)
Selected audio codec: [mp3] afm: mp3lib (mp3lib MPEG layer-2, layer-3)
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Video: no video
Starting playback...
A:75492.7 (20:58:12.6) of 31368.8 ( 8:42:48.7)  0.6%

MPlayer interrupted by signal 2 in module: play_audio

Any ideas?

-- Mike Holden

http://www.by-ang.com - the place to shop for all manner of hand crafted
items, including Jewellery, Greetings Cards and Gifts

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