Opened 2 years ago

Closed 18 months ago

Last modified 15 months ago

#13459 closed Bug Report - General (fixed)

v30.0 - multiple frontends - audio plays as white noise on playback of transcoded files

Reported by: robbak Owned by: Mark Kendall
Priority: minor Milestone: 30.1
Component: MythTV - Audio Output Version: v30-fixes
Severity: medium Keywords:
Cc: Ticket locked: no


On upgrading to version v30.0, playback of many existing transcoded recordings fails. The video plays slow, and the audio is replaced with generic white noise.

Problematic files, as far as I can see, are in .nuv format. .asx streams of problematic files play fine in mpv. Playback indicates that these files have mp3 audio, unlike normal files which use mp2:

(+) Video --vid=1 (mpeg4 720x576 25.000fps) (+) Audio --aid=1 (mp3 2ch 48000Hz)

Transcoded files that play fine are in .mpeg format, and contain this data:

(+) Video --vid=1 (mpeg2video 720x576 25.000fps) (+) Audio --aid=1 (mp2 2ch 48000Hz)

Audio --aid=2 (ac3 2ch 48000Hz)

Attachments (3)

Ccandreva-Lspci.txt (2.1 KB) - added by ccandreva 2 years ago.
Output of uname -a and lspci on my frontend
CCandreva-Mythfrontend.txt (1.1 KB) - added by ccandreva 2 years ago.
Output of mythfrontend --version
MythTV Frontend_007.png (287.0 KB) - added by Klaas de Waal 2 years ago.
Playback data of the nuppel video file 13459.nuv on today's master

Download all attachments as: .zip

Change History (15)

comment:1 Changed 2 years ago by gribnif

I am also running into this problem. It is especially bad, since I have about 1000 recordings that will no longer play. I generated a log file for you:

and you can download the original file played (111 Mb in size) here:

comment:2 Changed 2 years ago by ccandreva

I am having the same problem with older files. Attached is the Lspci and mththfrontend --version for my system . Please let me know what other information I can provide. While these are older recordings I kept them and would like to be able to play them.

Changed 2 years ago by ccandreva

Attachment: Ccandreva-Lspci.txt added

Output of uname -a and lspci on my frontend

Changed 2 years ago by ccandreva

Attachment: CCandreva-Mythfrontend.txt added

Output of mythfrontend --version

comment:3 Changed 2 years ago by Klaas de Waal

Here on both v30 and master the video file does play but at half the speed. The audio does have lots of noise but the original sound is still recognizable.

When playing the video, pressing Menu / Playback / Playback Data gives info about the video in a black bar on top of the screen. This shows "Video: 720x480@29.97 fps" but also "FPS:14.99+-0.00:". It also shows "AUDIO: NONE".

It looks to me that the wrong playback speed of 15fps instead of 30fps is the problem here.

Changed 2 years ago by Klaas de Waal

Attachment: MythTV Frontend_007.png added

Playback data of the nuppel video file 13459.nuv on today's master

comment:4 Changed 23 months ago by eyaleb

I cannot play any nuv file. I get only loud hiss and slow video. Please give this ticket a higher priority.

I originally reported this on mythtv-users@… list on 28/Aug:

The newest nuv file I have is from mid 2014, so I do not often watch these recordings. I now find that all nuv files produce only a very loud hiss and the video is slow.

mpg and ts files play just fine. vlc and mplayer play everything clearly. I fiddled with the frontend audio settings - no change.

I am on (almost) up-to-date fedora 30. This is a standard (7yo) desktop, using the onboard audio. I consider my setup very vanilla.

$ lspci ... 00:1b.0 Audio device: Intel Corporation 7 Series/C216 Chipset Family High Definition Audio Controller (rev 04)

$ uname -a Linux 5.2.8-200.fc30.x86_64 #1 SMP Sat Aug 10 13:21:39 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

$ mythfrontend --version Please attach all output as a file in bug reports. MythTV Version : v30.0-v30.0-53-g6bd8cd4993 MythTV Branch : fixes/30 Network Protocol : 91 Library API : 30.20181231-1 QT Version : 5.12.1 Options compiled in:

linux debug use_hidesyms using_alsa using_jack using_oss using_pulse using_pulseoutput using_backend using_bdjava using_bindings_perl using_bindings_python using_bindings_php using_crystalhd using_dvb using_firewire using_frontend using_hdhomerun using_vbox using_ceton using_hdpvr using_ivtv using_joystick_menu using_libcec using_libcrypto using_libdns_sd using_libfftw3 using_libxml2 using_lirc using_mheg using_opengl using_opengl_video using_opengl_themepainter using_qtwebkit using_qtscript using_qtdbus using_taglib using_v4l2 using_x11 using_xnvctrl using_xnvctrl_external using_libbluray_external using_xrandr using_xv using_debugtype using_systemd_notify using_systemd_journal using_bdjava using_bindings_perl using_bindings_python using_bindings_php using_fontconfig using_freetype2 using_mythtranscode using_opengl using_vaapi using_vaapi2 using_vdpau using_ffmpeg_threads using_mheg using_libass using_libxml2 using_libmp3lame

Testing on another (10yo) PC shows the same problem. Both systems were upgraded from f28 (mythtv 19.1) last month.

comment:5 Changed 20 months ago by gribnif

With some pointers from Mark Kendall, I am slowly working on this problem. It appears to lie in the native NuppelDecoder?, as it's possible to skirt the problem by modifying the code to use FFMpeg to decode the video instead. I'll post back when I have discovered the specific commit that introduced the problem, and a suggested fix, if I find one.

comment:6 Changed 20 months ago by Stuart Auchterlonie

Owner: changed from JYA to Mark Kendall
Status: newassigned

comment:7 Changed 20 months ago by eyaleb

Further to my earlier comment, the problem persists on a new (Z390) server using the onboard Intel GPU.

And good to see the issue is now getting attention, much appreciated.

comment:8 Changed 19 months ago by gribnif

Update: I isolated the problem down to commits d24aa8 and b7befa. Unfortunately, these represent a very large ffmpeg re-sync, so finding the specific reason for the problem will be difficult.

I have suggested to Mark that perhaps removing the functionality provided by NuppelDecoder?.cpp is the best way to go, since ffmpeg seems to handle things (almost entirely) correctly without it.

comment:9 Changed 18 months ago by Mark Kendall <mark.kendall@…>

Resolution: fixed
Status: assignedclosed

In 087208920/mythtv:

Fix playback of nuppel recordings

comment:10 Changed 15 months ago by Stuart Auchterlonie


does this need cherry-picking back to fixes/31? It appears to only be in master at the moment.

Regards Stuart

comment:12 Changed 15 months ago by Stuart Auchterlonie

Milestone: needs_triage30.1

Thanks, that'll be the trac hooks crapping out then!

Cheers Stuart

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