The VideoLAN Forums

Posted: **26 Nov 2010 05:01**

Playback of ANY MP3 audio is very poor, choppy and glitchy with dropouts. Both MP3 audio in Films, or MP3 music files.
Other formats are fine however, flac, aac, ogg...and so on...
This issue is only with VLC, all other media players will playback MP3 audio fine. Winamp, Foobar, MPC-HC, PotPlayer, WMP etc etc...

Tested...
Changed system output Freq. & Format.
makes no difference if its on 24bit 48,000, 24bit 41,000, 16bit 48,000 16bit 41,000.

Outputting on 3.5 jack / SP-Dif coax/optical makes no difference.
Unable to test HDMI.
Tried different output modules in VLC Audio settings. DirectX / waveout / simple.

Message log is full of these

Code: Select all

mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (42244)
main warning: audio drift is too big (158273), dropping buffer
main warning: audio drift is too big (122273), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
mpgatofixed32 debug: libmad error: Huffman data overrun
main warning: output date isn't PTS date, requesting resampling (52892)
main warning: audio drift is too big (135228), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (54120)
main warning: audio drift is too big (146379), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (43540)
main warning: audio drift is too big (148013), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (53066)
main warning: audio drift is too big (158923), dropping buffer
main warning: audio drift is too big (122923), dropping buffer
mpgatofixed32 debug: libmad error: Huffman data overrun
main warning: output date isn't PTS date, requesting resampling (53905)
main warning: audio drift is too big (132359), dropping buffer

No other irregularities, normal CPU load.
Any ideas?

VLC 1.5
Win 7 x64
AMD x3 @ 3gig.
5 gigs ram
RealTek HD Audio Driver 6.01.5859 Codec ALC888S DX10

Posted: **27 Nov 2010 05:42**

Ok, well, i found the source of the problem, and its a bit of a substantial bug i guess......
Chances are, its probably the same factor in these posts too...

viewtopic.php?f=14&t=84606
viewtopic.php?f=14&t=84772
viewtopic.php?f=14&t=84044
viewtopic.php?f=14&t=84370

Maybe more, i didn't look past a few pages..
But as my issue went unacknowledged, you'll have to ask nice to know what it is...

Posted: **27 Nov 2010 12:47**

I've also reported an issue in ticket http://trac.videolan.org/vlc/ticket/4331 vlc 1.1.5 audio output starving, playing silence every 10 sec. using directx audio on Windows XP.

Although your issue "sounds" as a different issue (not a clock thing but more of a driver and mine affects all audio), I also have a creative SB card.. and if I use win32 wave out it's slightly better but my audio and video drift and go out of sync either way. So I'll see if changing cards helps..

Posted: **27 Nov 2010 20:33**

It seems to be system timing issue.
VLC is using a clock that is affected by CPU reference clock (fsb) adjustment by software.
Overclocking the pc via BIOS doesn't present a problem, neither does CPU features such as cool n quite, speedstep, etc..

But, if you change the CPU reference clock (fsb) while windows is up, either with AMD overdrive, nVidia performance manager ,or similar, the timings fall apart.
If you only have a small (say 3% software overclock) the audio dropouts are further apart, as its takes longer for sync to drift. 15%, and dropouts are more frequent.
This is a bug with a lot of older pc games too, to increase performance, boot the system with a low fsb speed, and use software to raise clock speed, and the game will run x% faster, with synchronization between audio and video in cut-scenes suffering as a result.

I guess there is a chance this is a issue with users on Intel platform using EPU-x Engine software, that raises the fsb speed depending on workload.
You may have come across posts complaining of choppy sound when going fullscreen.
Fullscreen=greater workload=software raises fsb/ref clock=choppy audio OR loss of audio sync.
Just theory anyway, as i have no way to test.

The only thing i found odd, was that it only affected MP3 playback on my system.....

Posted: **28 Nov 2010 16:31**

Have you tested VLC 1.2.0 nightly builds? Remi changed some Win32 timing code there, so it might work somewhat better
http://nightlies.videolan.org/build/win32/?C=M;O=D (trunks are 1.2.0)

Posted: **29 Nov 2010 00:07**

Yes, and just tried vlc-1.2.0-git-20101128-0002-win32.
Still suffers sync drift with a software overclock.
Happy to try any test builds if any are make before available before applying code to trunk. Let me know if there is.

Code: Select all

main warning: output date isn't PTS date, requesting resampling (46761)
main warning: audio drift is too big (134457), dropping buffer
main warning: output date isn't PTS date, requesting resampling (47217)
main warning: audio drift is too big (147411), dropping buffer
main warning: audio drift is too big (121288), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46158)
main warning: audio drift is too big (133296), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46084)
main warning: audio drift is too big (143871), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46127)
main warning: audio drift is too big (153376), dropping buffer
main warning: audio drift is too big (127254), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46161)
main warning: audio drift is too big (137927), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46100)
main warning: audio drift is too big (146090), dropping buffer
mpgatofixed32 debug: libmad error: Huffman data overrun
main warning: output date isn't PTS date, requesting resampling (46146)
main warning: audio drift is too big (154119), dropping buffer
main warning: audio drift is too big (127996), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (45481)
main warning: audio drift is too big (135767), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46348)
main warning: audio drift is too big (142728), dropping buffer
main warning: output date isn't PTS date, requesting resampling (45903)
main warning: audio drift is too big (149197), dropping buffer
main warning: audio drift is too big (123075), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46118)
main warning: audio drift is too big (129148), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46146)
main warning: audio drift is too big (133366), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46101)
main warning: audio drift is too big (138855), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46132)
main warning: audio drift is too big (141722), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46777)
main warning: audio drift is too big (145279), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (45475)
main warning: audio drift is too big (147624), dropping buffer
main warning: audio drift is too big (121502), dropping buffer
main warning: output date isn't PTS date, requesting resampling (47838)
main warning: audio drift is too big (125644), dropping buffer
main warning: output date isn't PTS date, requesting resampling (45640)
main warning: audio drift is too big (126975), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46622)
main warning: audio drift is too big (127883), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer
main warning: output date isn't PTS date, requesting resampling (46164)
main warning: audio drift is too big (126813), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46083)
main warning: audio drift is too big (127636), dropping buffer
main warning: output date isn't PTS date, requesting resampling (46134)
main warning: audio drift is too big (125266), dropping buffer
mpgatofixed32 debug: libmad error: bad main_data_begin pointer

Posted: **08 Dec 2010 17:19**

So, you are saying that I need to overclock my Quadcore CPU to play MP3 files? lol

VideoLAN will play everything else great, but for MP3 files, I have a good old 2000 version of WinAmp that will work better for me...even though we shouldn't need to do this!

Posted: **08 Dec 2010 20:07**

So, you are saying that I need to overclock my Quadcore CPU to play MP3 files? lol

Maybe you should read this thread a second time

Posted: **09 Dec 2010 22:57**

VLC 1.1.5 has some timing problems. We are currently discussing about the issue.

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