Mailing List Archive

David Madsen wrote:

> Recently I have been noticing something strange happening in the backend
> while recording. I convert some the recorded files into mpegs for archiving
> by using mencoder to reencode the video. while running mencoder about
> halfway through the file it runs into a chunk of the .nuv file and dumps out
> a whole bunch of these messages, which I believe to be parts of the file
> where the backend has dropped video frames.
>
> 1 duplicate frame(s)!
> Pos:1731.3s 51807f (46%) 219fps Trem: 4min 1529mb A-V:-0.067 [3333:96]
> 1 duplicate frame(s)!
> Pos:1731.6s 51817f (46%) 219fps Trem: 4min 1529mb A-V:-0.067 [3333:96]
> 1 duplicate frame(s)!
> Pos:1732.0s 51827f (46%) 219fps Trem: 4min 1529mb A-V:-0.067 [3333:96]
> 1 duplicate frame(s)!
> Pos:1732.4s 51837f (46%) 219fps Trem: 4min 1529mb A-V:-0.067 [3333:96]
> 1 duplicate frame(s)!
> Pos:1732.7s 51847f (46%) 219fps Trem: 4min 1528mb A-V:-0.067 [3333:96]
> 1 duplicate frame(s)!
> Pos:1733.1s 51857f (46%) 219fps Trem: 4min 1528mb A-V:-0.067 [3333:96]
>
>
> The strange thing about this is that there are no dropped frames in any
> other part of the file, just consolidated to one group about halfway through
> recording a 1 hour show. I have looked through the system and there are no
> other crons or anything starting up that would cause something like this to
> happen. It also happens no matter what time of the day it is recording. I'm
> wondering if anyone else has noticed something similar? in the resulting
> file after mencoder is finished there is a section of the file where the
> missing frames are visible and causes the audio to go out of sync for a few
> minutes. I am recording at 640x480, 3300 bps on a Athlon XP 2000+. the
> CPU stays around 35-40% utilized while recording. DMA is turned on and
> hdparm reports about 40MB/s. I can't see what would be causing it to drop
> frames. Any ideas?
>
> David Madsen
>

i have been getting similar results when converting to divx .avi's with
a 2-pass mencoder run... audio is slightly out of sync... for me, the
duplicate frame errors are not centralized to that one part of the file
though, they are scattered throughout most of the file... i was using
mpeg4 640x480 2200 kbps, vhq, v4mv, on an athlon xp 1700.. and was
pushing my cpu up to 90% or so, so i just lowered my settings
considerably and am going to wait for the next recording to convert and
test... my mencoder conversion settings dont seem to make much
difference on the audio sync... from my understanding (searching
mplayers mailing list archives) those duplicate frame errors are
definitely bad news and im guessing are whats causing my problems.

Sean

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Let me know how your next conversion goes. I switched my ext3 file system
over to writeback mode, we'll see if that helps at all. I would like to
figure out what is causing this. I also noticed something else interesting
after I made the first post. all of those duplicate frame messages happen
spaced exactly 10 frames apart. I don't know what (if any) significance
that may have, but interesting none the less..

Dave

----- Original Message -----
From: "mojo" <mojospam@thegeekclub.net>
To: "Discussion about mythtv" <mythtv-users@snowman.net>
Sent: Wednesday, July 09, 2003 3:55 AM
Subject: Re: [mythtv-users] Frame Drop problems??


> David Madsen wrote:
>
> > Recently I have been noticing something strange happening in the backend
> > while recording. I convert some the recorded files into mpegs for
archiving
> > by using mencoder to reencode the video. while running mencoder about
> > halfway through the file it runs into a chunk of the .nuv file and dumps
out
> > a whole bunch of these messages, which I believe to be parts of the file
> > where the backend has dropped video frames.
> >
> > 1 duplicate frame(s)!
> > Pos:1731.3s 51807f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
[3333:96]
> > 1 duplicate frame(s)!
> > Pos:1731.6s 51817f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
[3333:96]
> > 1 duplicate frame(s)!
> > Pos:1732.0s 51827f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
[3333:96]
> > 1 duplicate frame(s)!
> > Pos:1732.4s 51837f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
[3333:96]
> > 1 duplicate frame(s)!
> > Pos:1732.7s 51847f (46%) 219fps Trem: 4min 1528mb A-V:-0.067
[3333:96]
> > 1 duplicate frame(s)!
> > Pos:1733.1s 51857f (46%) 219fps Trem: 4min 1528mb A-V:-0.067
[3333:96]
> >
> >
> > The strange thing about this is that there are no dropped frames in any
> > other part of the file, just consolidated to one group about halfway
through
> > recording a 1 hour show. I have looked through the system and there are
no
> > other crons or anything starting up that would cause something like this
to
> > happen. It also happens no matter what time of the day it is recording.
I'm
> > wondering if anyone else has noticed something similar? in the
resulting
> > file after mencoder is finished there is a section of the file where the
> > missing frames are visible and causes the audio to go out of sync for a
few
> > minutes. I am recording at 640x480, 3300 bps on a Athlon XP 2000+.
the
> > CPU stays around 35-40% utilized while recording. DMA is turned on and
> > hdparm reports about 40MB/s. I can't see what would be causing it to
drop
> > frames. Any ideas?
> >
> > David Madsen
> >
>
> i have been getting similar results when converting to divx .avi's with
> a 2-pass mencoder run... audio is slightly out of sync... for me, the
> duplicate frame errors are not centralized to that one part of the file
> though, they are scattered throughout most of the file... i was using
> mpeg4 640x480 2200 kbps, vhq, v4mv, on an athlon xp 1700.. and was
> pushing my cpu up to 90% or so, so i just lowered my settings
> considerably and am going to wait for the next recording to convert and
> test... my mencoder conversion settings dont seem to make much
> difference on the audio sync... from my understanding (searching
> mplayers mailing list archives) those duplicate frame errors are
> definitely bad news and im guessing are whats causing my problems.
>
> Sean
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
>
>

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> ----- Original Message -----
> From: "mojo" <mojospam@thegeekclub.net>
> To: "Discussion about mythtv" <mythtv-users@snowman.net>
> Sent: Wednesday, July 09, 2003 3:55 AM
> Subject: Re: [mythtv-users] Frame Drop problems??
>
>
>
>>David Madsen wrote:
>>
>>
>>>Recently I have been noticing something strange happening in the backend
>>>while recording. I convert some the recorded files into mpegs for
>
> archiving
>
>>>by using mencoder to reencode the video. while running mencoder about
>>>halfway through the file it runs into a chunk of the .nuv file and dumps
>
> out
>
>>>a whole bunch of these messages, which I believe to be parts of the file
>>>where the backend has dropped video frames.
>>>
>>>1 duplicate frame(s)!
>>>Pos:1731.3s 51807f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
>
> [3333:96]
>
>>>1 duplicate frame(s)!
>>>Pos:1731.6s 51817f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
>
> [3333:96]
>
>>>1 duplicate frame(s)!
>>>Pos:1732.0s 51827f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
>
> [3333:96]
>
>>>1 duplicate frame(s)!
>>>Pos:1732.4s 51837f (46%) 219fps Trem: 4min 1529mb A-V:-0.067
>
> [3333:96]
>
>>>1 duplicate frame(s)!
>>>Pos:1732.7s 51847f (46%) 219fps Trem: 4min 1528mb A-V:-0.067
>
> [3333:96]
>
>>>1 duplicate frame(s)!
>>>Pos:1733.1s 51857f (46%) 219fps Trem: 4min 1528mb A-V:-0.067
>
> [3333:96]
>
>>>
>>>The strange thing about this is that there are no dropped frames in any
>>>other part of the file, just consolidated to one group about halfway
>
> through
>
>>>recording a 1 hour show. I have looked through the system and there are
>
> no
>
>>>other crons or anything starting up that would cause something like this
>
> to
>
>>>happen. It also happens no matter what time of the day it is recording.
>
> I'm
>
>>>wondering if anyone else has noticed something similar? in the
>
> resulting
>
>>>file after mencoder is finished there is a section of the file where the
>>>missing frames are visible and causes the audio to go out of sync for a
>
> few
>
>>>minutes. I am recording at 640x480, 3300 bps on a Athlon XP 2000+.
>
> the
>
>>>CPU stays around 35-40% utilized while recording. DMA is turned on and
>>>hdparm reports about 40MB/s. I can't see what would be causing it to
>
> drop
>
>>>frames. Any ideas?
>>>
>>>David Madsen
>>>
>>
>>i have been getting similar results when converting to divx .avi's with
>>a 2-pass mencoder run... audio is slightly out of sync... for me, the
>>duplicate frame errors are not centralized to that one part of the file
>>though, they are scattered throughout most of the file... i was using
>>mpeg4 640x480 2200 kbps, vhq, v4mv, on an athlon xp 1700.. and was
>>pushing my cpu up to 90% or so, so i just lowered my settings
>>considerably and am going to wait for the next recording to convert and
>>test... my mencoder conversion settings dont seem to make much
>>difference on the audio sync... from my understanding (searching
>>mplayers mailing list archives) those duplicate frame errors are
>>definitely bad news and im guessing are whats causing my problems.
>>
>>Sean
>>
>>_______________________________________________
David Madsen wrote:
> Let me know how your next conversion goes. I switched my ext3 file
system
> over to writeback mode, we'll see if that helps at all. I would like to
> figure out what is causing this. I also noticed something else
interesting
> after I made the first post. all of those duplicate frame messages
happen
> spaced exactly 10 frames apart. I don't know what (if any) significance
> that may have, but interesting none the less..
>
> Dave


Well, long story short, i'm certain now that the main culprit behind my
inability to convert those .nuv's to .avi's was my original source
recording settings. Sure enough, reducing my ATI TV wonder card (not VE)
to 320x240 resolution reduced CPU usage from the 90 percentile to the
60's (would have been lower but to offset the resolution drop i upped
the framerate and activated vhq and v4mv).. the framerate does not seem
to have as major an impact as the resolution change... currently i am
using 3000-4000 ranges for my bitrate with mpeg4 at 320x240 resolution
and using a combination of mythmkmovie (to strip commercials accoring to
the cutlist) and a tweaked mythencode.pl script to get them down to the
exact file size i want and also to deinterlace them. One thing i also
noticed is that the mythencode.pl script has several extraneous
settings. I have found that it is not wise to alter the FPS too greatly
(unless you like bad a/v sync) and the default fps setting in
mythencode.pl is 30 fps while my sources are 29.97 while its not much of
a difference it produces more errors from mencoder than it would if it
was unchanged. I'm a complete idiot at perl but im trying to modify it
to the point where omitting the --fps argument at all simply removes it
altogether from the mencoder command line instead of just defaults it to
30fps. Also i would like to have an option for CBR mp3 audio instead of
VBR. I also may have a look at the mythmkmovie source to see if i can
add deinterlacing as an option, but my C++ abilities are well...
non-existent... printf("this is all i know how to do in C.");

if anyones interested in helping... what i'd ideally like to see is
mythmkmovie (with its slick database accessing abilities and cutlist
processing) with the added features of a built in bitrate calc and of
course my precious deinterlacing option. So I could go into mythmkmovie,
specify my desired file size then tweak the audio and video bitrates and
scale resolution based on the resulting bits per pixel per second ratio
returned by the program... with that coding framework layed i could move
on to a dvd ripping module... [sigh]... i wish i could do half this
stuff... well learning is half the fun right? (and all of the
frustration)... maybe ill take some C++ classes this fall. You guys
gotta help me with my homework ;-)

Sean

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