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PostPosted: Sat Dec 18, 2010 6:19 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
Is anyone else seeing a stuttering playback problem with over-the-air KMSP Fox 9.1 from Minneapolis (1280x720p, 60fps)?
This is using the built-in mythtv player.

My setup details: KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner.

The problem did not exist in May 2010 (end of the tv season).
I first noticed the stuttering problem with the season opener of House (Sept. 2010).

You can see/hear what I mean from viewing this camera-shot movie file:
http://www.sendspace.com/file/zbvgkp

I contacted technical staff at KMSP and, at first, they didn't believe this was their problem. After seeing recorded file samples from various dates, and seeing that the files that don't play right were recorded after a point in time when some equipment in the station had been changed, and getting a second report of a mythtv playback problem with KMSP recordings, they are thinking they may have a problem.

Key details:
1. The playback problem with KMSP recordings started sometime between May 2010 and Sept 2010.
2. I have not changed ANY mythtv settings, files, updates or hardware on my KM box for OVER A YEAR, and certainly not over the summer of 2010.
3. I did not change my tv antenna or coax over the summer of 2010.
4. In fall 2010, I checked out the channel 9.1 8VSB signal using a spectrum analyzer to be sure the RF envelope from my antenna is pretty flat across the entire 6MHz VHF 9 tv channel - it is. I only live 15 miles from the KMSP antenna tower, and reception has never been a problem.
5. There is no problem with recordings off any of the 1920x1080i over-the-air tv channels. KMSP 9.1 is 1280x720p.
6. Myth recordings made fall 2010 off KMSP Fox 9.1 do NOT play in VLC Player. VLC Player stops on the first frame and just sits there.
7. Myth recordings made in May 2010 (or before) off KMSP Fox 9.1 play just fine in VLC Player.
8. If I move KMSP recordings into the VIDEO folder of Knoppmyth (which is configured to use mplayer for playback) the files play smoothly.
9. I tried several different xorg output resolutions (edited the xorg.conf file) to other values (1920x1080, 1280x720). The stuttering occurs at all the screen resolutions I tried.
10. The R5.5 KM box at my friend's house shows the same symptoms - ruling out a hardware problem specific to my R5.5 KM computer.
10. over the summer of 2010 (late August?), Fox updated KMSP's "Fox Splicer" box to the new version 2.0

Fox Splicer details here:
http://www.hdrollout.com/splicer.html

Here are links to some short sample recordings of Fox/KMSP made post-summer 2010 with mythtv (Knoppmyth R5.5). These do not play properly in VLC Player:
http://www.sendspace.com/file/o6n3lm
http://www.sendspace.com/file/05u1h4
http://www.sendspace.com/file/e7r6gm

For comparison, here is a Fox/KMSP recording from May 5, 2010 (pre-summer) and this plays fine in ALL players I have, including myth and VLC Player:
http://www.sendspace.com/file/sy7gqt

My questions for the KM community:
1. given the details above, could the cause of this problem be in my KM box?
2. what tests can be run to reveal the source of the problem?

Eric

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


Last edited by neutron68 on Sun Jan 09, 2011 12:44 pm, edited 8 times in total.


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PostPosted: Sun Dec 19, 2010 12:08 am 
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Joined: Tue Aug 15, 2006 11:14 am
Posts: 1198
Location: Orlando FL
OMG that's the problem that I've been having with my Fox shows 1080 720 doesn't matter Family Guy is especially bad. I thought It was a hardware problem with my ancient gear. I too am getting Fox OTA. Sometimes it happens on other shows but it is defenitly worst on Fox. Maybe it's some kind of copy protection? (which is ironic because nothing makes me want to torrent like a crappy recording)

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 Post subject:
PostPosted: Sun Dec 19, 2010 8:23 am 
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Joined: Thu Mar 02, 2006 5:42 pm
Posts: 410
Location: middleton wi usa atsc
neutron68:
Are you using XVMC assisted decoding? Your sig looks like you have enough horse power to go without it. Try turning XVMC off if you are using it.


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 Post subject:
PostPosted: Sun Dec 19, 2010 9:19 am 
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Joined: Sun Jul 24, 2005 4:16 pm
Posts: 499
Location: Ft. Worth TX
You might want to consider it's time for 6..

I downgraded a 6 machine temporarily to 5.5 because I was having ir blaster problems. The result was a lot of frame dropping on HD...

(I eventually resolved the blaster problems with 6) and put it back on that machine.. the HD handling problems went away.. Just a thought...


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 Post subject: XVMC? No.
PostPosted: Sun Dec 19, 2010 10:26 am 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
jzigmyth wrote:
neutron68:
Are you using XVMC assisted decoding? Your sig looks like you have enough horse power to go without it. Try turning XVMC off if you are using it.
Hi. No, I'm not using XVMC. This install of R5.5 has always run with the STANDARD decoder. With the dual core processor, I have smooth OSD fadeaways without resorting to XMVC. For the first 1.5 years of this R5.5 install, channel 9.1 was fine, then over the summer, WHAM.....stutter stutter!
Could this be the broadcast flag in action?

Eric

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 Post subject: changing to R6
PostPosted: Sun Dec 19, 2010 10:43 am 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
snaproll wrote:
You might want to consider it's time for 6..

I downgraded a 6 machine temporarily to 5.5 because I was having ir blaster problems. The result was a lot of frame dropping on HD...

(I eventually resolved the blaster problems with 6) and put it back on that machine.. the HD handling problems went away.. Just a thought...

I am considering R6, but I note above that mattbatt has R6 running and also has issues with a Fox over-the-air station stuttering! Changing to R6 will be one of the last steps in this troubleshooting exercise.

Right now, I'm going on the premise: R5.5 has worked fine for 1.5 years. I didn't change anything. Why did this stuttering start over the summer?

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


Last edited by neutron68 on Sun Dec 19, 2010 9:18 pm, edited 1 time in total.


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 Post subject:
PostPosted: Sun Dec 19, 2010 4:11 pm 
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Joined: Thu Mar 25, 2004 11:00 am
Posts: 9551
Location: Arlington, MA
Most likely either a change in their encoding or signal.

Have you looked at the system load when the stuttering is occurring versus when it isn't? I'd start by ssh-ing into the machine and watching top, and follow that up with iostat to watch the disk load. If you see a significant bump in CPU or disk bandwidth used that may point to the cause.

Are the recording files significantly bigger or smaller since the change? (I'd calculate an average Mb/minute rate to get a good number) This may indicate a different bit rate or extra data streams. If it's the later you can tweak your recording profile to cut out extraneous stuff that can make the decoder work harder.

Have they stretched or shortened the key frame interval? Longer intervals also tend to mean more work for the decoder.

Anyway, that ought to be enough to get you started...


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 Post subject: system resources
PostPosted: Sun Dec 19, 2010 9:07 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
Hello again, tjc.

From what you said, you also conclude that something significant changed on the KMSP side of the equation.

One of the first metrics I looked at was usage in top during a stuttering playback of a KMSP 9.1 recording. Here is a typical playback after the change in summer 2010:
Code:
top - 20:46:14 up 1 day, 23:04,  2 users,  load average: 2.91, 1.31, 0.65
Tasks: 117 total,   1 running, 116 sleeping,   0 stopped,   0 zombie
Cpu(s): 36.4%us,  4.8%sy,  0.0%ni, 21.8%id, 35.2%wa,  0.3%hi,  1.5%si,  0.0%st
Mem:   2007752k total,  1952980k used,    54772k free,    10928k buffers
Swap:  1959920k total,      168k used,  1959752k free,  1391492k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
19844 mythtv    20   0  408m 223m  71m S   56 11.4  30:17.73 mythfrontend
19798 root      RT -10  268m 251m  63m S   11 12.8   5:17.83 Xorg
19854 mythtv    20   0 30784  25m  16m S    5  1.3   0:45.92 x11vnc
 3730 mythtv    20   0  270m  49m  11m S    4  2.5   9:40.24 mythbackend
 3442 mysql     20   0  127m  37m 5432 S    2  1.9   4:57.52 mysqld
20655 root      15  -5     0    0    0 S    1  0.0   0:10.63 cx88[0] dvb
 3534 root      20   0  7156 1600 1148 S    0  0.1   0:00.92 nmbd
21542 root      20   0  2264 1112  844 R    0  0.1   0:00.19 top
    1 root      20   0  2044  676  580 S    0  0.0   0:01.87 init
    2 root      15  -5     0    0    0 S    0  0.0   0:00.00 kthreadd
    3 root      RT  -5     0    0    0 S    0  0.0   0:00.04 migration/0
    4 root      15  -5     0    0    0 S    0  0.0   0:02.19 ksoftirqd/0
    5 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/0
    6 root      RT  -5     0    0    0 S    0  0.0   0:00.04 migration/1
    7 root      15  -5     0    0    0 S    0  0.0   0:02.18 ksoftirqd/1
    8 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/1
    9 root      RT -10     0    0    0 S    0  0.0   0:00.83 events/0
Fox 720p recordings off of KMSP are about the same size now as they were in the past: 30 minutes is about 3.4GB, 60 minutes is about 6.4GB.

I don't know how to tell if KMSP changed the key frame interval. Any suggested software or command? I believe that Fox 720p has always been a framerate of 60 frames per second.

Do you find it significant that current KMSP recordings won't play in VLC Player, where older recordings (pre summer 2010) DO play in VLC Player? Is this a helpful diagnostic tool?

Eric

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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 Post subject:
PostPosted: Sun Dec 19, 2010 9:30 pm 
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Joined: Fri Sep 19, 2003 7:05 pm
Posts: 5088
Location: Fontana, Ca
Have you tried rescanning for channels? Fox in LA, OTA use to suck until they made some changes recently. I'd try a scan and see if thing improve.

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When the source is open, the possibilities are endless!


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 Post subject: rescan
PostPosted: Sun Dec 19, 2010 11:06 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
cesman wrote:
Have you tried rescanning for channels? Fox in LA, OTA use to suck until they made some changes recently. I'd try a scan and see if thing improve.
It was worth a try. It didn't help. St-t-t-t-utering continues on KMSP Fox 9.

Eric

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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 Post subject:
PostPosted: Sun Dec 19, 2010 11:25 pm 
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Joined: Tue Aug 15, 2006 11:14 am
Posts: 1198
Location: Orlando FL
I have a similar issue with Fox Orlando WOFL transcoding these recordings ruins them. They play back at half speed on any computer.

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 Post subject: mpeg decoder version?
PostPosted: Mon Dec 20, 2010 9:05 am 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
Going on the assumption that KMSP and Fox changed their "digital formula", is it possible that some versions of mpeg decoder software respond differently? Is there a way to tell what version of the internal mythtv player is?

I got a report from a friend who's R5.5 KM box I sheppard, and he says he does not see stuttering with recordings from the same KMSP over-the-air signal. We have identical motherboards, same HD-3000 receiver cards, both are using the onboard nvidia 6150 chip for display and both have R5.5 on our machines.

The only differences I can think of between the 2 machines is versions of some software.
1. about a year ago, I updated the version of mplayer, and maybe ffmpeg software on my machine. I think his may still be stock versions of the mpeg software that comes with stock R5.5.
2. I think I updated the nvidia driver version on my machine about a year ago. I can't recall if I updated his, too.

Does the internal mythtv player use mplayer or ffmpeg? Would different versions of these 2 packages explain why the built-in myth player stutters on my KM machine but does not stutter on kent's KM machine?

Eric

Code:
eric's KM ffmpeg version:
eric@mythtv:~$ ffmpeg -ver
FFmpeg version SVN-r18890, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --prefix=/usr --extra-cflags='-Wall -g ' --cc='ccache cc' --lib                       dir=${prefix}/lib --shlibdir=${prefix}/lib --bindir=${prefix}/bin --incdir=${pre                       fix}/include/ffmpeg --enable-shared --enable-libmp3lame --enable-gpl --enable-li                       bfaad --mandir=${prefix}/share/man --enable-libvorbis --enable-pthreads --enable                       -libfaac --enable-libxvid --enable-postproc --enable-libamr-nb --enable-libamr-w                       b --enable-x11grab --enable-libgsm --enable-libx264 --enable-libtheora --enable-                       libdc1394 --enable-libspeex --enable-nonfree --disable-stripping --enable-avfilt                       er --enable-libdirac --disable-decoder=libdirac --enable-libschroedinger --disab                       le-encoder=libschroedinger --enable-avfilter-lavf --enable-libopenjpeg --disable                       -altivec --disable-armv5te --disable-armv6 --disable-vis
  libavutil     50. 3. 0 / 50. 3. 0
  libavcodec    52.29. 0 / 52.29. 0
  libavformat   52.33. 0 / 52.33. 0
  libavdevice   52. 2. 0 / 52. 2. 0
  libavfilter    0. 5. 0 /  0. 5. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on May 21 2009 10:42:53, gcc: 4.3.3
ffmpeg: missing argument for option '-ver'

kent's KM ffmpeg version:
kent@mythtv:~$ ffmpeg -ver
FFmpeg version SVN-r12391, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  configuration: --enable-libmp3lame --enable-libfaac --enable-liba52 --enable-l                          ibvorbis --enable-gpl --enable-shared --enable-libxvid --prefix=/usr --enable-li                          btheora --arch=i586 --cpu=i586 --enable-pthreads --enable-avfilter --enable-post                          proc
  libavutil version: 49.6.0
  libavcodec version: 51.51.0
  libavformat version: 52.9.0
  libavdevice version: 52.0.0
  libavfilter version: 0.0.0
  built on Apr 16 2008 05:24:04, gcc: 4.2.3 20071123 (prerelease) (Debian 4.2.2-                          4)
ffmpeg: missing argument for option '-ver'

eric's KM mplayer version:
eric@mythtv:~$ mplayer -v
MPlayer SVN-r29318-4.2.3 (C) 2000-2009 MPlayer Team
CPU vendor name: AuthenticAMD  max cpuid level: 1
CPU: AMD Athlon(tm)64 X2 Dual Core Processor  4200+ (Family: 15, Model: 43, Stepping: 1)
extended cpuid-level: 24
extended cache-info: 33587520
Detected cache-line size is 64 bytes
Testing OS support for SSE... yes.
Tests of OS support for SSE passed.
CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNowExt: 1 SSE: 1 SSE2: 1 SSSE3: 0
Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowExt SSE SSE2 CMOV
get_path('codecs.conf') -> '/home/eric/.mplayer/codecs.conf'
Reading /home/eric/.mplayer/codecs.conf: Can't open '/home/eric/.mplayer/codecs.conf': No such file or directory
Reading /usr/etc/mplayer/codecs.conf: Can't open '/usr/etc/mplayer/codecs.conf': No such file or directory
Using built-in default codecs.conf.

kent's KM mplayer version:
kent@mythtv:~$ mplayer -v
MPlayer dev-SVN-r26260-4.2.3 (C) 2000-2008 MPlayer Team
CPU: AMD Athlon(tm) 64 Processor 3500+ (Family: 15, Model: 47, Stepping: 2)
CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 1
Compiled with runtime CPU detection.
get_path('codecs.conf') -> '/home/kent/.mplayer/codecs.conf'
Reading /home/kent/.mplayer/codecs.conf: Can't open '/home/kent/.mplayer/codecs.conf': No such file or directory
Reading /etc/mplayer/codecs.conf: Can't open '/etc/mplayer/codecs.conf': No such file or directory
Using built-in default codecs.conf.

_________________
KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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PostPosted: Mon Dec 20, 2010 5:14 pm 
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Joined: Fri Jul 21, 2006 11:12 pm
Posts: 1016
Location: SC
neutron68 wrote:
Does the internal mythtv player use mplayer or ffmpeg?
It really shouldn't matter what version of ffmpeg you have installed because the internal MythTV player uses it own modified and embedded version of ffmpeg.

Do you see anything in the mythfronend.log or mythbackend.log? Can you playback the recording with mplayer and does it studder there? That might narrow down if it is a recording problem or playback problem.

Britney


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PostPosted: Mon Dec 20, 2010 6:38 pm 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
brfransen wrote:
neutron68 wrote:
Does the internal mythtv player use mplayer or ffmpeg?
It really shouldn't matter what version of ffmpeg you have installed because the internal MythTV player uses it own modified and embedded version of ffmpeg.

Do you see anything in the mythfronend.log or mythbackend.log? Can you playback the recording with mplayer and does it studder there? That might narrow down if it is a recording problem or playback problem.

Britney

Hi Britney. If you are still in SW MN, you may have KMSP on your cable system and could give it a look.

If I move KMSP recordings into the VIDEO folder of Knoppmyth (which is configured to use mplayer for playback) the files play smoothly.
Also, if I copy the files off to another machine and play them with mplayer, they play smoothly.

I just played back last night's Family Guy recording and the frontend log had a double framerate (deinterlace) error in it. I wonder if I have any logs from May 2010 still on the machine to see if that error was there during playback of KMSP recordings, back when they didn't stutter??
Do the logs get archived and put into a tar file somewhere? If yes, where?
Code:
2010-12-20 18:29:25.696 TV: Attempting to change from None to WatchingPreRecorded
2010-12-20 18:29:26.438 AFD: Opened codec 0x839f640, id(MPEG2VIDEO) type(Video)
2010-12-20 18:29:26.438 AFD: codec AC3 has 2 channels
2010-12-20 18:29:26.440 AFD: Opened codec 0x92331f0, id(AC3) type(Audio)
2010-12-20 18:29:26.440 AFD: codec AC3 has 1 channels
2010-12-20 18:29:26.441 AFD: Opened codec 0x8366480, id(AC3) type(Audio)
2010-12-20 18:29:26.446 Opening audio device '/dev/dsp'. ch 2(2) sr 48000
2010-12-20 18:29:26.446 Opening OSS audio device '/dev/dsp'.
2010-12-20 18:29:28.674 VideoOutputXv: XVideo Adaptor Name: 'NV17 Video Texture'
2010-12-20 18:29:28.874 OSD Theme Dimensions W: 640 H: 480
2010-12-20 18:29:29.783 The realtime priority setting is not enabled.
2010-12-20 18:29:29.784 TV: Changing from None to WatchingPreRecorded
2010-12-20 18:29:29.915 Video sync method can't support double framerate (refresh rate too low for bob deint)
2010-12-20 18:29:29.921 Video timing method: USleep with busy wait
2010-12-20 18:30:03.580 [mpeg2video @ 0xb7262e68]releasing zombie picture
2010-12-20 18:30:08.928 TV: Attempting to change from WatchingPreRecorded to None
2010-12-20 18:30:09.077 TV: Changing from WatchingPreRecorded to None
2010-12-20 18:30:09.687 Using runtime prefix = /usr
2010-12-20 18:30:09.694 Empty LocalHostName.
2010-12-20 18:30:09.695 Using localhost value of mythtv
2010-12-20 18:30:09.734 New DB connection, total: 1
2010-12-20 18:30:09.744 Connected to database 'mythconverg' at host: localhost
2010-12-20 18:30:09.746 Closing DB connection named 'DBManager0'
2010-12-20 18:30:09.747 Connected to database 'mythconverg' at host: localhost
2010-12-20 18:30:09.749 New DB connection, total: 2
2010-12-20 18:30:09.749 Connected to database 'mythconverg' at host: localhost
2010-12-20 18:30:09.751 Current Schema Version: 1214
2010-12-20 18:30:09.950 AFD: Opened codec 0x82d0450, id(MPEG2VIDEO) type(Video)
2010-12-20 18:30:09.951 AFD: codec AC3 has 2 channels
2010-12-20 18:30:09.952 AFD: Opened codec 0x82d09f0, id(AC3) type(Audio)
2010-12-20 18:30:09.952 AFD: codec AC3 has 1 channels
2010-12-20 18:30:09.953 AFD: Opened codec 0x82d0fa0, id(AC3) type(Audio)
2010-12-20 18:30:10.330 Preview: Grabbed preview '/myth/tv/1901_20101219200000.mpg' 1280x720@70s

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner


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 Post subject: Re: system resources
PostPosted: Mon Dec 20, 2010 8:45 pm 
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Joined: Thu Mar 25, 2004 11:00 am
Posts: 9551
Location: Arlington, MA
neutron68 wrote:
I don't know how to tell if KMSP changed the key frame interval. Any suggested software or command? I believe that Fox 720p has always been a framerate of 60 frames per second.

"Key frames" are part of the MPEG encoding scheme, which starts with a key frame, which is a complete screen image, followed by a bunch of incremental changes to that frame for the subsequent frames, until finally another key frame comes along.

The maximum interval between keyframes is one of those things that can vary. The easiest way to check it out is to go into cut-point editing mode, advance to the next keyframe, note it's position, then step forward one more. Do that a few times and you should quickly have a ballpark figure for the key frame interval.


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