This subject comes up often, but I've run into a 1080i LiveTV (Watch TV) playback issue on another MythBuntu 8.04 build.

It has a 7300GS PCIe, Biostar Nvidia chipset S939 mobo, 1GB DDR3200 and a single core A64 3500.

At first I thought the issue was the QAM demodulation with the Kworld 115 card, but I noticed the image in "Watch TV" only broke up and hesitated/jerked on 1080i channels- no issue with 720p channels.

I tried using the "Slim" setting (vs CPU+) in the Front End Setup->TV->Playback options, and it helped on the 1080i channels, but the System Monitor would still peg at 100% and jerk the image occasionally.

Since others here have stated good ATSC playback with as little as a Duron 1600, I thought an A64 3500 would be home free for 1080i ATSC/QAM.

Any other ideas for settings or tweaks?

...I may have to put an X2 in there :(

Have you installed/enabled the nvidia driver (not the default nv driver)?

Have you installed/enabled the nvidia driver (not the default nv driver)?

Yes, from EnvyNG

Any more hints on the "secret sauce" to reduce CPU utilization on live ATSC 1080i on Mythbuntu?

Although I have a beefier machine I've struggled with jittery video as well, but I believe it's primarily due to my ATI graphics card and driver. I have been able to clean it up a lot and maybe something here will work....

Make sure graphics drivers are installed (which you did).
Research and set appropriate driver configs (such as "VideoOverlay" "on" etc - card dependent).
Select the best-working playback profile within myth (either slim or cpu+) and then modify individual deinterlacers to get a bit better performance and reduce CPU load.

My CPU went from 105% during 1080 playback to ~55% (yeah, 105% is from running "top") with just changing some of the deinterlacers. That wasn't enough tho as it still required some video driver parameters to clean up the video.

I have been able to remove (nearly all of) the jitters but I still get video artifacts and anomalies that I'm starting to think are from the vid card driver (ATI Catalyst 8.5).

R

---
AMD 64 5000+ BE
Gigabyte GA-MA78G-__ (ATX) (ATI HD 3200 Graphics)
2GB Ram.

then modify individual deinterlacers to get a bit better performance and reduce CPU load.

My CPU went from 105% during 1080 playback to ~55% (yeah, 105% is from running "top") with just changing some of the deinterlacers. That wasn't enough tho as it still required some video driver parameters to clean up the video.


Where are the deinterlacing parameters in Myth?

I think the Mythbuntu guys need to do a better job of auto-setting the CPU intensive parameters related to video processing during the install wizard, checking the CPU and GPU/video driver for performance and then setting some video parameters for you.

Any more hints on the "secret sauce" to reduce CPU utilization on live ATSC 1080i on Mythbuntu?Did you enable XvMC (shudder)? Is UseEvents set to true in your xorg.conf?

X2's are so cheap now, it's an easy fix to pop one in.

Did you enable XvMC (shudder)? Is UseEvents set to true in your xorg.conf?

X2's are so cheap now, it's an easy fix to pop one in.

Unfortunately, socket 939 X2's are much harder to find. Anyone got a lead for retail boxed new S939 X2's? There's always ebay....

Use the XvMC setting for deinterlacing in playback. Your CPU should be good for that. I had a X2 3800 that ran @ 20%or so with XvMC and bobint. Try that and let us know.

Where are the deinterlacing parameters in Myth?

Settings->Settings->Tv Settings->Playback

Then hit next until you get the playback profiles where you select either Normal / CPU+ / CPU++ / CPU- etc...

Under each of those hit on the "edit" buttons and you will see the deinterlacer setup for that rule.

R

I assume the numbers on the rules are priorities?

THe first 3 rules were for 720p or below, and the last two appeared the same for res >0,0 -> xvMC, so I assume 1920x1080 would be covered by rules 4 and 5 since 1-3 were for 1280x720 or less.

I changed rules 4 and 5 to explicitly cover >1280x720, used standard xvMC and Bob deint- no change on 1080i channels :(

I still get flashes of small sqares every other second or so- different from the breakup you see with low signal strength.

I found this at mythtv.org

http://www.mythtv.org/docs/mythtv-HOWTO-3.html

"To playback HDTV content, plan on a powerful CPU. "How powerful?" depends on a number of factors, such as the capture resolution, whether the video is progressive or interlaced, and whether your display card has hardware-assist support for Linux.

The Simple Answer: Once you are in the 3.2 Ghz P4-class of CPU you should have no issues with viewing HDTV.

The Complicated Answer:

For 720p content (1280x720), a 2.4GHz P4 should be sufficient.

For 1920x1080i->1920x1080p with the better deinterlacing methods done in real time a 2.4GHz CPU is taxed, but should work if you use "Bob and Weave" deinterlacing, or if you have an NVIDIA card with MPEG-2 hardware acceleration. If you enable the hardware acceleration, you may be able to use a 1.8GHz processor."

Does XvMC being enabled with the current proprietary Nvidia driver installed guarantee MPEG2 GPU assist on FX5xxx, 6xxx and 7xxx series Nvidia cards?

I was also suspecting the DMA setting on the hard drive assigned to Myth recording- what is the simplest way to check/verify DMA setting on a hard disk?

Rgb,

hdparm should give you the information you need on DMA access and drive speed.

hdparm -i /dev/hdX or /dev/sdX will give you drive capabilities and current settings.

You can use hdparm to test drive transfer throughput, and offers a host of tweaks for IDE drives. It can't do much for SATA, but sdparm may help. Here's a few good links:

Gentoo Wiki page (http://gentoo-wiki.com/HOWTO_Use_hdparm_to_improve_IDE_device_performance) - very good hdparm primer
Old but decent hdparm primer (http://www.linuxdevcenter.com/pub/a/linux/2000/06/29/hdparm.html)
sdparm primer w/ section on SATA (http://sg.torque.net/sg/sdparm.html)

Does XvMC being enabled with the current proprietary Nvidia driver installed guarantee MPEG2 GPU assist on FX5xxx, 6xxx and 7xxx series Nvidia cards?

It's supposed to with the drawbacks being that the OSD is in greyscale on anything but 5xxx cards, and the video stuttering that accompanies OSD popups on some systems. It can help a lot with CPU usage, but it's often problematic.

I don't have it enabled for Myth TV playback because of these probs but I do have it enabled for mplayer and xine. It does make a noticeable diff with my onboard 6150.

Don't forget to make sure that "UseEvents" is set to "true" in the Device section for your card in xorg.conf. Makes a huge diff in X display usage in many cases.

Late to the party, sorry (updated my gentoo box on a celeron after about 2 years, lol), but I experience the same pauses and "squares" even on my dual-core opty.

The issue is clearly caused by hard drive usage (I only have a single-drive system for now). We all know that mythtv uses the hard drive 100% of the time while watching live tv. The solution is RAID0 and an external drive for backups. I'm planning a HOWTO on this, but the cost of getting my car out of the shop has escalated to $1800 (restoring a classic ;)) so my extra cash for drives is temporarily tied up.

Don't forget to make sure that "UseEvents" is set to "true" in the Device section for your card in xorg.conf. Makes a huge diff in X display usage in many cases.

BINGO!

You win the thread prize!

The SECRET SAUCE for this thread is:

Option "UseEvents" "True"

However, I added the line to *Screen* section of xorg.conf, NOT the Device section per:
http://www.debianhelp.org/node/3146

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
Option "AddARGBGLXVisuals" "True"
Option "UseEvents" "True"
Defaultdepth 24
EndSection

I attached my xorg.conf file.

Another link says to put it in the Devices section, but I didn't try it-
http://www.redhatmagazine.com/2007/11/20/tips-and-tricks-why-does-xorgs-cpu-usage-shoot-up-when-using-nvidias-driver/

I don't know if there's any difference between the Devices and Screen sections for the UseEvents parameter

1080i channels are now butter smooth, using ~70% CPU +/- 5%, and about 50% with 720p channels.

Why EnvyNG and/or the Nvidia driver doesn't add this important line to the xorg.conf file is unknown...

Rgb,

hdparm should give you the information you need on DMA access and drive speed.

hdparm -i /dev/hdX or /dev/sdX will give you drive capabilities and current settings.

You can use hdparm to test drive transfer throughput, and offers a host of tweaks for IDE drives. It can't do much for SATA, but sdparm may help. Here's a few good links:

Gentoo Wiki page (http://gentoo-wiki.com/HOWTO_Use_hdparm_to_improve_IDE_device_performance) - very good hdparm primer
Old but decent hdparm primer (http://www.linuxdevcenter.com/pub/a/linux/2000/06/29/hdparm.html)
sdparm primer w/ section on SATA (http://sg.torque.net/sg/sdparm.html)

I had used hdparm before- should have googled, but thanks. It returned:

sudo hdparm -i /dev/sda1

/dev/sda1:

Model=WDC WD800JB-00FMA0 , FwRev=13.03G13, SerialNo=WD-WMAJ91071310
Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=58
BuffType=unknown, BuffSize=8192kB, MaxMultSect=16, MultSect=?16?
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
AdvancedPM=no WriteCache=enabled
Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6

* signifies the current active mode


So I am good to go re: dma on the recording hard drive, which appears to be set to udma5.

The hard drive had nothing to do with the hesitating 1080i and flashes of small squares, apparently.

And this is with the Myth Back End record directories set to /home/$user on the same drive as / (i.e using a single hard disk, the WDC WD800JB above)

I intend to add a separate 200G drive dedicated to video recording anyways...

As always, the AVS braintrust saves the day :D

I deleted the Kworld 115 in the Myth backend, re-added it, then did a fresh channel scan on WoW basic analog cable to pick up the unencrypted OTA stations sent as QAM-256 digital.

After removing the music channels that don't work in the Front End, I exited, did a mythfilldatabase from schedulesdirect, then ran the Front End again.

I tested 1080i on NBC-HD (Today show) this morning- the CPU usage varied a consistent 60%-70%, rarely higher. This is with XVMC, bob deint, and the UseEvents=True option. Looks awesome, no hiccups for 1080i.

Based on these results, I feel comfortable with the single core A64 3500+ (2.2Ghz). I think you'd be good down to an A64 3200 or 3000, but wouldn't go lower, as you want some headroom. Nice to know a single core can still do OTA MPEG2 HD 1080i.

If someone tests a single core using a 64 bit Linux and Myth, please report CPU usage.

Based on these results, I feel comfortable with the single core A64 3500+ (2.2Ghz). I think you'd be good down to an A64 3200 or 3000, but wouldn't go lower, as you want some headroom. Nice to know a single core can still do the job.

If someone tests a single core using a 64 bit Linux and Myth, please report CPU usage.

That's the CPU I upgraded from. I don't think I tried the "UseEvents" option, but it used ~90+% CPU in 64-bit Linux watching HD via firewire. Don't even think about 264 HD, though...seconds per frame, lol. That's with 8500GT + 2GB RAM, btw.

That's the CPU I upgraded from. I don't think I tried the "UseEvents" option, but it used ~90+% CPU in 64-bit Linux watching HD via firewire. Don't even think about 264 HD, though...seconds per frame, lol. That's with 8500GT + 2GB RAM, btw.

To clarify for others, I *don't* recommend using anything less than an X2 4600-5000 for x264 1080p, x2 6000 even better.

This thread discussed the low end CPU "hard stop" for MPEG2 1080i from over the air or cable sources.

CPU requirements for video playback depends on both resolution (480p, 540p, 720p, 1080i, 1080p) and codec (MPEG2 vs x/h264 vs VC1 vs Xvid). A lot of people only need SD with any codec, and occasional HD MPEG2 from over the air sources only, which dramatically reduces CPU requirements. Others may want these plus x/h264 720p only, which also needs significantly less CPU than 1080p x/h264. I don't know exactly where the CPU low end "hard stop" is for 720p x264- I suspect any X2 would do it fine, plus the higher speed single cores (A64 4000-4600?)

To clarify for others, I *don't* recommend using anything less than an X2 4600-5000 for x264 1080p, x2 6000 even better.

This thread discussed the low end CPU "hard stop" for MPEG2 1080i from over the air or cable sources.

CPU requirements for video playback depends on both resolution (480p, 540p, 720p, 1080i, 1080p) and codec (MPEG2 vs x/h264 vs VC1 vs Xvid). A lot of people only need SD with any codec, and occasional HD MPEG2 from over the air sources only, which dramatically reduces CPU requirements. Others may want these plus x/h264 720p only, which also needs significantly less CPU than 1080p x/h264. I don't know exactly where the CPU low end "hard stop" is for 720p x264- I suspect any X2 would do it fine, plus the higher speed single cores (A64 4000-4600?)

Come on now. I've been using MythTV for about 4 years now and all I ever watch is ATSC mpeg2. The screen resolution never affected my cpu usage. What did affect it was the type signal sent form the stations. Until upgrading I watched 1080i on an old Duron 1600 clocked at 2GHz using XvMC with an old AGP FX5200 card at 1600x1200. Changing the screen resolution didn't make one bit of difference for CPU usage. It was about 60% IIRC and I could clock it down to 1.2GHz and still watch a 1080i signal at about 90% cou usage using XvMC. Without XvMC, it took 80%+ when clocked at 2GHz. Using OSD did affect the picture somewhat without XvMC, but not with it. I used deinterlacing with Bob. I did have some problem til I found the right settings for the video card. As for H264, I don't use it, but I did test my X2-3800+ from some clips someone pointed me to and it played them on this machine using onboard Geforce 6100 video. The changes for the best performance was to turn off sync to vblank in a couple of places. ymmv

0/SyncToVBlank=0
0/AllowFlipping=1
0/ForceGenericCpu=0
0/GammaCorrectedAALines=1
0/FSAAAppControlled=1
0/OpenGLImageSettings=2
0/XVideoTextureSyncToVBlank=0
0/XVideoBlitterSyncToVBlank=1
0/XVideoSyncToDisplay=1

Come on now. I've been using MythTV for about 4 years now and all I ever watch is ATSC mpeg2. The screen resolution never affected my cpu usage.



I meant the resolution of the source (mkv file, avi file, feed from antenna, etc), not the resolution the video card is set to. Sorry for the confusion.

Thanks for the tweak settings, though. Your results at 2Ghz with ATSC MPEG2 appear to agree with mine.

Bump to keep this active- good info for noobs or a new build.

Bump- prolly should be sticky...

I deleted the Kworld 115 in the Myth backend, re-added it, then did a fresh channel scan on WoW basic analog cable to pick up the unencrypted OTA stations sent as QAM-256 digital.

After removing the music channels that don't work in the Front End, I exited, did a mythfilldatabase from schedulesdirect, then ran the Front End again.

I tested 1080i on NBC-HD (Today show) this morning- the CPU usage varied a consistent 60%-70%, rarely higher. This is with XVMC, bob deint, and the UseEvents=True option. Looks awesome, no hiccups for 1080i.

Based on these results, I feel comfortable with the single core A64 3500+ (2.2Ghz). I think you'd be good down to an A64 3200 or 3000, but wouldn't go lower, as you want some headroom. Nice to know a single core can still do OTA MPEG2 HD 1080i.

If someone tests a single core using a 64 bit Linux and Myth, please report CPU usage.

Glad you were able to fix it. But I'm still wondering why your CPUs are very high. I've been doing 1080i either QAM or ATSC since 2005. I'm still using the machine. It's an athlon 64 3000 with 512mb. CPU max is 42%.

This machine can also do 1080p without framedrop but of course, the ones that were only encoded at 5mbits. I've downloaded a 1080p video clip with 25mbits encoding, it was slow and cpu was 95%. :p I should upgrade next year.

EDIT:
Sorry, adding Xorg's usage, cpu usage total was at 49%-58%. I was only looking at mplayer's cpu usage.

EDIT:
Sorry, adding Xorg's usage, cpu usage total was at 49%-58%. I was only looking at mplayer's cpu usage.

My CPU usage numbers are all *total* CPU- not per process.

Based on total CPU, it appears our numbers agree.

Cool!

Do you think if we want to play high bit rate rips like 25mbits smoothly, we should go with quad core or maybe just get a high-end nvidia card(8800s and above) now that Nvidia has released(still buggy though) VDPAU?

Cool!

Do you think if we want to play high bit rate rips like 25mbits smoothly, we should go with quad core or maybe just get a high-end nvidia card(8800s and above) now that Nvidia has released(still buggy though) VDPAU?

I think the safest route in the short run on Linux is to go with the most CPU cores and most CPU Ghz you can afford, as Linux currently needs to do more in software vs the proprietary hardware acceleration on Windows. The money you save on more expensive GPU's can go into more CPU cores/GHz, which helps your overall system more anyways.

Until AMD/ATI and Nvidia get XvBA and VDPAU up and running to enable hardware acceleration of video decoding in their Linux drivers with common media apps in Linux, we need to protect ourselves with ample cores and GHz to cover for CPU utilization for software decoding/post processing- no big deal, as Moore's Law is on our side. Until XvBA and VDPAU are working in an easy fashion (i.e. no special patches/compiling needed) with the mplayers, VLC's, Geexbox's, XBMC's and MythTV's of the world, just use Nvidia FX5xxx, 6xxx or 7xxx GPU's for the time being, which are practically free now. A side benefit for media PC use is that these are easy to find passively cooled- you don't want fans on your GPU.

Besides, software decoding is more flexible in the long run, and long time avsforum members know that the pendulum has swung several times back and forth between hardware and software decoding of video, with the consensus among avsforum members over which is "better/preferred" shifting every few years. At the moment, Linux and Windows are simply "out of sync" on what is preferred ;)

so much thanks for all the Myth/Linux info.

First time Mythbuntu builder here and it sure helps to have a better idea knowing what I'm in for :-) ... and all your explanations about CPU horsepower/HD playback for various file types/resolutions are very helpful, I would think even for Linux vets doing an HTPC for the first time.

Something I'm still a bit confused on. What is the ideal O/S & storage drive setup if I have 2 medium size drives, (around 200GB each)? Should I keep archived video files (.mpg, .mkx, avi) and also do live TV recordings to the same drive or make the new recordings on the O/S drive? Sorry for the weak questions, but I gotta start somewhere.


I vote yes to make this thread stick!

what is Myth/Linux ?

what is Myth/Linux ?


http://en.wikipedia.org/wiki/Linux

http://www.linux.org/

http://www.ubuntu.com/

http://en.wikipedia.org/wiki/MythTV

http://www.mythtv.org/

What is the ideal O/S & storage drive setup if I have 2 medium size drives, (around 200GB each)? Should I keep archived video files (.mpg, .mkx, avi) and also do live TV recordings to the same drive or make the new recordings on the O/S drive?



You should use Ubuntu 8.10, then install mythbuntu-desktop from Synaptic, then install the MythTV front and backends in Mythbuntu Control Centre, which is installed with mythbuntu-desktop.

Partition one of the 2 drives with an OS partition of about 20-30GB, the rest for archived video file storage (avi/mkv's, etc).

Use the second hard drive as Mythtv live TV/scheduled recording storage.

Or switch the two storage partitions/drives around if you plan to record less/have more archived video files.

thanks for the info Rgb.

I'm considering wiping my current Mythbuntu install and doing it the way you recommend. I'm a little nervous about wiping the first install, as the Grub loader is the first thing that runs during bootup and it will not longer have valid Linux installs to select. If I wipe the current Mythbuntu install drive, will Grub freak out? Even though I have most of my Mythbuntu working, I think a fresh re-install would be best to keep things clean, as the first time I installed Mythbuntu, it did not include some hardware I've added.

The box runs dual boot, with XP. XP running very well, but the damn thing does not recognize my plasma TV (using as a monitor on my HTPC box) unless I have it going through my AVR (H-K, AVR254) first, which does not produce an optimal 1080p video signal to the TV. I get graininess in the image from XP.

Although I can connect straight to the TV without a problem in Mythbuntu, it will not find the network tuners (HD Homerun), but I remember seeing a prompt for it during MythTV setup. Where can I find that now?

Btw, whereabouts in SE Mich? I grew up in a po-dunk town of Hudson MI, also in SE Mich.

We may need to revisit this thread since VDPAU has been released in a stable driver. Phoronix has achieved good HD playback results with a $20 45W Sempron and a $30 fanless 8400GS --> http://www.phoronix.com/scan.php?page=article&item=nvidia_vdpau_gpu&num=1

@LarZman:

Don't worry about grub getting hosed -- the MBR will be rewritten when you fresh install, and your XP partition will be auto-detected again if it's still there.

thx mythmaster. guess it's time to reload. Hope I learned something the first try. I kinda planned on this, as I'm nearly a noob to Linux and making an error or two is part of learning :-)

I'm a little nervous about wiping the first install, as the Grub loader is the first thing that runs during bootup and it will not longer have valid Linux installs to select.
Here's the approach I use for hard drive partitioning, which I have found gives me the most flexibility to play around with different installs. The order in which these are listed is their physical order on the disk
/dev/sda2 - 100 MB ext2 partition used for boot management
/dev/sda4 - 2 GB "extended partition"
/dev/sda1 - Windows, if I must have it
/dev/sda3 - LVM physical volume taking up the rest of the disk
The physical order probably isn't important if you have a modern BIOS, but I have just always been in the habit of wanting my boot manager at the front of the disk.

The first time I install Linux, I create a /boot filesystem on /dev/sda2 and install grub in the Master Boot Record. I then create an LVM volume group using the physical volume /dev/sda3, and create logical volumes for root, swap, mythtv storage (/var/lib/mythtv if you are using mythbuntu, /storage if you are using mythdora), and for my dvd library which I mount as /var/lib/mythtv/videos/dvds.

For the second and subsequent installs, I create a new 100 MB logical partition (e.g., /dev/sda5) for the /boot partition and install grub there, NOT IN THE MBR. I create new logical volumes for root and mythtv storage and reuse (without reformatting) the logical volumes for swap and my dvd library.
After the install is completed, I reboot the older linux and add a new entry to /boot/menu.lst which uses the 'configfile' command to link to the menu.lst on /dev/sda5. Now when I boot the computer it will bring up the grub menu from /dev/sda2, and the new entry I added will be one of the choices. Choosing that entry pulls up the grub menu from /dev/sda5 and lets me boot the new install.

What makes this even easier if I just go ahead and create more 'configfile' entries in the menu.lst on /dev/sda2 in advance, pointing to /dev/sda6, /dev/sda7, etc.

Just my .02

thanks for the info Rgb.


Although I can connect straight to the TV without a problem in Mythbuntu, it will not find the network tuners (HD Homerun), but I remember seeing a prompt for it during MythTV setup. Where can I find that now?

Btw, whereabouts in SE Mich? I grew up in a po-dunk town of Hudson MI, also in SE Mich.

re: Homerun tuners-

Just go into the Myth Backend, add Capture Card and select HD Homerun and the Tuner #, then the rest (Video Sources, Connections, channel Scan, etc)

Grew up in Detroit on the border of Dearborn Heights. Been in the Dearborn/Dearborn Heights area ever since.

Although I can connect straight to the TV without a problem in Mythbuntu, it will not find the network tuners (HD Homerun), but I remember seeing a prompt for it during MythTV setup.
I'v have sometime had problems with the firewall preventing my MythBox connecting to the HDHomeRun. If you defined an entry for the HDHR during mythtvsetup but can't scan channels, try turning off the firewall and see if that helps.

thanks.

I decided to reinstall Mythbuntu, as I made a couple of mistakes the first time around (noob to that O/S). Not a big deal, It found and scanned both HD tuners without a problem this time.

..., it will not find the network tuners (HD Homerun), ....

Have you verified that you can "see" the tuners with the "hdhomerun_config" CLI?

If not, then you should probably start at that point and make sure you have all the network settings correct before attempting to get Myth to recognize them.