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 Posted: Feb 21, 2012 - 05:38 PM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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| My tried and trusty DVR (Panasonic DMR-E85H) of 7 years or so is crashing more frequently, and any day now Cox will probably yank the analog feed on their cable service. So I've started looking into building a PVR unit. Has anyone gone down the path of MythTV, NextPVR, similar based systems to record their TV programs? |
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Posted: Feb 21, 2012 - 06:30 PM |
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Joined: Jul 18, 2005
Posts: 62324
Location: (using avr-gcc in) Finchingfield, Essex, England
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Quote:
Has anyone gone down the path of MythTV, NextPVR, similar based systems to record their TV programs?
The usual downside of any "home brew" system is that the PC hardware you run it on is too power hungry and noisy - noisy because of all the cooling fans dissipating the heat. As someone who worked on the designs of Europe's leading PVR system (SKY/Sky+ from BSkyB) the constant battle was to keep the cooling and hard drive noise to an acceptable level for a front room. A PC in an office can make a bit of noise and not be noticed - while a PVR in a front room recording a couple of channels while the TV/Hi-Fi is actually switched off and you are trying to read a book needs to be whisper quiet.
In the PVR manufacturing game we were always looking forward to the day when SSDs would become cheap enough to be a practical proposition (we're not there yet) but for one-off use I'd highly recommend them - obviously as big as you can afford.
The other issue with PVRs are the huge unreliability of HDDs. Again this is why we looked forward to SSD and the day we could ditch the magnetics all together. A population of about 3 million HDDs had an attrition rate of about 5% at just 4,000..5,000 hours use - that's actually horrendous when you think about it.
Google also did a study of something like 50,000 of their own HDDs and got similar MTBFs.
The difference between a PVR (or Google's) use of HDDs and "normal" office use is that they are being thrashed almost continuously (esp. if the PVR offers an "instant rewind" buffer). The HDD in a PC may do some pagefile.sys virtualisation from time to time and store the odd Word and Excel file but is not being used in the way that a PVR uses one.
So, really, if you can stretch to an SSD do!
Obviously a fanless board/CPU/graphics is a nice idea. There's Atom based boards such as the D510MO (and its later successor) that operate fanless though if they are subject to continual MPEG2/MPEG4 decode I imagine they are going to at least need a very "airy" box.
BTW I've run a D510MO using these wonderful little ATX (fanless!) power supplies:
http://www.mini-box.com/DC-DC
I can't recommend them highly enough (even if I did blow one up - but that was my expensive mistake!) |
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Posted: Feb 21, 2012 - 07:18 PM |
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Joined: Jun 27, 2005
Posts: 3412
Location: St.Petersburg, Russia
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| Can those systems write to network storage? It could solve the noise problem, or at least move it away. I know that I can play full non-recompressed DVD over a 100mbps ethernet from a Stora (a cheap NAS server) hidden in the wardrobe with XBMC running on a Mac Mini. I also do that using Android phone as a remote control for XBMC, pretty cool. |
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The Dark Boxes are coming.
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Posted: Feb 21, 2012 - 07:39 PM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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The DVR is currently in the bedroom, so I hear the fan spin up now and then, but it's hardly noticeable. What is noticeable is when it turns on, either the hard drive or the DVD drive does a head seek of some kind that's really loud. Normal operation never makes a noise like that. For the PVR I certainly want to go the fanless route is possible, but don't know if SSD is in the picture, I'll have to see what they go for nowadays. I can get 1TB HHD's real cheap now and if there's a failure, then you lose a few TV shows, nothing mission critical, just slap in another drive. Course if the wife misses an episode of Bachelor she'll say different.
Since SSD is basically flash technology, isn't there a limited lifetime on the number of write operations?
The other downside is I may have to learn Linux since that appears to be the OS of choice for these machines.
I'd have to get down and dirty with the numbers, but I don't see why network storage wouldn't be an option. Just go 1GB hardwire, not wireless. |
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Posted: Feb 21, 2012 - 11:07 PM |
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Joined: Sep 21, 2005
Posts: 2299
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The best option is the one that is no longer available. SageTV.
Google bought SageTV a while back and you can no longer buy the software or hardware. I knew this would happen when Google started into the tv thing (most 'good things' seem to get swallowed by 'big things' , then seem to disappear into black holes).
I have a 'server' whose only job is to run the SageTV software (4TB storage). It has a Dish receiver connected and is connected as a 'network' tuner via usb (receiver is legally modded to put out the ts stream). I also use an HDHomerun tuner. For the tv side, I use the HD200 media extender (little box- use at as many tv's as you have). As good as it gets right now. Pc does what its good at- moving data around. Extender does what its good at- receiving ir from remote control, getting data from server, decoding/displaying to tv.
I doubt Google will keep the good stuff from SageTV (recording from tuners being the primary feature for me, which I suspect Google will have no interest in).
To get the same type of thing out of Windows Media Center (server/client setup), you basically have to get an XBOX360 as the client hardware. You can run WMC from the pc directly to the tv (pc as only hardware), but then you have to deal with things that are not fun- getting good video from a pc to a tv (fighting drivers, tweaking settings, etc.), ir receiver for remote, noise, and so on. Certainly doable, but not ideal in my opinion. Probably the best option though (right now), for a single tv.
I have tried many different versions of these 'software' dvr's, but it seems it becomes an endless amount of tinkering. Then there is the guide data- can be a pain (Sage/WMC are easy of course).
I would also check what the cable company offers. Run the numbers and see if it pays to build your own. In my case, I don't want my recordings 'locked' in a box.
Not much of an answer. |
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Posted: Feb 22, 2012 - 12:14 AM |
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Joined: Jan 09, 2007
Posts: 1875
Location: Arlington, Texas, U.S.A.
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The Linux armhf (ARM hardware floating point) distributions are coming along for Debian and Ubuntu.
Some fan-less ARM hardware with HD video are: Genesi/Freescale Efika MX, Freescale i.MX53 Quick Start Board (QSB), TI PandaBoard (and likely BeagleBoard).
Hard drive interfaces: Efika MX = PATA, i.MX53 QSB = SATA; but Efika MX comes with a small SSD.
armel distributions of MythTV exist.
IIRC, armhf is running faster than armel.
Debian:
http://www.debian-multimedia.org/dists/unstable/main/binary-armhf/
If roll your own, Debian packaged armhf kernels exist for "mx5" and "omap4" and probably the installer exists since Debian moved armhf to the testing state.
Ubuntu:
https://wiki.ubuntu.com/PrecisePangolin/TechnicalOverview/Alpha2
Don't know if the armhf MythTV packages exist (I didn't check the repositories).
MythTV appears to be popular on Ubuntu by Mythbuntu.
ARM appeals due to the low total power consumption (IIRC 5 to 10 watts from 5VDC wall wart).
Cases:
PandaBoard and BeagleBoard have cases, Efika MX comes with a case (nettop or netbook).
i.MX53 QSB - IIRC, a Debian build farm was created using one QSB and one laptop hard drive onto one plastic sheet into a rack case (multiple QSBs per rack). |
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Posted: Feb 22, 2012 - 12:24 AM |
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Joined: Jan 09, 2007
Posts: 1875
Location: Arlington, Texas, U.S.A.
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dksmall wrote:
Since SSD is basically flash technology, isn't there a limited lifetime on the number of write operations?
Yes but SLC (single level cell) flash is robust enough for heavy industrial usage for, IIRC, several years continuous. Some MLC (multiple level cell) flash SSDs have 3 or 5 year warranties, are larger, and less expensive than SLC. The wear leveling MCUs and algorithms are impressive.
But laptop hard drives are difficult to beat in price, likely cost, and availability. |
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Posted: Feb 22, 2012 - 12:27 AM |
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Joined: Jan 09, 2007
Posts: 1875
Location: Arlington, Texas, U.S.A.
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dksmall wrote:
The other downside is I may have to learn Linux since that appears to be the OS of choice for these machines.
Maybe not much. IIRC, MythTV likely has some step-by-step instructions. |
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Posted: Feb 22, 2012 - 03:34 AM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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Wow lots of feedback.
I was reading about SageTV today and saw how Google acquired it and the trail seems to go cold at that point.
I've seen some of the MythTV instructions, they don't seem too bad. I would definitely be at the mercy of some Linus gurus when something goes South.
And as mentioned there's the cost comparison to just renting the local cable system's DVR. Rumor has it I can rent it for $5 a month since I give Cox so much money already, and that cost is hard to beat compared to building the PVR. |
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Posted: Feb 22, 2012 - 08:30 AM |
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Joined: Sep 07, 2004
Posts: 2527
Location: New York State
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dksmall wrote:
What is noticeable is when it turns on, either the hard drive or the DVD drive does a head seek of some kind that's really loud.
When my computers are turned on, the BIOS revs up the fans to full speed for a couple of seconds. If there is a disc in the optical drive it will spin up and make a lot of noise. |
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Posted: Feb 22, 2012 - 02:50 PM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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| All the new Dell's we get have the "dust blower" startup, but the Panasonic DVR has a very quiet fan and I don't leave a dvd in the optical drive. There are known issues if you power it up with a writeable dvd in the drive, the system may hang trying to figure out what to do with that disk. |
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Posted: Feb 22, 2012 - 03:10 PM |
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Joined: Jan 09, 2007
Posts: 1875
Location: Arlington, Texas, U.S.A.
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dksmall wrote:
I would definitely be at the mercy of some Linus gurus when something goes South.
PLUG, Linux Installfest - last Saturdays for 6 hours (wow).
One way is data (as much as possible) on one partition, video and audio on another, BusyBox on another, and boot (kernel and initial RAM file system) on the first partition.
A common way is to store some or a lot on a NAS; most NAS will have on-board backup software.
Incremental backups or at least the initial install media.
The ARM boards have the install program and install data on a SD card (plug and run via U-Boot or such); x86 boards likely use a USB stick via BIOS.
dksmall wrote:
... (cable's DVR) that cost is hard to beat compared to building the PVR.
Some of these may already run Linux or uCLinux and have BusyBox or similar; if so, the DVR maker should have available the open portion of their software. Very likely don't have access to unencrypted AV files but may be legal to backup encrypted AV files. There is backup state data in some encrypted AV files that indicates if backup is possible, how many copies are allowed, and the copy identifier. Some DVRs may have an external hard drive port. |
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Posted: Feb 22, 2012 - 04:19 PM |
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Joined: Sep 07, 2004
Posts: 2527
Location: New York State
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| So your rig is crashing and something is making a loud noise at startup. I can think of two things that spin up at startup and will wear out eventually. The fan and the hard drive. The hard drive should be easy to replace. The fan should be also unless it's an oddball size. |
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Posted: Feb 22, 2012 - 04:53 PM |
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Joined: Jul 18, 2005
Posts: 62324
Location: (using avr-gcc in) Finchingfield, Essex, England
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Quote:
One way is data (as much as possible) on one partition, video and audio on another, BusyBox on another, and boot (kernel and initial RAM file system) on the first partition.
In the PVRs I worked on the single FAT32 partition was actually logically divided into 2% of the space for "system files" and 98% for the video/audio data. A second layer of FAT on top of the first used (pretty standard) 32K clusters in the 2% region but 1.5MB clusters in the data region. This made video/audio access far more efficient.
I don't know if Linux applications like Myth have the "smarts" to do things like this?
Also note that PVRs have "ACE" hard drives. These have a different firmware in the HDD controller than normal desktop drives. For one thing they have all the power/noise reduction options switched on. The f/w is much more aggressive about ladder caching to prevent the head swinging about wildly over the disk platter and the write fail retry pattern is changed to only make something like 64 steps of attempts (left/right off-track adjustments, head, re-alignment, increased write current and all the other 60 odd strategies) whereas desktop drives try for much longer to get sectors to work. This is because in an MPEG2/MPEG4 stream if the odd sector is "missing" the worst that happens is a tiny "pop" on the audio or some green block mosaic-ing on the video which, in the great scheme of things, don't actually matter.
So at the very least I'd maybe consider two HDDs, one formatted with the largest cluster size the FS can support and one "normally" formatted for the OS and application. If possible make the data drive an ACE (consumer electronic) variant.
http://www.seagate.com/www/en-gb/produc ... lectronics
http://www.hitachigst.com/internal-driv ... ectronics/ |
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Posted: Feb 22, 2012 - 07:24 PM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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steve17 wrote:
So your rig is crashing and something is making a loud noise at startup. I can think of two things that spin up at startup and will wear out eventually. The fan and the hard drive. The hard drive should be easy to replace. The fan should be also unless it's an oddball size.
The startup sound has been there since the day I opened the brand new box, it sounds like the floppy drive head seek the old DOS pc's use to do. The hard drive will spin down if you aren't using it, i.e. just watching TV through the DVR's tuner. Once you hit play or some other action that needs the hard drive, it spins up with no noise at all. So that startup sequence only occurs when you turn on the DVR. The crashes average every 3 or 4 months. Recently it was occurring daily so I opened it up and found 2 electrolytic caps on the power card that had burst open. That makes 6 caps I've changed out on that board over the years. After replacing the last 2, it fired right up, grabbed guide data overnight (a good thing) so I thought I had it solved. But it crashed about 2 weeks after the repair.
Something else I should mention is this DVR uses TV Guide On Screen for it's guide data, and that system is rather temperamental and can crash with channel lineup changes, etc. So hopefully I'm back to a crash every 4 months or so. |
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Posted: Feb 22, 2012 - 07:29 PM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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Cliff, you got something you can just box up and send me? That would be much easier!  Course it needs to be NTSC, not PAL. |
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Posted: Mar 11, 2012 - 09:11 PM |
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Joined: Jan 09, 2007
Posts: 1875
Location: Arlington, Texas, U.S.A.
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Posted: Mar 12, 2012 - 07:52 AM |
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Joined: Dec 01, 2003
Posts: 2502
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| FWIW, I've finally been forced into digital video recording. We time-shift almost everything and "buffer" easily 400 hours of programming to view hours to many weeks later. This was until lately done with a pair of "rare" VHS units that had atsc/ntsc tuners to deal with both analog and digital material on cable. The issues of availability, reliability and obsolescence of digital vcrs finally became critical. I had no desire for subscription DVR equipment, but curiously, atsc/ntsc standalone dvrs with high capacity are rare birds, indeed! I discovered the Magnavox (Funai) MDR513, a 320 gig HDD/DVD at Walmart of all places. The reviews were very positive and this equipment family has a long history of apparent satisfaction. Imagine my surprise when the one I bought turned out to be totally flakey and unusable! Knowing "stuff" happens I replaced it with another, which was even worse! I could not accept that so many could be so happy with such a terrible product. I found a video forum that had a thread with about 20,000 posts on this specific equipment and almost all posters were happy. However, after about four or five hours of reading an issue did surface. The system can be driven completely nuts if the channel numbers of analog signals were reused somehow by digital channels on the cable feed. This turned out to indeed be the case and the fix was a simple procedural workaround when setting up the channel list. It now works just great and I ordered another 500 gig unit at an even better price from another online vendor. The kicker is that these recorders seem to be the only HDD units sold into the US that have atsc and ntsc tuners, and Funai is discontinuing them, while similar products seem to be freely available in other countries. Hopefully these units will do the job until something better comes along, or I finally geek something up with a Unix box. (functionally, they are pretty slick) |
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Tom Pappano
Tulsa, Oklahoma
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Posted: Mar 12, 2012 - 07:36 PM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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| Does the MDR513 support any type of guide data or is it all manual recordings? |
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Posted: Mar 12, 2012 - 10:21 PM |
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Joined: Dec 01, 2003
Posts: 2502
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Quote:
Does the MDR513 support any type of guide data or is it all manual recordings?
All manual. There is also no usb port or anything for transferring files, other than dubbing to dvds. The guys on the forum say they just pop the (SATA) drives out and plug them into another machine if they want to backup to another drive. The disk is in an ordinary format. Also, the units are smart enough to recognize and initialize a new drive, so you can replace the 320 with something larger, and by upgrading firmware via the dvd drive you can give the 513 the same operational features as the 500 gig 515. You can edit the titles of recorded programs to something more meaningful than dates and times. |
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Tom Pappano
Tulsa, Oklahoma
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Posted: Mar 13, 2012 - 03:16 AM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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| We have a DVD recorder that works much the same way. Don't understand why they can't let you enter a title as part of the timer program entry, and then that title can be applied to the recordings as they record. That would make things so much easier! |
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Posted: Apr 01, 2012 - 09:35 PM |
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Joined: Nov 28, 2004
Posts: 3552
Location: San Diego, Ca
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dksmall wrote:
How about a PCI card from Hauppauge ? I have a PVR150 and it has some good features . I like being able to edit the video, but it's just cut and splice . The picture quality looks really good . They have boards that have dual tuners also .
They're hardware compatible with MythTV :
http://www.mythtv.org/wiki/Hauppauge |
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Posted: Apr 02, 2012 - 04:47 AM |
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Joined: Apr 16, 2001
Posts: 3522
Location: Phoenix, Arizona
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| Actually I've ordered the PVR2250 which is the dual tuner, might see it tomorrow. I plan to try it our with an extra PC for awhile and see how that works out. If all looks good then I'll order the specific hardware for the final unit. |
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