AVS Forum banner

1 - 20 of 33 Posts

·
Registered
Joined
·
260 Posts
Discussion Starter #1
Hi, just getting down to researching processors and motherboards. I know there are thousands of processors out there, so can someone just give me the ball park on the minimum processor and Ram requirement I would need to build a system that can record 4 HD shows at once?
 

·
Registered
Joined
·
260 Posts
Discussion Starter #2
Let me ask this question an easier way and from a different angle...


If you have successfully recorded 4 shows at once please tell me what processor you are using and how much ram.


...Another question this brings to mind, do you need more than one hard drive in order to record 4 shows simultaneously?
 

·
Registered
Joined
·
16,749 Posts
Recording hows uses almost no processing power and very little Ram since the data from the tuner uses Direct Memory Access(DMA) to come into memory and also uses DMA to write it to Disk. The speed of the disk probably the critical item. A SATA 2 drive with a large cache may be required.
 

·
Registered
Joined
·
260 Posts
Discussion Starter #4

Quote:
Originally Posted by walford /forum/post/19518360


Recording hows uses almost no processing power and very little Ram since the data from the tuner uses Direct Memory Access(DMA) to come into memory and also uses DMA to write it to Disk. The speed of the disk probably the critical item. A SATA 2 drive with a large cache may be required.

Thanks for the input. I have heard that I need at least a dual core processor so if that is good enough, there are plenty of cheep motherboard/processor combos.


Since the tuner is doing the work, are there some specifics I need to look for in a tuner?
 

·
Registered
Joined
·
1,712 Posts
I can record 4 shows at once with my Core i5-661/DH55TC/8GB setup. It has plenty of CPU overhead. I do record it to my C: drive which is an SSD, and then I clip the commercials and archive them to one of my traditional hard drives. Because ATSC recordings are big and my SSD isn't very large, I have to be mindful of moving the shows off the SSD once they've finished recording.


Many ATSC shows are in the ballpark of 12 Mbps max (lowercase "b" is bits per second), and my WD green hard drives at their slowest are around 50-60 MBps (uppercase "B" is bytes per second, and 8 bits per byte) when copying a file to them. As long as the hard drive head isn't jumping around too much, even the current generation of traditional hard drives should be able to record 4 shows at once.
 

·
Registered
Joined
·
16,749 Posts
You don't need a dual core processor to record. However, there are very few single core processors still on the market and a dual core will come in handy when playing a recording since another task can run without causing a any problems while watching.
 

·
Registered
Joined
·
3,525 Posts
I record 3 at once to 5400RPM drives, and I never have an issue.


Of course, that drive is separate from my OS and programs drives, though.
 

·
Registered
Joined
·
260 Posts
Discussion Starter #8

Quote:
Originally Posted by walford /forum/post/19518906


You don't need a dual core processor to record. However, there are very few single core processors still on the market and a dual core will come in handy when playing a recording since another task can run without causing a any problems while watching.

Yes, I will want to conduct two activities at once. I want to build this thing to use it for 5 years. So if I want to surf over to some hulu or CBS site to watch something I completely missed sounds like I will want the dual core if I have the computer recording a show in the background.


Thanks for your input
 

·
Registered
Joined
·
260 Posts
Discussion Starter #9

Quote:
Originally Posted by gorthocar /forum/post/19518818


I can record 4 shows at once with my Core i5-661/DH55TC/8GB setup. It has plenty of CPU overhead. I do record it to my C: drive which is an SSD, and then I clip the commercials and archive them to one of my traditional hard drives. Because ATSC recordings are big and my SSD isn't very large, I have to be mindful of moving the shows off the SSD once they've finished recording.


Many ATSC shows are in the ballpark of 12 Mbps max (lowercase "b" is bits per second), and my WD green hard drives at their slowest are around 50-60 MBps (uppercase "B" is bytes per second, and 8 bits per byte) when copying a file to them. As long as the hard drive head isn't jumping around too much, even the current generation of traditional hard drives should be able to record 4 shows at once.

Thanks for the information, what you are doing I did not even think of, cutting commercials, very cool.
 

·
Registered
Joined
·
260 Posts
Discussion Starter #10

Quote:
Originally Posted by steven975 /forum/post/19519063


I record 3 at once to 5400RPM drives, and I never have an issue.


Of course, that drive is separate from my OS and programs drives, though.

This is good to know, i actually am considering buying a cheepo ebay special for a HD or something small on newegg for that purpose, and then throw on the TB size sucker for recordings and maybe also as a file share for my laptop and office pc.


I may rarely record 4 shows at once, but I know my wife records two and wants to watch a third at least once a month, and the cable company doesn't have that capability.
 

·
Registered
Joined
·
2,603 Posts
Are you planning to do this OTA, ClearQAM from your cable or analog (NTSC) from your cable? We've been speaking to ATSC whereby the data is mpeg-2 compressed and writes directly to the HDD. Depending on the tuner card it may or may not have on-board mpeg-2 hardware encoding if you're trying to record analog TV from your cable provider... if the card has software encoding you'll need to consider a higher processor or buy a tuner w/on-board hardware encoding. Keep in mind that while streaming ATSC to your HDD is a low CPU task, decoding video to watch a live tuner or playback a recorded file will need either CPU or a decent quality graphics card - yes a $50 one (in today's market) will do.


Ahhhh... you said "4 HD shows at once" so you ARE speaking of OTA or ClearQAM... not an issue w/encoding but still playback will need a good CPU or GPU.
 

·
Registered
Joined
·
3,364 Posts

Quote:
Originally Posted by caliskier /forum/post/19519247


This is good to know, i actually am considering buying a cheepo ebay special for a HD or something small on newegg for that purpose, and then throw on the TB size sucker for recordings and maybe also as a file share for my laptop and office pc.


I may rarely record 4 shows at once, but I know my wife records two and wants to watch a third at least once a month, and the cable company doesn't have that capability.

Suggestion: Dont use the rig to cap 4 shows concurrently while watching some **** from Hulu or YouTube or BD rip, or DVD rip, whatever your planning on playing back.

You should record to a non-OS hard drive (ie 2nd hard drive). If you need to playback content at the same time as recording then youll want fast processor, fast hard drive. If you record to your OS disk, then paging and other drive activity can cause buffer problems and therefore lost data in the stream, especially as you fill up the hard drive your machine will come to its knees.


BTW-I was using a 2003-2004 3.06 GHz intel machine to capture 8 simultaneous HD streams up until it died last year. (ATSC & QAM)
 

·
Registered
Joined
·
16,749 Posts
All graphics cards for the last several years have onboard MPEG decoding and endecing, All the digital progarms received from a OTA, cable or satellite souce are already MPEG2 encoded and some PayTV programs may be MPEG24 encoded. So there is absolutly no need for your graphics card to support MPEG2 encoding.
 

·
Registered
Joined
·
260 Posts
Discussion Starter #14
Wow, loving all of this help guys, thanks. So Hard drive speed, 7200RPM? I guess I need some specs there.
 

·
Registered
Joined
·
3,764 Posts
As mentioned, recording already encoded OTA or clear QAM streams takes very little CPU power. Even my Atom 330 can do it (yeah, I've tried) and that's while watching a recording in the background. Like others have said HDD speed matters more and it's best not to use your OS drive but a different drive for recording. It's also a good idea to format your recordings drive with 64K sectors instead of the default 4K. You mentioned cable, though. If you're planning on getting a Ceton card, I'm not sure if that affects processor requirements.
 

·
Registered
Joined
·
1,052 Posts

Quote:
Originally Posted by ilovejedd /forum/post/19520002


As mentioned, recording already encoded OTA or clear QAM streams takes very little CPU power.

This goes back to basic computer scheduling. There are jobs that can be CPU intensive. There can be jobs that are I/O intensive. Recording TV is simply I/O intensive, just like copying a file from one disk to another disk. Blame a CPU manufacturer for focusing the consumer only on processing power, e.g. two cores are much better than 1 core.


> Even my Atom 330 can do it


Is this an Ion board?

My Intel D945GCLF2 mobo doesn't have the I/O bandwidth to do a PVR task.



To clarify a possible misconception: the data does not directly go from the tuner to the disk. The data is not "streamed". The MPEG-2 data arrives in packets for audio, video and control information. The "Transport Stream" of packets is demuxed and then buffered in main memory. From main memory the data is then written out to the hard disk. Probably the buffers are no more than 2 cluster sizes per recording.



Regards
 

·
Registered
Joined
·
199 Posts
I can record 4 hd shows, two OTA and 2 hd-pvr on a pentium 4 2.4ghz. I have successfully done it several times. I do have two hard drives for recording.
 

·
Registered
Joined
·
533 Posts
E3300, 2gb ram, 2 HDHomeruns, 4 QAM channels at once using BeyondTV writing to a two drive Raid 0 array. The OS and programs are on a separate boot drive.
 

·
Registered
Joined
·
1,375 Posts
One thing that no one has mentioned.......Format your recording drive in 64k clusters rather than the default 4k cluster size. This has a tremendous impact on the I/O of the hdd. 1/16th the write operations = 1/16th the fragmentation. You can record 4 HD (ATSC or QAM) shows at once and play back another 1 or 2 shows even on a lower powered system.


BB
 

·
Registered
Joined
·
817 Posts

Quote:
Originally Posted by qz3fwd /forum/post/19519887


You should record to a non-OS hard drive (ie 2nd hard drive). If you need to playback content at the same time as recording then youll want fast processor, fast hard drive. If you record to your OS disk, then paging and other drive activity can cause buffer problems and therefore lost data in the stream, especially as you fill up the hard drive your machine will come to its knees.

I have an older HTPC system with one parallel IDE (ATA 100) 7200RPM hard disk for OS/programs, and 2 additional parallel IDE (ATA 100) 7200RPM hard disks for ATSC recording. I believe all the HDDs each have either 8MB or 16MB of cache.


ATM, I only have 2 tuners, and each one has a dedicated recording drive. If I were to add 1 or 2 more tuners, could I record 2 shows simultaneously to *one* hard drive without losing any data?


I ask this because I know from experience that certain types of drive accesses can cause recording problems. For example, I learned the hard way that you should never do a copy/paste or cut/paste operation on a HDD while it is recording from an ATSC tuner. Once I accidentally initiated such an operation not realizing that a recording was in progress, and heard the HDD heads thrashing about. I aborted after several seconds, but it was too late... several seconds of my recording were totally screwed up as a result



OTOH, I have also successfully watched a program while it was being recorded (i.e. timeshifting) without any detrimental effects on the recording.


So to sum up my experiences with simulaneous disk operations during recording:


1. Copy/paste or cut/paste = BAD

2. Watching file while it is being written to disk = OKAY


Of course I realize that my HDDs are not very fast, so other folks with newer, higher speed/bandwidth drives (i.e. SATA 300 or even SATA 600) may not have the problem I had.


So given my recording drive specs above, could I record 2 shows at once to a single HDD? Thanks!
 
1 - 20 of 33 Posts
Top