CPU & Memory Speed, ATEM TS recording & playback

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Ethan Harris

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CPU & Memory Speed, ATEM TS recording & playback

PostWed Dec 05, 2012 1:43 pm

I need to buy (or build) a new PC that will connect to an ATEM Television Studio via HD-SDI with everything operating at 1080i59.94. I'd like to make sure the computer has sufficient CPU/memory/disk bandwidth, etc. to work in both directions simultaneously.

I want to record the ATEM's output, as well as send video clips to the ATEM TS from the same computer at the same time and would use the usual BlackMagic SDI card(s) to do this. Any suggestions on a SSD or hard disks with sufficient sustained read/write speeds would be appreciated. Are there other bottlenecks that I should be concerned with before ordering an off-the-shelf computer or a motherboard/CPU/DDR/Disk? Is one multi-SDI port card preferable over 2 separate cards for this type of application? Thanks!
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D W Tnow

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostSun Dec 09, 2012 7:10 am

What is your budsget then 4k -6k
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Ethan Harris

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostTue Dec 11, 2012 1:59 pm

I'll do what it takes in terms of budget, either in terms of buying an off the shelf computer that is fast enough or a scratch computer build. I assume it is less money to buy a motherboard, CPU, DDR3 memory and a bunch of SSD and assemble a system of this sort. I just need to be certain that the hardware configuration is fast enough and am looking for advice on an assumption that others on the forum are already doing this sort of thing. I am unable to find minimum spec requirements anywhere in BMD's literature.

For example, would 1980i59.94 simultaneous record and playback require a 6 or 8 core Xeon or an overclocked quad core i7? What CPU speeds? How fast should the memory be? Should it be dual, triple or quad channel DDR3? And so on down the list. I'd hate to buy the hardware only to find out it isn't fast enough to handle the I/O and storage at these data rates, but I don't want to to the overkill thing either and pay for capabilities that are not needed.
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CMGoodin

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostThu Dec 13, 2012 6:09 am

Well I hate to low ball you but I have been able to record the H.264 output 1080i 59.94 of the TVS while playing back a 1080 Video from the same Acer Aspire One (725-0899) laptop that I bought for $299 from NewEgg. Since it is using compressed H.264 for record and playback the bitrate isn't so high as to be a problem for normal Drive I/O. As long as the GPU and the TVS is doing the encode and decode work.

It is pushing it but I put slightly faster Hybrid Seagate Momenus XT 500GB drive and upgraded the Ram to 8 GB. Get a computer with an ATI chipset as the Radeon seems to handle decode of H.264 a lot better than the Intel HD or nVidea drivers. Since the encoding of the H.264 happens in the TVS and the Playback decode happens in the GPU there is little load on the CPU so a dual core AMD can handle the load. Just don't use BM Media Express. That program is a CPU and Memory Hog. Use the TVS Capture from the switcher App. This has very low overhead since it is not concerned with displaying an image while capturing. You can use VLC or Windows Media Player to playback your clips on the same machine out of the Extended monitor HDMI port. It is undocumented but the Television Studio when in 1080i mode will accept HDMI inputs at 1366x768 1280x720 and 1600x900 and up-scale them to full screen 1080i. You may have to mess with the Refresh rate to get it to work but it does work. The lower resolutions can be used if your computer dosen't have enough horsepower to playback full 1080i at full frame rate without dropping frames.
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Ethan Harris

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostThu Dec 13, 2012 7:23 pm

I agree and have already done this. A reasonably low cost computer can capture the H.264 output from the ATEM TS's USB 2.0 interface. The same computer can also feed an HDMI output to the switcher at the same time. A modest modern computer can do this easily without maxing out memory, CPU, disk, etc. Using Black Magic Media Express software on my laptop to capture the USB 2.0 ATEM output at 20 Mb/s only loads my laptop at 22% CPU utilization.

However, if it will improve quality, I would like to do the same thing via a desktop computer equipped with SDI I/O interfaces instead, and this is where my worry about throughput and performance arise. I am uncertain if there is a quality improvement or not, as this depends on the quality of the ATEM's H.264 encoder running at its maximum data rate compared to the quality on the SDI. So the question still stands: How much horsepower is required in a computer to take the ATEM TS's SDI program out and capture / record it via one of BMD's SDI cards, while simultaneously using a separate BMD SDI port or card to supply a feed to the ATEM with everything running at 1080i59.94?
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CMGoodin

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostFri Dec 14, 2012 4:43 am

I don't know what application you have in mind where you have to playback one file while recording another file on the same computer, other than serial multilayer compositing, but a cheaper and more reliable setup would to get a couple of Hyperdeck Shuttles. You can get 2 for under $700 and they can record uncompressed or ProRez HQ 220 Mb. I have never tried it but I don't know if a single computer will support more than 1 Declink Pro card at a time. And usually when capturing it feeds the input signal to the output SDI port and HDMI port. Also only a few applications support IO on those SDI cards. Media Express, Premiere Pro, and Sony Vegas and Davinci Pro. You can't playback using Windows Media player or Quicktime Player or VLC and use the Decklink SDI outputs. I don't think 2 instances of Media Express will run at the same time since it uses the CPU for compression and display scaling. And if you have to use one of the above editng programs for playback, you might as well composit in those instead of using the TVS.

By the way I have done Serial Multilayer Compositing just using the laptop and the TVS and the H.264 Quality can be quite good and difficult to tell the 4th generation from the first. So unless your resulting file is destined for the Big Screen (and since the TVS won't accept 24p input that is unlikely) I don't see any reason to record Uncompressed or minimal intra Frame compression.
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Liam Kennedy

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostFri Dec 14, 2012 6:48 am

According to Blackmagic it is possible to launch two copies of Media Express.

viewtopic.php?f=18&t=3272&p=20005&hilit=media+express+two+instances#p20005
ATEM 1/ME, TVS, Hyperdeck Studio, Fujitsu Lifebook NH751 USB3
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Radman

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Re: CPU & Memory Speed, ATEM TS recording & playback

PostSat Dec 15, 2012 12:25 pm

My two cents worth,
Stay away from ATI. For what it is worth!
Radman.

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