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BloodyIron  
#1 Posted : Tuesday, June 20, 2017 1:48:25 PM(UTC)
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I'm working with a 4k version of vmix, and I am unsure if what I want to do should be achievable or not.

I have a few different inputs, and I would like to use the Instant Replay feature, while also doing multicorder on all the inputs I have, so I have "raw" versions of the sources for post-prod fun stuff (promo videos later on).

I can't quite figure out how though to get Instant Replay and Multicorder running at the same time. Is this a limit of the license, or am I doing it wrong, or what? I hope I'm doing it wrong, because I really want to have my cake and eat it too!

Please advise :)
dasmedienatelier  
#2 Posted : Wednesday, June 21, 2017 2:15:51 PM(UTC)
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The replay function already records inputs individually. I'm not quite sure why you would need an additional multicorder?

Knut
BloodyIron  
#3 Posted : Wednesday, June 21, 2017 3:05:09 PM(UTC)
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The Instant Replay for 4k is only one input, but I want to record 2-4 inputs to raw video for later production (not live replays), hence the mismatch and such. I want to figure out a way to do multicording of as many inputs as I can, agnostic of however many Instant Replay sources I am licensed for. Not trying to cheat here, just doing two similar, but different tasks, at the same time.


dasmedienatelier wrote:
The replay function already records inputs individually. I'm not quite sure why you would need an additional multicorder?

Knut

kricher1964  
#4 Posted : Thursday, June 22, 2017 9:07:40 PM(UTC)
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My recollection is that it is not possible to use both of these at the same time, by design.
BloodyIron  
#5 Posted : Thursday, June 22, 2017 9:10:08 PM(UTC)
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Well that seems really lame, having to choose between Instant Replay or Multicorder. Especially when there's enough resources to go around. I actually need both!

What does one do when they need both?

kricher1964 wrote:
My recollection is that it is not possible to use both of these at the same time, by design.

kricher1964  
#6 Posted : Thursday, June 22, 2017 9:34:10 PM(UTC)
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You could use a second machine and bring things in via NDI. Use Multicorder on the 2nd machine.
BloodyIron  
#7 Posted : Friday, June 23, 2017 11:56:10 AM(UTC)
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I've used a variety of network IP video senders in the past. I haven't fully explored NDI but I am really sceptical of the fidelity compared to original raw. Is this really the _ONLY_ way to do this? Or the only way that you are aware of? :/

kricher1964 wrote:
You could use a second machine and bring things in via NDI. Use Multicorder on the 2nd machine.

DWAM  
#8 Posted : Friday, June 23, 2017 12:15:36 PM(UTC)
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Hi!

first I'm gonna say that recording several RAW signals is nearly impossible on standard hardware due to the hard disk speed limitation.

I guess what you call RAW is something like a file with an intermediate codec like ProRes or DNxHD, which are compressed videos.
Once again, writing multiple ProRes files at the same time requires a serious configuration, aswell on the hard disks or the CPU (this cannot be done by the GPU). For example, a 1080p30 ProRes 422 requires 147 Mbits bandwidth on disk write. 422LT needs 102 Mbits. On a good Sata SSD you can only write 3 or 4 files at the same time IF your CPU can handle this...

NDI recording codec, SHQ2, is very similar to ProRes. It is visually lossless, high quality. Transmitting your inputs with NDI to a 2nd computer with vMix or Newtek ISOCorder seems to the best solution, especially if you want to use replay at the same time.

Guillaume
thanks 3 users thanked DWAM for this useful post.
BloodyIron on 6/23/2017(UTC), RobLambert on 11/16/2017(UTC), Ario on 5/23/2018(UTC)
BloodyIron  
#9 Posted : Friday, June 23, 2017 12:26:42 PM(UTC)
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To add some detail, I do system architecture regularly, so storage performance is part of my regular work.

147megabits converts to a little over 18megaBytes, which is very easily achievable on modern drives. But let's assume for a second that I could do multicording and Instant Replay on the same system for a second. Our inputs are about 20mbit/s for video fidelity, which actually turns into 2.5megaBytes/s for each input as sequential writes to disk.

Modern spinning disks (2-4TB and higher) can write at speeds starting at about 100megaBytes per second, and really good spinning disk HDDs can exceed 150megaBytes/s write speed.

Good SSDs can write at speeds of upwards of 500megaBytes/s, and that's just SATA SSDs. NVMe SSDs can go beyond 2,000megaBytes/s depending on which you get.

So, not only on paper, but in practice that we've seen, the situation is most definitely not a hard drive bandwidth issue. Now, when I say that, I'm talking about multicorder, not instant replay, since I know that's a completely different beast.

That being said, perhaps I should revisit the NDI element of this. The statement of "Lossless" seems rather unbelievable, as that is an absolute statement, but I'll have to see what it's really like.

In such a configuration though, wouldn't I need to buy two licenses of vMix then? :/

Also, our spec is 1080p60, 30 isn't enough FPS for us, as we deal with high-motion content ;P


DWAM wrote:
Hi!

first I'm gonna say that recording several RAW signals is nearly impossible on standard hardware due to the hard disk speed limitation.

I guess what you call RAW is something like a file with an intermediate codec like ProRes or DNxHD, which are compressed videos.
Once again, writing multiple ProRes files at the same time requires a serious configuration, aswell on the hard disks or the CPU (this cannot be done by the GPU). For example, a 1080p30 ProRes 422 requires 147 Mbits bandwidth on disk write. 422LT needs 102 Mbits. On a good Sata SSD you can only write 3 or 4 files at the same time IF your CPU can handle this...

NDI recording codec, SHQ2, is very similar to ProRes. It is visually lossless, high quality. Transmitting your inputs with NDI to a 2nd computer with vMix or Newtek ISOCorder seems to the best solution, especially if you want to use replay at the same time.

Guillaume

DWAM  
#10 Posted : Friday, June 23, 2017 12:58:15 PM(UTC)
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Sorry my mistake I meant MBytes not Mbits. In French we use MegaOctets (for MB) so I sometimes confuse myself.

Just replace Mb by MB in my previous post and you realize the task is not as easy as you thought... and my explanation is correct (apart from this stupid confusion)
BloodyIron  
#11 Posted : Friday, June 23, 2017 1:02:04 PM(UTC)
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I don't know where you're getting your info, but video devices rate data signal in megabits, not megabytes. It even says in vmix for the inputs I use that I'm getting a bitrate of 20mbits, not bytes.


DWAM wrote:
Sorry my mistake I meant MBytes not Mbits. In French we use MegaOctets (for MB) so I sometimes confuse myself.

Just replace Mb by MB in my previous post and you realize the task is not as easy as you thought... and my explanation is correct (apart from this stupid confusion)

DWAM  
#12 Posted : Friday, June 23, 2017 1:07:41 PM(UTC)
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Yes you should seriously consider NDI. Yes you'll need another licence for vMix or buy the pro version of Newtek ISOCorder.

You're right about SSD speeds, especially for U.2 SSDs, but as far as I know, using these raises another problem: storage capacity. So far I have never seen a motherboard accepting more than 2 of these drives and the biggest capacity I found is 1.2 TB by Intel which is not much when you have to deal with multiple cameras recordings in high quality.
BloodyIron  
#13 Posted : Friday, June 23, 2017 1:10:12 PM(UTC)
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1080p content, whether it's 30fps or 60fps, doesn't actually need as much speed as NVMe can do. So "regular" SATA SSDs can do the trick really well. Record to SSD, later move to spinning disk, bob's your uncle.

Should one need more NVMe devices, for whatever reason, you can get PCIe devices that add more.


DWAM wrote:
Yes you should seriously consider NDI. Yes you'll need another licence for vMix or buy the pro version of Newtek ISOCorder.

You're right about SSD speeds, especially for U.2 SSDs, but as far as I know, using these raises another problem: storage capacity. So far I have never seen a motherboard accepting more than 2 of these drives and the biggest capacity I found is 1.2 TB by Intel which is not much when you have to deal with multiple cameras recordings in high quality.

DWAM  
#14 Posted : Friday, June 23, 2017 1:47:10 PM(UTC)
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You're right, I mixed up everything between MBytes and Mbits. Sorry...

For storage, if you need 1080p60 :
- in ProRes 422HQ (220 Mbits), you will need 193.55 GB by camera per hour
- in ProRes 422LT (100 Mbits), you will need 90 GB by camera per hour
But CPU load might be a problem here for more than 3 cams at the same time.

If you go for NDI over multiple computers, you will need 125 Mbits of bandwidth for each camera @1080p60. On a gigabit network, Newtek recommends not to use more than 75% of the total bandwidth, so up to 6 or 7 NDi are possible from a single computer's ethernet interface.
NDI recordings data rates are pretty much the same as ProRes 422.
SHQ2 uses less CPU than ProRes.
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Ario on 5/23/2018(UTC)
BloodyIron  
#15 Posted : Friday, June 23, 2017 2:34:21 PM(UTC)
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I haven't looked at the NDI options just yet, probably won't be able to for a while. But the input devices we use currently we limit them to 20mbps, so available space is plenty at this time. It certainly is an important facet! But that's not the current hurdle. :)

Don't worry though, at least I know you're human now ;)


DWAM wrote:
You're right, I mixed up everything between MBytes and Mbits. Sorry...

For storage, if you need 1080p60 :
- in ProRes 422HQ (220 Mbits), you will need 193.55 GB by camera per hour
- in ProRes 422LT (100 Mbits), you will need 90 GB by camera per hour
But CPU load might be a problem here for more than 3 cams at the same time.

If you go for NDI over multiple computers, you will need 125 Mbits of bandwidth for each camera @1080p60. On a gigabit network, Newtek recommends not to use more than 75% of the total bandwidth, so up to 6 or 7 NDi are possible from a single computer's ethernet interface.
NDI recordings data rates are pretty much the same as ProRes 422.
SHQ2 uses less CPU than ProRes.

elvis55  
#16 Posted : Saturday, June 24, 2017 5:48:55 PM(UTC)
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Hello,
I do not know if that will work.
Second hard drive -SSD-
Sufficient CPU. ???

Settings - Options - Show Advanced Settings - Enable Advanced Settings

https://forums.vmix.com/...ts&m=38708#post38708

greeting
nicademus  
#17 Posted : Sunday, March 10, 2019 12:05:06 PM(UTC)
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@BloodyIron - Not sure if you were still after an answer on this...

The Option of NDI will work with a second dedicated box recording the NDI Output>Inputs - That said I have found the use of NDI does indeed increase CPU usage even on the VMix box as it sends. But at least you don't have to worry about latency since you aren't using the NDI box for anything other than External capturing - Limitation to this method is you can only really add 4 or so NDI outputs

Something else to consider instead though - I had wanted to do the same thing as yourself, Record Cam1, Cam2, Output have replays and also have a need for the Raw footage afterwards. To get around it (hopefully all you want is up to 4 Cameras...) - is to use the Replay feature itself. Replays are held as Complete streams Per Camera (up to 4) - the Replay function just works like an EVS, it doesn't cut the footage (until you export it.) - it is just XML files with timecodes. That way what you do at the end of Production is grab the "Replay" folder which will contain a whole lot of "Camera 1 - Date and time.mp4" files of around 11Gb each and "Camera 2 - date and time.mp4" files - all of which you can now import into your NLE and they are seamless end to end. Then the only thing hampering you is Storage speed (High end SSD suggested.) - and also capacity as well as the Bit rate you record them at within the Replay Control section.
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