FS7: QUHD 25p great playback experience vs. 4K/50p audio choking :(

moldcad

moldcad

Veteran
Hi Resolve Gurus :)

I've been happily grading my XAVC-I footage in the free Resolve version as long as it was just QUHD, 25p - but recently tried my 4K/50p XAVC-I footage; even though this Resolve version is officially limited to QUHD resolution, I was expecting some "linear" drop in play-back performance. Unfortunately - even though I have a lot of performance headroom with my QUHD, 25p files - with my 4K, 50p footage there is a drastic play-back performance hit... And what's interesting: even though the fps indicator goes red, it's not video (picture) that is preventing an acceptable editing experience - it's the audio choking like crazy... I've tried all the available measures to no avail:

- Generated Optimized Media: still choking, and the fps indicator in red
- Turned on Smart Cache and/or User Cache: still choking, and the fps indicator in red
- Toggled Proxy playback with Half and/or Quarter resolution on and off: still choking, and the fps indicator in red

In the Project Settings, I experimented with setting the Optimized Media and/or Clip Cache to lower and lower quality - all the way down to vanilla DNxHR - and while the video playback fps indicator did go up to the almost constantly green 50 fps region, the audio is still choking!

I'm completely at a loss - the audio format and number of tracks is exactly the same as with the QUHD 25p version of XAVC-I codec I'm using; what can be at play here? Is it some sort of hard-coded limitation of the free Resolve version? I'd almost certainly think so, BUT... here's the interesting part:

I'm getting exactly the same problem when playing back my unedited FS7 4K/50p footage in one of the most potent software video player I ever met - the Daum PotPlayer; the video looks full fps but the audio is choking - exactly as it does in Resolve. This would definitely point to some of my system limitations, and NOT Resolve preventing from higher-than-QUHD resolutions!

I'm open to all and each comments and suggestions, as I run short of any ideas on how to rectify the audio choking problem. TIA

Piotr

PS. One more interesting information: in my other NLE (don't laugh - Vegas Pro has always been the most under-estimated by most people piece of software I ever used), the situation with those 500 Mbps, 4K/50p XAVC-I clips is exactly the opposite: at Full/Best resolution settings for TL playback, it's the video that is slowed won (not even jerky - just never over 30 fps), while the audio is cristal clear and not posing any throughput problems. So if someone would think I may have the sound system severely under-performing in my PC, it cannot be the case... BTW, Vegas Pro has a switch for toggling between multichannel or just stereo (2 channels out of the FS7's 8) audio when importing mxf files; of course I only import stereo - but in Resolve, the audio choking thing doesn't go away even if I get rid of the extra 6 (empty) audio tracks...
 
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I am not a Resolve Guru :) but I see here that Resolve runs using XAVC-i UHD 50p footage from the FS7 with 50 fps. My system is a 8core i7 5960x, and the GPU that I use is a 8GB R9 390X. So preview performance is fine here, even if I apply a LUT.

I see also full playback with the Catalyst software what is great for this footage.

An I love the "underestimated" Vegas Pro Software too. However, the playback performance is weaker on system like mine, and you have to go down in the preview to half resolution. But it can be used, for sure.
 
Thanks, interesting input - I also have the 5960X, running happily @4.2GHz - but "only" have the Quadro M2000 graphics - which is super-stable, but seemingly not fast enough... I can observe how - playing back my 500 Mbps footage - the CPU usage is some 30% at the max, while the GPU labors at up to 100% load. Do you know whether my only solution is to replace the M2000 with a faster GPU, or can Resolve use more than a single GPU so that I could add another Quadro to my system? I really wouldn't like to go the GeForce or Radeon route...

Piotr
 
Please check the specifications for Resolve and 4K - I think they have specified 8GB Ram for the GPU for 4K. I have here also a Quadro 4200K with 4 GB in my system, but the free version of Resolve supports one GPU only I think. So I see that my Q4200K is selected first by Resolve, and 4GB seems to work for 4K but tends to be not enough = crashes from time to time. So what I do is that I disable the Quadro before I start Resolve, and then the AMD is selected and works fine.
 
XAVC is simply too much for today's generation of dual CPU machines. Whereas five streams of UHD Prores edits like it was DV. Even with four of those streams scaled down, picture overlaid on the fifth stream. But a single 1080 24 stream of XAVC drops frames. We need dedicated decoders for it in order to handle frame rates high than 24.
 
To get a bit better playback in Resolve make sure the edit timeline is not showing the thumbnails, audio waveforms, or at least allow the waveforms to generate.

also if you have not used the full 8 tracks do not add them to the timeline..

media-properties-audio, select only as many tracks as you recorded audio

personally I just transcode all to prores overnight and then edit that.

S
 
Is the footy on a raid drive? I'm not sure of the numbers but sata only has so big a pipe. I had to install a raid drive to get 4k raw to play in real time...
 
Prores HQ, UHD, five streams of it, play smoothly from a SSD drive.
But one stream of 1080p XAVC, not so smooth.
 
Didn't you say that "this Resolve version is officially limited to QUHD resolution"? Why are you surprised you have issues with 4K?
 
Chris Johnston said:
Is the footy on a raid drive? I'm not sure of the numbers but sata only has so big a pipe. I had to install a raid drive to get 4k raw to play in real time...
Click to expand...

yes of course, sir - 4x WD Black 3TB each. CrystalDiskMark64 0 when run on the empty volume, using its fastest external sectors: 715 MB/s read, 732 MB/s write. After filling it up somewhat, the same benchmark still shows strong 600-ish numbers. PLUS, I have the Toshiba version of this (originally OCZ) NVMe drive:

http://www.pcper.com/reviews/Storag...ull-Review-M2-RevoDrive/Internals-Testing-Met

- for scratch files Resolve writes when caching stuff. Before I bought it, even though the 600 MBps writes would seem to be be fast enough, in practice they suffered a huge performance hit from the fact both reads and writes were done on the same physical volume (partitioning it helped in maintenance, but the logical drives created were still the same physical disks). With the 512GB of a separate, super-fast scratch disk, I'm witnessing really short times of saving Optimized Media or creating media caches WHILE playing back the timeline in Edit, or clips in Color page, at the same time - highly recommended!

broughtonfilm said:
Didn't you say that "this Resolve version is officially limited to QUHD resolution"? Why are you surprised you have issues with 4K?
Click to expand...

Good point, even if intended to be a bit... hmm... - anyway, I'm taking it for a good coin: I was hoping you guys would tell me if this abrupt (i.e. non-linear) drop in performance between QUHD 25p and 4K DCI 50p is solely due to the bandwidth increase from ca. 250 to almost 500 Mbps, or some artificial limitation hard-coded in the free Resolve version. As for now, I didn't get this answer - do YOU know it? 'cause you see, I AM going to pay for the Studio version - if only for HDR1000 support my entire workflow & hardware would be capable of (not to mention goodies like noise reduction and a couple more). Wouldn't like to spend $1000 on it though if it proved my hardware is not up to the task. Speaking of which:

- Wolfgang said the free Resolve version only supports a single GPU. I never found an official description of they way Studio version utilizes multiple GPU cards; in fact the official DaVinci_Resolve_12_Configuration_Guide_2015-07-27.pdf, or more specifically - its "Shopping Guide" for Windows systems - suggests a single nVidia or AMD GPU for Resolve UI, and a Decklink card for the best video preview... But I'd rather avoid spending on a Decklink (I do not need all this plenitude of I/Os) and either replace my under-powered (at least for DCI 4K) M2000 Quadro with something more potent (like the M6000 with the whopping 12 GB of its own VRAM), or keeping my M2000 and adding something like the K5200 (or even a Tesla) solely for Resolve computing...

So - can anyone tell me how well would Resolve Studio utilize such 2 nVidia cards? Or does using BlackMagic's own Decklink provide for a better experience? One thing that indeed points at the Decklink solution is that running GUI and video monitoring from the same GPU card, and with the silly GUI arrangement, once I switch to "Cinema Viewer" for full-screen monitoring I'm losing access to all the grading controls and scopes (and with 2 monitor workspace, the only thing that can be seen simulataneously with full screen video is scopes.. what do I need them for if all controls are inaccessible? - BOTH scopes AND CC/grade controls should be put on floating/dockable panels!)... Of course, in the perfect world I'd expand the nVidia GPU (by number, or replacing my entry model with a single, but more powerful one) and use them for compute mainly, plus driving my system monitor with Resolve GUI - while having constant video preview through a Decklink card, but:

- my X99-Pro/USB3.1 Asus MoBo has only so many x16 PCIe slots, plus
- such a "perfect solution" is currently weel above my financial means :(

So, back to @broughtonfilm's question: I'm trying to tax my free Resolve in order to test my system's readiness for the Studio version - and I'd appreciate some more constructive comments on that from you guys. TIA

Piotr

PS. One of the observations in my OP still remains unaddressed: why is it audio which is suffering more than video when taxing free Resolve with DCI 4K/50 fps footage? Incidentally, it's the same choking issue I'm getting in the PotPlayer - but on the other hand, Vegas Pro doesn't suffer from it at all; isn't that an interesting subject for a constructive discussion here? :)
 
PS. Or perhaps - considering I'm planning to purchase the Studio version of Resolve soon - the best investment into my current system, in order to efficiently edit DCI 4K 50p - would be to purchase a Decklink card for driving my preview screen? If so, please tell me which exactly model I should buy, taking into account I only have a HDMI 2.0a-compatible display (the Samsung 49KS8000 SUHD TV). Which Decklink model offers the HDMI capabilities I'd need for 10-bit editing and previewing with HDR1000?
 
If 24 or 25p is at the limit of say, dual Xeon processor capability, then of course, when you double the frame rate, you're going to drop more frames than you display.
 
moldcad said:
PS. Or perhaps - considering I'm planning to purchase the Studio version of Resolve soon - the best investment into my current system, in order to efficiently edit DCI 4K 50p - would be to purchase a Decklink card for driving my preview screen? If so, please tell me which exactly model I should buy, taking into account I only have a HDMI 2.0a-compatible display (the Samsung 49KS8000 SUHD TV). Which Decklink model offers the HDMI capabilities I'd need for 10-bit editing and previewing with HDR1000?
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You have two possibilities, that would make some sense.

The first and cheaper one would be the Decklink 4K Extreme. Is a great Card, and is capable to deliver an Output of UHD 50p/60p (Output only). Restrictions seems to be that this card is not prepared for HDR. I have this card at the moment, and it is a great card I think.

https://www.blackmagicdesign.com/products/decklink/techspecs/W-DLK-04


The second and nore expensive one would be the Decklink 4K Extreme 12G. Is the bigger solution, capable of UHD 50p/60p, and is prepared for HDR.
https://www.blackmagicdesign.com/products/decklink/techspecs/W-DLK-25

Please be Aware that both Cards will Support DCI 4K up to 25p only!
 
Thanks Wolfgang - these are the models I was considering. And I must admit that I might just give up on the DCI 4K/50p option - this would make my edits/grades less compute-intensive, so my current hardware plus the Extreme version of the Decklink cards you mention would be all I need. If I ever fancy 50p, it'd have to be QUHD only... Hmm - decisions, and cash :)

PS. Oh, and Wolfgang- have you ever tried any of the Decklinks with Vegas Pro, as well? Or do you consider them Resolve only?
 
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You can also edit UHD 50p with the smaller card the Extreme 4K. That works also fine here, and we use the same processor both overclocked to 4.2 GHz. But take care with the GPU. With my Quadro K4200 4GB I have something about 10fps only. Another user reported that even with his Quadro K5200 (with 8GB) he has not more. So the GPU is central for the playback in Resolve.
 
Wolfgang - are you saying 10 fps only with 3840x2160 @ 50p (which I call QUHD) is all you're getting with K4200 or even K5200 cards? This would mean my Maxwell M2000 is a real little monster, as I'm getting full 50 fps in Resolve with those files - without any caching, proxies or anything like it...

Oh, and sorry for confusing your name in my question about using Decklink cards with Vegas :)

Thanks,

Piotr
 
The M2000 seems to have special HEVC support and support for up to 4 UHD streams. Maybe that explains the good performance?

To Vegas - every Blackmagic card is supported by Vegas up to 1080 24p/25p only. That is true for the older Intensity Pro, the Intensity 4K but also the Decklink cards. So you will not have an UHD output with Vegas at all. However, the preview picture is better also for Vegas compared to the secondary display of Vegas using graphic cards to my opinion, even if that way offers UHD and with a Quadro 10bit. The Decklink offers a 10bit preview from a 32floating point project in Vegas too.

However, for Vegas Pro 13 alone the Decklink 4K would be a waste of money, but the Decklink works fine with a lot of other applications (Edius up to UHD 30p, Looks3 with UHD, Boris Red up to HD, and with UHD also Resolve, Catalyst Prepare and Catalyst Edit are what I have here and what I know).
 
Wolfgang - thanks for all the great info :)

Cheers

Piotr

PS. Do you think that with my M2000, it's still a good idea to install the Decklink? I'm asking seriously - I'm seriously planning on buying Resolve Studio; would that make use of another M2000 in my system?
 
moldcad said:
PS. Do you think that with my M2000, it's still a good idea to install the Decklink? I'm asking seriously - I'm seriously planning on buying Resolve Studio; would that make use of another M2000 in my system?
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That depends on your needs and budget.

I have not seen a good preview support for Resolve with a GPU only. The GPU will allow you a good playback behaviour of Resolve only, but does not give you a sound preview. Especially for UHD 50p the Deckling is great for the preview in Resolve. I do not know why you want to purchase Resolve Studio - since I am happy with the free version. Up to you, but maybe the Decklink is more important for you?
 
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