Software, Cont: ShadowPlay and "Reason Flags"

Along with providing the game optimization service and SHIELD’s PC client, GeForce Experience has another service that’s scheduled to be added this summer. That service is called ShadowPlay, and not unlike SHIELD it’s intended to serve as a novel software implementation of some of the hardware functionality present in NVIDIA’s latest hardware.

ShadowPlay will be NVIDIA’s take on video recording, the novel aspect of it coming from the fact that NVIDIA is basing the utility around Kepler’s hardware H.264 encoder. To be straightforward video recording software is nothing new, as we have FRAPS, Afterburner, Precision X, and other utilities that all do basically the same thing. However all of those utilities work entirely in software, fetching frames from the GPU and then encoding them on the CPU. The overhead from this is not insignificant, especially due to the CPU time required for video encoding.

With ShadowPlay NVIDIA is looking to spur on software developers by getting into video recording themselves, and to provide superior performance by using hardware encoding. Notably this isn’t something that was impossible prior to ShadowPlay, but for some reason recording utilities that use NVIDIA’s hardware H.264 encoder have been few and far between. Regardless, the end result should be that most of the overhead is removed by relying on the hardware encoder, minimally affecting the GPU while freeing up the CPU, reducing the amount of time spent on data transit back to the CPU, and producing much smaller recordings all at the same time.

ShadowPlay will feature multiple modes. Its manual mode will be analogous to FRAPS, recording whenever the user desires it. The second mode, shadow mode, is perhaps the more peculiar mode. Because the overhead of recording with the hardware H.264 encoder is so low, NVIDIA wants to simply record everything in a very DVR-like fashion. In shadow mode the utility keeps a rolling window of the last 20 minutes of footage, with the goal being that should something happen that the user decides they want to record after the fact, they can simply pull it out of the ShadowPlay buffer and save it. It’s perhaps a bit odd from the perspective of someone who doesn’t regularly record their gaming sessions, but it’s definitely a novel use of NVIDIA’s hardware H.264 encoder.

NVIDIA hasn’t begun external beta testing of ShadowPlay yet, so for the moment all we have to work from is screenshots and descriptions. The big question right now is what the resulting quality will be like. NVIDIA’s hardware encoder does have some limitations that are necessary for real-time encoding, so as we’ve seen in the past with qualitative looks at NVIDIA’s encoder and offline H.264 encoders like x264, there is a quality tradeoff if everything has to be done in hardware in real time. As such ShadowPlay may not be the best tool for reference quality productions, but for the YouTube/Twitch.tv generation it should be more than enough.

Anyhow, ShadowPlay is expected to be released sometime this summer. But since 95% of the software ShadowPlay requires is also required for the SHIELD client, we wouldn’t be surprised if ShadowPlay was released shortly after a release quality version of the SHIELD client is pushed out, which may come as early as June alongside the SHIELD release.

Reasons: Why NVIDIA Cards Throttle

The final software announcement from NVIDIA to coincide with the launch of the GTX 780 isn’t a software product in and of itself, but rather an expansion of NVIDIA’s 3rd party hardware monitoring API.

One of the common questions/complaints about GPU Boost that NVIDIA has received over the last year is about why a card isn’t boosting as high as it should be, or why it suddenly drops down a boost bin or two for no apparent reason. For technically minded users who know the various cards’ throttle points and specifications this isn’t too complex – just look at the power consumption, GPU load, and temperature – but that’s a bit much to ask of most users. So starting with the recently released 320.14 drivers, NVIDIA is exposing a selection of flags through their API that indicate what throttle point is causing throttling or otherwise holding back the card’s clockspeed. There isn’t an official name for these flags, but “reasons” is as good as anything else, so that’s what we’re going with.

The reasons flags are a simple set of 5 binary flags that NVIDIA’s driver uses to indicate why it isn’t increasing the clockspeed of the card further. These flags are:

  • Temperature Limit – the card is at its temperature throttle point
  • Power Limit – The card is at its global power/TDP limit
  • Voltage Limit – The card is at its highest boost bin
  • Overvoltage Max Limit – The card’s absolute maximum voltage limit (“if this were to occur, you’d be at risk of frying your GPU”)
  • Utilization Limit – The current workload is not high enough that boosting is necessary

As these are simple flags, it’s up to 3rd party utilities to decide how they want to present these flags. EVGA’s Precision X, which is NVIDIA’s utility of choice for sampling new features to the press, simply records the flags like it does the rest of the hardware monitoring data, and this is likely what most programs will do.

With the reason flags NVIDIA is hoping that this will help users better understand why their card isn’t boosting as high as they’d like to. At the same time the prevalence of GPU Boost 2.0 and its much higher reliance on temperature makes exposing this data all the more helpful, especially for overclockers that would like to know what attribute they need to turn up to unlock more performance.

Software: GeForce Experience, Out of Beta Our First FCAT & The Test
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  • SymphonyX7 - Thursday, May 23, 2013 - link

    *mildly/narrowly trailing the GTX 680 Reply
  • chizow - Thursday, May 23, 2013 - link

    AMD released some significant driver updates in ~Oct 2012, branded "Never Settle" drivers that did boost GCN performance significantly, ~10-20% in some cases where they were clearly deficient relative to Nvidia parts. It was enough to make up the difference in a lot of cases or extend the lead to where the GE is generally faster than the 680.

    On the flipside, some of AMD's performance claims, particularly with CF have come under fire due to concerns about microstutter and frame latency, ie. the ongoing runtframe saga.
    Reply
  • Vayra - Thursday, May 23, 2013 - link

    Drivers possibly? Reply
  • kallogan - Thursday, May 23, 2013 - link

    High end overpriced gpu again ! Next ! Reply
  • wumpus - Thursday, May 23, 2013 - link

    Except that the 780 is nothing more than a Titan with even more cuda performance disabled. Presumably, they are expecting to get Titan sales to people interested in GPU computing, if only for geeklust/boasting. Reply
  • wumpus - Thursday, May 23, 2013 - link

    My above comment was supposed to be a reply. Ignore/delete if possible. Reply
  • ifrit39 - Thursday, May 23, 2013 - link

    Shadow Play is the most interesting news here. It costs a not-insignificant amount of money to buy a decent capture card that will record HD video. This is a great alternative as it requires no extra hardware and has little CPU/GPU overhead. Anything that ends up on the net will be compressed by youtube or other service anyway. I can't wait to remove fraps and install shadow play. Reply
  • ahamling27 - Saturday, May 25, 2013 - link

    Fraps isn't the best, but they somehow have the market cornered. Look up Bandicam, I use it exclusively and I get great captures at a fraction the size. Plus they aren't cut up into 4 gig files. It has at least 15x more customization like putting watermarks in your capture or if you do like to segment your files you can have it do that at any size or time length you want. Plus you can record two sound sources at once, like your game and mic, or your game and whatever voice chat software you use.

    Anyway, I probably sound like I work for them now, but I can assure you I don't. This Shadow Play feature is definitely piquing my interest. If it's implemented wisely, it might just shut all the other software solutions down.
    Reply
  • garadante - Thursday, May 23, 2013 - link

    There were two things that instantly made me dislike this card, much as I've liked Nvidia in the past: completely disabling the compute performance down to 600 series levels which was the reason I was more forgiving towards AMD in the 600/7000 series generation, and that they've priced this card at $650. If I remember correctly, the 680 was priced at $500-550 at launch, and that itself was hard to stomach as it was and still is widely believed GK104 was meant to be their mid-range chip. This 780 is more like what I imagined the 680 having been and if it launched at that price point, I'd be more forgiving.

    As it is... I'm very much rooting for AMD. I hope with these new hires, of which Anandtech even has an article of their new dream team or some such, that AMD can become competitive. Hopefully the experience developers get with their kind-of-funky architecture with the new consoles, however underwhelming they are, brings software on the PC both better multithreaded programming and performance, and better programming and performance to take advantage of AMD's module scheme. Intel and Nvidia both need some competition so we can get this computer hardware industry a bit less stagnated and better for the consumer.
    Reply
  • EJS1980 - Tuesday, May 28, 2013 - link

    The 680 was $500 at launch, and was the main reason why AMD received so much flak for their 7970 pricing. At the time it launched, the 680 blew the 7970 away in terms of gaming performance, which was thee reason AMD had to respond with across the board price drops on the 7950/70, even though it took them a few months. Reply

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