NVIDIA GeForce GTX 780 Review: The New High End
by Ryan Smith on May 23, 2013 9:00 AM ESTSoftware, 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.
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Stuka87 - Thursday, May 23, 2013 - link
The video card does handle the decoding and rendering for the video. Anand has done several tests over the years comparing their video quality. There are definite differences between AMD/nVidia/Intel.JDG1980 - Thursday, May 23, 2013 - link
Yes, the signal is digital, but the drivers often have a bunch of post-processing options which can be applied to the video: deinterlacing, noise reduction, edge enhancement, etc.Both AMD and NVIDIA have some advantages over the other in this area. Either is a decent choice for a HTPC. Of course, no one in their right mind would use a card as power-hungry and expensive as a GTX 780 for a HTPC.
In the case of interlaced content, either the PC or the display device *has* to apply post-processing or else it will look like crap. The rest of the stuff is, IMO, best left turned off unless you are working with really subpar source material.
Dribble - Thursday, May 23, 2013 - link
To both of you above, on DVD yes, not on bluray - there is no interlacing, noise or edges to reduce - bluray decodes to a perfect 1080p picture which you send straight to the TV.All the video card has to do is decode it, which why a $20 bluray player with $5 cable will give you exactly the same picture and sound quality as a $1000 bluray player with $300 cable - as long as TV can take the 1080p input and hifi can handle the HD audio signal.
JDG1980 - Thursday, May 23, 2013 - link
You can do any kind of post-processing you want on a signal, whether it comes from DVD, Blu-Ray, or anything else. A Blu-Ray is less likely to get subjective quality improvements from noise reduction, edge enhancement, etc., but you can still apply these processes in the video driver if you want to.The video quality of Blu-Ray is very good, but not "perfect". Like all modern video formats, it uses lossy encoding. A maximum bit rate of 40 Mbps makes artifacts far less common than with DVDs, but they can still happen in a fast-motion scene - especially if the encoders were trying to fit a lot of content on a single layer disc.
Most Blu-Ray content is progressive scan at film rates (1080p23.976) but interlaced 1080i is a legal Blu-Ray resolution. I believe some variants of the "Planet Earth" box set use it. So Blu-Ray playback devices still need to know how to deinterlace (assuming they're not going to delegate that task to the display).
Dribble - Thursday, May 23, 2013 - link
I admit it's possible to post process but you wouldn't, a real time post process is highly unlikely to add anything good to the picture - fancy bluray players don't post process, they just pass on the signal. As for 1080i that's a very unusual case for bluray, but as it's just the standard HD TV resolution again pass it to the TV - it'll de-interlace it just like it does all the 1080i coming from your cable/satelight box.Galidou - Sunday, May 26, 2013 - link
''All the video card has to do is decode it, which why a $20 bluray player with $5 cable will give you exactly the same picture and sound quality as a $1000 bluray player with $300 cable - as long as TV can take the 1080p input and hifi can handle the HD audio signal.''I'm an audiophile and a professionnal when it comes to hi-end home theater, I myself built tons of HT system around PCs and or receivers and I have to admit this is the funniest crap I've had to read. I'd just like to know how many blu-ray players you've personnally compared up to let's say the OPPO BDP -105(I've dealt with pricier units than this mere 1200$ but still awesome Blu-ray player).
While I can certainly say that image quality not affected by much, the audio on the other side sees DRASTIC improvements. Hardware not having an effect on sound would be like saying: there's no difference between a 200$ and a 5000$ integrated amplifier/receiver, pure non sense.
''the same picture and sound quality''
The part speaking about sound quality should really be removed from your comment as it really astound me to think you can beleive what you said is true.
eddman - Thursday, May 23, 2013 - link
http://i.imgur.com/d7oOj7d.jpgEzioAs - Thursday, May 23, 2013 - link
If I were a Titan owner (and I actually purchase the card, not some free giveaway or something), I would regret that purchase very, very badly. $650 is still a very high price for the normal GTX x80 cards but it makes the Titan basically a product with incredibly bad pricing (not that we don't know that already). Still, I'm no Titan owner, so what do I know...On the other hand, when I look at the graphs, I think the HD7970 is an even better card than ever despite it being 1.5 years older. However, as Ryan pointed out for previous GTX500 users who plan on sticking with Nvidia and are considering high end cards like this, it may not be a bad card at all since there are situations (most of the time) where the performance improvements are about twice the GTX580.
JeffFlanagan - Thursday, May 23, 2013 - link
I think $350 is almost pocket-change to someone who will drop $1000 on a video card. $1K is way out of line with what high-quality consumer video cards go for in recent years, so you have to be someone who spends to say they spent, or someone mining one of the bitcoin alternatives in which case getting the card months earlier is a big benefit.mlambert890 - Thursday, May 23, 2013 - link
I have 3 Titans and don't regret them at all. While I wouldn't say $350 is "pocket change" (or in this case $1050 since its x3), it also is a price Im willing to pay for twice the VRAM and more perf. With performance at this level "close" doesn't count honestly if you are looking for the *highest* performance possible. Gaming in 3D surround even 3xTitan actually *still* isn't fast enough, so no way I'd have been happy with 3x780s for $1000 less.