Blu-ray is supposed to offer the best quality for film buffs, but does that claim stand up to scrutiny? We pitch the online services against it to find out
Online video streaming services are the easiest and most convenient way for people to get the latest movies. When it comes to renting, streaming is often the only option. While convenience is important, we wanted to find out what you might lose along the way, so we used our HDMI capture kit to find out how Blu-ray stacks up against its online rivals and if the disc is still the best format for those who really want the best quality.
Our testing kit allows us to grab raw footage from any HDMI-enabled device, letting us compare the actual quality, with no image correction or processing applied. For this test we captured footage from a PlayStation 4, using it for Blu-ray playback and for the most common video-streaming services. Using the same device means that any quality differences are down to the services, not different processing from different playback devices.
THE RAW FACTS
Before we get into the testing, it’s worth looking at the specifications for Blu-ray and streaming services. On paper, Blu-ray is the winner, with support for video encoded using H.264 at a resolution of 1,920x1,080, delivered at a bit rate of up to 40Mbit/s.
Compare that to Netflix, which is representative of other streaming services. It also uses the H.264 codec at a resolution of 1,920x1,080, but streams at around 12Mbit/s maximum. That’s a big difference. To get its streaming rate down, Netflix has to throw away more detail in its video stream compared to Blu-ray.
There are a couple of caveats. The Blu-ray figures are maximum bit rates, not a required amount. Some discs are encoded at lower bit rates, reducing quality, but allowing a film to fit on a single disc. This is the reason that quality can vary on Blu-ray. Even so, on average, a Blu-ray film will use higher-quality video than a streaming service; but the question is, can you really spot the detail that’s lost?
TESTED IMAGE QUALITY
The top streaming services we tested all performed well, with a detailed Full HD picture we were more than happy with. When we fired up Blu-ray and started looking at the differences, we noticed that they’re very subtle, but the disc-based format is better.
In our sample shots, comparing the Blu-ray version to that from Amazon Instant Video (one of the best services we’ve tested), you start to see some differences. In particular, the Blu-ray frame is sharper throughout, while Amazon (and all the other streaming services) look a little soft in comparison.
Fine detail is removed from the streaming services, too. Look at our close-up of Benedict Cumberbatch from Star Trek Into Darkness (opposite), and you can see his hair and face are sharper and more defined in the Blu-ray version. As you look further into the distance, the differences are more pronounced: the guy on the left’s jacket loses its padded detail, and the face of the woman in the brown dress has less detail in the streamed version.
Switching to a different part of the scene, you can see that the lady in red’s dress has less detail in the streaming version, losing some of its creases and finer detail. Colour from the Blu-ray version is better across the entire frame, with the streaming versions often looking a little drab in some areas.
All of this might not seem like much, but the combined effect when the film is in full motion is much more. In short, the Blu-ray version looks sharper, cleaner and punchier. It’s a cumulative effect, where if you watched the Blu-ray version of a film and then switched to the streamed version, you’d notice that the latter wasn’t quite as good.
SOUND QUALITY
This is one area where Blu-ray is ahead of the pack. Most streaming services offer at least Dolby Digital 5.1 surround sound, if not Dolby Digital Plus 7.1 sound (on some programmes and films), but sound is compressed using lossy compression, which means that some detail is lost. Blu-ray supports Dolby TrueHD and DTS-HD Master Audio, both of which are lossless and of a higher quality. In addition, the vast majority of discs use these formats, making Blu-ray a better choice for people that want immersive surround sound.
4K AND THE FUTURE
Streaming services have the advantage here, with Netflix and Amazon streaming in 4K, with a select group of applications. It requires a lot more bandwidth, with Netflix recommending a staggering 25Mbit/s for Ultra HD broadcasts. Streamed 4K content looks better than Full HD content from Blu-ray, for now. The limitation is that the streaming 4K format requires an H.265 – also known as a High Efficiency Video Coding (HEVC) – codec built into the receiver. This codec gives you better quality at a lower bit rate, but the downside is that video requires about three times the processing power as it does for H.264 and Full HD. As such, it’s not possible to just add HEVC decoding to existing devices, limiting the availability of 4K streaming to only the latest TVs for now.
While Blu-ray may lag behind for now, an Ultra HD version of the format is due out at Christmas. This will support HEVC decoding and higher-capacity discs, with films encoded at a higher bit rate than for streaming. In other words, 4K Blu-ray will have better image quality once again.
HEVC AND FULL HD
One of the benefits of HEVC is that it can be used to encode HD video. While it still requires new kit to decode it, there are two possible advantages. First, HD video can be streamed using less bandwidth; second, the same amount of bandwidth could be used as now, but the quality of the picture could improve to Blu-ray levels.
VERDICT
Blu-ray is the superior format for HD video at the moment, although streaming could catch up. When it comes to the future, if you want the best-quality Ultra HD films, the new Blu-ray format will be the best way to get it.