Lossless is lossless. So how can lossless audio get any better? Dolby has found a way and the best part is you likely don’t need to upgrade anything in your system to hear the benefit.
Home Theater Forum was one of a select group of sites recently invited to Dolby to demo some new products, one of which was their new Advanced 96k Upsampling. When I saw the 48k/96k comparison demo on the agenda I thought for sure that I wasn’t going to be able to hear a difference. The only “golden ears” I have are attached to a hat I got at Disneyland!
A group of 8 of us filed into a mid-sized room (approx. 15x25) along with several Dolby employees including Craig Eggers, Director of Content Creation and Playback, Poppy Crum, Senior Staff Scientist, and Rhonda Wilson, Senior Member Technical Staff. The demo was conducted by Senior Application Support Engineer James Spezialy using the following system configuration:
The demo consisted of short (20 second to one minute) TrueHD encoded clips:
Joe Satriani: Live in Montreal, [*]
The Lost Bladesman, [*]
Batman Returns, [*]
Kung Fu Panda, [*]
Flowers of War[*]
San Francisco Symphony Orchestra playing Also sprach Zarathustra, Op. 30.
They were first played in with Advanced 96k TrueHD and then immediately played in 48k TrueHD. We were instructed to focus on the clarity and naturalness, longer “ring out” to reverb and ambience on the high frequency sounds, consistent audio quality during frequency decay and better definition between instruments on the concert demos and on the more natural sounding dialogue.
During the first round of demos, I sat in the front row center and was amazed at the overall difference in sound. On some clips it was subtle, on others --- dramatic. It was interesting that different people in the room seemed to be drawn to different differences between the two encodes. The Joe Satriani clip was of the “count off”. Several attendees focused on the wood on wood of the drumsticks during the count off and other high frequency sounds like the cymbals. While I could hear some subtle differences with those sounds, for me there was a dramatic improvement with parts of the midrange with specific notes. The clip from the Lost Bladesman was a fight sequence in a narrow outdoor corridor. The high frequency sword hits sounded smoother and the mid-range “swooshes” that the fighters made as they were dodging each other were crisper. The differences were subtle, but there were definitely audible. We heard two clips from Batman Returns: Flying into the skyscraper in Hong Kong and chasing the Joker in Gotham City on the Batcycle. There was a high frequency countdown timer and a lot of glass breaking in the first scene all of which weren’t as harsh on the 96k. The effect on the second clip was more subtle to me but there were some improvements heard when a trash can was knocked over. The scene from Kung Fu Panda was the hardest for me to hear a difference in. Some attendees heard some improvements in the voice of Ian McShane (Tai Lung), or in some of the effects sounds, but the differences I personally heard in this clip were minimal. We didn’t have video for Flowers of War or the San Francisco Symphony. On Flowers the overall clip was cleaner. I had a better understanding of the room environment where the scene was occurring. The Symphony playing Also sprach Zarathustra was another clip with a huge difference with increased clarity and a much clearer separation of the individual instruments. For the second round of demos, we switched seats and I moved to the side of the back row. The differences I heard from that seat were more subtle, but still noticeable.
Why Dolby’s Advanced 96k?
There are several advantages to Dolby’s Advanced 96k Upsampling. DACS work better at higher sampling rates, with fewer artifacts. Dolby’s Advanced 96k Upsampling has a big advantage over just upsampling a 48k signal to 96k as they have licensed Meridian’s apodizing filter. Standard filters used in the analog to digital conversion process leave distortions or artifacts called pre and postringing around the converted sounds. Preringing is interpreted as distortion by the brain and creates a harsh tone, but postringing is ignored as it’s masked by the actual sound you are hearing. Meridian’s filter eliminates the preringing, moving all the artifacts to the postring where it is ignored by your brain:
Based on my limited exposure to Advanced 96k Upsampling and conversations with the Dolby the impact of using it seems to vary based on the material, the person listening and their environment. There is no downside to this for the end user. From the content creator’s perspective, the 96k encode does take up more space on the disc, but Dolby has some ways that are transparent to the listener to minimize this during the encoding. An Advanced 96K Upsampling encodes takes about 2.5 times longer than the 48K version to encode, but Dolby is working aggressively to cut down the encoding time. For content creators currently using Dolby TrueHD, the next version of Dolby Media Producer will add the ability to do the Advanced 96k Upsampling encoding simply by clicking a button.
In some cases, the improvement of Advanced 96k Upsampling was subtle, in others it was more pronounced, but regardless --- it is an improvement, and one that just about all consumers can benefit from with no additional cost to consumers or to the content creators. Home Theater Forum sees only upsides to Advanced 96k Upsampling and urges all content creators using TrueHD to quickly adopt it, and for our readers to give it a listen.