Dolby Atmos comparison: Dolby Digital Plus vs TrueHD on "The Hurting" album

[Jean.Francois]

Hello,

After the full review of Tears for Fears' album "The Hunting", here's a focus on the comparison of the two Dolby Atmos versions: the streaming version offered in Dolby Digital Plus and the Blu-ray version offered in Dolby Digital TrueHD.

Dolby Digital Plus is a lossy compression format with a bit rate of 768 Kbits/s (for streaming), unlike Dolby Digital True HD which is a lossless format offering variable bit rates up to 10,000 Kbits/s. In the case of the album "The Hurting", the maximum bit rate in Dolby Digital TrueHD is around 6,500 Kbits/s. For both formats, the maximum number of channels available simultaneously is 16.

To achieve such a low bit rate, Dolby Digital Plus has to optimize a number of parameters, starting with bandwidth. Although it uses a sampling frequency of 48 kHz, giving a maximum signal frequency of 24 kHz (white arrow), Dolby Digital Plus limits itself to 20 kHz (yellow arrow), reducing bandwidth and associated information by 20%.
It also makes a further optimization in the bass channel, with a fairly sharp cutoff at 120 Hz (green arrow).
The graphs below illustrate these limitations at 20 kHz and 120 Hz for the bass channel.

You can find the full technical analysis HERE, as well as a few extracts so you can hear the differences between the two formats. In particular, the comparison of top channels between the DDP and TrueHD versions is truly significant.

Enjoy listening,
Jean-François

 

[MacCali]

Without a doubt you can hear the difference, not only in music but on movies that possesses TrueHD are for more immersive.

Unfortunately I believe only some physical media actually comes with it, but again from physical media to streaming has a large jump as well.

I’m already preparing to get a NAS and rip all my movies onto that and utilize a Zidoo player.

They just had the dark side of the moon blue ray disk on sale and I bought that. Still haven’t it had a chance to play it but I’m sure it will be fire

 

[voodooless]

This is quite neet. A few questions on the top channel examples. The lossy version seems to have a double voice, while the TrueHD version seems to have a more focused voice recording. I wonder if this is really codec related, or just a different master? On its own the lossless version certainly sounds cleaner, but I don’t know if that was the Artist’s intent.

The different spectrums also show that they may not have used the same master. The full bandwidth LFE seems wacky as well .