21st May 2012
Ok so I’m still a generation behind and not got to 3D yet, but a conversation with a customer recently confirmed a suspicion I’d had for some time: Blu-ray discs sound much better than DVDs.
When I got my full HD LCD TV and Blu-ray player connected a while back, I noticed the Blu-ray picture quality was much better. I could see eyes glistening properly, crowd scenes with such detail they gained depth, and far less blocky graphics during large, sudden scene changes. Animations like “Monsters vs Aliens” were so much better too. But what I also noticed, when I powered up my 5.1 surround system (connected to the player via optical S/PDIF), was a dramatic improvement in sound quality. I was actually enjoying the Blu-ray sound, whereas DVD had always been merely adequate.
So I did a bit of digging on numbers. DVD movie sound tracks typically squeeze the 5.1 channels in to a total of 448kbit/s (Dolby) or 768/1536kbit/s (DTS). This means that those 6 channels are rather tightly squeezed in and probably make standard 128kbit/s MP3 files look generous. In my view, MP3s don’t get bearable until at least double that (AAC is better). So DVD is quite a compromise, but a DTS sound track is likely to sound better due to the higher bit-rate.
In total contrast, the Blu-ray movie HD sound tracks are lossless encodings and can run at up to 25Mbit/s. The detailed numbers show that this means that the audio is at better-than-CD quality. All my Blu-ray discs are HD for the English sound tracks, as it happens. What a big difference! No wonder they sound so much better.
In my next blog, I’ll go in to more detail on how to get the audio from the player to the surround processor.
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