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What are the Differences Between Blu-Ray and DVD?

by Edwin Liu | May 5, 2013 15:41 PM
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What’s the difference between Blu-Ray discs and DVD discs? Many people keep asking this question, because they think these two kinds of discs looks just the same and both of them are used to store data or videos and the only difference is that Blu-Ray is more expensive than DVD. Actually, there are many differences between them. Just follow this article to eliminate the misunderstanding and learn the differences between Blu-Ray and DVD.

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1. Storage capacity

The storage capacity of single-layer blu-ray is 25GB and the dual-layer blu-ray can store 50GB of data. However, a single-layer DVD or called DVD-5 only can hold 4.7 GB of data and the dual-layer DVD or DVD-9 is able to store 8.5 GB of data.

2. Laser wavelength

Blu-Ray uses a blue-violet laser as and the DVD uses a red laser. The laser wavelength of blu-ray is 405nm, while that of DVD is 650nm, which is much longer than that of blu-ray. The grooves of DVD need to be wide enough to accommodate the longer wavelength and the grooves on a blu-ray disc are much thinner and closer to allow Blu-Ray discs store much more information than DVD.

3. Video Resolution

Blu-ray video is much sharper than DVD video as the resolution of blu-ray is 1920×1080 maximally and the resolution of standard DVD is 720×480. This enables blu-ray to store higher-definition video. By the way, the bit rate of blu-ray video is up to 40.0Mbps and the maximal bit rate of DVD is 9.8Mbps.

4. Video codec and audio codec

Blu-ray supports more video and audio codecs than DVD. DVD video can only be encoded by H.264 and the audio codecs of it are Linear PCM, Dolby Digital and DTS Digital Surround. As for blu-ray, the video of it can be encoded by MPEG-2, MPEG-4 AVC and SMPTE VC-1 and the audio can be encoded by Linear PCM, Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS Digital Surround and DTS-HD.

5. Player compatibility

A standard DVD Players cannot play blu-ray discs, because the red laser used in DVD players is too large to read the tiny grooves in a Blu-ray disc. But all current existing blu-ray players are compatible with DVD discs and can play standard DVDs. However, the DVD image displayed on the blu-ray player will not be high definition quality like a Blu-ray disc but still keep the good DVD quality.

6. Other differences between blu-ray and DVD

Generally speaking, the data transfer rate of blu-ray is much faster than DVD; the protection layer of blu-ray is 0.1mm and that of DVD is 0.6mm; blu-ray has hard coating to protect scratches while DVD doesn’t have one.

All in all, blu-ray represents a big improvement of DVD. It stands for better image quality, better sound quality and larger storage capability. As long as the cost of blu-ray discs is as low as DVD, it will totally replace the role DVD plays now.

 

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