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-   -   VHS capture quality - DVD vs. Bluray? (http://www.digitalfaq.com/forum/video-conversion/7380-vhs-capture-quality.html)

elpablo1 05-26-2016 12:37 AM

VHS capture quality - DVD vs. Bluray?
 
I understand that proper equipment is key for quality VHS captures but was wondering if authoring to Bluray opposed to DVD can provide higher quality since Bluray supports a higher MPEG2 bitrate. Any info is appreciated, thanks!

Edit: The thread title should read "authoring" vs "capturing" but it appears I can't edit the title. My apologies.

dpalomaki 05-26-2016 06:49 AM

VHS-sourced material will be limited by the bandwidth and signal-to-noise performance of the source VHS media and equipment. This is substantially lower than DVD is capable of, much less Blu-ray's potential. Both are 8-bit and 4:2:0 coding and support 720/704x480 for SD source material. A major reason for uncompressed 4:2:2 capture from tape is to facilitate restoration.

What Blu-ray can do is show more of the noise and other warts in the signal from the VHS tape, other things being equal. With certain source material the higher bit-rate may result in fewer MPG2 compression playback artifacts on screen. How it ultimately looks on screen will depend on the details of the playback and display gear as well.

Transcoding to a HD resolution generally offers no benefit. However, not all BD/HDTV playback combinations deal with DVD/SD material equally. In some cases it might be better to covert for HD display before authoring to media rather than trusting to the playback system's upscaling.

Blu-ray does offer some additional authoring capabilities/features, may be a bit more robust media, offers longer run-time on a single disc, and supports additional CODECs. However, it will not play on DVD players if that is a concern. With 50 GB capacity on the Blu-ray DL disk it may be attractive for storing the original (uncompressed) capture data files.

If you already have the Blu-ray authoring capability give it a test with some material and see what works best for you.

elpablo1 05-26-2016 11:04 AM

Thanks for your feedback! I don't have a Bluray drive so am trying to decide if I should invest in one. Prices aren't bad so I suppose I should purchase and compare with DVD. If quality isn't lower then the benefit will being able to store more content. If I understand correctly MPEG2 will always be a better choice then H264 in regards to VHS source material. Thanks again!

lordsmurf 05-26-2016 11:14 AM

15mbps MPEG-2 is much better than DVD-spec max 9.8mbps (realistically 6mbps at most). All of my personal video work is done to BD specs.

For SD material, BD doesn't really show more noise. It actually prevents noise. It's HD where the "more noise" issue comes in.

I can try to expand on this later. Busy now.

elpablo1 05-26-2016 11:27 AM

Thanks for your input lordsmurf! It sounds like your opinion is that Bluray should produce better results compared to DVD when viewed on a HD TV which is what everyone has now.

lordsmurf 06-08-2016 02:12 AM

Yes, MPEG @ 15 mbps looks better than "DVD" (DVD-Video 2.5 mbps to 6 mbps average) bitrate. :congrats:

Even though DVD spec goes to 9.8 mbps, you almost never see that. Why? A 9.8 single-layer disc would hold less than 1 hour of content at CBR. A DL would hold about 1.5 hours. Make it VBR, and you can squeeze on a tad more, though not much.

But a BD-spec SD MPEG is 15 mbps CBR. No more, no less. So it's often about 3x as good. Multiple compression issues are gone.

There are plateaus for bitrate encoding. You see obvious different from 2.5 up to about 7, and it levels off. You don't really see improvement until it exceeds 12.5, and again it quickly plateaus after 15. The 15 encode looks the same as a 20-25 encode in many cases. It's not until you get to the 40+ are where you seen obvious improvements again.

It's all about how MPEG distributes the bits in the 8x8 encoding. Certain errors disappear at 7, 15, and 40 -- noting the 40 is a broadcast spec with a more complicated signal.

The exact issue change per encoder as well.

elpablo1 06-08-2016 08:47 PM

Thanks for taking your time to share this great info!


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