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Old January 7th, 2008, 09:01 AM   #1
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blueray and dv

With "normal" dv and dvd you have to compress quite a bit and maintain a bitrate of about 8mbs in order to make it play on a regular dvd player.

I have not been working with high def yet but I was just wondering, is it not possible to burn regular dv material on a blue ray disk with much less/no compression and a much higher bitrate? Since blue ray players can handle much higher bitrates, shouldn"t that give you a better image quality, comparable to what you see if you connect a tv directly to your pc when you are editing the uncompressed avi's?? Or am I just daydreaming?
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Old January 7th, 2008, 12:11 PM   #2
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Dream on. There is not enough information on DV to warrant higher bit rates than afforded by DVD. Commercial films look at regular bit rates...

How long are your projects anyway?
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Old January 7th, 2008, 12:42 PM   #3
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I wondered this myself. I know for a fact that my old PDX10 can render some awesome images.

However, after compressing for DVD[granted I don't have the most robust encoder], there is definitely a quality loss.

I wish there was a full quality DV mode for next generation High Definition media that equals what comes off that DV tape.
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Old January 7th, 2008, 01:01 PM   #4
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Originally Posted by John C. Chu View Post
I wish there was a full quality DV mode for next generation High Definition media that equals what comes off that DV tape.
That was my question and I was not sure if that was possible with blue ray being able to handle higher bitrates. For project lengths Emre it's between 1-1,5 hour but does this matter if dv can't go beyond 9mbs?
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Old January 7th, 2008, 01:08 PM   #5
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DV is always 25Mbps. It's MPEG-2 on DVD that's limited to 9.8Mbps. If you have a good encoder you should not experience significant loss. ----, most DV cameras do not even have a full 480p of resolution. That is why films on DVD look so much better; because they do have that much resolution.
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Old January 7th, 2008, 06:52 PM   #6
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Blu-ray mandates MPEG-2 compatibility. This means that you can take advantage of the large capacity of the disc format - 25GB for single sided - for SD material.

Because MPEG-2 is supported, it is worthwhile converting DV to MPEG-2. What's more, you can use minimal compression. Indeed, you can use I-frame only compression. In effect, you can create MPEG-2 with almost identical quality to the original DV (I-frame only = no motion artifacts to worry about etc). Such MPEG-2 streams can be edited at a later date as if they were DV.

It seems like a great way to put DV material onto an optical disc that can be played like any other disc while maintaining high quality and no motion artifacts.

Crudely, the MPEG-2 stream would have the same bit rate as the original DV (I-frames in MPEG-2 are almost identical in compression format as DV frames).

At 25Mbps, that would permit approx. 115 minutes on a single-sided blu-ray disc. That's two typical DV tapes or three typical DVCAM tapes.

Regarding the resolution, all DV camcorders have the same resolution - 720 x 480 (NTSC) or 720 x 576 (PAL). Progressive vs. interlaced is immaterial.

In summary, if you have the blu-ray capability already, it would be a great way of archiving DV material with virtually no loss in quality and permitting playing them in a blu-ray player. The only thing that would be forfeited would be the meta data in the DV stream (timecode, date/time etc). The alternative is to store the DV files as-is but you lose the ability to play them in a standalone blu-ray player.
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Old January 8th, 2008, 12:14 AM   #7
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Would you not also lose some color space information?

I think DV is 4:1:1 and MPEG2 is 4:2:0, so in the conversion process you would end up with 4:1:0.

That may be partly why downconverted HDV looks so good, they are both MPEG2 4:2:0.

I know that I can play high bit rate SD MPEG on my PS3, but what limited amounts I have done have not looked better.
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Old January 8th, 2008, 08:18 AM   #8
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Would you not also lose some color space information?

I think DV is 4:1:1 and MPEG2 is 4:2:0, so in the conversion process you would end up with 4:1:0.

That may be partly why downconverted HDV looks so good, they are both MPEG2 4:2:0.

I know that I can play high bit rate SD MPEG on my PS3, but what limited amounts I have done have not looked better.
This is true for NTSC DV. PAL DV uses 4:2:0 so the colorspace issue won't arise - Noa is in Belgium.

MPEG2 also supports 4:2:2 so NTSC could be encoded without chroma loss though it will require more compression to achieve the same bit rate.
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Old January 9th, 2008, 11:00 AM   #9
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Thanks John for the clear answer, if I switch to hd this year I will keep one dv cam as back up only for sd projects and will purchase one hd cam and use it only if the clients wants it on blue ray. (for weddings) I needed to know that if my main cam would fail and I had to continue with a dv cam which will be a dvx100 if I could raise the quality a bit on a blue ray disk. It's ofcourse allways better to have 2hd cams but I don't have the budget for it. I'd rather deliver something to a client which will be a bit less in quality (compared to hd) then nothing at all.
The first thing I will purchase is a blue ray burner but I will wait a bit more as the prices continue to drop. Then I can test and see for myself if it's worth taking the risk of using a dv camera if the client wants it on blue ray to display on a bigger full hd screen.
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