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Bit rate and Quality

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pasha777
Bit rate and Quality
on Apr 4, 2003 at 7:32:13 pm

I understand what maximum bit Rate for DVD is 22 mbps.
I tried Power Director, Ulead DVD Workshop and Sonic DVDit PE.
and in all of them I used max quality/bit-rate settings.
However compression/quality on the end result appears much worse when
on professional DVDs. Also by simply dividing Size of final DVD copy to amount of seconds I figured what non of those programs give me more then 7 mbps.
is that professional DVD authoring programs out there? What is been used to professionally master DVD titles?


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John Q
Re: Bit rate and Quality
on Apr 5, 2003 at 1:35:12 am

The maximum bitrate for a DVD is 9.8 megabits per second, including both audio and video. If you're encoding the audio as PCM, that's 1.6 of the total. With the video encoded at 7 mbps, you can get about 75 minutes on a DVD. If you have an authoring program that will encode the audio as Dolby Digital, you can get more on the DVD, because your audio will typically be encoded at 192 kb/sec.

To get 2 hours on the DVD, you'll have to encode the video at 4.5 variable bitrate (vbr). With Dolby, you can encode at 5.

I think your confusion is that digital video (DV) is encoded at 25 mb/sec. DVD's use a different encoding scheme to achieve similar quality at the lower bitrate.


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newguy
Re: Bit rate and Quality
on Apr 5, 2003 at 4:35:45 am

If you want better quality, don't blame DVD authoring, use a better encoder which will give you better quality for you movie.
Yes, there are a lot of better encoder and DVD authoring application. It depends on how much you want to spend on it.


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pasha777
Re: Bit rate and Quality
on Apr 6, 2003 at 6:05:32 am

For example..?


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John Q
Re: Bit rate and Quality
on Apr 7, 2003 at 2:53:03 am

I've encoded down to even 4 mb/sec variable bitrate (vbr) using my RT.X100 and haven't noted any serious artifacts. I'm using DVDit PE, so I can encode my audio in AC3 at 192 kb/sec. I can fit 2 hours of video onto a DVD at 5 mb/sec vbr with AC3 audio.

What you may be observing is a field-order problem. If your video is encoded with the wrong field order, it will have a venetian blind effect during any motion. Is this what you're observing?


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pasha777
Re: Bit rate and Quality
on Apr 7, 2003 at 6:07:41 pm

That is correct i do seems to have problemm with fields.
But what interestuing no meterer what field order is in enitial AVI
Eather I use Top_field _first or top_field _second. on DVD player I see Both fields at the same time, instead of smooth motion. It's looks exactly like if you would play interlaced video on a computer screen - picture is striped and fast motion is fuzzy.




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