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Old 28th June 2002, 20:00   #1  |  Link
hyperspaced
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Why BeSweet and not DVD2AVI ?

Hello all.

I use DVD2AVI to extract the sound data from the VOB files. When the sound is Dolby Digital 5.1, I usually mux the AC3 file with the compressed AVI stream. When the sound is Dolby Digital 2.0, I create a WAV file (using Dobly Surround downmix when necessary). For normalization, I either use DVD2AVI's normalization function, or I use another WAV editor, e.g. Cool Edit Pro.
For the MP3 compression, I use Lame with the sample rate downconversion function (48KHz to 44.1KHz). Everything is OK.


Now, why am I telling you this ? There is a lot of hype concerning BeSweet, and I'm not sure why.

First of all, Azid, an AC3 decoder (and more). Is it better than DVD2AVI's AC3 decoding to WAV ?
Then SSRC, a sampling rate converter. Is it better than Lame's or DVD2AVI's downconversion ?
Finally, when converting from 5.1 to Stereo (actually Dolby Prologic) does "Dolby Surround downmix" function of DVD2AVI, produce worse results than BeSweet's ?

I know that the "is that better than the other" question allows a subjective answer, but a lot of the same subjective answers indicate the reality :-)
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Old 28th June 2002, 20:12   #2  |  Link
pacohaas
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1. even the lame developers admit that the resampling algorithms are lacking, SSRC is the way to go if you want quality.

2. as far as the downmixing, there's been a lot of talk lately about Dolby Surround 2, and BeSweet has this option. As for the default dowmixings of Azid, they are to the correct specs, so if anything(i don't know about DVD2AVI) azid would be better, but I believe the default behavior for both is the same.

Doing everything in one step is one thing that makes BeSweet and HeadAC3he so powerful. This allows floating point data to flow between the programs and there's no intermediate files. and now that vob support is back in BeSweet, you should be able to make the transition fairly easily.

last but not least, try it for yourself, personal experience/preference is what's important anyhow.
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Old 28th June 2002, 22:44   #3  |  Link
Nic
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Also remembering, of course, that DVD2AVI uses AC3Dec which is bad quality compared to Azid....

-Nic
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Old 28th June 2002, 23:02   #4  |  Link
DJ Bobo
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I don't have a surround system, but some "trusted" people assumed that the downmixing of DVD2AVI isn't done correctly (in the way that the channels aren't downmixed into the right place/way)
Another thing is that the normalization is sometimes inaccurate (kinda light)
In those 2 points, AZID is clearly better.

About SSRC: theory is a thing, what the practice shows is another thing. There is NO hearable difference between Lame downsampling & SSRC downsampling or any other downsampling software.
Talking about downsampling from 48 to 44,1KHz: AC3s havn't frequencies over 20,3KHz, that's why a downsampling down to 44,1KHz won't even touch the encoded frequencies, since the cut will accure at 22,05KHz
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