5 Replies Latest reply on May 16, 2009 9:13 AM by the_wine_snob

    Sound quality question

    N9JCR Level 2

      I understand that the more video data you add to a DVD, the more compression that takes place and therefore impacts the picture quality.  I was wondering how much that holds true for audio as well.  I have a long concert to produce and the video is less critical than the sound.  At what point would sound quality become noticeable?

       

      Thanks!


      Bob

        • 1. Re: Sound quality question
          Steve Grisetti Adobe Community Professional

          "Noticeable" is the relative term here, of course.

           

          How much lower can the bitrate be before YOU start noticing a drop in quality.

           

          I certainly wouldn't put more than an hour and a half onto a standard DVD, or three hours onto a dual-layer disc. But you might be able to get acceptable sound quality even with 2 hours worth on a standard DVD.

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          • 2. Re: Sound quality question
            the_wine_snob Level 9

            I completely agree with Steve, on his Duration suggestions. How long do you anticipate the edited version will run? Is this SD, or HD material?

             

            If the DVD-9 (Double Layer) is not an option, I would look into doing a multiple DVD-5 set.

             

            One additional consideration would be to not do your DVD authoring in PE. I use a workflow that includes NLE work (some Audio) in PrPro and then use Adobe Encore for the authoring. Since you posted to the PE forum, I will assume that you do not have PrPro/Encore in, say CS3 or CS4. You can use other authroing programs, such as DVD Architect. There, I will also have to assume a few things, and perhaps Steve can fill in the blanks, and also correct any misinformation that I give for that program - after all, he wrote the book on it, and I've never used it.

             

            Now, you state that the Audio is more important, than is the Video. Were this my case, I'd Export from my NLE in elemental streams, i.e. one file with Video only and one file with Audio only. The Video would be DV-AVI Type II and the Audio would be PCM/WAV 48KHz 16-bit. [I use the Minnetonka SurCode encoder plug-in and work in Dolby Digital 5.1 Surround Sound, so I Export as a DVD-compliant AC3 for the Surround Sound - PE doesn't allow for this]. However, I believe that PE automatically Transcodes Audio to AC3, one of the two DVD-spec allowed Audio formats. It is a very good compression scheme, though the PCM/WAV is even better, albeit with larger files - read less room for Video. The PCM/WAV route is uncompressed Audio, though AC3 is still very, very good, and does allow for some compression.

             

            With these two elemental streams, I would Import into Encore (DVD Architect in your case, and please substitute it, whenever I type "Encore") and set the Transcode setting for the Audio file(s). Then, I would let Encore automatically set the Transcode settings for the Video. In this case, one has to do a little "bit-budgeting," in that they will be setting the rate for the Audio, and need to make sure that they have adequate room left for "acceptable" Video data-rate. [Here, I am assuming that one can manually set the Transcode rate for just the Audio in DVD Architect.]

             

            Were I doing a concert DVD/DVD-set, I would do two additional treatmenst: the above mentioned DD 5.1 SS mix to AC3, and would also produce a second mix with DTS Audio, using the Minnetonka SurCode DTS encoder. Through an Audio source selection Menu, the user could choose either the DD 5.1 SS of the main Audio, or switch to the DTS Audio in the "optional" Audio Track on the DVD. Note: this takes up even more room on the disc, so a multi-DVD set, or DVD-9 would definitely be a probability, if the Duration is much over 1 hour. This way, the user can decide which version they want, and can also tailor their playback to accommodate their gear. If you have never heard DTS, you will be blown away, even when one has only used a stereo source and just mixed for the spatial aspects of that content. It really comes into its own, if one has recorded in 5-channel (and then mixed for the LFE channel). The same can be said for DD 5.1 SS. With discreet, properly recorded 5-channel source material (mixing for the LEF in post), it is awsome, and even with a proper mix from stereo sources, it can astound the audience. In either, the mixing is crucial and very time-consuming, but the results are well worth the effort, if the subject is a musical concert..

             

            The good news is that even if you use AC3, it is far better, than either MP3, or MPEG Audio. Since the DVD-spec is for either the PCM/WAV, or AC3 (MPEG is still an "optional" Audio encoding for PAL, but is disappearing), I'd do nothing in the workflow, that even got close to MP3, or MPEG Audio, i.e. for the latter, NO multiplexing of the file, even if one does the bit-budgeting and Exports a fully DVD-compliant MPEG-2 Video, keep it as an elemental stream and separately Export the Audio as the aforementioned PCM/WAV, or AC3.

             

            Remember, in my outlined workflow above, I am assuming that you will use a separate authoring program (not from within PE), and that DVD Architect can do most of the necessary things, like allowing manual Transcode settings for the Audio. [Steve - I'm relying on you to set me straight on this one.]

             

            Just some ideas, to allow for the greatest possible control. Still, by far, the easiest way to get similar results (except for the DD 5.1 SS and the DTS) is to follow Steve's advice and just use the minimal amount of material, but spread it over either the DVD-9, or a set of DVD-5's.

             

            Good luck,

             

            Hunt

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            • 3. Re: Sound quality question
              N9JCR Level 2

              Thanks Steve and Hunt, I appreciate very much the detail you went into.   In this case it turns out to be only 1:45 in duration so perhaps not as significant, but I have had some over 3 hours and in the past I have just split into Volume I and II.

               

              I've never tried burning DL DVDs, although my drive says it will so I'll have to try that.   I have been very fortunate - since I switched to T-Y media I have not had a single coaster.  Should I be concerned about most DVD players being able to read a DL DVD?

               

              Thanks! again

               

              Bob

              • 4. Re: Sound quality question
                Steve Grisetti Adobe Community Professional

                Virtually all commercial DVDs are dual-layer discs, Robert, so all DVD players are capable of playing them.

                • 5. Re: Sound quality question
                  the_wine_snob Level 9

                  To quote Jim Taylor from DVD Demystified, Third Edition, Section 11 pages 10& 11, McGraw Hill, ISBN 0-07-142396-6. © McGraw Hill

                  Myth: "Some Units Cannot Play Dual-Layer of Double-Sided Discs."

                  Dual-layer compatibility is required by the DVD specification. Almost every DVD-Video player and DVD-ROM drive, even the first ones sold, can read dual-layer discs. Occasinal problems with dual-layer discs are caused by faulty disc production, flawed players (which often can be fixed via firmware upgrade), or bugs in DVD-ROM driver software (which can be upgraded to fixt the problems).

                  {Emphasis mine]

                   

                  Hope that this helps. Again, using quality media (I use Verbatim DL DVD-9's and have never had one returned), and burning at the slowest speed is good advice.

                   

                  Good luck with the Project, and please report how it goes.

                   

                  Hunt

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