4 Replies Latest reply on Aug 17, 2012 3:05 PM by BJBBJB1

    Maximum project length for Blu-Ray using H.264 and 5.1 Audio

    BJBBJB1 Level 1



      I tried to post this in what I thought was the appropriate area (AME) without success. Perhaps I should have posted here based on past experience as this forum is always most helpful?  Not sure, but the basic question is what is the approximate maximum project size/length to fit on a Blu-Ray disc with 5.1 Audio using the "new" H.264 codec at HIGH quality?  Of course this assumes the recommendation is to use the new H.264 codec. 


      And also, if I am using the new codec, and my source is HDV, and output is Blu-Ray, should I render using H.264 to 1400x1080i/60  (the source format- which worked well with CS5 and MPEG2 and let the TV change to square pixels ), or to one of the Blu-Ray presets at say 1920X1080 (i or P?) and make AME make the conversion? 


      The issue is I have a rather large Blu-Ray project and trying to determine whether it is 2 discs or 3 for my first CS6 project....




        • 1. Re: Maximum project length for Blu-Ray using H.264 and 5.1 Audio
          Jim_Simon Level 8

          Here's the problem with your question.


          There are too many variables that affect the maximum allowable length for anyone to provide a coherent answer.  It will depend on the frame rate of your program (24p will need fewer bits to look good than will 30i or 60p), the resolution of your program (1080 needs more bits than does 720), the content of your program (static scenes need fewer bits than high motion), the encoder you use (x264 can do a better job at fewer bits than other encoders), the encoding method used (CQ vs Constant Bitrate vs Variable Bitrate), whether or not your have single or dual-layer BDs, what level of quality you find acceptable, etc.


          There's just no possible way anyone can predict how much content you can fit on a disk with any degree of accuracy.  You'll just have to do the work, see how it turns out, and make any adjustments as needed.


          About the only thing we can say with certainty is that H.264 will give you better quality at the same bitrate, or the same quality at a lower bitrate, over traditional MPEG2.  So yes, use H.264.

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          • 2. Re: Maximum project length for Blu-Ray using H.264 and 5.1 Audio
            Harm Millaard Level 7

            You may want to have a look at DVD-HQ  Bitrate & GOP calculator and try out some different time-lengths to get a feel for what fits on what disk.

            1 person found this helpful
            • 3. Re: Maximum project length for Blu-Ray using H.264 and 5.1 Audio
              cfg_2451 Level 2

              Well, the blu-ray spec. says that a single layer blu-ray disc can hold as much as 25GB. Dual layer can hold 50GB. You can of course fit your entire project into a single layer blu-ray disc... if you use a low enough bit rate so you don't exceed its 25GB capacity.


              So your question devolves down to a question of how much quality you want, however you choose to define quality. And the only person who can answer that question, is you.


              I suggest you get yourself some BD-RE disks, burn some examples from your project at different bit rates, shove it into a blu-ray player and have a look. Iterate as required (that's the joy of the re-writable disks) to find out how much quality you want. Once you know that, you've got a basis to use to start trying to figure out how to get the full project on disk(s).

              1 person found this helpful
              • 4. Re: Maximum project length for Blu-Ray using H.264 and 5.1 Audio
                BJBBJB1 Level 1


                Thanks for the calculator, and thanks to everyone for their thoughts!  As always they are most appreciated.   

                Another calulator I had found did not consider H.264 and 5.1 audio.


                All of my questions revolve around how much can fit at highest quality per my post.  I am not trying to squeeze as much as I can on a disc and try to subjectively evaluate the quality.  I don't really try to do A/B comparisons with bitrates for quality, I just render at highest bitrates/quality and know it's the best I can make it! 


                I absolutely know you can't calculate exactly how much can fit on a disc. However after a good amount of time making SD and then BD discs(with the MPEG2 encoder) and even a few HD-DVD's, I can pretty much guess how much I can fit with high quality rendering settings based on my source.


                I was just trying to determine if there was a similar rule of thumb for H.264 and 5.1 at high quality.  I mean +/- a 15 minutes or a half hour.  Not a granularity of 5 minutes.


                Thanks again,