12 Replies Latest reply: Feb 9, 2015 8:55 PM by HarleyTDavis RSS

    Downsides to multiplexing audio for H.264 Blu-ray disc?

    joneisele Community Member

      I have a 9 minute video; personal/consumer use; 1280x720; 59.94; source video from a Contour+ helmet camera that stores .mov, H.264; audio is on a separate track from my own selection of mp3 files (it is a music video).   I have three intended playback targets: Blu-ray disc, Sony PS3 native, and PC/Windows Media Player.   Is there a big downside on video or audio quality in this case using multiplexing to produce a single .m2t file imported into Encore to produce the BD vs. separate .m4v/.wav files?   Not a huge deal, but having to maintain one production files vs. three is a minor plus if it makes little to no difference on the BD front.

       

      Depending on the answer, If I use the H.264 Blu-ray format/preset in PP to produce the .m2t file does Encore have to re-encode?   I am assuming Encore does not reencode if I am using separate .m4v/.wav files.

       

      Thanks

        • 1. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
          Ann Bens CommunityMVP

          If you export either with or without multiplexing Encore will not re-encode.

          Encore works better with two separate files.

          • 2. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
            joneisele Community Member

            Ok, got it on the not re-encoding.   Would the quality of the resultant BD be noticeably different with multiplexed vs. not?  

            • 3. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
              Harm Millaard Community Member

              The quality is not influenced by muxing or not.

              • 4. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                joneisele Community Member

                Sanity checking here ...  I noticed that if I import a separate .m4v (and audio file) into Encore it does some thinking ("pending ...") and eventually comes back with "Don't transcode".    However, if I produce a .m2t file using exactly the same settings other than TS multiplexing Encore comes back with untranscoded/Automatic.

                 

                Is the above to be expected or not?   If yes, is Encore saying it needs to transcode simply to demux the audio, or is it going to transcode the video stream as reported?

                 

                Thanks

                • 5. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                  Jeff Bellune CommunityMVP

                  If the audio stream is muxed, to the best of my knowledge Encore will re-transcode both video and audio if the audio stream doesn't match the project audio settings.  Yet another reason to use elementary audio and video streams whenever possible.

                   

                  Jeff

                  • 6. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                    joneisele Community Member

                    Hi Jeff - I am using the defaults for H.264 Blu-ray and the 720p 59.94 preset within PP which has Dolby Digital for the audio format, which in turn matches the default transcoding settings in Encore.   If I export with separate .m4v and .ac3 files Encore reports "don't transcode".  If I go back and export with the only change being TS multiplexing Encore reports that it will transcode (I assume that is what untranscoded and automatic mean).  

                     

                    I wasn't sure exactly what you meant by match the project audio settings, so let me know if I missed something here.

                     

                    Understood on separate being better.  I was trying to kill two birds with one stone by having a playable .m2t file that I could also burn to BD.    It's not a huge deal, worst case I will just have to deal with multiple exported variants when I complete a movie.  

                    • 7. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                      JSS1138 Community Member

                      the defaults for H.264 Blu-ray and the 720p 59.94 preset within PP which has Dolby Digital for the audio format

                       

                      The default for all H.264 Blu-ray presets is actually PCM audio.  If it's set to DD, then you must have changed it.  This happens when you change the default Multiplexer from None to TS.

                       

                      Best to leave it at None and create two exports, one for BD and one for computer playback.

                      • 8. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                        joneisele Community Member

                        I see the default audio format for H.264 Blu-ray presets is PCM.   What is odd is that if I turn on TS multiplexing not only is the format changed to Dolby Digital, but that is the only option.  PCM as an audio option dissappears from the user  interface.  Is that to be expected?  

                         

                        Further, if I change the default transcode settings in Encore to be Dolby Digital, my .m2t file stills says it needs transcoding.  Earlier Jeff thought that if the audio project settings matched Encore would not need to transcode.

                        • 9. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                          JSS1138 Community Member

                          Don't create an .m2t file and it won't be an issue.

                          • 10. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                            joneisele Community Member

                            Jim - undertsood.  I'm just grappling with export file overload.  Every time I put together a home or bicycle video I have to create a .m2t file to playback on PS3 and computer, separate audio/video for making BD's, project archive using the project manager feature, and then a master file using a less lossy codec in case of a future backwards compatibility issue with reloading old projects.    I will do what it takes here, but am admittedly confused as to why Encore (apparently) needs to transcode the video stream here.

                            • 11. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                              Stan Jones CommunityMVP

                              am admittedly confused as to why Encore (apparently) needs to transcode the video stream here.

                              I don't  understand it either, I just know that is the way it works. There are more variables than you may think on how the audio stream is formed, and some variations are not bd legal. Also, when you mux, Encore must demux before it can build. We don't know if Encore is takingthe easy way out and declaring anything muxed to be illegal, or whether Encore predicts what it has once demuxed and finds that that demuxed product is illegal.

                               

                              It seems illogical for a mux to work and a demux not, if they are really the same streams. But muxing/demuxing is really not that simple.

                               

                              I have not tested dynamic link in CS6. Many users believe it does not work well enough, but the combination of adobe media encoder and dynamic link would be one of the best ways for these multiple export formats to work.

                              • 12. Re: Downsides to multiplexing audio for H.264 Blu-ray disc?
                                HarleyTDavis Community Member

                                You must always remember gents, when you multiplex, there is a BUFFER attached to that (computer term that means a chunk of size and bit defined fast memory space that holds an intermediate piece of data for shuttling to the next piece of hardware).  This changes the MAX Bitrate allowed for your video (but it doesn't show in AME cs6 and I don't think it shows in lower versions; not sure about cc).  Since you are tying one stream to another, and effectively weaving the data into one stream, you are maxing out the amount of data you can pass in that stream.  Only certain types of data can be read in this manner.  Think of it this way, you have taken two sets of data with different bit widths, and different bit-sample rates, and tied them together into one stream.  This stream still has to fit in the max data rates of the medium.  Your video cannot exceed 30mb\s and you are also left with another problem.  Audio, without mux, has so many different formats and bit fiddling profiles that it would be difficult to make sure it was within the sizing for data.  If, however, you limit it to one major codec, and use predefined bit\sample rates that can be sized up, you'll be able to tell if all the settings are "legal" or not, as you then have a predefined data-size for both audio and video.  If you don't multiplex, you get 2 streams.  It takes longer to load the disc, but both streams are cached.  Typically, with more motion, I like to non-plex, but with more emphasis on audio, I start leaning toward a TS file.  IF you want forward compatibility, select an intermediate codec, with little to no compression, save to a disc image, then burn a disc and file it away.  Every 10-15 years, hire an intern to turn their hair white recoding all your video and following the same procedure (unpaid internship time), but make them happy by hiring them as "Labor" on a short job or two and pay them well for standing around or stroking the egos of the "Talent".  What can I say, we all work more diligently and creatively when we feel more connected with it, whether we're brooding and trying to communicate the angst of a lost generation, or felling powerful enough to choreograph leaping tall buildings in a single bound.  Misery loves company, and powerful loves to be reminded it is by everybody whether it is or isn't.

                                 

                                If you need better clarification...

                                Lets go back to dvd for a moment.  DVD structure is Video TS and Audio TS.  TS is Transport Stream.  A stream is a BUFFERED movement of data that is transferred quickly in set sized chunks.  In DVD there were two transport streams to play back early on.  Later, many started muxing those streams and encrypting them, so that upon Decrypting they could be played.  Muxing made the encryption easier, as only one stream needed to be encrypted and it was all in the Video TS.  Audio TS folders are still written, but there is little data there.  In fact, removing this folder when no data is actually present has shown in some cases to do no damage, while in others, it will not play.  This is because, it is used as a shell to copy.  It initiates the audio stream playback on older players, and on newer players it isn't necessary.

                                Blu-ray yields similar limitations.  You need to match the size of the buffer you are feeding.  Most players max out around 35mps from the old sets, and newer players actually pull more like 50mps.  If you don't know your target, you'll be out of luck.  I've seen blu-rays that don't play on older players being sold at video stores, at Frys, everywhere.  I've played them on an old one and found them to be unplayable.  Newer formats do not work with older players, but, they note it on the package that you need to meet certain specs, and those specs can usually be found on a sticker on your device so you can see if they match.  Remember your Target BitRate and Max Bitrate.  The Target should be less than the max for the device you aim for.  CS6 won't usually allow anything over 32.7mps, anyway, so setting this in AME even with dynamic linking could cause problems.  However, you do have the choice to locate a transcode... ...presents an interesting possibility.  I've been trying to get a project done or I'd try this myself:

                                I'd use the x264 free codec, with some basic options and blu-ray-compatible flag, with --fake-interlaced, to create a transcode and link it into encore.  However, encore hasn't liked any of my transcodes that use multiple passes.  I'm going to try with a single pass later, and produce an intermediate output for now.