9 Replies Latest reply on Nov 8, 2010 7:16 PM by Todd_Kopriva

    1-Pass or 2-Pass??

    jimclark1947 Level 1

      I asked this question in the AME forum earlier and have received no comments, so I thought I would try here as well.

       

      I'm just curious what others have experienced.

       

      As an experiment I used a 30 second AVCHD clip that had a few effects added and encoded it to H.264-Blu-Ray using 1-Pass, then again using 2-Pass.  All other settings were the same for each.

       

      When I play both of the resulting clips I can see absolutely no difference in the picture quality.

       

      Other than taking twice as long to process, what benefit should I be getting from 2-Pass?  I fully understand the purpose of 2-Pass, but the few times I have tried it I haven't seen any resulting benefit, so I'm just curious what others have experienced.  Perhaps there are some specific conditions where 2-Pass will actually produce a better final product??  Are there specific video effects or filters that end up looking better if 2-Pass is applied??

       

      Any thoughts??

       

      Jim

        • 1. Re: 1-Pass or 2-Pass??
          JaysonM-Y Level 3

          Hey Jim, I read a post a few days back with regards to the quality of certain transitions and fading in and out, that two pass eliminates artifacts on that dip to black and shaved maybe 2 mbs of the file size.... or something to that magnitude. For me tho, I just think I if I have a good amount of time on my hands, I'd go 2 if not I hit 1. Not a good reason to do anything really, but hey...

          • 2. Re: 1-Pass or 2-Pass??
            Harm Millaard Level 7

            2-pass VBR will show it's benefits if your footage contains hard to encode shots, like grass slowly moving in the wind, pans, and similar. Often it will be hard to discern the advantage, especially with 90% of the average footage.

             

            For me, but this is purely personal, I prefer 2-pass VBR over CBR to give that tiny bit of extra quality, since I do not really care about encoding times during the night.

            • 3. Re: 1-Pass or 2-Pass??
              jimclark1947 Level 1

              Ah, ok.  That makes sense.  I just have this fairly big project that I'm working on and want to get the best quality output, but didn't want to double the time to process unless there is a good reason.

               

              But you have given me something to think about now.  Guess I'll go back and split up that clip with various transitions and such and rerun my test.

               

              Thanks,

               

              Jim

              • 4. Re: 1-Pass or 2-Pass??
                jimclark1947 Level 1

                Harm,

                 

                Yeah, I know what you mean.  The test clip I was using has a fair amount of fast motion in it, but I have some clips with fall leaves blowing in a soft wind like you describe.  That may make a better test for me.

                 

                In the end I will likely just stick with 2-Pass, but it is interesting to explore just what makes the differences in quality between the two choices.

                 

                Thanks,

                 

                Jim

                • 5. Re: 1-Pass or 2-Pass??
                  John T Smith Adobe Community Professional & MVP

                  >specific conditions where 2-Pass will actually produce a better final product??

                   

                  Go record something like a soccer or basketball game with lots of fast movement and then do a comparison test

                  • 6. Re: 1-Pass or 2-Pass??
                    jimclark1947 Level 1

                    John,

                     

                    That's a good idea.  In fact, I recorded a soccer game just two days ago and haven't gotten to that yet.  It was an indoor match so the lighting is going to be less than perfect as well, so that may yield even more difference in a comparison.

                     

                    Thanks,

                     

                    Jim

                    • 7. Re: 1-Pass or 2-Pass??
                      Harm Millaard Level 7

                      Jim,

                       

                      The most notable gain is when you have lots of changing frame content, like pans, fast moving objects, etc. The lighting conditions do not play a significant role here. Badly lit scenes do not influence that. It is all about the change in frame content.

                      • 8. Re: 1-Pass or 2-Pass??
                        Jim_Simon Level 8
                        want to get the best quality output

                         

                        http://handbrake.fr/

                         

                        "No more looking for the perfect bitrate for a source--HandBrake is migrating to quality-based encoding. This means that instead of telling encoders to use a specific size and vary quality to meet it, we tell the encoder to vary size to meet a given quality level. Overall quality improves, since bits are spent only when they are needed, and are saved when they are not. While this means output size is somewhat unpredictable, the results in picture quality speak for themselves."

                        • 9. Re: 1-Pass or 2-Pass??
                          Todd_Kopriva Level 8

                          If you're going to cross-post, please leave links in both copies of the thread so that people don't waste time answering in one when the answer has already been provided in another.

                           

                          Here's a link to the duplicate thread in the AME forum:

                          http://forums.adobe.com/message/3260492

                           

                          Note that I could've saved myself the trouble of answering there if I'd seen that folks over here had already given the same answer.