12 Replies Latest reply on Jul 27, 2013 1:18 AM by Keano66

    Where is my bottleneck when I drop frames?

    Dave Dugdale Level 1

       

      OK I totally understand that I will not run 6 DSLR streams at the same time, but I am curious what is causing the dropped frames in this video since it appears I do not have a bottleneck from the tools I was using to monitor the playback.

       

      I also understand that using the .mov h.264 files to edit and grade with is also not the right answer too but well I am lazy.

        • 1. Re: Where is my bottleneck when I drop frames?
          Kevin-Monahan Adobe Employee

          Hi Dave,

          Thanks for all the great videos. My guess is that you are experiencing dropped frames because:

           

          a) You working with QuickTime wrapped DSLR footage. Premiere Pro has to send it through QuickTime server to interpret the 32 bit file in a 64 bit application.

          b) You are working with a highly compressed codec: H.264

          c) You have 6 streams of QuickTime wrapped H.264 footage.

           

          You might try your test leaving QuickTime out of the test, but I understand if that's not practical for you.

           

          Thanks,
          Kevin

          • 2. Re: Where is my bottleneck when I drop frames?
            Dave Dugdale Level 1

            Hi Kevin,

             

            Thanks, I'm glad you like my videos.

             

            Any ideas what the bottleneck can be? In your video http://tv.adobe.com/watch/cs6-creative-cloud-feature-tour-for-video/get-blazing-performanc e-and-rock-solid-stability-with-the-enhanced-mercury-playback-engine/ you are using a more powerful CPU than my 3930k and you are running 11 streams at the same time, my guess is my CPU is not up for the task of decoding all the streams even though it is not maxing my CPU out.

             

            Since it is not maxing out my CPU then it must be the way the software is being used to do decode and render for playback the DSLR QT wrapped footage. I will mostly likely never stream 6 DSLR clips at the same time, this is mostly me trying to understand how this all works.

             

            I just ran another test where instead of 6 different DSLR streams I used only one stream 6 times and it did not drop frames. The CPU usage was much lower and also the disk transfer rate was also much lower. The GPU load for the diff streams was 15% and for the same streams was 5%.

            • 3. Re: Where is my bottleneck when I drop frames?
              Dave Dugdale Level 1

              OK I took the 6 clips and transcoded them to DNxHD highest quality and they didn’t drop any frames in that same test.

              • The CPU worked just as hard as the other test but only used 10 out of the 12 threads. (the dslr h.264 footage used all 12 threads)
              • The GPU worked at the same level as before
              • The amount of data transferred off the SSD was much higher if not double, peaking at 100MB/s.

              So if I were to reach the right conclusion the SSD is not the issue because it could stream 100MB/s peaks no problem without dropping frames (earlier test it peaked at 43MB/s). The GPU does not seem to be a factor here because it was under the same load as in the earlier test. So that leaves the CPU, just because it is not peaking all threads at 100% doesn’t mean it can handle decoding all 6 streams at the same time. Perhaps it is a mutli-threading issue.

              • 4. Re: Where is my bottleneck when I drop frames?
                cscooper2013 Level 2

                With today's fast hard drives and SSDs, my understanding is that any decoding bottleneck is most likely in the CPU.  Even a 7200 RPM drive is fast enough to handle, in theory, 7 streams of 100Mbps DVCPro or similar, etc.  What bit-rate does your DNxHD have?

                 

                I don't know how much power each core needs to do any particular task, but it seems like almost any task I perform (except encoding) never uses the full power of any single CPU, until it uses all 8 cores (or what have you).

                 

                Kevin makes an interesting point about quicktime being 32-bit in a 64-bit world.  I didn't know that.  Any ideas when Apple will update their software?  How many years have we been on ver. 7.x?

                • 5. Re: Where is my bottleneck when I drop frames?
                  Dave Dugdale Level 1

                  I encoded it at the highest Davinci would output which if I remember right is 220MB/s.

                   

                  Interesting that so many create fast raid arrays, I guess they are not doing it for playback perfomance they are doing it for the rendering speeds on export.

                  • 6. Re: Where is my bottleneck when I drop frames?
                    Kevin-Monahan Adobe Employee

                    Dave,

                    I wonder what your test would look like in Premiere Pro CC?

                     

                    Kevin

                    • 7. Re: Where is my bottleneck when I drop frames?
                      Jim_Simon Level 8

                      Perhaps it is a mutli-threading issue.

                       

                      Given the bugs and outdatedness of QuickTime, I wouldn't be surprised.

                      • 8. Re: Where is my bottleneck when I drop frames?
                        nw42 Level 2

                        don't think a single SATA HDD can handel too much stuff... the key for stable playback with lots of different clips and most important - fast export times is a really fast storage...

                         

                        to work with 2K DPX and DNXHD 200MBit/s I use some 600MB/s Raid-0 Arrays... Premiere will use max 50% of it never writes faster than 250 to 350MB/s to them...

                         

                        If you read and write form a single SATA HDD the export times will explode... a SSD with high I/O performance can handle this a lot better...

                         

                        Example: Export 6Ch Audio with about 6GB from SATA HDD - 25min - the same from SSD 3min...

                         

                        The CPU and GPU only can help you if they will be used - if you wait for a low performance Quicktime I/O - you will wait and your CPU too... (compare export time to MPEG2 100MBit/s with some 100MBit/s Quicktime exports...)

                        • 9. Re: Where is my bottleneck when I drop frames?
                          Dave Dugdale Level 1

                          Kevin, sure I can give it a try. I am downloading the trial version of CC now.

                           

                          I'll let you know how it goes.

                          • 10. Re: Where is my bottleneck when I drop frames?
                            Dave Dugdale Level 1

                            Kevin,

                             

                            Can't seem to download premiere CC, I get this error each time I try:

                            http://www.flickr.com/photos/davedugdale/9371582901/

                             

                            I tried stopping the existing CS6 CS6ServiceManager.exe but it keeps coming back, I also uninstalled the Adobe CS6 update manager but that didn't help either.

                             

                            So I gave up trying to install Pr CC, sorry.

                            • 11. Re: Where is my bottleneck when I drop frames?
                              cscooper2013 Level 2

                              Dave D. wrote:

                               

                              So I gave up trying to install Pr CC, sorry.

                              You're seriously better off, Dave (sorry, Kevin and everyone at Adobe).  Premiere Pro CC is far from ready to be released to the public (even though it already has been).  I'm going back to CS6 tomorrow starting fresh with a new project.  I'm putting a complete halt on a current project that is stuck in CC (too far to back out and start over in CS6) until the next bug fix update when I'll try again. 

                               

                              Playing in the Adobe support forums for the last month or so has been fun, but it's time to get back to work.

                               

                              Consider yourself lucky you were unable to download it.

                              • 12. Re: Where is my bottleneck when I drop frames?
                                Keano66 Level 1

                                Dave, I would be extremely interested if you conducted a similar test using Edius (which I am thinking of moving over to.)  Great videos!