5 Replies Latest reply on Jul 20, 2011 3:50 PM by OneOfTheseWillBeAvailable

    Realtime performance with uncompressed media

    OneOfTheseWillBeAvailable

      Hi,

       

      Here's what I have so far, playing a single stream of each with no effects:

       

      Uncompressed 10-bit YUV in AVI (V210) - plays realtime, marked yellow

      Uncompressed 8-bit RGB in AVI - not marked yellow, plays OK for a few frames then freezes for the duration of the clip

      Uncompressed 10-bit RGB in AVI (R210) - Marked yellow, plays fine

      10-bit RGB DPX - plays OK for a few frames then freezes for the duration of the clip

       

      This is on 5.0.3 under Win7 on a Core i7 950. RAID comprises eight 1TB Samsung HD103SJs in RAID10 on a Rocketraid 2720.

       

      This is clearly not about data rate:

       

      - Blackmagic speed test utility puts the RAID at 300MB a second at worst, while only around 200 is required;

      - Some media that requires a lot of data rate (10-bit RGB) plays OK, while less-demanding stuff (8-bit RGB) fails

      - Other software plays the same media perfectly well on this configuration.

       

      What's strange is that the failure mode with 8-bit RGB AVI is exactly the same as 10-bit RGB DPX; it plays fluidly for a few frames then freezes for the rest of the clip. That's what I'd expect for a disk bandwidth issue but then why would it play 10-bit RGB AVI plus audio without a glitch? The killer issue is that the "coloured bar" indication is rather naive, as someone from Adobe recently admitted on this very forum, and if it doesn't think you're in a "red bar" situation, it won't let you render a preview, leaving you simply unable to edit; the software is actually unusable at that point.

       

      Really, Adobe, what on earth is going on here?  I can stream 10-bit RGB DPX sequences on the same hardware in .net apps (yes, that's in actual managed code, fer chrissakes). I will buy more hardware if I have to but it's hard to know what to upgrade when the problem is just one piece of software which could be failing anywhere.

       

      P

        • 1. Re: Realtime performance with uncompressed media
          Jim_Simon Level 8

          What is the resolution/frame rate of all clips?

           

          Where did the 8 bit RGB AVI come from?

          • 3. Re: Realtime performance with uncompressed media
            digitlman Level 1

            I have never had any problems playing back any clips on my system and have tried several uncompressed formats. However i was just thinking about an aspect to this yesterday. It really bothers me that premiere does the audio conforming, it really needs to go away! our computers are so fast these days that converting audio bitrate on the fly must use VERY LITTLE cpu.

             

            If i have a 170MB/sec uncompressed clip on my raid premiere is going to conform the audio and write it to the same drive (because that is where i wanted it) however that means when you play back the clip it must read BOTH files at the same time! it is reading the full 170MB/sec file and it is constantly interupted by having to read the conformed audio at the same time which will significantly slow down the speed compared to a single stream reading benchmark. I could see how this could cause problems with users reading multiple files at once, 3 or 4 clips could be accessing 6 or 8 files at once from your drives.

             

            Adobe please flush your conformed audio crap down the drain where it belongs!

            • 4. Re: Realtime performance with uncompressed media
              Jim_Simon Level 8
              because that is where i wanted it

               

              Your point is why separating Media and Scratch is the recommended practice, so that the files are read from two different drives.

               

              The ideal minimum setup is:

               

              C: Windows and Programs

              D: Projects/Scratch

              E: Media

               

              Having said that, much of the conforming you see being done is actually just the creation of the .pek files, which are used to display the audio waveform.  They're very small and will not tax even a single modern drive.  The .cfa files are the bigger ones, and PP doesn't normally create those for standard audio streams (16 bit, 48 kHz, PCM).

              • 5. Re: Realtime performance with uncompressed media
                OneOfTheseWillBeAvailable Level 1

                This is all very interesting. Of course, playing back external conformed audio files could mess things up, and it's not even much to do with disk bandwidth - if you're trying to stream 2K DPX or something like that, the mere fact of seeking off to find some other file would be a problem, regardless of how big that other file is.

                 

                But that doesn't change the core issue. None of these audio or peak file issues would apply to DPX, and the DPX performance is just awful. It also doesn't explain why some filetypes play back OK, whereas others, which should be less demanding, fail horribly. It doesn't explain the weird failure mode, where you get the first five or ten frames of the clip fluidly, then nothing else at all until the next clip.

                 

                So again, Adobe, please, why is the performance so bad?