12 Replies Latest reply on Jul 18, 2008 10:51 PM by Dan Isaacs

    Preconverting HD to SD  - (New Thread)

    shooternz Level 6
      I have brought this in from another Thread to avoid the Thread jack that I started and I wanted to continue the discussion.

      >How are you "pre converting" HD material to SD?
      (*.m2t) DGIndex -> AviSynth -> VirtualDub (*.avi)

      The gist of the process is explained here, but instead of frameserving from Premiere, I frameserve the MPEG2 TS from DGIndex. Instead of encoding to MPEG2, I write DV .avi files from VirtualDub.

      It sounds more complicated than it is. In reality, I just capture the HDV and then batch it all out to DV. It takes some time to convert, but very little effort (once the process was established).

      1.) I run a .bat file to create the indexes from the MPEG2 TS files
      2.) I use a batch scripting utility to generate the AviSynth scripts
      3.) I put the scripts in a common folder and choose "Process Directory" from VirtualDub
      4.) Do anything I like while I wait for the process to finish

      Steps 1 through 3 take about 5 minutes total. Step 4? Well, that depends on how many clips and how long they are.

      You can do a similar process for AVCHD files using DGAVCIndex. You can skip the "indexing" part for HD .AVI files, like Matrox or Cineform.

      Why?
      1.) It looks better: a ... b (better colors, less interlacing artifacts, better sharpness, more accurate PAR, less noise)
      2.) You get much better performance editing in SD if you only plan to deliver in SD.
        • 1. Re: Preconverting HD to SD  - (New Thread)
          shooternz Level 6
          Have you ever done a comparison by simply Opening the HDV files in a SD DV Premiere Project and Exporting them out again.

          (I realise, inconveniently you would not be able to Batch them which could be a show stopper)

          Interested to know if there is a quality difference In the methods?

          How does your process handle the scaling of the HDV Clip and I assume it is a "centre extraction"?

          BTW - I am at this every moment doing just this with 720p mxf files that I need in SD projects.

          I open them in a DV PAl Project. Select the clips and scale to 80% ( this is the vertical height adjustment to match PAL dimensions)

          The quality is excellent. Only prob is I can not batch the Export process. Only about 20 clips so no real issue ( and I can waste some time over here while its doing it)
          • 2. Re: Preconverting HD to SD  - (New Thread)
            Dan Isaacs Level 2
            Hi Craig --

            With 720p sources this is much less of an issue. However, if they are using the Rec. 709 colorspace (and you don't have Cineform or Matrox) then the colors will likely not be converted accurately.

            I may be able to help you fix this (and batch the files in any case), but I've never worked with .mxf files before.

            Can you play the .mxf files in Windows Media Player? If so, we're in business. If not, you need a DirectShow filter that handles .mxf (I know there are some... don't know if they are free).

            > Have you ever done a comparison by simply Opening the HDV files in a SD DV Premiere Project and Exporting them out again.

            Many times. Many ways. Yes. Again, I'm dealing with 1080i HDV media.

            > How does your process handle the scaling of the HDV Clip and I assume it is a "centre extraction"?

            Unless it's widescreen, yes. There is also a parameter to offset the center of the cropping.
            • 3. Re: Preconverting HD to SD  - (New Thread)
              shooternz Level 6
              Thanx for responding Dan

              mxf files will not open in WMP

              I use an Application called P2 Forge for viewing outside of Premiere and I have no idea what drives that except it does need the P2 Drivers installed

              http://www.lightstir.com/p2forge/

              (or I use a simple Panasonic app called P2 Viewer.)
              • 4. Re: Preconverting HD to SD  - (New Thread)
                Dan Isaacs Level 2
                Can't you use P2 Forge to batch the files out to another format (like DV)?
                • 5. Re: Preconverting HD to SD  - (New Thread)
                  shooternz Level 6
                  Yes I can and have done so.

                  P2 Forge does not play out to the external monitor and is slightly less user friendly in terms of playback useability\ but is a great app to have with mxf /P2

                  It is preferable for me as a workflow to view the files out of Premiere to my external HD monitor and make good take selections based on this. I also have the option of some Pan /Scan from Premiere

                  In Premiere I then import the SD Project back to a 720 Project and create native file size clips. These files I use as my Stock Footage Library for this client (Major Burger Chain - food/product shots for TVCs).

                  Only reason I go near SD these days is when I re edit some Legacy Projects and this will gradually fade away (hopefully).
                  • 6. Re: Preconverting HD to SD  - (New Thread)
                    Dan Isaacs Level 2
                    OK Craig. I'll try to help you. A few more questions:

                    1.) do you have/use Cineform?
                    2.) are you .mxf files 720p/25 or 720p/50?
                    3.) are you looking for interlaced or progressive SD output?
                    4.) does your camera use the 709 color matrix? I'm assuming it does, but I've heard of a few HD cameras that still use 601. Perhaps this is in the documentation/specs?
                    • 7. Re: Preconverting HD to SD  - (New Thread)
                      shooternz Level 6
                      Hi Dan.

                      Please do not go to any trouble on my account because I do cope fine with the workflow outlined and no real issue apart from no batch Export. Originally I was curious to see what and how your alternate workflows achieve and what kind of quality.

                      Downconverting to SD will become less of my "life" as time progresses and in fact I do very little of it now. Essentially I have reshot most of my stock footage that we require ongoing.

                      Anyway for your info (because of course this might help someone else if you have a cool idea)

                      1 - No Cineform (I own it but I have no need for it)

                      2 - 720p/25, 720p/50 and 720pn (ie. all of them)

                      3 - Progressive

                      4 - Color Matrix - can not find this info but we shoot with Panasonic HVX202 (PAL) and I would be fairly sure that wont be 601
                      • 8. Re: Preconverting HD to SD  - (New Thread)
                        Dan Isaacs Level 2
                        Truthfully, I'd just open the clips in a 720p PPro project and make some notes on which clips are good, bad, etc.

                        Then I'd open the "good clips" in P2 Forge and batch them out to some SD format, such as PAL DV.

                        One "trick" I sometimes use for things like this is to quickie-edit the clips on the PPro timeline and export an EDL. Refer to this for in / out points of the clips.
                        • 9. Re: Preconverting HD to SD  - (New Thread)
                          shooternz Level 6
                          You are right. That could work very nicely if I dont want to pan or scan them while downconverting (which is rare anyway)

                          EDL is a cool trick that I had not thought of. Havent used an EDL for years and might be time to re in state it as a tool.

                          (Different paradigm but very choice idea Dan)

                          Must test if the EDL will read the mxf file names accurately. They are kind of weird and actually they are a pain to hand write and read because they use many "0"s and "O"s a lot.
                          • 10. Re: Preconverting HD to SD  - (New Thread)
                            Dan Isaacs Level 2
                            > Different paradigm but very choice idea Dan

                            Well, let's shift this paradigm back now...

                            You can also set PPro's timeline display to "frames" instead of timecode. This will be reflected in the EDL. I find frame numbers easier to work with, especially in AviSynth and VirtualDub.

                            One case where I use this is when I need to "batch" multiple sequences.

                            Here's a special variation of this process for you: In your case (assuming your PPro project is 1280x720p), you can use my hd2sd() function to handle the colorspace conversion and scaling, and to facilitate easy batching through VirtualDub:

                            1.) edit your clips on the timeline
                            2.) set timeline to display frame numbers, export EDL
                            3.) frameserve from PPro using the DebugMode FrameServer as YUY2
                            4.) copy / paste the frame numbers from the EDL to AviSynth scripts like:

                            Notepad: save as x:/avs_batch/sequence01.avs


                            AviSource("x:/path_to/signpost.avi")
                            Trim(0,999)
                            hd2sd(interlaced=false, outputcolorspace="yuy2", outputfieldrate=25)


                            Notepad: save as x:/avs_batch/sequence02.avs


                            AviSource("x:/path_to/signpost.avi")
                            Trim(1000,1999)
                            hd2sd(interlaced=false, outputcolorspace="yuy2", outputfieldrate=25)


                            etc...

                            5.) use VirtualDub to batch process the x:/avs_batch/ folder, saving out each file to an .avi (sequence01.avi, sequence02.avi, etc.) These files will be 720x576 widescreen, 25p -- using whatever compressor you choose in VirtualDub (DV most likely).

                            This can save tons of time. You can set up 30 sequences in about 5 minutes, then let them process for as long as needed.
                            • 11. Re: Preconverting HD to SD  - (New Thread)
                              shooternz Level 6
                              I will take a look at that sugestion Dan once I get my head around it. Thanx for the info and all your effort.

                              Brilliant thing about the very simple 'EDL & P2 Forge' idea for me is that I dont even need to do any editing. (My files (mxf) are all just takes. I shoot P2 just like I shoot film. Roll /Action/Cut. ie no long runs)

                              This means I only need to identify the select takes using Premiere playback. Drop them on a timeline and create the EDL to use as a printed list of Source Files. Load them in P2 Forge and use the Batch Encode Function.

                              BTW - it is possible to set In and Out points in P2 Forge.

                              Aside : P2 Forge has all the hallmarks of other applications that Adobe have purchased in the past. eg On Location from Serious Magic, Cool Edit Pro from Syntrillium ...

                              It allegedly does or is going to handle and manage Intra AVC .
                              • 12. Re: Preconverting HD to SD  - (New Thread)
                                Dan Isaacs Level 2
                                > I will take a look at that sugestion Dan once I get my head around it.

                                Try out my regular HD -> SD DVD workflow. I think you'll instantly understand it then.

                                > Thanx for the info and all your effort.

                                No probs.