0 Replies Latest reply on Aug 6, 2013 10:40 PM by Guy Burns

    VC-1 coded file imports: I thought it wasn't possible?

    Guy Burns Level 1

      I consider myself a novice in Premiere. Also learning Encore. Have a few smallish projects under my belt, but I'm aiming for a much deeper understanding. So I've been playing around with codecs for the last week, trying to figure out the optimum way of pre-processing shorts in a variety of formats so that I can dump a selection of them into Encore, without transcoding being necessary, and write to Blu-ray in half an hour instead of half a day. The shorts might be a home-theatre promo from my GH2; other shorts of mine; 1950s cigarette commercials; Movietone newsreels, all combined into an hour or so of before-interval viewing, reminiscent of going to the pictures in the 1950s.


      That brings me to VC-1. Never heard of it till a few days ago. And I don't understand why this series of steps seems to work:


      1. I have a 2-minute clip in an MKV container with the video in VC-1 format and the audio in AC-3. The contents are reported as:


      Format profile:   Advanced@L3

      Codec ID:          V_MS/VFW/FOURCC / WVC1


      I don't fully understand what the Codec ID is telling me. Maybe someone could explain.


      2. I can open the file in QuickTime 7 Pro, and it plays. FPS is reported in MediaInfo as a constant 23.976.


      3. When I Save As, the clip ends up in an MOV container without being transcoded. MediaInfo says the format is MPEG-4, QT profile. The file size is virtually identical to the original, but the FPS is now reported as:


      Frame rate mode:               Variable

      Frame rate:                            23.976 fps

      Minimum frame rate:          23.810 fps

      Maximum frame rate:         24.390 fps


      The file plays okay in QT.



      QUES 1

      I don't understand what's happened. Has the VC-1 data been re-wrapped inside the MOV container unchanged (except from the frame-rate change), or did it get in there a different way? For example, put inside a MPEG-4 stream, and that has been put inside a MOV container?


      QUES 2

      Why the change in frame rate?



      4. I import the MOV file into Premiere, which reports the frame rate as 24.39. This file appears to play correctly, but a close inspection reveals that every now and then a frame may be repeated several times, or the video jumps back to a previous frame just for an instant, and then continues. Audio and video never get out of sync.


      5. If I have the video "interpreted" as 23.976 (Modify Clip > Interpret Footage > Assume this frame rate) the problems disappear.


      6. When I de-multiplex the original MK file to a wmv video file, that file can be imported in Premiere, but it is reported as 10fps, and all sorts of strange things happen. If I de-multiplex to a VC1 file, Premiere doesn't allow import at all.



      QUES 3

      Why does Premiere import a VC-1 file when it is wrapped inside a MOV container, but when the raw video stands alone the import is either not possible or is corrupted (and unfixable)?