Don Blish
March 22nd, 2007, 10:17 AM
Like many of you, I have been saving an .m2t copy of each HDV project over the last 15 months. I had always planned to author these to Blu-Ray as BDMV projects with menus etc. Over the last week I have successfully used DVDit Pro HD to make a number of them into discs that to play in my Sony BDP-S1 player (updated to 1.55). I have found the video to be stunning viewed on a 1080 screen. What was disappointing is that several times over a one hour project, a “hard cut”, usually but not always to a still image, failed to appear cleanly. The lower third of the screen would hold the previous scene’s data for 6 to 8 frames. This never appeared in the DVDs from the same material. Those DVDs were output to a Cineform .avi as 480p and encoded with Adobe Encore 1.5.
These defects could have been the player’s error, DVDit transcoding or the Cineform file itself. After opening a test Cineform project in PremPro and hauling into it both DVDit’s .m2v transcode and the Cineform .m2t archive, I discovered the error came from the Cineform .m2t file. All I can surmise is that the 24mbps CBR bandwidth of this format will not handle hard cuts if they fall unluckily.
I believe each recorded clip in the camera starts with a complete “I frame” and updates of varying completeness extend over the next 14 frames. The constraints of a CBR output to tape apparently do not smartly deal with hard transitions that do not fall fortunately. Since this never appeared on authoring from a fresh standard definition .avi, I’ll have to do my HD authoring from .avi too. I still have .avi files for a few projects on disc. On others I’ll have to use HDlink to turn the .m2t files back to .avi, find the bad spots and repair them. That is easy if they are just stills. If they are the beginnings of video footage I’ll have to either recapture or snip the bad spot out.
These defects could have been the player’s error, DVDit transcoding or the Cineform file itself. After opening a test Cineform project in PremPro and hauling into it both DVDit’s .m2v transcode and the Cineform .m2t archive, I discovered the error came from the Cineform .m2t file. All I can surmise is that the 24mbps CBR bandwidth of this format will not handle hard cuts if they fall unluckily.
I believe each recorded clip in the camera starts with a complete “I frame” and updates of varying completeness extend over the next 14 frames. The constraints of a CBR output to tape apparently do not smartly deal with hard transitions that do not fall fortunately. Since this never appeared on authoring from a fresh standard definition .avi, I’ll have to do my HD authoring from .avi too. I still have .avi files for a few projects on disc. On others I’ll have to use HDlink to turn the .m2t files back to .avi, find the bad spots and repair them. That is easy if they are just stills. If they are the beginnings of video footage I’ll have to either recapture or snip the bad spot out.