Hello, I have many terabytes of OP atom/Avid MediaFiles that I wish to make into OP1a versions. The content of the files was originally recorded onto Beta and DigiBeta tapes and digitised at MPEG 50. I have been researching how to export the Avid MediaFiles and have concluded that using the MXF OP1a DNxHR 444 setting produces the best results in terms of image quality, file size and a bitrate of 77 Mbit/s. The file codec is DNxHR (720x592). Firstly though, I make a sequence of a clip while in PAL 25i. Then I change the format to progressive, PAL 25p, and use Timewarp with the Adaptive Deinterlace Source checked. However, to save storage space I do not render the clip sequence. The size to clip duration ratio of the files produced with the MXF OP1a DNxHR 444 setting works out at 0.59 GB per minute. This is compared to the rate of the original Avid MediaFiles at 0.4 GB per minute. By the same method, MXF OP1a ProRes 422 gives a rate of 0.363 GB per minute and a bitrate of 48 Mbit/s. Visually, I can see no difference between the two Video compression settings. But I prefer to have the DNxHR codec and a higher bitrate as I have the storage available for the bigger files. My question is, do my findings tally with industry best practice for producing OP1a versions of OP atom files? Thanks Andy

Here is a question and some thoughts. What is the ultimate goal of this project? If it could at all be considered "archive for future use" I see some issues. The first and biggest issue is the conversion of interlace to progressive. There is NO perfect way to do this. Most methods actually reduce resolution. They are destructive. New, potentially better methods come about with some regularity. So irrevocably using any method to go to progressive is a one way street. Now, if you decide to stay interlace, I would test the DNxHR format you are discussing. DNxHR specifically does NOT support interlace. And early tests I did showed that it could actually harm interlace footage. That may have changed but I would be surprised that Avid would have changed anything about the DNxHR spec once it was released. OP atom /Avid MediaFiles are generally files where the video and audio have been separated into individual video and audio files. They can be the original codec in many cases (if they are supported by Avid). Or they can have been transcoded to a codec that Avid does support. Again, the ultimate goal of the project would inform how you might approach moving the media out of the Avid media managed world which is what it seems as if you are trying to do.

Great response Jef......

Hope ajatt responds so we can help further.

Marianna