Codec question for remote conform

mik gojic Feb 5, 2016

  1. G'day I've got a project coming up that will require the delivery of a 30 minute show from around rural Australia. The edit will be done on site before being uploaded for grade, audio & conform then delivery to broadcast.
    Because of the locations, we're expecting slow upload speeds so file limit is 10Gb so we can make deadlines. I can do some things to up the transcode quality like making the dialogue single track mono, having the grader drop in the open / close titles, possibly even the supers & segment transitions, I'm open to any other tips.

    So my big questions are

    1) Recommendations on a codec for the transfer keeping in mind it will still need to be graded and acceptable for broadcast.
    2) Is there a benefit in dropping the frame size from 1080 to 720 or possibly even SD
    3) Is it better to give the grader the shots in log even after they've been transcoded to what is likely to be a pretty compressed codec OR do I apply a first pass balance to give a bigger dynamic range then transcode for upload.

    Is there anything else I've missed ?
  2. So the whole 30min video needs to be under 10GB? Maybe stick with DNxHD/Prores but use the smaller variants? such as Prores LT. Not sure what the size would come out to be.
  3. The 10 Gb limit for 30 minutes of material would roughly give you 45 Mbps allowance. The only DNxHD option at that rate is DNxHD 36 which is not the greatest quality.
  4. Zach, LT is to big at 22Gb & Igor is right about DNxHD, 36 is the only one that's under at 6.5 but that's pretty close to ProRes Proxy which doesn't cut it quality-wise.
    Now if I downres to 720 or SD I can use LT or even ProRes 422, at this point I'm thinking I'll just have to run a bunch of tests to get the best output for the size constraint.
  5. A good option to upload might be H265. If needed convert it back to a more lightweight format after downloading (e.g. ProRes 422 HQ).
    No experience with it myself, but was the first that came to mind :) .
  6. I wouldn’t expect to do much grading at those bitrates… Use h.264 or h.265. At 45 Mbps you might attempt to encode it to 10-bit 4:2:0 via AVC-I 50 Mbps files - but losing part of horizontal resolution (1920->1440).

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