Transcoding H.264 to DNxHD for Fast Import in Media Composer 6

Transcoding H.264 to DNxHD for Fast Import in Media Composer 6

For a new project I’m working on, we have almost 500GB of 5D footage acquired over 10 days of shooting.  The project will be divided up into six episodes, and in order make all of that footage available for editing as quickly as possible, we’ll be pre-transcoding the H.264s as DNxHD36 MOV files and then Fast importing them into Media Composer 6 on OS X. The big benefit of this workflow is that it allows you to quickly set-up any Macs you have available for transcoding, while keeping your Media Composers free for editing.

We tested MPEG Streamclip, Compressor, and Avid Media Encoder. While Compressor will utilize all of the cores in a Mac, it requires a license and takes a bit more effort to install. MPEG Streamclip, is easy to install and freely available, while also utilizing up to four cores which is just right for the Mac Book Pros and iMacs we have sitting around. Batches in Streamclip are easy to set-up, and performance-wise we found it was about 3x faster than Adobe Media Encoder using equivalent settings (20 mins Vs over 60 mins to transcode 670MB of H.264s).

We are primarily using this process to create and import DNxHD36 Quicktimes for editorial. It includes pretty much every mouse click, in the hope it can be distributed without explanation. So far, everyone has had a good experience with it, and you’ll probably see some project specific instructions pertaining to our workflow.

Each episode will be getting it’s own, dedicated external FW800 drive to keep re-linking and organization simple. It also allows each episode to move through our pipeline independently, so we can meet our deadlines over the course of the project. At various milestones, each drive is being duplicated on a rotating back-up.

Thanks to Josh Petok for suggesting the idea of Fast Importing, as well as Juan Salvo, Craig Quinlan, and Eric Bordeur for their input. Also, thanks to Michael Kammes for his detailed fast import tutorial.

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Transcoding H264 to DNxHD for Fast Import in Media Composer 6

Step 1: Transcode H264 to DNxHD.mov Media 
Install and Launch MPEG Streamclip
Go to List menu > Batch List

Add Files…
Select H.264 .mov files for transcode
Click “To Batch”
Please Choose a task: Export to Quicktime (nothing else selected)
Click OK
Select a destination folder
Click Select.

In Movie Exporter Window: MPEG Streamclip Settings 
Compression: AVID DNxHD Codec

Options… 
Color Levels: 709
Alpha: None
Resolutions: 1080p/23.976 DNxHD36 8-Bit
Click OK.

Settings (Cont..) 
Quality: Leave at 50% (this only applies to JPEG codecs)
Sound: Uncompressed – Stereo Auto – 48KHz
Framesize: 1920×1080 (Unscaled)
Interlaced Scaling: OFF
De-interlace Video: OFF
Field Dominance: Upper Field First
Rotation: No
Zoom: 100%

 

Save the Preset
Click Presets…
Click New
Create New Preset?: Yes
Click Save

When settings are complete… 
Click To Batch
Click Go

Transcode Begins.

Step 2: Fast Import DNxHD Media into Media Composer 

On External Drive
Create a directory for your project.

Launch Media Composer 
In Select Project Window at Boot:
Click “External”
Click Folder Icon, set path to the folder you created.
Click New Project.
Name your project.
Click OK.

In Media Composer

Bin Window
Right-Click inside the bin window.
Choose New Sequence.
Name your Sequence.

Project Window
In Format Tab, verify sequence settings
Project Type: 1080p/23.98
Color Space: YCbCr 709
Stereo: OFF
Aspect Ratio: 16:9 Raster: 1920×1080

Bin Window
Right-click inside the bin window.
Choose Import.
OR
File menu > Import

Click OPTIONS

Import Settings Window: IMAGE Tab 
Image Size Adjustment: Image Sized for current format
File Pixel to Video Mapping: 601SD or 709 HD (16-235)
Frame Import Duration: Leave at 30s
Autodetect Sequentially-Numbered Files: OFF
Alpha Channel: Invert on Import (white = opaque)

Import Settings Window: OMFI/AAF Tab 
Resolution: Use the source files’s resolution
Click OK.

Select Files to Import 
Choose your files

Resolution: 
Select DNxHD36 for 23.98
Select DNxHD45 for 29.97

Audio+Video –> Your Project Drive
Enable: ANY
Click OPEN

Import Will Begin 
You will see an import dialogue box indicating “Fast Import.”
Import should take several seconds per clip.
Fast import only requires Media Composer to copy the files to Avid MediaFiles and re-wrap them in an MXF container.
Approximately 80% faster than tranditional importing
If you do not specifically see the words “Fast Import”, there is a settings mis-match between the imported DNxHD file and your sequence settings.
They MUST be identical or Fast import will not work.

And you’re done. Your project media should now be imported and ready for editing.