1080i50 to 23.98p Workflow

Re-Authoring Non-US BD Content for US Players

by Danny Ludwig

Introduction

In theory, BD supports a lot of formats with different frame rates, which should be playable worldwide without problems, but within the US not all frame rates work. We have discovered that many US BD players have problems with frame rates commonly used in European authoring, resulting in no video display during playback. This document describes a workflow for re-authoring international BD content to work with US BD players.

In outline, the process involves changing 1080i50 video to 1080p23.98, and adjusting the audio and subtitles to match.

Before starting with this workflow, output your content as a QuickTime movie containing all audio tracks (2.0 and/or 5.1). Be sure to keep the original files, in case you need to make changes later.

Step 1. Deinterlacing 1080i50 video

We will use BitVice Purifier (version 1.4.5) to deinterlace the video to 1080p25. Purifier has very good quality output, as it uses high quality FIR-filters.

  • Open your 1080i50 video (Command-O) and then display the project properties (Command-P).
  • test

  • In the “Interlacing/Deinterlacing” section at the bottom, check the “Interlaced 2:1” checkbox, then check the “Use deinterlacer” checkbox. (If you do not check “Interlaced 2:1” first, the “Use deinterlacer” checkbox will be disabled.)
  • Make sure that your output dimensions are set to 1920 x 1080. (Even if you’re using HDV or any other 1440 x 1080 content, you should use still 1920 x 1080 for the output.)
  • Close the project properties by clicking the OK button.
  • Start the conversion by clicking the Process button in the right lower corner. You will be asked for a destination folder for the output, and also for the codec to use.

test

As Purifier works with 16-bit values internally, Innobits recommends the use of 10-bit uncompressed format for the best results on the output, but you may use other formats if you wish.

Step 2. Conforming the 1080p25 video to 1080p23.98

For conforming, we will use Apple’s Cinema Tools from the Final Cut Pro suite. It’s also possible to use Adobe’s After Effects.

  • Drag the output video from step 1 onto the Cinema Tools application icon.
  • Click the Conform button in the main window, choose the correct frame rate from the “Conform Clip” dialog:
  • test

  • Press the dialog’s Conform button.

Note that if you have no existing Cinema Tools database, you will be asked to create it, but it’s not needed for the conforming process. Also keep in mind that Cinema Tools will discard QuickTime chapter markers when conforming to a different frame rate.

Step 3. Conforming the audio

If your QuickTime movie contains all its audio tracks, they will be conformed along with the video in step 2, and you do not need to process the audio separately. (However, see the note below about changes in audio pitch.)

If your audio is separate, you can create a dummy 1080i50 sequence in Final Cut Pro, put all the audio into it, export it (not self-contained), conform it to 23.98 fps, and finally export the individual audio tracks using QuickTime Player. This will give you back the native mono audio tracks.

If you create a 5.1 channel sequence setting in Final Cut Process, note that there are some level reductions on some channels which you should fix before exporting. Control-click on your sequence and go to the Audio Output tab:

test

You’ll need to restore channel 3 (center), channel 4 (LFE) and channels 5 & 6 (rear) to the 0 dB setting:

test

A final note: when you conform a 1080p25 movie to 1080p23.98, your audio will be slightly lowered in pitch. If you want to maintain the original pitch, you need to start with audio that has been raised in pitch. Increase the pitch about 12 cent (1 semitone) using any competent audio editing application, such as Logic or Soundtrack.

Step 4. Conform subtitle timing

For conforming subtitle time codes, we recommend Subtitle TC-Converter, which is available as a freeware application from the www.truevision-video.de website.

  • Click the Import STL File button and choose the subtitle file. In the Import Settings dialog, choose the correct frame rate and text encoding, then click the Import button.
  • test

  • In the main window, set the new frame rate to “23.98 (non-dropped)” and click the Conform button:
  • test

  • You can also set a tape offset if you wish.
  • When prompted, click Save As to name your new conformed subtitle file:

test

You can then create your subtitles from the conformed subtitle file.