HIGH DEFINITION - TECHNICAL DETAILS
Our first two High Definition productions based on the new h.264 codec were Les Misérables and "Radley at Christmas 2009". Since the process of filming in HD and using the h.264 codec for Blu-ray is new, there is little information available - hence this page. We also cover downscaling to standard definition (which is more difficult than we hoped!) and producing video for the internet.
FILMING
- Our HD cameras were all set to 50th shutter, and indoor white balance.
- Wide angle (S270): Fixed focus set to 20m (mid-stage). Exposure manual, aperture from f2.8 to f4. Gain 9dB
- Other cameras: AE Shift set to around -4
SOUND
Microphones situated above stage, with nearby pre-amps. Test recordings done each night. Best settings: Ultragain Pro: Output +4dB Mic gain zero. Compression 3. Threashold -15dB. Output zero. Peak limit -3dB. Recorded via mixer to computer.
NOTE THAT THE FOLLOWING IS BASED ON ADOBE CS4. We have since changed to CS5 so much of the detail is out of date for exisiting projects.
CAPTURE
Capture straight to computer for reference. Also to separate hard-drive unit. But all capture for the full HD and SD projects was from tape or memory card taken from cameras.
ORGANISATION
The project was captured to separate hard drives on Video 2, and MPH Home, with backup on ICY portable. Act 1 and Act 2 were placed on separate drives as separate projects.
EDITING
Editing was with multicam, with 4 cameras producing a single sequence which was nested with the 3 extra cameras. This was reasonably stable, especially with soundtracks unlinked and treated separately. Fortunately the scrolling credits were treated as a separate project, as they are very memory hungry. On reflection it would have been better to export these as an avi file and import into Act 2. (instead of placing separately on timeline in Encore).
EXPORTING
The High Def timeline sequence was exported using Adobe Media Encoder directly to h.264. The bug which caused black levels to rise had been fixed. The HD project was able to fit on a single side 25GB blu-ray disc.
Bitrate: Act 1 & 2: 16 Mb/s. The Bonus Feature: 14 Mb/s. The sound was exported as Dolby Digital at the same time, set to 256.
HIGH DEF FILE SIZE SUMMARY
High Def: Total running time 195 mins.
Act1 + Act2 = 144 mins @ 16 MB/s = 17 GB.
Bonus + Wed Cosette = 51 mins @ 14 MB/s = 6.5 GB
The size of each stereo sound file converted to Dolby Digital was insignificant (e.g. 1 hour < 0.2 GB)
CONVERSION FROM HD TO SD
The HD timeline sequence was also exported as Matrox avi without sound (to avoid another bug). These were MPEG2-i-frame avi sequences, ready for conversion to standard definition.
When encoding the Carol Services, it was found that Adobe Media Encoder produced poor results when exporting and downscaling direct to standard def MPEG2. Using the avi export (above) results were a little better using Procoder. Tests indicated that scaling down by importing to a SD project in Premiere (as used by many people) was not good, especially at low bitrates. (The Carol Services were initially attempted this way, but quality was too poor to continue).
The most successful (but very slow) method was using AviSynth (free to download) combined with Procoder. AviSynth is a text based programme which does a remarkable job of downscaling from HD to SD, ready for Procoder to convert to MPEG2. The complete conversion requires a time of 5X running time - on a very fast computer, with 4 cores working at 98%.
Bitrate: Act 1: 6 Mb/s, Act 2 and Bonus: 5 Mb/s. The sound files for the SD project were copied from the HD project.
DVD AUTHORING
The HD menu was prepared with Photoshop and all the HD files and soundtracks imported without re-encoding. The HD menu was scaled to SD in photoshop - using 720 by 576 frame size, but setting the pixel aspect ratio to widescreen. Quality, including text was virtually identical to creating a SD menu from scratch. The TV image displays also scaled down very well.
Chapter points had to be re-entered for the SD project. And the files would not fit on a single disc so Act1 and Act2 + Bonus Feature, were on separate DVDs.
INTERNET (and INTRANET)
We have adopted the settings used by the BBC iPlayer to take advantage of the extensive research carried out by the BBC in determining bitrates which work for the wide variety of internet users.
- Basic iPlayer settings> Codec: h264 / Bitrate: 500 to 800 kbps / Image size: 640 x 360
- High Quality iPlayer settings> Codec: h264 / Bitrate: 1.5 Mbps / Image size: 832x468
- Full HD iPlayer> Codec: h264 / Bitrate: 3.2Mbps with 192kbps audio / Image size: 1280 x 720 (i.e. 720p)
e.g. Les Mis Bonus Feature (on Intranet), total file size (h264 .f4v) = 243 MB. Running time 45 minutes. Bitrate 600 kbps, image size: 640 x 360
Note that the .f4v files require a player (or skin) which must be included with the file before it will play. Radley Video has adopted Flowplayer which also provides automated timings. Flowplayer is free (with the Flowplayer logo) or available to purchase in which case the logo can be removed or replaced with another logo.