NEWS
TECH BLOG / May 28, 2018
Guidelines for Master File Creation of 360° Films
By Sergio Sanz-Rodriguez, PhD — The purpose of the guidelines presented in this blog is to help Virtual Reality (VR) and 360° content providers to prepare master files with the highest possible quality for submission to film festivals, film markets, online Video-on-Demand (VoD) platforms, or archiving systems. Master files produced according to these guidelines will enable service providers to generate compressed versions for high quality screenings to target viewers.
This blog includes a set of recommendations on video and audio parameters, exporting formats, and file formats or containers. These guidelines have been created as part of the EU-funded DDD60 project (ddd60.eu), and are the result of the collaboration between the project partners that include media technology companies and film festivals and markets, and content creators and artist
The guidelines presented in this document are aligned with those provided by the VR Industry Forum (VRIF) group to facilitate the creation of next generation VR applications, and meet the specifications given in the Omnidirectional Media Application Format (OMAF) standard.
Master File Creation
The master file with multimedia VR and 360° content is the highest-quality file that can be obtained after post-production. The quality of the original master content depends on the artistic and technical resources utilized in the production (camera) and post-production (stitching, color grading, editing, exporting software) workflows.
In order to preserve the original quality of the content, the master file should have the less amount of transcoding operations possible, and should be either uncompressed or lightly compressed with post-production codecs, such as ProRes or Cineform.
The set of preferred video and audio parameters, codecs, and formats listed in the next sections mostly fulfills the common working procedure for VR content creation. However, for further details or questions, the reader can be referred to the VRIF guidelines or contact the authors of the document.
Video Parameters
| Bit Depth | In order of preference: - 12-bit - 10-bit |
| Color Sampling | In order of preference: - 4:4:4 - 4:2:2 |
| Color Space | ITU Rec. 709 (gamut levels within the threshold defined by EBU R103) |
| Scan | Progressive |
| Resolution Mono | In order of preference: - Beyond 8Kx4K - 8Kx4K: 8192x4096 - 6Kx3K: 6144x3072 - 4Kx2K: 4096x2048 |
| Resolution Stereo | In order of preference: - Beyond 8Kx4K per eye - 8Kx4K per eye: 8192x4096 - 6Kx3K per eye: 6144x3072 - 4Kx2K per eye: 4096x2048 |
| Layout Stereo | Top-bottom (L-R) |
| Frame Rate | In order of preference: - 100 / 120 frames/s - 75 / 90 frames/s - 50 / 60 frames/s - 24 / 25 / 30 frames/s |
| Projection Format | Equirectangular with no visible stitching artefacts |
| Video Codec | In order of preference: - ProRes (422 HQ or 4444) - Cineform - DNxHD - DPX - TIFF |
Audio Parameters
| Bit Depth | In order of preference: - 32 bit floating point - 24 bit - 16 bit |
| Sampling Rate | 48 KHz |
| Non-spatial Format (Mandtory) | In order of preference: - 7.1 - 5.1 - 2.0 |
| Spatial Format (Optional*) | In order of preference: - 2nd order ambiX - 1st Order ambix |
| Audio Codec | In order of preference: - WAV - AAC |
* Please, ask the service provider (e.g., the organizer of a VR/360° library for film festivals) for information about spatial audio support.
Container
| ProRes,Cineform, DNxHD | MOV |
| RAW | DPX TIFF |
Metadata
The MOV format already includes metadata describing the projection method (equirectangular, cubemap) and the stereo-3D layout (top-bottom, side-by-side). This information can be embedded in the distribution file and conveyed for the decoding and rendering operations in the media player.
References
- The Virtual Reality Industry Forum, “VRIF Guidelines”: http://www.vr-if.org/guidelines/, Sep. 2017.
- The Moving Picture Expert Group (MPEG), “Omnidirectional Media Format”: https://mpeg.chiariglione.org/standards/mpeg-i/omnidirectional-media-format, Jan. 2018.
Funding
This activity has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 732717 (ddd60.eu)