Mini Movie Trailers Ease Post Industry Into Mobile Media World

Movie trailers are bite-sized and bombastic ‘ the perfect guinea pigs for the post industry’s first tests of content distribution to portable players like cell phones and iPods. A good thing, too, since the post-production business is just this side of having to address small content on a big scale, along with impending changes in workflow and technical culture.

“Right now, the new-media work we’re doing for trailers is essentially being overlaid on top of the conventional workflow, but that’s in the process of changing,” comments Noam Dromi, vice president of digital media at CMP Impact, the new-media division of Craig Murray Productions. Noting that film trailers have become a highly specialized art and craft of their own, with post houses combining both editorial and creative work, Dromi says studios see post-production for online trailer distribution as a more mechanical process. “We’re participating after the fact; we should be involved more in the creative aspects of trailers for portable devices,” he states. “The post house has to make qualitative decisions based on a range of technical issues. There is definitely some conflict as the culture changes.”

A conventional two-and-a-half-minute trailer is a manageable chunk of content for theaters. But even that needs significant modification for handheld distribution. For starters, studios are cutting deals with individual cellular carriers, Each carrier has its own network and a variety of operating systems for the individual phones, none of which can support 30 fps video now anyway. “Each carrier has a different way of integrating video into its system,” says Dromi. “We have to know their standards first, and we also have access to the specifications of every manufacturer’s handsets.”

Trailers are processed and edited for mobile devices mainly with streaming in mind rather than downloading. Downloads, which are played back from a complete file on the phone, offer higher quality. However, files could overwhelm or exceed the memory capacity of many cell phones, and there are DRM issues associated with widely distributing a complete file. Streaming sends the file in packets to the consumer device without demanding memory space. However, it does require buffering as the stream progresses, and is subject to packet loss due to consistency problems in the carriers’ networks. The same issues that cause dropped calls can also cause jerky picture and audio as the buffer fills and empties. Buffering can slow the frame rate further, which limits the level of video effects and dynamics a scene can have.

These trailers are created using elements from the theatrical versions. “We're going to be looking for the elements from which we can create a 25- to 30-second digital trailer version that can still tell the story,” says Dromi. The film trailer is digitized to the D-1 tape format and reviewed to identify the key scenes.

The editors are looking for key scenes that do not involve camera pans. “If you try to stream panning, you're going to get a lot of artifacts,” he says. “Pans require a lot of complex information, and that translates into bandwidth when you're streaming it. Too much data diminishes the quality of the experience, so we have to do a data analysis of each frame.”

The chosen scenes are edited together on an Avid system and then sent for compression and programming. MPEG-2 and MPEG-4 are the most common compression engines, in addition to DivX and Windows Media formats. Dromi says compression choices are dependent on the handset and the mobile operating system (MOS). “If you have a PDA phone with a Windows Mobile 5 MOS, you'd want to use MPEG-4,” he says. “If it's a Treo, you'd usually want MPEG-2.”

Programming is farmed out to companies that specialize in the Java or Brew environments. “They'll take the video asset and create a Java media player,” says Dromi. “You have to have the proprietary solution that enables the playback of media on each type of device. In Windows Mobile 5, it's Windows Media Player. You're better off going to somewhere where they have expertise in this domain.”

The transcoded clips are then conformed to the handset specifications and the Java code is communicated to the carrier, which tests the clip on its network and reports back on any anomalies, such as frame drop-outs.

Ascent Media does this programming work in-house. It’s part of what company CTO Jose Royo says is a far-reaching integration of the digital services group he heads up and the larger post-production environment at Ascent’s facilities. His group’s major digitization clients include Sony Pictures and BMW.

“This won’t be a parallel universe,” Royo says, pointing out that the transcoding and programming his group is already doing for virtual distribution of digital master prints to theaters translates well for streaming and downloading applications, too. “So we have to integrate the workflow as much as possible.” The foundations have been laid with a scalable networked storage server system that extends to all post departments. But, while the server can make sure everyone is connected, it will take more to make them feel included. “We have a file-based workflow now, but like many post-production companies we’re still largely niche-oriented operationally ‘ one does editing only, one does audio only, and so on. The file server is the basis for the ability to collaborate totally.”

Company 3 and Encore Hollywood are the two Ascent Media companies that are working most closely with the creation of movie trailers that are edited or packaged for streaming and downloadable content. They finish those trailers in HD and possibly SD, then deliver them to Ascent’s Digital Media Distribution Center in Burbank, where they are digitized to meet various mobile operator specifications. In some instances, instead of a direct encode to a specified streaming format, a high-definition digital file is created at high data rates (160 mbps or more) as a mezzanine file (a partially compressed file) for transcode to multiple outputs. In other instances, mobile derivatives are created from the Digital Cinema Distribution Masters (DCDM) in the JPEG-2000 format.

These mezzanine files are saved to online servers or LTO tape. From those masters, mobile outputs are generated using transcoding engines from companies including Digital Rapids, Rhozett, Inlet and others. These outputs are 20 Mbps sub-master files that are transcoded by the wireless carriers into their final formats for streaming. The final data rates range from 300 kbps to 1.2 mbps, according to the specs of the mobile device formats, which include QuickTime, Windows Media and H.264. Frame rates are about half that of NTSC video, though never less than 12 fps, Royo says. Delivery can be electronic, via DVD, or on a FireWire drive.

Just as the amount of information in a frame is crucial to how well it translates to the small screen, audio has to be truncated and remixed to mono. Dromi says QuickTime, which integrates the Sorenson codec, usually offers the best audio outcomes, with better synchronization to picture during a progressive download or streaming. “Downloads are best for audio, but the reality is that sound will always be limited by the capabilities of the playback device,” he says. “For best results with audio quality in a piece of encoded video, we try to use uncompressed 44.1-kHz 16-bit sources. Using an uncompressed source is particularly important when encoding to a high bit-rate output, such as AAC-LC at 32-Kbps or higher. With AAC-LC encoding at this bit rate, there will be a noticeable difference in the audio quality if your source is only 22-kHz or 8-bit.”

Trailers, along with broadcast commercial spots, lend themselves well to experimentation. They’re well-suited by size, important but ultimately disposable, and familiar. Both Dromi and Royo expect the tools to create streaming and download versions of content to get progressively better, and as the cost of bandwidth and storage decline and personal playback devices improve, what the post business learns from trailers will be applied to long-format content. “We’re still at the very early stages of the technology and of understanding what consumers want in terms of content for personal devices,” says Dromi. “But it’s where the post-production industry has to go.”