Preparing Video Files for Event Processors and AV Vendors

The specification questions to ask the AV vendor before designing, the codecs that actually play, and the delivery checklist that prevents a failure on the night.

The most avoidable failure in event content is a file that will not play. It happens regularly, it is discovered late, and it is entirely a communication problem rather than a technical one: the studio delivered what it normally delivers and the venue runs something that expects otherwise. Ten minutes of questions at the start of the project removes the entire category of risk.

The questions to ask the AV vendor before designing are short. What media server or playback system is being used. What codec and container does it prefer. What is the maximum resolution it will handle without dropping frames. What frame rate is the show running at. What are the exact pixel dimensions of each screen surface. Is there a separate processor scaling the output, and if so what does it expect. Who is loading the file and when do they need it.

The exact pixel dimensions are the answer that matters most and the one most often supplied loosely. A screen described as roughly nine metres by two and a half is not a specification. The canvas is a specific pixel count determined by the panel arrangement, and delivering at any other size means the server scales, which costs sharpness. Wang et al. (2022), reviewing image quality measurement for large screen displays including LED, emphasise assessing quality from realistic viewing conditions, and scaling artefacts are precisely the kind of degradation that is invisible on a laptop and obvious in the room.

Codec choice is where studio habits and venue reality diverge. Delivery codecs designed for web distribution are efficient and computationally expensive to decode, which is the opposite of what a playback system wants. Media servers generally prefer intra frame codecs, where every frame is complete and no frame depends on its neighbours, because they scrub and loop reliably and decode predictably. Asking the vendor which they want, and delivering that, is more reliable than delivering the format that looks best in a file size comparison.

Frame rate should match the show rather than the edit. A file at a different rate than the system is running will be converted, which introduces judder that is far more visible on a large surface than on a monitor. Confirming the show rate before the edit is finished avoids a conversion that cannot be undone cleanly.

Audio needs an explicit decision rather than an assumption. Some event files carry embedded audio played through the house system; others are silent because sound is run separately from a different source. Delivering a file with audio when the vendor expects silence, or the reverse, produces either a doubled track or no sound at all. If audio is embedded, the level should be mixed for the room rather than for broadcast, since a ballroom system behaves differently from a monitor.

Loops need to be built as loops rather than trimmed to length. A holding loop with a one frame discontinuity at the wrap point will be visible to everyone in the room every few minutes, and it is one of the most common defects in ambient event content. The file should be checked by playing it repeatedly rather than watching it once.

A test file sent several days ahead is the single most effective safeguard available and it costs almost nothing. A short clip at the final specification, loaded onto the actual system by the actual operator, confirms the codec, the resolution, the frame rate and the audio configuration while there is still time to re-export. Discovering an incompatibility at rehearsal is recoverable; discovering it an hour before doors is not.

The delivery package should contain more than the master. A complete set typically includes the main film at the exact canvas specification, a looping holding state, a lower intensity variant for speaking segments, individual surface exports if the server requires them, and a simple fallback file in a widely compatible format in case the primary fails. The fallback is rarely needed and has rescued a great many events.

Naming matters more here than in most delivery contexts because the person loading the files did not make them and is working under time pressure. Files should be named with the event, the segment, the surface and the version, in a form that sorts correctly and cannot be misread. A folder containing final_v3 and final_new is a folder in which the wrong file will eventually play in front of an audience.

References

Wang, J., Mou, X., & Wen, C. (2022). Measurement of image quality for large-screen displays based on audience viewing: Overview of standardization and preliminary study on laser projection displays and LED displays. Journal of the Society for Information Display, 30(6), 523–530. https://doi.org/10.1002/jsid.1095