How to send large video files to clients

Why is sending a 4K video so hard?

A finished 4K wedding film can easily be tens of gigabytes. A single upload of that size takes hours on most connections, and one drop in the connection can mean starting again. On the other side, a client has to download the whole file before watching, often on a phone with limited storage. The tools most people reach for were built for documents and short clips, not for feature-length films in high quality.

Why do file-transfer links expire?

Storing large files costs money, so most file-transfer services keep them for a short window and then delete them. That is reasonable for a quick hand-off between colleagues, but wedding couples are busy, often travelling, and may not open the email for a week or two. When the link expires, they ask you to resend, you upload again, and the delivery loses its magic. For a film meant to be kept, a link that lasts a few days is the wrong tool.

How do you work out a video's file size?

File size is bitrate multiplied by duration, then divided by eight to turn bits into bytes. Bitrates are quoted in megabits per second (Mbps), so the maths is: Mbps x seconds / 8 = megabytes. Divide by 1,000 for gigabytes. Audio adds a little on top, usually small next to the video.

Worked example: a 30-minute 4K film

• Master at 100 Mbps: 100 x 1,800 seconds = 180,000 megabits. Divide by 8 = 22,500 MB, or about 22.5 GB.
• 4K delivery file at 50 Mbps: half the bitrate, so about 11.25 GB.
• Streaming rung at around 16 Mbps: 16 x 1,800 / 8 = 3,600 MB, or about 3.6 GB for the whole film, delivered a few seconds at a time as it plays.
• 1080p download at 20 Mbps: 20 x 1,800 / 8 = 4,500 MB, or about 4.5 GB.

This is why streaming matters: a client watching on a TV needs only a fraction of the master's data per second, and it arrives as they watch. Try your own numbers in the delivery size calculator.

How long will a large upload take?

Upload time is the same maths in reverse: file size in megabits divided by your upload speed. Most connections upload far more slowly than they download, so check your upstream figure, not the headline speed. Taking the 22.5 GB master above, that is 180,000 megabits. On a 50 Mbps upload, 180,000 / 50 = 3,600 seconds, so about an hour in perfect conditions. On a 10 Mbps upload it is roughly five hours. Real-world speeds are usually a little lower than the line rating, so leave headroom, and plan big uploads around your editing day rather than squeezing them in before a deadline.

Should you send clients the master file?

Usually not. A master exported at a very high bitrate, or in a professional codec such as ProRes, is enormous, and many phones, TVs and home computers will not play it smoothly. Couples are better served by a high-quality delivery file in H.264 or H.265 that plays everywhere. Keep the master in your own archive, where it can be used to re-export if a client ever needs a different version.

What makes a large upload reliable?

The single most important feature is resumable uploading. Instead of sending one enormous file in one go, a resumable uploader splits it into parts and sends them one by one. If the connection drops, only the part in progress is lost; the upload carries on from where it stopped. A few other habits help too.

• Use a wired connection where you can. Wi-Fi drops are the most common cause of failed uploads.
• Stop your computer sleeping during long uploads.
• Upload overnight if your upstream speed is modest.
• Check integrity. A fingerprint (checksum) of the file proves that what arrived is exactly what you sent.

Dellro accepts up to 500 GB per file. Uploads go in parts and resume after a dropped connection or even a closed browser: add the same file again and it carries on. Each file is fingerprinted (SHA-256) in your browser before upload, and duplicate files already in the gallery are not stored twice. See large file uploads.

How can you make video files smaller without losing quality?

• Use H.265 for 4K downloads when you know your clients' devices support it; it reaches similar quality at a lower bitrate than H.264.
• Use two-pass or quality-based encoding so the encoder spends bits on complex scenes and saves them on simple ones.
• Do not over-specify. Beyond a point, extra bitrate adds size without visible gain for typical viewing.
• Match the source. Do not export 4K from a 1080p finish, and do not exceed the frame rate you shot at.
• Keep masters separate. Your archive master can be enormous; the client file does not need to be.

What is the best way to send large videos to wedding clients?

Upload once to a gallery that streams and downloads. The couple presses play straight away, family can watch on the TV, and the original files are there to save. In Dellro, each film is encoded into an adaptive ladder up to its source resolution, playback starts at a lower rung and steps up as the connection allows, and originals stay downloadable for 12 months from gallery creation. Read the full guide to delivering a wedding film or see downloads.