H.264

What is H.264?

H.264, also called AVC (Advanced Video Coding) or MPEG-4 Part 10, is a video compression standard that delivers good image quality at small file sizes and plays on virtually every device and browser. Published in 2003, it remains the most widely used codec for web video, streaming and client deliverables. H.264 video is usually stored in an MP4 or MOV container.

Why it matters

Compatibility is the main reason filmmakers use H.264. A client may open your film on an older laptop, a work PC with locked-down software, a smart TV or a phone on mobile data. An H.264 MP4 will almost certainly play on all of them without extra software. That makes it the safe default for the main file most clients receive, and the standard format for uploading to social platforms.

How it works

H.264 reduces file size by removing information the eye is unlikely to miss and by avoiding repeated data between frames:

• Inter-frame compression. Frames are grouped into a GOP (group of pictures). Full keyframes (I-frames) are stored periodically, and the frames between them (P- and B-frames) store only what changed.

• Profiles. High Profile is standard for delivery. Most H.264 is 8-bit 4:2:0; 10-bit H.264 exists but has limited playback support.

• Bitrate control. Constant bitrate (CBR) or variable bitrate (VBR, often 2-pass) decides how much data each second gets. Higher bitrates mean better quality and bigger files.

• Fast-start. Placing the "moov atom" at the start of an MP4 lets players begin streaming before the whole file loads. Most NLEs call this "fast start" or "web optimized".

Sensible starting bitrates for client delivery: around 15 to 25 Mbps for 1080p and 40 to 80 Mbps for 4K, with VBR 2-pass. Social platforms recompress anything you upload, so going much higher mainly increases file size.

H.264 vs HEVC vs ProRes

H.265/HEVC achieves similar quality at roughly half the bitrate and handles 10-bit and HDR well, but older devices and some browsers do not decode it smoothly. ProRes is a lightly compressed editing codec with very large files, ideal as a master but impractical for casual viewing. A common pattern: H.264 for maximum compatibility, HEVC when file size or HDR matters and you know the client's devices, and ProRes as the master for clients who will edit or broadcast. Hosting platforms such as Vimeo and YouTube also convert uploads to H.264 or newer codecs for playback.

Does DLVRD support H.264?

Yes. You can upload H.264 files to DLVRD, and the original is stored and downloaded untouched. For streaming in the gallery, DLVRD creates H.264 8-bit playback copies with fast-start by default, because H.264 plays on effectively every browser and device.