HEVC (H.265) to MP4 (H.264)

Why HEVC will not play on some PCs

HEVC, finished in 2013, stores 4K and HDR video at about half the size of H.264, so phone makers adopted it quickly. iPhones record it by default under the High Efficiency setting, many Android phones offer it, and GoPro and DJI cameras and many security systems use it too. On an iPhone, switching the camera format to Most Compatible records H.264 instead, which avoids the problem for future clips.

Playing it is another story. On Windows, the built-in Media Player and Photos app need Microsoft's HEVC Video Extensions, a paid add-on in the Microsoft Store unless your PC maker included it. Older laptops, TVs and video editors may have no HEVC decoder at all. VLC plays HEVC by itself, but the people you send a video to may not have it. H.264, by contrast, has played on nearly every phone, TV, browser and editor for well over a decade.

Getting H.264, not a copy

MP4 can hold HEVC, so Octoolo's default, As it is, copies HEVC into the MP4 unchanged. That is right for a lossless change of container, but the video is still HEVC. To get H.264, pick High, Balanced or Small: each re-encodes the picture, and with Video codec left on Automatic, the codec is H.264.

The line under each file confirms it. “H.264 on the NVIDIA graphics card” means H.264 is being made. If you see “Copied as it is, nothing re-encoded” there instead, the HEVC was kept as it was, and the file needs converting again with High. The quality you pick is remembered for next time, so switch back to As it is when you want plain copies again.

Size, speed and your graphics card

H.264 is the older codec and needs more data for the same picture, so at High the MP4 is usually larger than the HEVC original. Balanced keeps it nearer the original's size at some cost in fine detail, and Small suits messages.

Under More settings, a 4K clip headed for an older laptop or TV can come down to a Size of 1080p, and 60 frames a second to 30. Octoolo only ever lowers these.

Re-encoding is heavy work, so Octoolo uses the video encoder on your graphics card when there is one: NVIDIA, AMD and Intel all work. PCs without such a chip fall back to Windows' encoder, and then to the processor. One file is re-encoded at a time, while the rest of the list waits. A 4K clip takes longer than a 1080p one, and the time left is shown as it goes.

Going the other way

To save space instead, turn H.264 into HEVC: choose H.265 (HEVC) under More settings › Video codec. That too is encoded on the graphics card when it has an HEVC encoder, with Windows' encoder or the processor as fallbacks; older cards that only encode H.264 simply hand the job to the next in line. Octoolo labels HEVC MP4s the way Apple's players expect, so they play on iPhones and Macs.

Keep in mind who will watch: an HEVC file saves room on your drive but brings back the playback problem above on PCs without the extension. The video compressor covers other ways to make videos smaller while staying with H.264.