If you've been trying to understand video codecs and keep running into "H.264" and "H.265" (and sometimes "AVC" and "HEVC") as though they're different things, they mostly aren't. They're the current dominant video codec and its successor - two generations of the same family, developed by the same engineers ten years apart, doing exactly the same job: fitting a video into as few bytes as possible without it looking obviously worse. The newer one does the job about 40% better. That's the whole story; everything else in this piece is context.

Think of the naming this way. Cars work fine even though the same model has different names in different markets - a Honda Civic in the US is the same car as a Honda Civic Type R Hatchback GXi in some other regions. Video codecs are similar. The international standards body (ITU) calls them "H.264" and "H.265". The film-industry body (MPEG) calls the same two things "AVC" and "HEVC". Marketing calls the newer one "H.265" one week and "HEVC" the next. All four names refer to two codecs. Once you have that lodged, half the confusion vanishes.

#The naming, in one place

  • H.264 = ITU-T H.264 = MPEG-4 Part 10 = AVC (Advanced Video Coding). Ratified in 2003. This is the workhorse codec of the modern internet - YouTube's primary delivery format for over a decade, the default recording format of essentially every consumer camera from 2005-2015, and the codec every hardware decoder chip on every device supports.
  • H.265 = ITU-T H.265 = MPEG-H Part 2 = HEVC (High Efficiency Video Coding). Ratified in 2013. Roughly 40-50% better compression at the same visual quality as H.264, at the cost of being harder for older devices to decode and being tangled up in patent licensing that slowed adoption.

"H.264" and "AVC" refer to the same codec. "H.265" and "HEVC" refer to the same codec. The ITU number (H.26x) is what standards documents use; the MPEG name (AVC/HEVC) is what consumer marketing uses. Same underlying technology, same encoded bitstream, same decoder chip - just different labels depending on who's writing.

#What HEVC does better

HEVC is smarter about squeezing video for three specific reasons, and you don't need to know the details to trust the outcome - but they're worth naming so the "40% smaller" number doesn't feel like magic. First, HEVC works with bigger pieces of the picture at once - up to 64x64 pixel blocks compared to H.264's smaller 16x16, so a flat region of sky can be compressed as one big chunk instead of 16 little ones. Second, it does a better job predicting how each frame moves from the previous frame (which is how video codecs avoid re-storing pixels that didn't really change). Third, it smooths the edges between compressed blocks more elegantly so the result looks less obviously chunked.

Add all three up and HEVC averages about 40% smaller files at the same visible quality. You can spend that saving in three ways: keep the file size the same and get higher quality, keep the quality the same and get a smaller file, or keep both the same and use the savings to fit 4K where 1080p used to fit. That's what streaming platforms and iPhone cameras have done: they moved the savings into more pixels rather than smaller files.

Practical example: a 5-minute 1080p clip encoded to visually-transparent H.264 lands at about 380 MB. The same clip encoded to visually-transparent HEVC lands at about 230 MB. On 4K content the gap widens further: 4K HDR HEVC content on streaming platforms is roughly half the size of the equivalent H.264 encode, which is why Netflix, Apple TV, Amazon Prime, and Disney+ all deliver 4K in HEVC exclusively.

#What H.264 does better

  • Universal decode support. Every device, every browser, every OS, every embedded player made in the last 15 years decodes H.264 natively without extra codec install. HEVC decode is universal on modern devices (post-2016) but still needs the HEVC Video Extensions app on Windows 10 and doesn't work reliably in Chrome on all platforms.
  • Faster software encode. H.264 encoding via libx264 is 2-3x faster than HEVC via libx265 for equivalent quality output. On machines without hardware HEVC encoders, H.264 is the practical choice for encode-heavy workflows.
  • Simpler patent story. H.264 has a single well-known patent pool (MPEG-LA). HEVC has three (MPEG-LA, HEVC Advance, Velos Media) with overlapping terms, which is the reason browser vendors stalled on shipping in-browser HEVC playback for years.

#The compatibility split, by device

  • iPhone / iPad (post-iPhone 6): Both codecs decode in hardware. iPhones record HEVC by default in High Efficiency mode (iPhone 8+).
  • macOS (Big Sur 11.0+): Both codecs decode in hardware. QuickTime Player, Safari, Chrome all play HEVC natively.
  • Windows 10 and 11: H.264 native; HEVC needs the HEVC Video Extensions app ($0.99 in the Microsoft Store, often preinstalled free by the PC maker). Neither version includes it out of the box. Once installed, every app that uses the Windows decoder plays HEVC - see HEVC Video Extensions explained.
  • Android (post-2016): Both codecs decode in hardware on most devices. Cheap Android devices from certain manufacturers may skip HEVC decode - depends on the chipset.
  • Chrome on Windows/Linux/Android: H.264 native; HEVC only recently added (Chrome 107+ on desktops, spotty on mobile). Requires a supported hardware decoder path.
  • Firefox: H.264 native; HEVC not supported in the browser.
  • Smart TVs: Both codecs decode in hardware on any TV from 2016+; older TVs might skip HEVC.
  • Consumer video players (VLC, MPC-HC): Both codecs, all versions.

#Where H.265 wins in practice

  • iPhone camera storage. HEVC recording lets iPhone photos and videos take about 40% less space at the same visual quality. That's why Apple defaults to HEVC in the High Efficiency setting.
  • 4K streaming and download. Netflix, Apple TV+, Disney+, and Amazon Prime all deliver 4K exclusively as HEVC. Roughly half the bandwidth of an H.264 4K encode.
  • Blu-ray Ultra HD. Every UHD Blu-ray is HEVC. H.264 was never used for UHD Blu-ray - the bitrate math didn't fit.
  • Broadcast (ATSC 3.0, DVB-T2). Modern digital TV standards use HEVC because delivering 4K over broadcast bandwidth requires the compression efficiency.

#Where H.264 still wins

  • Everything sent to a stranger. If you're sharing a video via email, Discord, WhatsApp, or a website, H.264 is the safe default. Every recipient decodes it without extra install. HEVC works for most but not all.
  • Editing intermediate. Editors (Premiere, Final Cut, Resolve) work with H.264 more predictably than HEVC because H.264's decode is faster in software. ProRes or DNxHD are the actual editing-optimal codecs, but H.264 as a "reasonable file to edit" is more common than HEVC.
  • Live streaming. YouTube Live, Twitch, and every streaming CDN accepts H.264 with universal compatibility. HEVC live streaming exists but the encoder cost and decoder support are more constrained.

#The conversion between them

Converting H.264 to HEVC or HEVC to H.264 always requires a full re-encode - decode every frame, re-encode to the target codec. The visual quality trade-off depends on the encoder settings: a high-bitrate H.264 source converted to a similar-bitrate HEVC will be nearly indistinguishable from the source, but a low-bitrate HEVC converted to H.264 will show visible generation loss because H.264 at low bitrates can't match HEVC's efficiency.

By default Wave copies HEVC video into MP4 as it is, without re-encoding, because HEVC is a valid MP4 format and copying keeps full quality. When you need broader compatibility (Windows PCs without the HEVC extension, older TVs, embedded players), turn on Make it play everywhere and Wave re-encodes it to H.264 in your browser; HandBrake's H.264 presets do the same on a desktop, faster for long files. When your source is H.264 and you want HEVC's smaller files, HandBrake with the x265 encoder is the practical tool - Wave only writes H.264.

#The takeaway

H.264 and H.265 are consecutive generations of the same codec family. HEVC (H.265) gives roughly 40% better compression at equivalent quality, which matters for storage-limited devices (iPhones), bandwidth-limited delivery (4K streaming), and mass distribution (broadcast, Blu-ray). H.264 is universal - everything decodes it, everything encodes it fast. For sharing to strangers, H.264 is the safe default; for storing your own footage efficiently or delivering high-quality 4K, HEVC is the win. See H.264 vs HEVC vs AV1 for the full three-codec comparison including AV1 as the next generation.