MP4 is primarily a container format. It can contain video encoded with codecs such as H.264, HEVC, or AV1 and audio such as AAC.

No. MKV, or Matroska, is a container that can hold many different video, audio, subtitle, and metadata streams.

Codec vs Container: MKV, MP4, H.264 & HEVC Explained

Q: What is the difference between H.264 and MP4?

H.264 is a video codec; MP4 is a container. An MP4 file can contain H.264 video, but it can also contain other video codecs.

Quick answer

MP4, MKV, MOV, AVI, and WebM are containers. H.264/AVC, HEVC/H.265, AV1, AAC, AC3, and DTS are codecs. A familiar container can still fail to play when one of the streams inside uses a codec the current playback path cannot decode.

Container

A container is the file structure that holds one or more media streams and related information.

Examples: MP4, MKV/Matroska, MOV/QuickTime, AVI, WebM, MPEG-TS.

Codec

A codec defines how a video or audio stream is compressed/encoded and decoded for playback.

Video: H.264, HEVC, AV1, MPEG-2, ProRes.
Audio: AAC, AC3, EAC3, DTS, FLAC, MP3.

One container can hold many different codecs

movie.mp4\n├─ Container: MP4\n├─ Video: H.264 / AVC\n└─ Audio: AAC\n\nmovie-4k.mp4\n├─ Container: MP4\n├─ Video: HEVC / H.265\n└─ Audio: EAC3

Both files end in .mp4, but they require different decoding support. That is why “MP4 works on my computer” does not guarantee that every MP4 file will play.

Common containers and codecs

Name	Type	Common role
MP4	Container	Common delivery container for H.264, HEVC, AV1 and AAC-based media.
MKV / Matroska	Container	Flexible container for many video, audio and subtitle formats.
MOV / QuickTime	Container	Common in phones, cameras, editing and Apple workflows.
AVI	Container	Older Windows-era container that can hold many legacy codecs.
H.264 / AVC	Video codec	Very widely supported HD and web/video codec.
HEVC / H.265	Video codec	More efficient compression, common in 4K, HDR, phones and cameras.
AV1	Video codec	Modern high-efficiency codec used in newer web and distribution workflows.
AAC	Audio codec	Common audio codec in MP4 and streaming media.
AC3 / EAC3	Audio codec	Common surround-sound formats in video media.
DTS	Audio codec	Surround-sound format often found in disc-derived or MKV media.

Why this matters when a file will not play

If Windows recognises the container but cannot decode the video stream, you may see black video or an unsupported-video message.
If the video stream works but the audio codec is unsupported, the picture may play normally with no sound.
If neither stream is the problem, investigate corruption, incomplete transfers, DRM, hardware acceleration, player configuration, or output devices.

Inspect a media file Troubleshoot playback

Frequently asked questions

Is MP4 a codec?

No. MP4 is primarily a container. It can hold H.264, HEVC, AV1, and other video streams together with audio such as AAC.

Is MKV a codec?

No. MKV (Matroska) is a container. Its flexibility is one reason two MKV files can have very different playback requirements.

What is the difference between H.264 and MP4?

H.264 is a video codec; MP4 is a container. H.264 is commonly stored inside MP4, but MP4 can also contain other codecs.

Codec vs Container: MKV, MP4, H.264 and HEVC Explained