Video Codecs and Containers Explained: MP4, MOV, H.264, ProRes

Video files confuse many new editors because the extension at the end of the name says little about what is inside. A file ending in .mp4 can contain several different kinds of video, and a file ending in .mov can do the same. Two separate ideas are involved: the container and the codec. Understanding both makes export choices clearer, prevents surprises when files will not play, and helps you pick the right format for editing, sharing and long-term storage.

Container versus codec

A container is the wrapper. It holds video streams, audio streams, subtitles, timing information and metadata, and it defines how those pieces are arranged on disk. Common containers include MP4, MOV, MKV and AVI. The container does not decide how the picture is compressed.

A codec is the method used to compress and decompress the video or audio. Codec stands for coder and decoder. Common video codecs include H.264, H.265 (HEVC), ProRes and DNxHR. The codec decides the quality, file size and how much processing power is needed to play or edit the footage.

The two can be combined in many ways. An MP4 file can hold H.264 or H.265 video with AAC audio. A MOV file can hold ProRes video with PCM audio. Software and devices support specific combinations, which is why a file can open on one machine and fail on another even when the extension matches.

Why compression matters

Uncompressed video is enormous. A single second of 1080p video at 30 frames per second, stored as uncompressed 8-bit 4:2:2 data, runs to about 124 megabytes, so a few minutes of footage would fill a large drive quickly. Codecs make video practical by removing redundancy within each frame and between frames.

Compression comes in two broad types. Intraframe codecs compress each frame independently. Interframe codecs predict frames from their neighbors, storing only the changes. Intraframe codecs are easier to edit because each frame can be decoded alone. Interframe codecs produce smaller files but need more processing to seek to a specific frame.

H.264 and H.265 for delivery

H.264, also called AVC, is the most widely supported delivery codec. It plays on nearly every phone, computer, television and browser, and it is the default for many upload pipelines. It is an interframe codec, so it is efficient for final files but can be slow to scrub in an editor, especially at high resolution.

H.265, also called HEVC, compresses more efficiently than H.264 at the same visual quality. Smaller files are the main advantage, and they matter for 4K delivery and long videos. Support is broad on modern devices, but older hardware and some browsers may not decode it, so check the requirements of the platform before choosing it.

The table below compares common choices in broad terms. Exact file sizes depend on resolution, frame rate, bitrate and content, so use these as directional guidance rather than fixed numbers.

Format	Type	Typical use	Editing speed	File size
H.264 in MP4	Interframe	Upload and general playback	Moderate	Small
H.265 in MP4 or MOV	Interframe	Compact 4K delivery	Moderate to slow	Smallest
ProRes 422 in MOV	Intraframe	Editing and finishing	Fast	Large
DNxHR in MOV	Intraframe	Cross-platform editing	Fast	Large

ProRes and DNxHR for editing

Intraframe codecs such as ProRes and DNxHR are designed for editing. Each frame can be decoded on its own, so scrubbing and playing multiple streams is smooth. They keep more detail and tolerate repeated re-encoding better than interframe formats, which matters when you apply effects or export intermediate versions.

The cost is size. ProRes and DNxHR files can be many times larger than H.264 files at similar resolution. Plan storage accordingly, and keep intermediate files on fast external drives so playback does not stall during editing.

ProRes is most common in Apple workflows, while DNxHR is widely used in cross-platform environments. Both are professional formats, and either is a sound choice for an editing timeline when the software you use supports it well.

Choosing the export format

Match the export to the destination. For a final upload to a video platform, H.264 in an MP4 container is the safest choice, because the platform will re-encode the file anyway and the widest compatibility matters most. For a finished master that another editor or colorist will work with, an intraframe codec in a MOV or MXF container keeps quality high and avoids generation loss.

For archives, keep the highest-quality master you can afford to store. A lossless or near-lossless master lets you create new deliverables later without degrading the picture. Store a compressed delivery copy next to it for quick sharing.

Frame rate, resolution and bit depth

Codecs work alongside other settings. Frame rate defines how many pictures appear each second. Common rates include 24, 25, 30, 50 and 60 frames per second. Match the frame rate of the export to the source footage whenever possible, because converting between rates can cause uneven motion.

Resolution is the number of pixels in the picture. Bit depth is the number of levels used to describe color in each channel, commonly 8 bits or 10 bits. Higher bit depth reduces banding in smooth gradients such as skies, and it gives color grading more room to work. A 10-bit master exported to an 8-bit delivery is a good combination when grading is part of the job.

Chroma subsampling describes how much color detail is kept compared with brightness. Formats written as 4:2:0 keep less color detail than 4:2:2 or 4:4:4. Most consumer video uses 4:2:0, which is efficient but can soften fine colored edges, so higher subsampling is preferred for graphics-heavy or green-screen work.

Test before you commit

Before exporting a long project, export a short test segment with the exact settings you plan to use. Play it on the target device, check the audio sync, confirm the frame rate, and look for banding or blocking in dark areas. A ten-second test costs little compared with re-exporting a finished film.

Keep a note of the settings that worked. A short written record of codec, container, resolution, frame rate and bit depth saves time on the next project and makes it easy to explain your choices to a client or collaborator.

Key takeaways

A container holds the streams, and a codec compresses them. H.264 gives the widest compatibility and small files for delivery, H.265 gives smaller files at high resolution, and ProRes or DNxHR give fast, high-quality editing at the cost of storage. Match the format to the destination, keep a high-quality master for the long term, and test every export before committing. Understanding these two layers turns format choices from guesswork into deliberate decisions.