AVC usually means H.264/AVC compression, which is the compression technology rather than the file container, and common formats like MP4, MKV, MOV, or TS just include AVC video alongside audio, leading to mix-ups where users call an MP4 “an AVC file” even though MP4 is the container; when you see extensions like .avc or .h264/.264, they often represent raw streams or specific device exports that may open in VLC but can lack proper seeking, accurate timing, or audio because containers normally deliver indexing and multi-track support.

Some CCTV/DVR devices save clips under unexpected file types even when the underlying format is normal, meaning a video might just need to be renamed to .mp4 to play, though other cases require the manufacturer’s player to convert it; the fastest way to tell is to test it in VLC, check codec info, or use MediaInfo to confirm whether it’s a proper container (MP4/MKV/TS) and whether audio exists, and if it turns out to be a raw AVC stream you typically need to remux it into an MP4 for improved compatibility and seekability.

Here’s more info on universal AVC file viewer take a look at our own web-site. A `.mp4` file usually functions as a proper MP4 *container*, meaning it includes video, audio, timing information, seek indexes, and metadata, whereas a `.avc` file commonly represents a raw AVC/H.264 stream or a special export format without full container “plumbing”; it may play but often shows issues like incorrect duration because much of the structural guidance isn’t there.

This is also why `.avc` files commonly contain no embedded audio: audio may not be bundled and might live elsewhere, while MP4 typically includes both; further confusion comes from CCTV/DVR exports that use nonstandard extensions, meaning a mislabeled `.avc` might behave normally if renamed to `.mp4`, though some require proprietary exporters; overall, `.mp4` suggests complete multimedia packaging, while `.avc` often suggests vendor-specific wrapping, which leads to missing audio and poor seek accuracy.

Once you determine what kind of “AVC file” you have, the solution varies based on whether it’s mislabeled, raw H.264, or a proprietary export; when VLC or MediaInfo indicates a real container like MP4 (you may see “Format: MPEG-4” or normal seeking), simply renaming `clip.avc` to `clip.mp4` often solves compatibility—just make a copy first; if the file is a raw bitstream instead, typically shown by “Format: AVC” with sparse container info and glitchy seeking, the fix is to wrap into an MP4 container without re-encoding, adding the indexing and timing structure raw streams don’t have.

If your file came from a CCTV/DVR or a system with its own packaging, the most reliable fix is using the manufacturer’s software to export as MP4 or AVI, because some proprietary structures can’t wrap into MP4 cleanly unless processed through the official exporter; this is a true conversion, not just a rename, and if playback remains corrupted, refuses to open, or the duration stays off even after remuxing, that often indicates a damaged recording or missing sidecar/index data, requiring re-export from the device or retrieving the related metadata.