AVC commonly refers to H. Here is more info about AVC file structure review our site. 264/AVC, a compression format rather than a file container, and most videos you encounter are actually MP4, MKV, MOV, or TS containers that simply include an AVC-encoded track plus audio, which creates the habit of calling the entire file an "AVC file" even though the container is what defines the file type; when the extension is .avc or .h264/.264, it often signals a raw bitstream or device-specific output that VLC may play but with limited seeking, inaccurate timing, or no audio because true containers provide indexes and multiple streams.

Some CCTV/DVR setups save recordings under odd extensions even when the data is perfectly normal, so simply renaming to .mp4 may fix playback, while other clips are proprietary and need the vendor tool to convert; the simplest way to identify the format is to load it in VLC, view codec info, or check with MediaInfo to see if it’s a true container (MP4/MKV/TS), and if it shows a raw AVC stream the typical solution is to wrap it into MP4 to get better compatibility and seeking.

A `.mp4` file is normally a standard MP4 *container*, offering organized video, audio, timing, indexing, subtitles, and metadata, but a `.avc` file is frequently just a raw H.264/AVC stream or device-specific output with none of that structure; it can decode, yet players might show wrong duration reports because essential container-level information is absent.

This is also why `.avc` files commonly contain video only: 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 proper container formatting, while `.avc` often suggests vendor-specific wrapping, which leads to missing audio and poor seek accuracy.

Once you’ve determined whether the "AVC file" is mislabeled, raw H.264, or proprietary, you can pick the right fix; when VLC/MediaInfo shows a standard container—look for "Format: MPEG-4" or normal seek behavior—just renaming the `.avc` to `.mp4` often restores compatibility (after copying it), but if the file is a raw H.264 stream indicated by "Format: AVC" with sparse container details and erratic seeking, then the usual remedy is to remux it into an MP4 container without re-encoding, adding essential timing and indexing data for proper playback.

If the clip was generated by a CCTV/DVR or similar device with a custom wrapper, the best solution is to use the official viewer/export tool to produce an MP4 or AVI, since some proprietary formats refuse to convert as-is until they’re exported properly; here you’re converting from a unique structure to a standard container, not just renaming, and if playback breaks, won’t load, or the timing is still wrong after remuxing, it likely points to corruption or absent companion files, making a new export or locating the index/metadata files necessary.