AVC usually refers to H.264/AVC video compression, meaning it’s a way of compressing video, not the file type, and everyday video files are really containers like MP4, MKV, MOV, or TS that simply carry an AVC-encoded video stream plus audio such as AAC, which is why people mistakenly call an MP4 an “AVC file” even though the true file type is the container; confusion grows when the extension is .avc or .h264/.264, since that often means a raw bitstream or a device-specific export that may play in VLC but lacks proper seeking, accurate duration, or audio because containers normally supply indexing and multiple tracks.

Some CCTV/DVR units use strange extension schemes despite the content being standard, so renaming to .mp4 often works unless the file is genuinely proprietary and must be processed in the vendor’s export tool; the fastest approach is testing in VLC, checking codec details, or using MediaInfo to see if it’s a proper container format with audio, and if it’s actually a raw AVC stream you’ll usually need to wrap into an MP4 container for smoother playback and navigation.

A `.mp4` file works as a full-featured MP4 *container*—with organized video, audio, indexes, timing data, and metadata—while a `.avc` file typically lacks these container elements and is simply a raw AVC stream or device-specific file; it can decode, but players may show misreported length since crucial structural information isn’t included.

This is also why `.avc` clips often carry video without sound: audio is frequently separate or never included, unlike MP4 which typically bundles both streams; meanwhile, some CCTV/DVR tools generate files with odd extensions, so a `.avc` may merely be a mislabeled MP4/TS that works after renaming, though proprietary ones require the vendor utility to convert; in summary, `.mp4` usually implies a complete indexed container, while `.avc` often indicates a proprietary export, causing playback inconsistencies and weak seeking.

Once you know whether the “AVC file” is simply mislabeled, a raw stream, or something proprietary, you can choose the right fix; if tools like VLC or MediaInfo report a standard container such as MP4—e. If you cherished this post and you would like to get more information concerning AVC file structure kindly go to our own website. g., “Format: MPEG-4” or normal playback—renaming `.avc` to `.mp4` often restores compatibility (copy the file first), but if it’s a raw H.264 bitstream, usually indicated by “Format: AVC” with little structural info and shaky seeking, the standard solution is to remux an MP4 container without re-encoding to supply proper timing and indexing.

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 convert smoothly 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.