This usually means your device lacks an HEVC decoder. If using a Windows PC, you may need the "HEVC Video Extensions" from the Microsoft Store or to update your graphics drivers.
The most reliable choice for MKV files. It handles Tamil audio tracks and HEVC decoding natively. You can download it for any platform at videolan.org . This usually means your device lacks an HEVC decoder
If the Tamil audio doesn't match the lip movements, players like VLC allow you to fix this on the fly. Press the J or K keys to shift audio backward or forward in 50ms increments. This usually means your device lacks an HEVC decoder
Since this is an encoded MKV file, it requires a player that supports modern codecs to avoid stuttering or "file not supported" errors. This usually means your device lacks an HEVC decoder