MKV (Matroska Video) is an open container format that can hold multiple video tracks, audio tracks, and subtitles in a single file.
No. The conversion repackages the video stream without re-encoding, so quality stays the same. MKV just offers more flexibility for subtitles and multiple audio tracks.
Yes. MKV natively supports embedded subtitle tracks, which is one of the main reasons people prefer it over AVI.
Yes. Tools like MKVToolNix let you add SRT or ASS subtitle files to an MKV without re-encoding the video.
Yes. MKV natively supports chapter markers, which you can add using MKVToolNix after conversion.
MKV supports virtually any video codec including H.264, H.265, VP9, AV1, and many others. It is a flexible container format.
Most modern smart TVs support MKV playback. Older models may not. Check your TV's specifications for supported formats.