容器（封装）Container

容器是装音视频轨道的盒子——装几条轨道、带什么元数据；跟画质无关。

• 常见四种：MOV、MP4、MKV、MXF——MXF 多见于广播。
• 别拿后缀猜画质：.mov 和 .mp4 多数情况下只是盒子不同，画质由里面的编码决定（见 编码器）。
• 换容器不改画质：换编码才改——这是格式地图的第一句话。
• 影院的容器：DCP 用的也是 MXF，但那是影院标准，不是普通 MP4（见 DCP（数字电影包））。

A container is the box that carries audio and video tracks — how many tracks, what metadata; it has nothing to do with quality.

• The common four: MOV, MP4, MKV, MXF — MXF is broadcast-flavoured.
• Never guess quality from the extension: .mov vs .mp4 is usually just a different box; quality is decided by the codec inside (see Codec).
• Changing the container never changes quality: changing the codec does — the first sentence of the format map.
• Cinema's container: DCP also rides on MXF, but that is the cinema standard, not an ordinary MP4 (see DCP).