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  "contentMarkdown": "# 为什么 ASTC压缩打出的APK包体 大于采用ETC2压缩打出的APK\n\n> [!note] 我的 UWA 问答\n> 本文收录我在 UWA 问答发表的公开回答。问题内容归原提问者；回答保留当时语境，技术结论可能受 Unity 版本、平台和项目条件限制。\n\n## 问题\n\n在一个空工程里面 我放了几张大图 2048*2048的\n\n我采用ETC2 4压缩的时候 单张大小为2M\n\n我采用ASTC 6X6压缩的时候 单张大小是1.8M\n\n按照我的理解 采用ASTC压缩格式 打出的APK应该更小才对 可是事实和我预想的相反\n\n采用ETC2压缩打出的apk为21.1M\n\n采用ASTC压缩打出的apk为25.7M\n\n为什么采用ETC2压缩的包体反而更小呢 ASTC打出的APK更大呢\n\n- 提问者：肖先生\n- 提问时间：2021-03-24 01:13:46\n\n## 我的回答\n\n占用包体的大小和在Editor下的preview界面看到的大小是两回事。\n\npreview界面看到的大小是ASTC或者ETC2格式的资源的大小，而打包后，会对资源进行进一步的压缩（LZ4或LZMA）。只能说明ETC2压缩成LZ4后占用的包体大小确实比ASTC压缩成LZ4后占用的大小更小，至于原因就要看具体压缩算法的实现了吧。\n\n可以用AssetBundle来验证，如果打AB包时选择NoCompression，那么确实ASTC格式的比ETC2格式的AB包更小。 如果选择LZ4或LZMA压缩，那么ETC2格式的AB包比ASTC格式的AB包要小。\n\n- 回答时间：2021-03-24 03:20:47\n- 最后更新：2021-03-24 03:20:47\n- 采纳状态：未采纳\n\n## 来源与关系\n\n- 上位集合：[[10-计算机、信息技术与工程/05-游戏图形与运行时/我的UWA问答/我的UWA问答|我的 UWA 问答]]\n- UWA 标签：资源管理\n- 原始问题：[为什么 ASTC压缩打出的APK包体 大于采用ETC2压缩打出的APK](https://answer.uwa4d.com/question/6059b14acfa35d5b53669bdd)\n- 源页最后更新：2021-03-24 03:20:47\n"
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