支持配置 fmp4 HLS 切片文件扩展名 (.mp4/.m4s) (#4746)

## 背景 / 问题
fmp4 模式下，HLS 切片文件名被硬编码为 `.mp4`（见 `HlsMakerImp::onOpenSegment`），无法改用 fmp4
媒体段更规范、更常见的 `.m4s` 扩展名（`init` 段用 `init.mp4`、媒体段用 `.m4s` 是 CMAF/DASH
的通行约定）。

## 改动
- 新增配置项 `hls.fmp4SegExt`，默认 `.mp4`，**完全向后兼容**；用户可设为 `.m4s`。
- `init` 段仍固定为 `init.mp4`，mpegts 切片仍为 `.ts`，相关行为不变。
- 切片文件名同时用作 m3u8 中的分片 URI，因此扩展名变更后 playlist 自动保持一致，无需额外同步。
- 在 HTTP MIME 表中注册 `.m4s` -> `video/mp4`；否则会以 `text/plain` 返回，导致 Safari
等播放器无法播放 HLS-fmp4。
- 配置值不带前导点（如 `m4s`）时自动规范化为 `.m4s`。

## 涉及文件
`src/Common/config.h`、`src/Common/config.cpp`、`src/Record/HlsRecorder.h`、`src/Record/HlsMakerImp.h`、`src/Record/HlsMakerImp.cpp`、`src/Http/HttpConst.cpp`、`conf/config.ini`

## 测试
- **默认（未配置）**：切片仍为 `*.mp4`，`init` 为 `init.mp4`，行为与改动前一致（回归正常）。
- **`hls.fmp4SegExt=.m4s`**：切片文件为 `*_N.m4s`，m3u8 中 `#EXTINF` 的 URI 指向
`.m4s`，`#EXT-X-MAP` 仍为 `init.mp4`；HTTP 拉取切片返回 `Content-Type:
video/mp4`；hls.js 与 Safari 播放正常。
- **`hls.fmp4SegExt=m4s`（无前导点）**：自动规范化，仍生成 `*.m4s`。

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

conf/config.ini

@@ -284,6 +284,11 @@ segKeep=0
 # If set to 1, the length of the first segment is forcibly set to exactly 1 GOP.
 # When the GOP is smaller than `segDur`, this can improve the initial startup (instant playback) speed.
 fastRegister=0
+
+# fmp4 HLS切片文件的扩展名，例如 .mp4 或 .m4s(fmp4媒体段的标准扩展名)；init段始终为init.mp4，mpegts切片始终为.ts
+# File extension for fMP4 HLS segment files, e.g. .mp4 or .m4s (the standard extension for fMP4 media segments).
+# The init segment is always init.mp4, and mpegts segments are always .ts.
+fmp4SegExt=.mp4
 [hook]
 # 是否启用hook事件，启用后，推拉流都将进行鉴权
 # Whether to enable webhook events. When enabled, pushing and pulling streams requires authentication.

src/Common/config.cpp

@@ -355,6 +355,7 @@ const string kFileBufSize = HLS_FIELD "fileBufSize";
 const string kBroadcastRecordTs = HLS_FIELD "broadcastRecordTs";
 const string kDeleteDelaySec = HLS_FIELD "deleteDelaySec";
 const string kFastRegister = HLS_FIELD "fastRegister";
+const string kFmp4SegExt = HLS_FIELD "fmp4SegExt";
 
 static onceToken token([]() {
     mINI::Instance()[kSegmentDuration] = 2;
@@ -366,6 +367,7 @@ static onceToken token([]() {
     mINI::Instance()[kBroadcastRecordTs] = false;
     mINI::Instance()[kDeleteDelaySec] = 10;
     mINI::Instance()[kFastRegister] = false;
+    mINI::Instance()[kFmp4SegExt] = ".mp4";
 });
 } // namespace Hls
 

src/Common/config.h

@@ -531,6 +531,9 @@ extern const std::string kDeleteDelaySec;
 // 如果设置为1，则第一个切片长度强制设置为1个GOP  [AUTO-TRANSLATED:fbbb651d]
 // If set to 1, the length of the first slice is forced to be 1 GOP
 extern const std::string kFastRegister;
+// fmp4 HLS切片文件的扩展名(例如 .mp4 或 .m4s)；mpegts切片始终为.ts
+// File extension for fMP4 HLS segment files (e.g. .mp4 or .m4s); mpegts segments are always .ts
+extern const std::string kFmp4SegExt;
 } // namespace Hls
 
 // //////////Rtp代理相关配置///////////  [AUTO-TRANSLATED:7b285587]

src/Http/HttpConst.cpp

@@ -183,6 +183,7 @@ static const char *s_mime_src[][2] = {
         {"3gp", "video/3gpp"},
         {"ts", "video/mp2t"},
         {"mp4", "video/mp4"},
+        {"m4s", "video/mp4"},
         {"mpeg", "video/mpeg"},
         {"mpg", "video/mpeg"},
         {"mov", "video/quicktime"},

src/Record/HlsMakerImp.cpp

@@ -31,13 +31,16 @@ std::string getDelayPath(const std::string& originalPath) {
 }
 
 HlsMakerImp::HlsMakerImp(bool is_fmp4, const string &m3u8_file, const string &params, uint32_t bufSize, float seg_duration,
-                         uint32_t seg_number, bool seg_keep) : HlsMaker(is_fmp4, seg_duration, seg_number, seg_keep) {
+                         uint32_t seg_number, bool seg_keep, const string &fmp4_seg_ext) : HlsMaker(is_fmp4, seg_duration, seg_number, seg_keep) {
     _poller = EventPollerPool::Instance().getPoller();
     _path_prefix = m3u8_file.substr(0, m3u8_file.rfind('/'));
     _path_hls = m3u8_file;
     _path_hls_delay = getDelayPath(m3u8_file);
     _params = params;
     _buf_size = bufSize;
+    // 兼容用户配置不带前导点的扩展名(例如 m4s)，统一补上"."  [AUTO-TRANSLATED]
+    // Tolerate user-configured extensions without a leading dot (e.g. m4s) by normalizing to ".m4s"
+    _fmp4_seg_ext = fmp4_seg_ext.empty() ? ".mp4" : (fmp4_seg_ext.front() == '.' ? fmp4_seg_ext : "." + fmp4_seg_ext);
     _file_buf.reset(new char[bufSize], [](char *ptr) { delete[] ptr; });
     _info.folder = _path_prefix;
 }
@@ -151,7 +154,7 @@ string HlsMakerImp::onOpenSegment(uint64_t index) {
         auto strHour = getTimeStr("%H");
         auto strTime = getTimeStr("%M-%S");
         auto current_dir = strDate + "/" + strHour + "/";
-        segment_name = current_dir + strTime + "_" + std::to_string(index) + (isFmp4() ? ".mp4" : ".ts");
+        segment_name = current_dir + strTime + "_" + std::to_string(index) + (isFmp4() ? _fmp4_seg_ext : ".ts");
         segment_path = _path_prefix + "/" + segment_name;
         if (isLive()) {
             // 直播

src/Record/HlsMakerImp.h

@@ -22,7 +22,8 @@ namespace mediakit {
 class HlsMakerImp : public HlsMaker {
 public:
     HlsMakerImp(bool is_fmp4, const std::string &m3u8_file, const std::string &params, uint32_t bufSize = 64 * 1024,
-                float seg_duration = 5, uint32_t seg_number = 3, bool seg_keep = false);
+                float seg_duration = 5, uint32_t seg_number = 3, bool seg_keep = false,
+                const std::string &fmp4_seg_ext = ".mp4");
     ~HlsMakerImp() override;
 
     /**
@@ -68,6 +69,7 @@ private:
 private:
     int _buf_size;
     std::string _params;
+    std::string _fmp4_seg_ext;
     std::string _path_hls;
     std::string _path_hls_delay;
     std::string _path_init;

src/Record/HlsRecorder.h

@@ -26,9 +26,10 @@ public:
         GET_CONFIG(bool, hlsKeep, Hls::kSegmentKeep);
         GET_CONFIG(uint32_t, hlsBufSize, Hls::kFileBufSize);
         GET_CONFIG(float, hlsDuration, Hls::kSegmentDuration);
+        GET_CONFIG(std::string, hlsFmp4SegExt, Hls::kFmp4SegExt);
 
         _option = option;
-        _hls = std::make_shared<HlsMakerImp>(is_fmp4, m3u8_file, params, hlsBufSize, hlsDuration, hlsNum, hlsKeep);
+        _hls = std::make_shared<HlsMakerImp>(is_fmp4, m3u8_file, params, hlsBufSize, hlsDuration, hlsNum, hlsKeep, hlsFmp4SegExt);
         // 清空上次的残余文件  [AUTO-TRANSLATED:e16122be]
         // Clear the residual files from the last time
         _hls->clearCache();