Fix OSS build (#1200)

Due to Shai-Hulud malware, the GitHub Action was disabled past few days,
and the changes made during that time caused OSS build to fail.
This commit fixes it.

Author: mthrok

src/libspdl/core/CMakeLists.txt

@@ -44,6 +44,7 @@ set(srcs
   muxer.cpp
   packets.cpp
   utils.cpp
+  rational_utils.cpp
   )
 
 if(SPDL_USE_TRACING)

src/libspdl/core/detail/ffmpeg/demuxer.cpp

@@ -220,12 +220,13 @@ PacketsPtr<media> DemuxerImpl::demux_window(
     auto s = std::get<0>(*window);
     auto tb = stream->time_base;
     auto t = av_rescale(s.num, tb.den, s.den * tb.num);
+    auto start = to_double(s);
     {
       TRACE_EVENT("demuxing", "av_seek_frame");
       CHECK_AVERROR(
           av_seek_frame(fmt_ctx_, index, t - 1, AVSEEK_FLAG_BACKWARD),
           "Failed to seek to the timestamp {} ({}/{}) [sec]",
-          to_double(s),
+          start,
           s.num,
           s.den);
     }

src/libspdl/core/frames.cpp

@@ -35,8 +35,8 @@ namespace spdl::core {
 // FFmpeg Common
 ////////////////////////////////////////////////////////////////////////////////
 template <MediaType media>
-Frames<media>::Frames(uintptr_t id_, Rational time_base_)
-    : id_(id_), time_base_(time_base_) {
+Frames<media>::Frames(uintptr_t id, Rational time_base)
+    : id_(id), time_base_(time_base) {
   TRACE_EVENT("decoding", "Frames::Frames", perfetto::Flow::ProcessScoped(id_));
   if (time_base_.den == 0) {
     SPDL_FAIL(