Avoid HLS temp file for accessing lossless context.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/sfinputstream.cc

@@ -29,12 +29,21 @@ SFInputStream::~SFInputStream()
 
 Error
 SFInputStream::open (const string& filename)
+{
+  return open ([&] (SF_INFO *sfinfo) {
+    return sf_open (filename.c_str(), SFM_READ, sfinfo);
+  });
+}
+
+
+Error
+SFInputStream::open (std::function<SNDFILE* (SF_INFO *)> open_func)
 {
   assert (m_state == State::NEW);
 
   SF_INFO sfinfo = { 0, };
 
-  m_sndfile = sf_open (filename.c_str(), SFM_READ, &sfinfo);
+  m_sndfile = open_func (&sfinfo);
 
   int error = sf_error (m_sndfile);
   if (error)
@@ -155,3 +164,96 @@ SFInputStream::close()
       m_state = State::CLOSED;
     }
 }
+
+static sf_count_t
+virtual_get_len (void *data)
+{
+  SFInputStream::VirtualData *vdata = static_cast<SFInputStream::VirtualData *> (data);
+
+  return vdata->mem->size();
+}
+
+static sf_count_t
+virtual_seek (sf_count_t offset, int whence, void *data)
+{
+  SFInputStream::VirtualData *vdata = static_cast<SFInputStream::VirtualData *> (data);
+
+  if (whence == SEEK_CUR)
+    {
+      vdata->offset = vdata->offset + offset;
+    }
+  else if (whence == SEEK_SET)
+    {
+      vdata->offset = offset;
+    }
+  else if (whence == SEEK_END)
+    {
+      vdata->offset = vdata->mem->size() + offset;
+    }
+
+  /* can't seek beyond eof */
+  vdata->offset = bound<sf_count_t> (0, vdata->offset, vdata->mem->size());
+  return vdata->offset;
+}
+
+static sf_count_t
+virtual_read (void *ptr, sf_count_t count, void *data)
+{
+  SFInputStream::VirtualData *vdata = static_cast<SFInputStream::VirtualData *> (data);
+
+  int rcount = 0;
+  unsigned char *uptr = static_cast<unsigned char *> (ptr);
+  for (sf_count_t i = 0; i < count; i++)
+    {
+      size_t rpos = i + vdata->offset;
+      if (rpos < vdata->mem->size())
+        {
+          uptr[i] = (*vdata->mem)[rpos];
+          rcount++;
+        }
+    }
+  vdata->offset += rcount;
+  return rcount;
+}
+
+static sf_count_t
+virtual_write (const void *ptr, sf_count_t count, void *data)
+{
+  SFInputStream::VirtualData *vdata = static_cast<SFInputStream::VirtualData *> (data);
+
+  const unsigned char *uptr = static_cast<const unsigned char *> (ptr);
+  for (sf_count_t i = 0; i < count; i++)
+    {
+      unsigned char ch = uptr[i];
+
+      size_t wpos = i + vdata->offset;
+      if (wpos >= vdata->mem->size())
+        vdata->mem->resize (wpos + 1);
+      (*vdata->mem)[wpos] = ch;
+    }
+  vdata->offset += count;
+  return count;
+}
+
+static sf_count_t
+virtual_tell (void *data)
+{
+  SFInputStream::VirtualData *vdata = static_cast<SFInputStream::VirtualData *> (data);
+  return vdata->offset;
+}
+
+Error
+SFInputStream::open (const vector<unsigned char> *data)
+{
+  virtual_data.mem = const_cast<vector<unsigned char> *> (data);
+  SF_VIRTUAL_IO sf_virtual_io = {
+    virtual_get_len,
+    virtual_seek,
+    virtual_read,
+    virtual_write,
+    virtual_tell
+  };
+  return open ([&] (SF_INFO *sfinfo) {
+    return sf_open_virtual (&sf_virtual_io, SFM_READ, sfinfo, &virtual_data);
+  });
+}

src/sfinputstream.hh

@@ -19,6 +19,7 @@
 #define AUDIOWMARK_SF_INPUT_STREAM_HH
 
 #include <string>
+#include <functional>
 
 #include <sndfile.h>
 
@@ -26,6 +27,16 @@
 
 class SFInputStream : public AudioInputStream
 {
+public:
+  /* to support read from memory */
+  struct VirtualData
+  {
+    std::vector<unsigned char> *mem    = nullptr;
+    sf_count_t                  offset = 0;
+  };
+
+private:
+  VirtualData virtual_data;
   SNDFILE    *m_sndfile = nullptr;
   int         m_n_channels = 0;
   int         m_n_values = 0;
@@ -40,10 +51,12 @@ class SFInputStream : public AudioInputStream
   };
   State       m_state = State::NEW;
 
+  Error open (std::function<SNDFILE* (SF_INFO *)> open_func);
 public:
   ~SFInputStream();
 
   Error               open (const std::string& filename);
+  Error               open (const std::vector<unsigned char> *data);
   Error               read_frames (std::vector<float>& samples, size_t count) override;
   void                close();
 

src/testhls.cc

@@ -24,6 +24,7 @@
 #include "mpegts.hh"
 #include "wavdata.hh"
 #include "wmcommon.hh"
+#include "sfinputstream.hh"
 
 using std::string;
 using std::regex;
@@ -76,21 +77,16 @@ ff_decode (const string& filename, WavData& out_wav_data)
 Error
 decode_context (const TSReader& reader, WavData& out_wav_data)
 {
-  FILE *tmp_file = tmpfile();
-  ScopedFile tmp_file_s (tmp_file);
-  string tmp_file_name = string_printf ("/dev/fd/%d", fileno (tmp_file));
-
-  /* write wav data */
   auto full_wav = reader.find ("full.wav");
   if (!full_wav)
     return Error ("no embedded context found");
 
-  size_t r = fwrite (full_wav->data.data(), 1, full_wav->data.size(), tmp_file);
-  if (r != full_wav->data.size())
-    return Error (string_printf ("unable to write decode_context"));
-  fflush (tmp_file);
+  SFInputStream input_stream;
+  Error err = input_stream.open (&full_wav->data);
+  if (err)
+    return err;
 
-  Error err = out_wav_data.load (tmp_file_name);
+  err = out_wav_data.load (&input_stream);
   return err;
 }