HLS: support non-stereo channel layout

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

src/hls.cc

@@ -249,6 +249,8 @@ hls_add (const string& infile, const string& outfile, const string& bits)
   int    bit_rate  = atoi (get_var ("bit_rate"));
   size_t prev_ctx  = min<size_t> (1024 * 3, prev_size);
 
+  string channel_layout = get_var ("channel_layout");
+
   if (missing_vars)
     return 1;
 
@@ -258,6 +260,7 @@ hls_add (const string& infile, const string& outfile, const string& bits)
   HLSOutputStream out_stream (in_stream.n_channels(), in_stream.sample_rate(), in_stream.bit_depth());
 
   out_stream.set_bit_rate (bit_rate);
+  out_stream.set_channel_layout (channel_layout);
 
   const size_t shift = 1024;
   const size_t cut_aac_frames = (prev_ctx + shift) / 1024;
@@ -326,7 +329,7 @@ load_audio_master (const string& filename, WavData& audio_master_data)
 }
 
 Error
-validate_input_segment (const string& filename)
+probe_input_segment (const string& filename, map<string, string>& params)
 {
   TSReader reader;
 
@@ -353,8 +356,6 @@ validate_input_segment (const string& filename)
   for (auto o : format_out)
     {
       /* parse assignments stream|index=0|codec_name=aac|... */
-      map<string, string> params;
-
       string key, value;
       bool in_key = true;
       for (char c : '|' + o + '|')
@@ -378,18 +379,6 @@ validate_input_segment (const string& filename)
                 value += c;
             }
         }
-
-      /* now the actual validation */
-      if (atoi (params["index"].c_str()) != 0)
-        {
-          error ("audiowmark: hls segment '%s' contains more than one stream\n", filename.c_str());
-          return Error ("failed to validate input segment");
-        }
-      if (params["codec_name"] != "aac")
-        {
-          error ("audiowmark hls segment '%s' is not encoded using AAC\n", filename.c_str());
-          return Error ("failed to validate input segment");
-        }
     }
   return Error::Code::NONE;
 }
@@ -473,12 +462,34 @@ hls_prepare (const string& in_dir, const string& out_dir, const string& filename
     }
   for (auto& segment : segments)
     {
-      Error err = validate_input_segment (in_dir + "/" + segment.name);
+      map<string, string> params;
+      string segname = in_dir + "/" + segment.name;
+
+      Error err = probe_input_segment (segname, params);
       if (err)
         {
           error ("audiowmark: hls: %s\n", err.message());
           return 1;
         }
+      /* validate input segment */
+      if (atoi (params["index"].c_str()) != 0)
+        {
+          error ("audiowmark: hls segment '%s' contains more than one stream\n", segname.c_str());
+          return 1;
+        }
+      if (params["codec_name"] != "aac")
+        {
+          error ("audiowmark hls segment '%s' is not encoded using AAC\n", segname.c_str());
+          return 1;
+        }
+
+      /* get segment parameters */
+      if (params["channel_layout"].empty())
+        {
+          error ("audiowmark hls segment '%s' has no channel_layout entry\n", segname.c_str());
+          return 1;
+        }
+      segment.vars["channel_layout"] = params["channel_layout"];
     }
 
   /* find bitrate for AAC encoder */

src/hlsoutputstream.cc

@@ -63,6 +63,12 @@ HLSOutputStream::set_bit_rate (int bit_rate)
   m_bit_rate = bit_rate;
 }
 
+void
+HLSOutputStream::set_channel_layout (const string& channel_layout)
+{
+  m_channel_layout = channel_layout;
+}
+
 HLSOutputStream::~HLSOutputStream()
 {
   close();
@@ -107,18 +113,22 @@ HLSOutputStream::add_stream (AVCodec **codec, enum AVCodecID codec_id)
       if (!match)
         return Error (string_printf ("no codec support for sample rate %d", m_sample_rate));
     }
-  m_enc->channels       = av_get_channel_layout_nb_channels (m_enc->channel_layout);
-  m_enc->channel_layout = AV_CH_LAYOUT_STEREO;
+  uint64_t want_layout = av_get_channel_layout (m_channel_layout.c_str());
+  if (!want_layout)
+    return Error (string_printf ("bad channel layout '%s'", m_channel_layout.c_str()));
+  m_enc->channel_layout = want_layout;
   if ((*codec)->channel_layouts)
     {
       m_enc->channel_layout = (*codec)->channel_layouts[0];
       for (int i = 0; (*codec)->channel_layouts[i]; i++)
         {
-          if ((*codec)->channel_layouts[i] == AV_CH_LAYOUT_STEREO)
-              m_enc->channel_layout = AV_CH_LAYOUT_STEREO;
+          if ((*codec)->channel_layouts[i] == want_layout)
+              m_enc->channel_layout = want_layout;
         }
     }
-  m_enc->channels     = av_get_channel_layout_nb_channels (m_enc->channel_layout);
+  if (want_layout != m_enc->channel_layout)
+    return Error (string_printf ("codec: unsupported channel layout '%s'", m_channel_layout.c_str()));
+  m_enc->channels = av_get_channel_layout_nb_channels (m_enc->channel_layout);
   m_st->time_base = (AVRational){ 1, m_enc->sample_rate };
 
   /* Some formats want stream headers to be separate. */

src/hlsoutputstream.hh

@@ -55,6 +55,7 @@ class HLSOutputStream : public AudioOutputStream {
   AudioBuffer       m_audio_buffer;
   size_t            m_delete_input_start = 0;
   int               m_bit_rate = 0;
+  std::string       m_channel_layout;
 
   enum class State {
     NEW,
@@ -81,6 +82,8 @@ public:
   ~HLSOutputStream();
 
   void set_bit_rate (int bit_rate);
+  void set_channel_layout (const std::string& channel_layout);
+
   Error open (const std::string& output_filename, size_t cut_aac_frames, size_t keep_aac_frames, double pts_start, size_t delete_input_start);
   int bit_depth() const override;
   int sample_rate() const override;