Bento4 muxer

app/src/main/cpp/MP4.cpp

@@ -4,6 +4,14 @@
 
 #include "MP4.h"
 
+void
+MP4::MakeDsi(unsigned int sampling_frequency_index, unsigned int channel_configuration, unsigned char* dsi)
+{
+    unsigned int object_type = 2; // AAC LC by default
+    dsi[0] = (object_type<<3) | (sampling_frequency_index>>1);
+    dsi[1] = ((sampling_frequency_index&1)<<7) | (channel_configuration<<3);
+}
+
 void MP4::openFile (std::string _filename) {
     filename = _filename ;
     result = AP4_FileByteStream::Create(filename.c_str(), AP4_FileByteStream::STREAM_MODE_WRITE, output);
@@ -13,7 +21,67 @@ void MP4::openFile (std::string _filename) {
         return ;
     }
 
+    AP4_AacFrame frame;
+    result = parser.FindFrame(frame);
+    if (AP4_SUCCEEDED(result)) {
+        LOGI("AAC frame [%06d]: size = %d, %d kHz, %d ch\n",
+                  sample_count,
+                  frame.m_Info.m_FrameLength,
+                  frame.m_Info.m_SamplingFrequency,
+                  frame.m_Info.m_ChannelConfiguration);
+    } else {
+        HERE LOGE("[mp4] failed to find frame");
+        return;
+    }
+
+    initialized = true;
     sample_table = new AP4_SyntheticSampleTable();
+    AP4_DataBuffer dsi;
+    unsigned char aac_dsi[2];
+    MakeDsi(frame.m_Info.m_SamplingFrequencyIndex, frame.m_Info.m_ChannelConfiguration, aac_dsi);
+    dsi.SetData(aac_dsi, 2);
+
+    AP4_MpegAudioSampleDescription* sample_description =
+            new AP4_MpegAudioSampleDescription(
+                    AP4_OTI_MPEG4_AUDIO,   // object type
+                    frame.m_Info.m_SamplingFrequency,
+                    16,                    // sample size
+                    frame.m_Info.m_ChannelConfiguration,
+                    &dsi,                  // decoder info
+                    6144,                  // buffer size
+                    256000,                // max bitrate
+                    128000);               // average bitrate
+    sample_description_index = sample_table->GetSampleDescriptionCount();
+    sample_table->AddSampleDescription(sample_description);
+    sample_rate = frame.m_Info.m_SamplingFrequency;
+
+    AP4_MemoryByteStream* sample_data = new AP4_MemoryByteStream(frame.m_Info.m_FrameLength);
+    frame.m_Source->ReadBytes(sample_data->UseData(), frame.m_Info.m_FrameLength);
+    sample_table->AddSample(*sample_data, 0, frame.m_Info.m_FrameLength, 1024, sample_description_index, 0, 0, true);
+    sample_data->Release();
+    sample_count++;
+
+    movie = new AP4_Movie();
+    track = new AP4_Track(AP4_Track::TYPE_AUDIO,
+                          sample_table,
+                          0,     // track id
+                          sample_rate,       // movie time scale
+                          sample_count*1024, // track duration
+                          sample_rate,       // media time scale
+                          sample_count*1024, // media duration
+                          "eng", // language
+                          0, 0); // width, height
+
+    movie->AddTrack(track);
+    file = new AP4_File(movie);
+
+    AP4_UI32 compatible_brands[2] = {
+            AP4_FILE_BRAND_ISOM,
+            AP4_FILE_BRAND_MP42
+    };
+
+    file->SetFileType(AP4_FILE_BRAND_M4A_, 0, compatible_brands, 2);
 
+}
 
-}
+void MP4::writeFile ()

app/src/main/cpp/MP4.h

@@ -24,7 +24,14 @@ class MP4 {
     AP4_Cardinal sample_count = 0;
     bool eos = false;
 
+    AP4_Movie* movie = nullptr ;
+    AP4_Track* track = nullptr ;
+    AP4_File* file = nullptr ;
+
     void openFile(std::string _filename);
+
+    void MakeDsi(unsigned int sampling_frequency_index, unsigned int channel_configuration,
+                 unsigned char *dsi);
 };