Added aac bitstream converter

media/filters/ffmpeg_aac_bitstream_converter.h

Index: media/filters/ffmpeg_aac_bitstream_converter.h
diff --git a/media/filters/ffmpeg_aac_bitstream_converter.h b/media/filters/ffmpeg_aac_bitstream_converter.h
new file mode 100644
index 0000000000000000000000000000000000000000..f9b622bc435fcce4474bdc331922a5ee916eaa5c
--- /dev/null
+++ b/media/filters/ffmpeg_aac_bitstream_converter.h
@@ -0,0 +1,52 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_FILTERS_FFMPEG_AAC_BITSTREAM_CONVERTER_H_
+#define MEDIA_FILTERS_FFMPEG_AAC_BITSTREAM_CONVERTER_H_
+
+#include "base/basictypes.h"
+#include "media/filters/ffmpeg_bitstream_converter.h"
+
+// Forward declarations for FFmpeg datatypes used.
+struct AVCodecContext;
+struct AVPacket;
+
+namespace media {
+
+// Bitstream converter that adds ADTS headers to AAC frames.
+class FFmpegAACBitstreamConverter : public FFmpegBitstreamConverter {
+ public:
+  // The |stream_codec_context| will be used during conversion and should be the
+  // AVCodecContext for the stream sourcing these packets. A reference to
+  // |stream_codec_context| is retained, so it must outlive this class.
+  explicit FFmpegAACBitstreamConverter(AVCodecContext* stream_codec_context);
+  ~FFmpegAACBitstreamConverter() override;
+

[xhwang, 2014/11/06 04:35:28]

// FFmpegBitstreamConverter implementation.

[kjoswiak, 2014/11/07 02:14:38]

Done.

+  // Uses FFmpeg allocation methods for buffer allocation to ensure
+  // compatibility with FFmpeg's memory management.
+  bool ConvertPacket(AVPacket* packet) override;
+
+ private:
+  enum { kAdtsHeaderSize = 7 };
+
+  // Variable to hold a pointer to memory where we can access the global
+  // data from the FFmpeg file format's global headers.
+  AVCodecContext* stream_codec_context_;
+
+  bool header_generated_;
+  uint8_t hdr_[kAdtsHeaderSize];
+
+  bool GenerateAdtsHeader(int codec, int layer, int audio_profile,
+                          int sample_rate, int private_stream,
+                          int channel_configuration, int originality, int home,
+                          int copyrighted_stream, int copyright_start,
+                          int frame_length, int buffer_fullness,
+                          int number_of_frames_minus_one);

[xhwang, 2014/11/06 04:35:28]

nit: You can make this a file scoped static function in the cc file. The new
function can return the header, which will be more clear.

[kjoswiak, 2014/11/07 02:14:38]

You meant just move into unnamed namespace, correct? Did that, made pointer to
hdr an arg so as to keep bool success status. Done.

+
+  DISALLOW_COPY_AND_ASSIGN(FFmpegAACBitstreamConverter);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_FFMPEG_AAC_BITSTREAM_CONVERTER_H_