media/webm/chromeos/webm_encoder.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_WEBM_CHROMEOS_WEBM_ENCODER_H_
   6 #define MEDIA_WEBM_CHROMEOS_WEBM_ENCODER_H_
   7
   8 #include <stdio.h>
   9 #include <stack>
  10
  11 #include "base/files/file_path.h"
  12 #include "media/base/media_export.h"
  13 #include "media/webm/chromeos/ebml_writer.h"
  14
  15 extern "C" {
  16 #define VPX_CODEC_DISABLE_COMPAT 1
  17 #include "third_party/libvpx/source/libvpx/vpx/vpx_encoder.h"
  18 #include "third_party/libvpx/source/libvpx/vpx/vp8cx.h"
  19 }
  20
  21 class SkBitmap;
  22
  23 namespace base {
  24 class FilePath;
  25 }
  26
  27 namespace media {
  28
  29 namespace chromeos {
  30
  31 // WebM encoder using libvpx. Currently only supports one-pass, constant bitrate
  32 // encoding of short files consisting of a single video track. Seek info and
  33 // cues are not supported, so generated .webm file does not strictly adhere to
  34 // WebM standard (http://www.webmproject.org/code/specs/container/).
  35 class MEDIA_EXPORT WebmEncoder {
  36  public:
  37   // Create new instance for writing to |output_path|. If |realtime| is |true|,
  38   // uses realtime deadline, otherwise - "good quality" deadline.
  39   WebmEncoder(const base::FilePath& output_path, int bitrate, bool realtime);
  40   ~WebmEncoder();
  41
  42   // Encodes video from a Nx(N*M) sprite, having M frames of size NxN with FPS
  43   // |fps_n/fps_d|. Must be called on a thread that allows disk IO.
  44   // Returns |true| iff encoding and writing to file is successful.
  45   bool EncodeFromSprite(const SkBitmap& sprite, int fps_n, int fps_d);
  46
  47  private:
  48   // Writes global WebM header and starts a single video track. Returns |false|
  49   // if there was an error opening file for writing.
  50   bool WriteWebmHeader();
  51
  52   // Writes VPX packet to output file.
  53   void WriteWebmBlock(const vpx_codec_cx_pkt_t* packet);
  54
  55   // Finishes video track and closes output file. Returns |false| if there were
  56   // any error during encoding/writing file.
  57   bool WriteWebmFooter();
  58
  59   // Starts a new WebM sub-element of given type. Those can be nested.
  60   void StartSubElement(unsigned long class_id);
  61
  62   // Closes current top-level sub-element.
  63   void EndSubElement();
  64
  65   // libmkv callbacks.
  66   void EbmlWrite(const void* buffer, unsigned long len);
  67   void EbmlSerialize(const void* buffer, int buffer_size, unsigned long len);
  68
  69   template <typename T>
  70   void EbmlSerializeHelper(const T* buffer, unsigned long len);
  71
  72   // Video dimensions and FPS.
  73   size_t width_;
  74   size_t height_;
  75   vpx_rational_t fps_;
  76
  77   // Number of frames in video.
  78   size_t frame_count_;
  79
  80   // VPX config in use.
  81   vpx_codec_enc_cfg_t config_;
  82
  83   // VPX parameters.
  84   int bitrate_;
  85   unsigned long deadline_;
  86
  87   // EbmlWriter context.
  88   EbmlGlobal ebml_writer_;
  89
  90   // Stack with start offsets of currently open sub-elements.
  91   std::stack<long int> ebml_sub_elements_;
  92
  93   base::FilePath output_path_;
  94   FILE* output_;
  95
  96   // True if an error occured while encoding/writing to file.
  97   bool has_errors_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(WebmEncoder);
 100 };
 101
 102 }  // namespace chromeos
 103
 104 }  // namespace media
 105
 106 #endif  // MEDIA_WEBM_CHROMEOS_WEBM_ENCODER_H_