Motown: New wrapper classes for ffmpeg format context and io context

services/media/framework_ffmpeg/av_format_context.h

+// Copyright 2016 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 SERVICES_MEDIA_FRAMEWORK_FFMPEG_AV_FORMAT_CONTEXT_H_
+#define SERVICES_MEDIA_FRAMEWORK_FFMPEG_AV_FORMAT_CONTEXT_H_
+
+#include "services/media/framework_ffmpeg/av_io_context.h"
+extern "C" {
+#include "third_party/ffmpeg/libavcodec/avcodec.h"
+#include "third_party/ffmpeg/libavformat/avformat.h"
+}
+
+namespace mojo {
+namespace media {
+
+struct AVFormatContextDeleter {
+  inline void operator()(AVFormatContext* ptr) const {
+    avformat_free_context(ptr);
+  }
+};
+
+using AvFormatContextPtr =
+    std::unique_ptr<AVFormatContext, AVFormatContextDeleter>;
+
+struct AvFormatContext {
+  static AvFormatContextPtr OpenInput(const AvIoContextPtr& io_context) {
+    AVFormatContext* format_context = avformat_alloc_context();
+    format_context->flags |= AVFMT_FLAG_CUSTOM_IO | AVFMT_FLAG_FAST_SEEK;
+    format_context->pb = io_context.get();
+
+    // TODO(dalesat): This synchronous operation may take a long time.
+    int r = avformat_open_input(&format_context, nullptr, nullptr, nullptr);
+    if (r < 0) {
+      delete format_context;
+      format_context = nullptr;
+    }
+
+    return AvFormatContextPtr(format_context);
+  }
+};
+
+}  // namespace media
+}  // namespace mojo
+
+#endif // SERVICES_MEDIA_FRAMEWORK_FFMPEG_AV_FORMAT_CONTEXT_H_