shaka-packager/packager/mpd/base/mpd_builder.h

131 lines
4.4 KiB
C++

// Copyright 2014 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
//
/// All the methods that are virtual are virtual for mocking.
/// NOTE: Inclusion of this module will cause xmlInitParser and xmlCleanupParser
/// to be called at static initialization / deinitialization time.
#ifndef MPD_BASE_MPD_BUILDER_H_
#define MPD_BASE_MPD_BUILDER_H_
#include <libxml/tree.h>
#include <list>
#include <memory>
#include <string>
#include "packager/base/atomic_sequence_num.h"
#include "packager/base/time/clock.h"
#include "packager/mpd/base/mpd_options.h"
// TODO(rkuroiwa): For classes with |id_|, consider removing the field and let
// the MPD (XML) generation functions take care of assigning an ID to each
// element.
namespace shaka {
class AdaptationSet;
class MediaInfo;
class Period;
namespace xml {
class XmlNode;
} // namespace xml
/// This class generates DASH MPDs (Media Presentation Descriptions).
class MpdBuilder {
public:
/// Constructs MpdBuilder.
/// @param mpd_options contains options on how this MPD should be built.
explicit MpdBuilder(const MpdOptions& mpd_options);
virtual ~MpdBuilder();
/// Add <BaseURL> entry to the MPD.
/// @param base_url URL for <BaseURL> entry.
void AddBaseUrl(const std::string& base_url);
/// Check the existing Periods, if there is one matching the provided
/// @a start_time_in_seconds, return it; otherwise a new Period is created and
/// returned.
/// @param start_time_in_seconds is the period start time.
/// @return the Period matching @a start_time_in_seconds if found; otherwise
/// return a new Period.
virtual Period* GetOrCreatePeriod(double start_time_in_seconds);
/// Writes the MPD to the given string.
/// @param[out] output is an output string where the MPD gets written.
/// @return true on success, false otherwise.
// TODO(kqyang): Handle file IO in this class as in HLS media_playlist?
virtual bool ToString(std::string* output);
/// Adjusts the fields of MediaInfo so that paths are relative to the
/// specified MPD path.
/// @param mpd_path is the file path of the MPD file.
/// @param media_info is the MediaInfo object to be updated with relative
/// paths.
static void MakePathsRelativeToMpd(const std::string& mpd_path,
MediaInfo* media_info);
// Inject a |clock| that returns the current time.
/// This is for testing.
void InjectClockForTesting(std::unique_ptr<base::Clock> clock) {
clock_ = std::move(clock);
}
private:
MpdBuilder(const MpdBuilder&) = delete;
MpdBuilder& operator=(const MpdBuilder&) = delete;
// LiveMpdBuilderTest needs to set availabilityStartTime so that the test
// doesn't need to depend on current time.
friend class LiveMpdBuilderTest;
template <DashProfile profile>
friend class MpdBuilderTest;
// Returns the document pointer to the MPD. This must be freed by the caller
// using appropriate xmlDocPtr freeing function.
// On failure, this returns NULL.
xmlDocPtr GenerateMpd();
// Set MPD attributes common to all profiles. Uses non-zero |mpd_options_| to
// set attributes for the MPD.
void AddCommonMpdInfo(xml::XmlNode* mpd_node);
// Adds 'static' MPD attributes and elements to |mpd_node|. This assumes that
// the first child element is a Period element.
void AddStaticMpdInfo(xml::XmlNode* mpd_node);
// Same as AddStaticMpdInfo() but for 'dynamic' MPDs.
void AddDynamicMpdInfo(xml::XmlNode* mpd_node);
float GetStaticMpdDuration();
// Set MPD attributes for dynamic profile MPD. Uses non-zero |mpd_options_| as
// well as various calculations to set attributes for the MPD.
void SetDynamicMpdAttributes(xml::XmlNode* mpd_node);
// Gets the earliest, normalized segment timestamp. Returns true if
// successful, false otherwise.
bool GetEarliestTimestamp(double* timestamp_seconds);
MpdOptions mpd_options_;
std::list<std::unique_ptr<Period>> periods_;
std::list<std::string> base_urls_;
std::string availability_start_time_;
base::AtomicSequenceNumber period_counter_;
base::AtomicSequenceNumber adaptation_set_counter_;
base::AtomicSequenceNumber representation_counter_;
// By default, this returns the current time. This can be injected for
// testing.
std::unique_ptr<base::Clock> clock_;
};
} // namespace shaka
#endif // MPD_BASE_MPD_BUILDER_H_