blob: d9fb41aaeb361c0e6375e07c8b2b912e26093d7e [file] [log] [blame]
// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/media/media_internals.h"
#include <stddef.h>
#include <array>
#include <list>
#include <string>
#include <string_view>
#include <tuple>
#include <utility>
#include "base/compiler_specific.h"
#include "base/containers/adapters.h"
#include "base/feature_list.h"
#include "base/functional/bind.h"
#include "base/memory/raw_ptr.h"
#include "base/metrics/field_trial_params.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/values.h"
#include "build/build_config.h"
#include "content/browser/media/session/media_session_impl.h"
#include "content/browser/renderer_host/media/media_stream_manager.h"
#include "content/public/browser/audio_service.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_ui.h"
#include "content/public/common/content_client.h"
#include "content/public/common/content_features.h"
#include "media/audio/audio_features.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_log_record.h"
#include "media/base/media_switches.h"
#include "media/webrtc/webrtc_features.h"
#include "mojo/public/cpp/bindings/self_owned_receiver.h"
#include "sandbox/policy/features.h"
#include "sandbox/policy/sandbox_type.h"
#if !BUILDFLAG(IS_ANDROID)
#include "media/filters/decrypting_video_decoder.h"
#endif
namespace content {
namespace {
std::u16string SerializeUpdate(std::string_view function,
const base::ValueView value) {
base::ValueView args[] = {value};
return content::WebUI::GetJavascriptCall(function, args);
}
std::string EffectsToString(int effects) {
if (effects == media::AudioParameters::NO_EFFECTS)
return "NO_EFFECTS";
struct Flags {
int flag;
const char* name;
};
auto flags = std::to_array<Flags>({
{media::AudioParameters::ECHO_CANCELLER, "ECHO_CANCELLER"},
{media::AudioParameters::DUCKING, "DUCKING"},
{media::AudioParameters::HOTWORD, "HOTWORD"},
{media::AudioParameters::NOISE_SUPPRESSION, "NOISE_SUPPRESSION"},
{media::AudioParameters::AUTOMATIC_GAIN_CONTROL,
"AUTOMATIC_GAIN_CONTROL"},
{media::AudioParameters::DEEP_NOISE_SUPPRESSION,
"DEEP_NOISE_SUPPRESSION"},
});
std::string ret;
for (size_t i = 0; i < std::size(flags); ++i) {
if (effects & flags[i].flag) {
if (!ret.empty())
ret += " | ";
ret += flags[i].name;
effects &= ~flags[i].flag;
}
}
if (effects) {
if (!ret.empty())
ret += " | ";
ret += base::NumberToString(effects);
}
return ret;
}
std::string FormatToString(media::AudioParameters::Format format) {
switch (format) {
case media::AudioParameters::AUDIO_PCM_LINEAR:
return "pcm_linear";
case media::AudioParameters::AUDIO_PCM_LOW_LATENCY:
return "pcm_low_latency";
case media::AudioParameters::AUDIO_BITSTREAM_AC3:
return "ac3";
case media::AudioParameters::AUDIO_BITSTREAM_EAC3:
return "eac3";
case media::AudioParameters::AUDIO_BITSTREAM_DTS:
return "dts";
case media::AudioParameters::AUDIO_BITSTREAM_DTS_HD:
return "dtshd";
case media::AudioParameters::AUDIO_BITSTREAM_DTSX_P2:
return "dtsxp2";
case media::AudioParameters::AUDIO_BITSTREAM_IEC61937:
return "iec61937";
case media::AudioParameters::AUDIO_BITSTREAM_DTS_HD_MA:
return "dtshd_ma";
case media::AudioParameters::AUDIO_FAKE:
return "fake";
}
}
const char kAudioLogStatusKey[] = "status";
const char kAudioLogUpdateFunction[] = "media.updateAudioComponent";
} // namespace
// This class works as a receiver of logs of events occurring in the
// media pipeline. Media logs send by the renderer process to the
// browser process is handled by the below implementation in the
// browser side.
class MediaInternals::MediaInternalLogRecordsImpl
: public content::mojom::MediaInternalLogRecords {
public:
MediaInternalLogRecordsImpl(content::MediaInternals* media_internals,
int render_process_id);
MediaInternalLogRecordsImpl(const MediaInternalLogRecordsImpl&) = delete;
MediaInternalLogRecordsImpl& operator=(const MediaInternalLogRecordsImpl&) =
delete;
~MediaInternalLogRecordsImpl() override = default;
void Log(const std::vector<::media::MediaLogRecord>& arr) override;
private:
const raw_ptr<content::MediaInternals> media_internals_;
const int render_process_id_;
};
MediaInternals::MediaInternalLogRecordsImpl::MediaInternalLogRecordsImpl(
content::MediaInternals* media_internals,
int render_process_id)
: media_internals_(media_internals),
render_process_id_(render_process_id) {}
void MediaInternals::MediaInternalLogRecordsImpl::Log(
const std::vector<::media::MediaLogRecord>& events) {
media_internals_->OnMediaEvents(render_process_id_, events);
}
class MediaInternals::AudioLogImpl : public media::mojom::AudioLog,
public media::AudioLog {
public:
AudioLogImpl(int owner_id,
media::AudioLogFactory::AudioComponent component,
content::MediaInternals* media_internals,
int component_id,
int render_process_id,
int render_frame_id);
AudioLogImpl(const AudioLogImpl&) = delete;
AudioLogImpl& operator=(const AudioLogImpl&) = delete;
~AudioLogImpl() override;
void OnCreated(const media::AudioParameters& params,
const std::string& device_id) override;
void OnStarted() override;
void OnStopped() override;
void OnClosed() override;
void OnError() override;
void OnSetVolume(double volume) override;
void OnLogMessage(const std::string& message) override;
void OnProcessingStateChanged(const std::string& message) override;
private:
// If possible, i.e. a WebContents exists for the given RenderFrameHostID,
// tells an existing AudioLogEntry the WebContents title for easier
// differentiation on the UI. Note that the log entry must be created (by
// calling OnCreated() before calling this method.
void SetWebContentsTitle();
void SendSingleStringUpdate(const std::string& key, const std::string& value);
void StoreComponentMetadata(base::Value::Dict* dict);
std::string FormatCacheKey();
static void SendWebContentsTitleHelper(const std::string& cache_key,
base::Value::Dict dict,
int render_process_id,
int render_frame_id);
const int owner_id_;
const media::AudioLogFactory::AudioComponent component_;
const raw_ptr<content::MediaInternals> media_internals_;
const int component_id_;
const int render_process_id_;
const int render_frame_id_;
};
MediaInternals::AudioLogImpl::AudioLogImpl(
int owner_id,
media::AudioLogFactory::AudioComponent component,
content::MediaInternals* media_internals,
int component_id,
int render_process_id,
int render_frame_id)
: owner_id_(owner_id),
component_(component),
media_internals_(media_internals),
component_id_(component_id),
render_process_id_(render_process_id),
render_frame_id_(render_frame_id) {}
MediaInternals::AudioLogImpl::~AudioLogImpl() {
// Ensure log is always closed. This covers the case of crashes in the audio
// service utility process, in which case the log may not be closed
// explicitly.
OnClosed();
}
void MediaInternals::AudioLogImpl::OnCreated(
const media::AudioParameters& params,
const std::string& device_id) {
base::Value::Dict dict;
StoreComponentMetadata(&dict);
dict.Set(kAudioLogStatusKey, "created");
dict.Set("device_id", device_id);
dict.Set("device_type", FormatToString(params.format()));
dict.Set("frames_per_buffer", params.frames_per_buffer());
dict.Set("sample_rate", params.sample_rate());
dict.Set("channels", params.channels());
dict.Set("channel_layout", ChannelLayoutToString(params.channel_layout()));
dict.Set("effects", EffectsToString(params.effects()));
media_internals_->UpdateAudioLog(MediaInternals::CREATE, FormatCacheKey(),
kAudioLogUpdateFunction, dict);
SetWebContentsTitle();
}
void MediaInternals::AudioLogImpl::OnStarted() {
SendSingleStringUpdate(kAudioLogStatusKey, "started");
}
void MediaInternals::AudioLogImpl::OnStopped() {
SendSingleStringUpdate(kAudioLogStatusKey, "stopped");
}
void MediaInternals::AudioLogImpl::OnClosed() {
base::Value::Dict dict;
StoreComponentMetadata(&dict);
dict.Set(kAudioLogStatusKey, "closed");
media_internals_->UpdateAudioLog(MediaInternals::UPDATE_AND_DELETE,
FormatCacheKey(), kAudioLogUpdateFunction,
dict);
}
void MediaInternals::AudioLogImpl::OnError() {
SendSingleStringUpdate("error_occurred", "true");
}
void MediaInternals::AudioLogImpl::OnSetVolume(double volume) {
base::Value::Dict dict;
StoreComponentMetadata(&dict);
dict.Set("volume", volume);
media_internals_->UpdateAudioLog(MediaInternals::UPDATE_IF_EXISTS,
FormatCacheKey(), kAudioLogUpdateFunction,
dict);
}
void MediaInternals::AudioLogImpl::OnProcessingStateChanged(
const std::string& message) {
SendSingleStringUpdate("processing state", message);
}
void MediaInternals::AudioLogImpl::OnLogMessage(const std::string& message) {
MediaStreamManager::SendMessageToNativeLog(message);
}
void MediaInternals::AudioLogImpl::SetWebContentsTitle() {
if (render_process_id_ < 0 || render_frame_id_ < 0)
return;
base::Value::Dict dict;
StoreComponentMetadata(&dict);
SendWebContentsTitleHelper(FormatCacheKey(), std::move(dict),
render_process_id_, render_frame_id_);
}
std::string MediaInternals::AudioLogImpl::FormatCacheKey() {
return base::StringPrintf("%d:%d:%d", owner_id_,
base::to_underlying(component_), component_id_);
}
// static
void MediaInternals::AudioLogImpl::SendWebContentsTitleHelper(
const std::string& cache_key,
base::Value::Dict dict,
int render_process_id,
int render_frame_id) {
// Page title information can only be retrieved from the UI thread.
if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
GetUIThreadTaskRunner({})->PostTask(
FROM_HERE,
base::BindOnce(&SendWebContentsTitleHelper, cache_key, std::move(dict),
render_process_id, render_frame_id));
return;
}
WebContents* web_contents = WebContents::FromRenderFrameHost(
RenderFrameHost::FromID(render_process_id, render_frame_id));
if (!web_contents)
return;
// Note: by this point the given audio log entry could have been destroyed, so
// we use UPDATE_IF_EXISTS to discard such instances.
dict.Set("render_process_id", render_process_id);
dict.Set("web_contents_title", web_contents->GetTitle());
MediaInternals::GetInstance()->UpdateAudioLog(
MediaInternals::UPDATE_IF_EXISTS, cache_key, kAudioLogUpdateFunction,
dict);
}
void MediaInternals::AudioLogImpl::SendSingleStringUpdate(
const std::string& key,
const std::string& value) {
base::Value::Dict dict;
StoreComponentMetadata(&dict);
dict.Set(key, value);
media_internals_->UpdateAudioLog(MediaInternals::UPDATE_IF_EXISTS,
FormatCacheKey(), kAudioLogUpdateFunction,
dict);
}
void MediaInternals::AudioLogImpl::StoreComponentMetadata(
base::Value::Dict* dict) {
dict->Set("owner_id", owner_id_);
dict->Set("component_id", component_id_);
dict->Set("component_type", base::to_underlying(component_));
}
MediaInternals* MediaInternals::GetInstance() {
static content::MediaInternals* internals = new content::MediaInternals();
return internals;
}
MediaInternals::MediaInternals() = default;
MediaInternals::~MediaInternals() {}
void MediaInternals::OnRenderProcessHostCreated(
content::RenderProcessHost* host) {
if (!host_observation_.IsObservingSource(host)) {
host_observation_.AddObservation(host);
}
}
void MediaInternals::RenderProcessExited(
RenderProcessHost* host,
const ChildProcessTerminationInfo& info) {
EraseSavedEvents(host);
host_observation_.RemoveObservation(host);
}
void MediaInternals::RenderProcessHostDestroyed(RenderProcessHost* host) {
// TODO(sandersd): Is there ever a relevant case where
// RenderProcessHostDestroyed is called without RenderProcessExited also being
// called?
EraseSavedEvents(host);
host_observation_.RemoveObservation(host);
}
// Converts the |event| to a |update|. Returns whether the conversion succeeded.
static bool ConvertEventToUpdate(int render_process_id,
const media::MediaLogRecord& event,
std::u16string* update) {
DCHECK(update);
base::Value::Dict dict;
dict.Set("renderer", render_process_id);
dict.Set("player", event.id);
// TODO(dalecurtis): This is technically not correct. TimeTicks "can't" be
// converted to to a human readable time format. See base/time/time.h.
const double ticks = event.time.ToInternalValue();
const double ticks_millis = ticks / base::Time::kMicrosecondsPerMillisecond;
dict.Set("ticksMillis", ticks_millis);
base::Value::Dict cloned_params = event.params.Clone();
switch (event.type) {
case media::MediaLogRecord::Type::kMessage:
dict.Set("type", "MEDIA_LOG_ENTRY");
break;
case media::MediaLogRecord::Type::kMediaPropertyChange:
dict.Set("type", "PROPERTY_CHANGE");
break;
case media::MediaLogRecord::Type::kMediaEventTriggered: {
// Delete the "event" param so that it won't spam the log.
std::optional<base::Value> exists = cloned_params.Extract("event");
DCHECK(exists.has_value());
dict.Set("type", std::move(exists.value()));
break;
}
case media::MediaLogRecord::Type::kMediaStatus:
dict.Set("type", "PIPELINE_ERROR");
base::Value::Dict wrapped_parameters;
wrapped_parameters.Set("error", std::move(cloned_params));
cloned_params = std::move(wrapped_parameters);
break;
}
dict.Set("params", std::move(cloned_params));
*update = SerializeUpdate("media.onMediaEvent", dict);
return true;
}
void MediaInternals::OnMediaEvents(
int render_process_id,
const std::vector<media::MediaLogRecord>& events) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
// Notify observers that |event| has occurred.
for (const auto& event : events) {
if (CanUpdate()) {
std::u16string update;
if (ConvertEventToUpdate(render_process_id, event, &update))
SendUpdate(update);
}
SaveEvent(render_process_id, event);
}
}
void MediaInternals::AddUpdateCallback(UpdateCallback callback) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
update_callbacks_.push_back(std::move(callback));
base::AutoLock auto_lock(lock_);
can_update_ = true;
audio_focus_helper_.SetEnabled(true);
}
void MediaInternals::RemoveUpdateCallback(const UpdateCallback& callback) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
for (size_t i = 0; i < update_callbacks_.size(); ++i) {
if (update_callbacks_[i] == callback) {
update_callbacks_.erase(update_callbacks_.begin() + i);
break;
}
}
base::AutoLock auto_lock(lock_);
can_update_ = !update_callbacks_.empty();
audio_focus_helper_.SetEnabled(can_update_);
}
bool MediaInternals::CanUpdate() {
base::AutoLock auto_lock(lock_);
return can_update_;
}
void MediaInternals::SendHistoricalMediaEvents() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
for (const auto& saved_events : saved_events_by_process_) {
for (const auto& event : saved_events.second) {
std::u16string update;
if (ConvertEventToUpdate(saved_events.first, event, &update))
SendUpdate(update);
}
}
// Do not clear the map/list here so that refreshing the UI or opening a
// second UI still works nicely!
}
void MediaInternals::SendGeneralAudioInformation() {
base::Value::Dict audio_info_data;
// Audio feature information.
auto set_feature_data = [&audio_info_data](auto& feature) {
audio_info_data.Set(
feature.name,
base::Value(base::FeatureList::IsEnabled(feature) ? "Enabled"
: "Disabled"));
};
auto set_explicit_feature_data = [&audio_info_data](auto& feature,
bool feature_value) {
audio_info_data.Set(feature.name,
base::Value(feature_value ? "Enabled" : "Disabled"));
};
set_feature_data(features::kAudioServiceOutOfProcess);
set_feature_data(features::kAudioServiceLaunchOnStartup);
set_explicit_feature_data(
features::kAudioServiceSandbox,
GetContentClient()->browser()->ShouldSandboxAudioService());
#if BUILDFLAG(CHROME_WIDE_ECHO_CANCELLATION)
std::string chrome_wide_echo_cancellation_value_string =
media::IsChromeWideEchoCancellationEnabled() ? "Enabled" : "Disabled";
audio_info_data.Set(media::kChromeWideEchoCancellation.name,
base::Value(chrome_wide_echo_cancellation_value_string));
#endif
#if (BUILDFLAG(IS_MAC) || BUILDFLAG(IS_WIN))
std::string system_echo_cancellation_value_string =
media::IsSystemEchoCancellationEnforced() ? "Enabled" : "Disabled";
audio_info_data.Set(media::kEnforceSystemEchoCancellation.name,
base::Value(system_echo_cancellation_value_string));
#endif
std::u16string audio_info_update =
SerializeUpdate("media.updateGeneralAudioInformation", audio_info_data);
SendUpdate(audio_info_update);
}
void MediaInternals::SendAudioStreamData() {
std::u16string audio_stream_update;
{
base::AutoLock auto_lock(lock_);
audio_stream_update = SerializeUpdate("media.onReceiveAudioStreamData",
audio_streams_cached_data_);
}
SendUpdate(audio_stream_update);
}
void MediaInternals::SendVideoCaptureDeviceCapabilities() {
DCHECK_CURRENTLY_ON(BrowserThread::IO);
if (!CanUpdate())
return;
SendUpdate(SerializeUpdate("media.onReceiveVideoCaptureCapabilities",
video_capture_capabilities_cached_data_));
}
void MediaInternals::SendAudioFocusState() {
audio_focus_helper_.SendAudioFocusState();
}
void MediaInternals::GetRegisteredCdms() {
cdm_helper_.GetRegisteredCdms();
}
void MediaInternals::UpdateVideoCaptureDeviceCapabilities(
const std::vector<std::tuple<media::VideoCaptureDeviceDescriptor,
media::VideoCaptureFormats>>&
descriptors_and_formats) {
DCHECK_CURRENTLY_ON(BrowserThread::IO);
video_capture_capabilities_cached_data_.clear();
for (const auto& device_format_pair : descriptors_and_formats) {
base::Value::List control_support;
base::Value::List format_list;
// TODO(nisse): Representing format information as a string, to be
// parsed by the javascript handler, is brittle. Consider passing
// a list of mappings instead.
const media::VideoCaptureDeviceDescriptor& descriptor =
std::get<0>(device_format_pair);
const media::VideoCaptureFormats& supported_formats =
std::get<1>(device_format_pair);
if (descriptor.control_support().pan)
control_support.Append("pan");
if (descriptor.control_support().tilt)
control_support.Append("tilt");
if (descriptor.control_support().zoom)
control_support.Append("zoom");
for (const auto& format : supported_formats)
format_list.Append(media::VideoCaptureFormat::ToString(format));
base::Value::Dict device_dict;
device_dict.Set("id", descriptor.device_id);
device_dict.Set("name", descriptor.GetNameAndModel());
device_dict.Set("controlSupport", std::move(control_support));
device_dict.Set("formats", std::move(format_list));
device_dict.Set("captureApi", descriptor.GetCaptureApiTypeString());
video_capture_capabilities_cached_data_.Append(std::move(device_dict));
}
SendVideoCaptureDeviceCapabilities();
}
std::unique_ptr<media::AudioLog> MediaInternals::CreateAudioLog(
AudioComponent component,
int component_id) {
return CreateAudioLogImpl(component, component_id, -1, MSG_ROUTING_NONE);
}
mojo::PendingRemote<media::mojom::AudioLog> MediaInternals::CreateMojoAudioLog(
media::AudioLogFactory::AudioComponent component,
int component_id,
int render_process_id,
int render_frame_id) {
mojo::PendingRemote<media::mojom::AudioLog> audio_log;
CreateMojoAudioLog(component, component_id,
audio_log.InitWithNewPipeAndPassReceiver(),
render_process_id, render_frame_id);
return audio_log;
}
void MediaInternals::CreateMojoAudioLog(
media::AudioLogFactory::AudioComponent component,
int component_id,
mojo::PendingReceiver<media::mojom::AudioLog> receiver,
int render_process_id,
int render_frame_id) {
mojo::MakeSelfOwnedReceiver(
CreateAudioLogImpl(component, component_id, render_process_id,
render_frame_id),
std::move(receiver));
}
// static
void MediaInternals::CreateMediaLogRecords(
int render_process_id,
mojo::PendingReceiver<content::mojom::MediaInternalLogRecords> receiver) {
mojo::MakeSelfOwnedReceiver(
std::make_unique<MediaInternalLogRecordsImpl>(
MediaInternals::GetInstance(), render_process_id),
std::move(receiver));
}
std::unique_ptr<MediaInternals::AudioLogImpl>
MediaInternals::CreateAudioLogImpl(
media::AudioLogFactory::AudioComponent component,
int component_id,
int render_process_id,
int render_frame_id) {
base::AutoLock auto_lock(lock_);
return std::make_unique<AudioLogImpl>(
UNSAFE_TODO(owner_ids_[base::to_underlying(component)]++), component,
this, component_id, render_process_id, render_frame_id);
}
void MediaInternals::SendUpdate(const std::u16string& update) {
// SendUpdate() may be called from any thread, but must run on the UI thread.
if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
GetUIThreadTaskRunner({})->PostTask(
FROM_HERE, base::BindOnce(&MediaInternals::SendUpdate,
base::Unretained(this), update));
return;
}
for (size_t i = 0; i < update_callbacks_.size(); i++)
update_callbacks_[i].Run(update);
}
void MediaInternals::SaveEvent(int process_id,
const media::MediaLogRecord& event) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
auto& saved_events = saved_events_by_process_[process_id];
saved_events.push_back(event);
if (saved_events.size() > media::MediaLog::kLogLimit) {
// Remove all events for a given player as soon as we have to remove a
// single event for that player to avoid showing incomplete players.
const int id_to_remove = saved_events.front().id;
std::erase_if(saved_events, [&](const media::MediaLogRecord& event) {
return event.id == id_to_remove;
});
}
}
void MediaInternals::EraseSavedEvents(RenderProcessHost* host) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
// Orderly cleanup can be expensive if there are a lot of active players, so
// just skip it during shutdown -- it'll be cleared up by the process kill.
if (GetContentClient()->browser()->IsShuttingDown()) {
return;
}
// TODO(sandersd): Send a termination event before clearing the log.
saved_events_by_process_.erase(host->GetDeprecatedID());
}
void MediaInternals::UpdateAudioLog(AudioLogUpdateType type,
std::string_view cache_key,
std::string_view function,
const base::Value::Dict& value) {
{
base::AutoLock auto_lock(lock_);
const bool has_entry = audio_streams_cached_data_.Find(cache_key);
if ((type == UPDATE_IF_EXISTS || type == UPDATE_AND_DELETE) && !has_entry) {
return;
} else if (!has_entry) {
DCHECK_EQ(type, CREATE);
audio_streams_cached_data_.Set(cache_key, value.Clone());
} else if (type == UPDATE_AND_DELETE) {
std::optional<base::Value> out_value =
audio_streams_cached_data_.Extract(cache_key);
CHECK(out_value.has_value());
} else {
base::Value::Dict* existing_dict =
audio_streams_cached_data_.FindDict(cache_key);
CHECK(existing_dict);
existing_dict->Merge(value.Clone());
}
}
if (CanUpdate())
SendUpdate(SerializeUpdate(function, value));
}
} // namespace content