# Audio/Video Playback Development ## When to Use Audio and video playback is a process to decode audio and video files or stream data and play them by an output device. During the process, playback tasks are managed. ## Available APIs The following table describes APIs available for audio and video playback. **Table 1** APIs available for media playback

API

Function

Description

Player

int32_t SetSource(const Source &source);

Sets the playback source for the player.

Player

int32_t Prepare();

Prepares the playback environment.

Player

int32_t Play();

Starts playback.

Player

bool IsPlaying()

Checks whether the player is playing.

Player

int32_t Pause();

Pauses playback.

Player

int32_t Stop();

Stops playback.

Player

int32_t Rewind(int_64 mSeconds, int32_t mode);

Changes the playback position.

Player

int32_t SetVolume(float leftVolume, float rightVolume);

Sets player volume, including volume of left and right channels.

Player

int32_t SetVideoSurface(Surface *surface)

Sets a surface for video playback.

Player

int32_t EnableSingleLooping(bool loop)

Enables loop playback.

Player

bool IsSingleLooping();

Checks whether loop playback is enabled.

Player

int32_t GetCurrentTime(int64_t &time) const;

Obtains the current playback duration, accurate to millisecond.

Player

int32_t GetDuration(int64_t &duration) const;

Obtains the total duration of media files, in milliseconds.

Player

int32_t GetVideoWidth(int32_t &videoWidth);

Obtains the width of the video.

Player

int32_t GetVideoHeight(int32_t &videoHeight);

Obtains the height of the video.

Player

int32_t Reset();

Restores the player to the initial state.

Player

int32_t Release();

Releases player resources.

Player

void SetPlayerCallback(const std::shared_ptr<PlayerCallback> &cb);

Sets a player callback.

Source

Source(const std::string& uri);

A constructor used to create a Source instance based on a specified URI.

Source

Source(const std::shared_ptr<StreamSource> &stream, const Format &formats);

A constructor used to create a Source instance based on the stream source and format information.

Source

SourceType GetSourceType() const;

Obtains the source type.

Source

const std::string &GetSourceUri() const;

Obtains the media source URI.

Source

const std::shared_ptr<StreamSource> &GetSourceStream() const;

Obtains information about the media source stream.

Source

const Format &GetSourceStreamFormat() const;

Obtains the media source stream format.

Format

bool PutIntValue(const std::string &key, int32_t value);

Sets metadata of the integer type.

Format

bool PutLongValue(const std::string &key, int64_t value);

Sets metadata of the long integer type.

Format

bool PutFloatValue(const std::string &key, float value);

Sets metadata of the single-precision floating-point type.

Format

bool PutDoubleValue(const std::string &key, double value);

Sets metadata of the double-precision floating-point type.

Format

bool PutStringValue(const std::string &key, const std::string &value);

Sets metadata of the string type.

Format

bool GetIntValue(const std::string &key, int32_t &value) const;

Obtains the metadata value of the integer type.

Format

bool GetLongValue(const std::string &key, int64_t &value) const;

Obtains the metadata value of the long integer type.

Format

bool GetFloatValue(const std::string &key, float &value) const;

Obtains the metadata value of the single-precision floating-point type.

Format

bool GetDoubleValue(const std::string &key, double &value) const;

Obtains the metadata value of the double-precision floating-point type.

Format

bool GetStringValue(const std::string &key, std::string &value) const;

Obtains the metadata value of the string type.

Format

const std::map<std::string, FormatData *> &GetFormatMap() const;

Obtains the metadata map.

Format

bool CopyFrom(const Format &format);

Sets all metadata to a specified format.
## Limitations and Constraints When the input source is a media stream, the playback progress cannot be controlled and the file duration cannot be obtained. ## How to Develop 1. Implement a **PlayerCallback** function, register the callback via **SetPlayerCallback** for event processing. ``` class TestPlayerCallback : public PlayerCallback{ void OnPlaybackComplete() override { // Process the event that the file playback is complete. } void OnError(int32_t errorType, int32_t errorCode) override { // Process the error event. } void OnInfo(int type, int extra) override { // Process a common event. } void OnRewindToComplete() override { // Process the event that playback position is changed. } }; ``` 2. Create a **Player** instance, set the playback source, and start playback. ``` Player *player = new Player(); std::shared_ptr callback = std::make_shared(); player->SetPlayerCallback(callback);// Set a player callback. std::string uri(filePath);// filePath is a local file path. Source source(uri);// Create a Source instance and save the URI to the instance. player->SetSource(source);// Set the Source instance to the player. player->Prepare(); // Prepare for the playback. player->SetVideoSurface(surface);// Set the playback surface. player->Play(); // Start playback. ``` 3. Control the playback as needed. ``` player->SetVolume(lvolume, rvolume);// Set volume for left and right channels. player->EnableSingleLooping(true);// Enable loop playback. player->Pause(); // Pause playback. player->Play(); // Resume playing. ``` 4. Release resources after the playback is complete. ``` player->Stop(); // Stop playback. player->Release(); // Release resources. ```