Starboard Module Reference: player.h

Defines an interface for controlling playback of media elementary streams.



The value of the initial ticket held by the player before the first seek. The player will use this ticket value to make the first call to SbPlayerStatusFunc with kSbPlayerStateInitialized.


The value to pass into SbPlayerCreate's duration_pts argument for cases where the duration is unknown, such as for live streams.


Well-defined value for an invalid player.


The audio write duration when all the audio connectors are local.


The audio write duration when at least one of the audio connectors are remote.



An indicator of whether the decoder can accept more samples.


  • kSbPlayerDecoderStateNeedsData

    The decoder is asking for one more sample.


Identify the type of side data accompanied with SbPlayerSampleInfo, as side data may come from multiple sources.


  • kMatroskaBlockAdditional

    The side data comes from the BlockAdditional data in the Matroska/Webm container. The first 8 bytes of the data contains the value of BlockAddID in big endian format, followed by the content of BlockAdditional. See:



An indicator of the general playback state.


  • kSbPlayerStateInitialized

    The player has just been initialized. It is expecting an SbPlayerSeek() call to enter the prerolling state.

  • kSbPlayerStatePrerolling

    The player is prerolling, collecting enough data to fill the pipeline before presentation starts. After the first preroll is completed, there should always be a video frame to render, even if the player goes back to Prerolling after a Seek.

  • kSbPlayerStatePresenting

    The player is presenting media, and it is either paused or actively playing in real-time. Note that the implementation should use this state to signal that the preroll has been finished.

  • kSbPlayerStateEndOfStream

    The player is presenting media, but it is paused at the end of the stream.

  • kSbPlayerStateDestroyed

    The player has been destroyed, and will send no more callbacks.



An opaque handle to an implementation-private structure representing a player.


typedef struct SbPlayerPrivate* SbPlayer


Callback to free the given sample buffer data. When more than one buffer are sent in SbPlayerWriteSample(), the implementation only has to call this callback with sample_buffer points to the first buffer.


typedef void(* SbPlayerDeallocateSampleFunc) (SbPlayer player, void *context, const void *sample_buffer)


Callback for decoder status updates, called in response to a call to SbPlayerSeek() or SbPlayerWriteSample(). This callback will never be called until at least one call to SbPlayerSeek has occurred. ticket will be set to the ticket passed into the last received call to SbPlayerSeek() at the time this callback was dispatched. This is to distinguish status callbacks for interrupting seeks. These callbacks will happen on a different thread than the calling thread, and it is not valid to call SbPlayer functions from within this callback. After an update with kSbPlayerDecoderStateNeedsData, the user of the player will make at most one call to SbPlayerWriteSample() or SbPlayerWriteEndOfStream(). The player implementation should update the decoder status again after such call to notify its user to continue writing more frames.


typedef void(* SbPlayerDecoderStatusFunc) (SbPlayer player, void *context, SbMediaType type, SbPlayerDecoderState state, int ticket)


Callback for player errors, that may set a message.

error: indicates the error code.

message: provides specific informative diagnostic message about the error condition encountered. It is ok for the message to be an empty string or NULL if no information is available.


typedef void(* SbPlayerErrorFunc) (SbPlayer player, void *context, SbPlayerError error, const char *message)


Callback for player status updates. These callbacks will happen on a different thread than the calling thread, and it is not valid to call SbPlayer functions from within this callback.


typedef void(* SbPlayerStatusFunc) (SbPlayer player, void *context, SbPlayerState state, int ticket)



The playback related parameters to pass into SbPlayerCreate() and SbPlayerGetPreferredOutputMode().


  • SbDrmSystem drm_system

    Provides an appropriate DRM system if the media stream has encrypted portions. It will be kSbDrmSystemInvalid if the stream does not have encrypted portions.

  • SbMediaAudioStreamInfo audio_stream_info

    Contains a populated SbMediaAudioStreamInfo if audio_stream_info.codec isn't kSbMediaAudioCodecNone. When audio_stream_info.codec is kSbMediaAudioCodecNone, the video doesn't have an audio track.

  • SbMediaVideoStreamInfo video_stream_info

    Contains a populated SbMediaVideoStreamInfo if video_stream_info.codec isn't kSbMediaVideoCodecNone. When video_stream_info.codec is kSbMediaVideoCodecNone, the video is audio only.

  • SbPlayerOutputMode output_mode

    Selects how the decoded video frames will be output. For example, kSbPlayerOutputModePunchOut indicates that the decoded video frames will be output to a background video layer by the platform, and kSbPlayerOutputDecodeToTexture indicates that the decoded video frames should be made available for the application to pull via calls to SbPlayerGetCurrentFrame().


Information about the current media playback state.


  • int64_t current_media_timestamp

    The position of the playback head, as precisely as possible, in microseconds.

  • int64_t duration

    The known duration of the currently playing media stream, in microseconds.

  • int64_t start_date

    The result of getStartDate for the currently playing media stream, in microseconds since the epoch of January 1, 1601 UTC.

  • int frame_width

    The width of the currently displayed frame, in pixels, or 0 if not provided by this player.

  • int frame_height

    The height of the currently displayed frame, in pixels, or 0 if not provided by this player.

  • bool is_paused

    Whether playback is currently paused.

  • double volume

    The current player volume in [0, 1].

  • int total_video_frames

    The number of video frames sent to the player since the creation of the player.

  • int dropped_video_frames

    The number of video frames decoded but not displayed since the creation of the player.

  • int corrupted_video_frames

    The number of video frames that failed to be decoded since the creation of the player.

  • double playback_rate

    The rate of playback. The video is played back in a speed that is proportional to this. By default it is 1.0 which indicates that the playback is at normal speed. When it is greater than one, the video is played in a faster than normal speed. When it is less than one, the video is played in a slower than normal speed. Negative speeds are not supported.


Information about the samples to be written into SbPlayerWriteSamples().


  • SbMediaType type
  • const void * buffer

    Points to the buffer containing the sample data.

  • int buffer_size

    Size of the data pointed to by buffer.

  • int64_t timestamp

    The timestamp of the sample in microseconds since Windows epoch UTC.

  • SbPlayerSampleSideData* side_data

    Points to an array of side data for the input, when available.

  • int side_data_count

    The number of side data pointed by side_data. It should be set to 0 if there is no side data for the input.

  • SbMediaAudioSampleInfo audio_sample_info

    Information about an audio sample. This value can only be used when type is kSbMediaTypeAudio.

  • SbMediaVideoSampleInfo video_sample_info

    Information about a video sample. This value can only be used when type is kSbMediaTypeVideo.

  • union SbPlayerSampleInfo::@0 @1

  • constSbDrmSampleInfo* drm_info

    The DRM system related info for the media sample. This value is required for encrypted samples. Otherwise, it must be NULL.


Side data accompanied with SbPlayerSampleInfo, it can be arbitrary binary data coming from multiple sources.


  • SbPlayerSampleSideDataType type
  • const uint8_t * data

    data will remain valid until SbPlayerDeallocateSampleFunc() is called on the SbPlayerSampleInfo::buffer the data is associated with.

  • size_t size

    The size of the data pointed by data, in bytes.



Creates a player that will be displayed on window for the specified video_codec and audio_codec, acquiring all resources needed to operate it, and returning an opaque handle to it. The expectation is that a new player will be created and destroyed for every playback.

This function returns the created player. Note the following:

  • The associated decoder of the returned player should be assumed to not be in kSbPlayerDecoderStateNeedsData until SbPlayerSeek() has been called on it.

  • It is expected either that the thread that calls SbPlayerCreate is the same thread that calls the other SbPlayer functions for that player, or that there is a mutex guarding calls into each SbPlayer instance.

  • If there is a platform limitation on how many players can coexist simultaneously, then calls made to this function that attempt to exceed that limit must return kSbPlayerInvalid. Multiple calls to SbPlayerCreate must not cause a crash.

window: The window that will display the player. window can be kSbWindowInvalid for platforms where video is only displayed on a particular window that the underlying implementation already has access to.

video_codec: The video codec used for the player. If video_codec is kSbMediaVideoCodecNone, the player is an audio-only player. If video_codec is any other value, the player is an audio/video decoder. This can be set to kSbMediaVideoCodecNone to play a video with only an audio track.

audio_codec: The audio codec used for the player. The caller must provide a populated audio_sample_info if audio codec is kSbMediaAudioCodecAac. Can be set to kSbMediaAudioCodecNone to play a video without any audio track. In such case audio_sample_info must be NULL.

drm_system: If the media stream has encrypted portions, then this parameter provides an appropriate DRM system, created with SbDrmCreateSystem(). If the stream does not have encrypted portions, then drm_system may be kSbDrmSystemInvalid.

audio_sample_info: Note that the caller must provide a populated audio_sample_info if the audio codec is kSbMediaAudioCodecAac. Otherwise, audio_sample_info can be NULL. See media.h for the format of the SbMediaAudioSampleInfo struct.

Note that audio_specific_config is a pointer and the content it points to is no longer valid after this function returns. The implementation has to make a copy of the content if it is needed after the function returns.

max_video_capabilities: This string communicates the max video capabilities required to the platform. The web app will not provide a video stream exceeding the maximums described by this parameter. Allows the platform to optimize playback pipeline for low quality video streams if it knows that it will never adapt to higher quality streams. The string uses the same format as the string passed in to SbMediaCanPlayMimeAndKeySystem(), for example, when it is set to "width=1920; height=1080; framerate=15;", the video will never adapt to resolution higher than 1920x1080 or frame per second higher than 15 fps. When the maximums are unknown, this will be set to NULL.

sample_deallocator_func: If not NULL, the player calls this function on an internal thread to free the sample buffers passed into SbPlayerWriteSample().

decoder_status_func: If not NULL, the decoder calls this function on an internal thread to provide an update on the decoder's status. No work should be done on this thread. Rather, it should just signal the client thread interacting with the decoder.

player_status_func: If not NULL, the player calls this function on an internal thread to provide an update on the playback status. No work should be done on this thread. Rather, it should just signal the client thread interacting with the decoder.

player_error_func: If not NULL, the player calls this function on an internal thread to provide an update on the error status. This callback is responsible for setting the media error message.

context: This is passed to all callbacks and is generally used to point at a class or struct that contains state associated with the player.

output_mode: Selects how the decoded video frames will be output. For example, kSbPlayerOutputModePunchOut indicates that the decoded video frames will be output to a background video layer by the platform, and kSbPlayerOutputDecodeToTexture indicates that the decoded video frames should be made available for the application to pull via calls to SbPlayerGetCurrentFrame().

provider: Only present in Starboard version 3 and up. If not NULL, then when output_mode == kSbPlayerOutputModeDecodeToTexture, the player MAY use the provider to create SbDecodeTargets on the renderer thread. A provider may not always be needed by the player, but if it is needed, and the provider is not given, the player will fail by returning kSbPlayerInvalid.

If NULL is passed to any of the callbacks (sample_deallocator_func, decoder_status_func, player_status_func, or player_error_func if it applies), then kSbPlayerInvalid must be returned.


SbPlayer SbPlayerCreate(SbWindow window, const SbPlayerCreationParam *creation_param, SbPlayerDeallocateSampleFunc sample_deallocate_func, SbPlayerDecoderStatusFunc decoder_status_func, SbPlayerStatusFunc player_status_func, SbPlayerErrorFunc player_error_func, void *context, SbDecodeTargetGraphicsContextProvider *context_provider)


Destroys player, freeing all associated resources.

  • Upon calling this method, there should be one call to the player status callback (i.e. player_status_func used in the creation of the player) which indicates the player is destroyed. Note, the callback has to be inflight when SbPlayerDestroyed is called.

  • No more other callbacks should be issued after this function returns.

  • It is not allowed to pass player into any other SbPlayer function once SbPlayerDestroy has been called on that player.

player: The player to be destroyed. Must not be kSbPlayerInvalid.


void SbPlayerDestroy(SbPlayer player)


Returns the audio configurations used by player.

Returns true when out_audio_configuration is filled with the information of the configuration of the audio output devices used by player. Returns false for index 0 to indicate that there is no audio output for this player. Returns false for index greater than 0 to indicate that there are no more audio output configurations other than the ones already returned.

The app will use the information returned to determine audio related behaviors, like:

  • Audio Write Duration: Audio write duration is how far past the current playback position the app will write audio samples. The app will write all samples between current_playback_position and current_playback_position

    • audio_write_duration, as soon as they are available.
  • audio_write_duration will be to kSbPlayerWriteDurationLocal when all audio configurations linked to player is local, or if there isn't any audio output. It will be set to kSbPlayerWriteDurationRemote for remote or wireless audio outputs, i.e. one of kSbMediaAudioConnectorBluetooth or kSbMediaAudioConnectorRemote*.

  • The app only guarantees to write audio_write_duration past current_playback_position, but the app is free to write more samples than that. So the platform shouldn't rely on this for flow control. The platform should achieve flow control by sending kSbPlayerDecoderStateNeedsData less frequently.

  • The platform is responsible for guaranteeing that when only audio_write_duration audio samples are written at a time, no playback issues occur (such as transient or indefinite hanging).

The audio configurations should be available as soon as possible, and they have to be available when the player is at kSbPlayerStatePresenting, unless the audio codec is kSbMediaAudioCodecNone or there's no written audio inputs.

The app will set audio_write_duration to kSbPlayerWriteDurationLocal when the audio configuration isn't available (i.e. the function returns false when index is 0). The platform has to make the audio configuration available immediately after the SbPlayer is created, if it expects the app to treat the platform as using wireless audio outputs.

Once at least one audio configurations are returned, the return values and their orders shouldn't change during the life time of player. The platform may inform the app of any changes by sending kSbPlayerErrorCapabilityChanged to request a playback restart.

player: The player about which information is being retrieved. Must not be kSbPlayerInvalid.

index: The index of the audio output configuration. Must be greater than or equal to 0.

out_audio_configuration: The information about the audio output, refer to SbMediaAudioConfiguration for more details. Must not be NULL.


bool SbPlayerGetAudioConfiguration(SbPlayer player, int index, SbMediaAudioConfiguration *out_audio_configuration)


Given a player created with the kSbPlayerOutputModeDecodeToTexture output mode, it will return a SbDecodeTarget representing the current frame to be rasterized. On GLES systems, this function must be called on a thread with an EGLContext current, and specifically the EGLContext that will be used to eventually render the frame. If this function is called with a player object that was created with an output mode other than kSbPlayerOutputModeDecodeToTexture, kSbDecodeTargetInvalid is returned.

player must not be kSbPlayerInvalid.


SbDecodeTarget SbPlayerGetCurrentFrame(SbPlayer player)


Gets a snapshot of the current player state and writes it to out_player_info. This function may be called very frequently and is expected to be inexpensive.

player: The player about which information is being retrieved. Must not be kSbPlayerInvalid.

out_player_info: The information retrieved for the player.


void SbPlayerGetInfo(SbPlayer player, SbPlayerInfo *out_player_info)


Returns the maximum number of samples that can be written in a single call to SbPlayerWriteSamples(). Returning a value greater than one can improve performance by allowing SbPlayerWriteSamples() to write multiple samples in one call.

Note that this feature is currently disabled in Cobalt where SbPlayerWriteSamples() will always be called with one sample.

player: The player for which the number is retrieved.

sample_type: The type of sample for which the number is retrieved. See the SbMediaType enum in media.h.


int SbPlayerGetMaximumNumberOfSamplesPerWrite(SbPlayer player, SbMediaType sample_type)


Returns the preferred output mode of the implementation when a video described by creation_param is played. It is assumed that it is okay to call SbPlayerCreate() with the same video described by creation_param, with its output_mode member replaced by the returned output mode. When the caller has no preference on the output mode, it will set creation_param->output_mode to kSbPlayerOutputModeInvalid, and the implementation can return its preferred output mode based on the information contained in creation_param. The caller can also set creation_param->output_mode to its preferred output mode, and the implementation should return the same output mode if it is supported, otherwise the implementation should return an output mode that it is supported, as if creation_param->output_mode is set to kSbPlayerOutputModeInvalid prior to the call. Note that it is not the responsibility of this function to verify whether the video described by creation_param can be played on the platform, and the implementation should try its best effort to return a valid output mode. creation_param must not be NULL.


SbPlayerOutputMode SbPlayerGetPreferredOutputMode(const SbPlayerCreationParam *creation_param)


Returns whether the given player handle is valid.


static bool SbPlayerIsValid(SbPlayer player)


Tells the player to freeze playback (if playback has already started), reset or flush the decoder pipeline, and go back to the Prerolling state. The player should restart playback once it can display the frame at seek_to_timestamp, or the closest it can get. (Some players can only seek to I-Frames, for example.)

  • Seek must be called before samples are sent when starting playback for the first time, or the client never receives the kSbPlayerDecoderStateNeedsData signal.

  • A call to seek may interrupt another seek.

  • After this function is called, the client should not send any more audio or video samples until SbPlayerDecoderStatusFunc is called back with kSbPlayerDecoderStateNeedsData for each required media type. SbPlayerDecoderStatusFunc is the decoder_status_func callback function that was specified when the player was created (SbPlayerCreate).

player: The SbPlayer in which the seek operation is being performed. Must not be kSbPlayerInvalid.

seek_to_timestamp: The frame at which playback should begin.

ticket: A user-supplied unique ID to be passed to all subsequent SbPlayerDecoderStatusFunc calls. (That is the decoder_status_func callback function specified when calling SbPlayerCreate.)

The ticket value is used to filter calls that may have been in flight when SbPlayerSeek was called. To be very specific, once SbPlayerSeek has been called with ticket X, a client should ignore all SbPlayerDecoderStatusFunc calls that do not pass in ticket X.


void SbPlayerSeek(SbPlayer player, int64_t seek_to_timestamp, int ticket)


Sets the player bounds to the given graphics plane coordinates. The changes do not take effect until the next graphics frame buffer swap. The default bounds for a player is the full screen. This function is only relevant when the player is created with the kSbPlayerOutputModePunchOut output mode, and if this is not the case then this function call can be ignored.

This function is called on every graphics frame that changes the video bounds. For example, if the video bounds are being animated, then this will be called at up to 60 Hz. Since the function could be called up to once per frame, implementors should take care to avoid related performance concerns with such frequent calls.

player: The player that is being resized. Must not be kSbPlayerInvalid.

z_index: The z-index of the player. When the bounds of multiple players are overlapped, the one with larger z-index will be rendered on top of the ones with smaller z-index.

x: The x-coordinate of the upper-left corner of the player.

y: The y-coordinate of the upper-left corner of the player.

width: The width of the player, in pixels.

height: The height of the player, in pixels.


void SbPlayerSetBounds(SbPlayer player, int z_index, int x, int y, int width, int height)


Set the playback rate of the player. rate is default to 1.0 which indicates the playback is at its original speed. A rate greater than one will make the playback faster than its original speed. For example, when rate is 2, the video will be played at twice the speed as its original speed. A rate less than 1.0 will make the playback slower than its original speed. When rate is 0, the playback will be paused. The function returns true when the playback rate is set to playback_rate or to a rate that is close to playback_rate which the implementation supports. It returns false when the playback rate is unchanged, this can happen when playback_rate is negative or if it is too high to support.

player must not be kSbPlayerInvalid.


bool SbPlayerSetPlaybackRate(SbPlayer player, double playback_rate)


Sets the player's volume.

player: The player in which the volume is being adjusted. Must not be kSbPlayerInvalid.

volume: The new player volume. The value must be between 0.0 and 1.0, inclusive. A value of 0.0 means that the audio should be muted, and a value of 1.0 means that it should be played at full volume.


void SbPlayerSetVolume(SbPlayer player, double volume)


Writes a marker to player's input stream of stream_type indicating that there are no more samples for that media type for the remainder of this media stream. This marker is invalidated, along with the rest of the stream's contents, after a call to SbPlayerSeek.

player: The player to which the marker is written.

stream_type: The type of stream for which the marker is written.


void SbPlayerWriteEndOfStream(SbPlayer player, SbMediaType stream_type)


Writes samples of the given media type to player's input stream. The lifetime of sample_infos, and the members of its elements like buffer, video_sample_info, and drm_info (as well as member subsample_mapping contained inside it) are not guaranteed past the call to SbPlayerWriteSamples(). That means that before returning, the implementation must synchronously copy any information it wants to retain from those structures.

SbPlayerWriteSamples() allows writing of multiple samples in one call.

player: The player to which the sample is written. Must not be kSbPlayerInvalid.

sample_type: The type of sample being written. See the SbMediaType enum in media.h.

sample_infos: A pointer to an array of SbPlayerSampleInfo with number_of_sample_infos elements, each holds the data for an sample, i.e. a sequence of whole NAL Units for video, or a complete audio frame. sample_infos cannot be assumed to live past the call into SbPlayerWriteSamples(), so it must be copied if its content will be used after SbPlayerWriteSamples() returns.

number_of_sample_infos: Specify the number of samples contained inside sample_infos. It has to be at least one, and at most the return value of SbPlayerGetMaximumNumberOfSamplesPerWrite().


void SbPlayerWriteSamples(SbPlayer player, SbMediaType sample_type, const SbPlayerSampleInfo *sample_infos, int number_of_sample_infos)