PPB_VideoDecoder Struct Reference

Data Fields

PP_Resource(* Create )(PP_Instance instance)
PP_Bool(* IsVideoDecoder )(PP_Resource resource)
int32_t(* Initialize )(PP_Resource video_decoder, PP_Resource graphics3d_context, PP_VideoProfile profile, PP_HardwareAcceleration acceleration, uint32_t min_picture_count, struct PP_CompletionCallback callback)
int32_t(* Decode )(PP_Resource video_decoder, uint32_t decode_id, uint32_t size, const void *buffer, struct PP_CompletionCallback callback)
int32_t(* GetPicture )(PP_Resource video_decoder, struct PP_VideoPicture *picture, struct PP_CompletionCallback callback)
void(* RecyclePicture )(PP_Resource video_decoder, const struct PP_VideoPicture *picture)
int32_t(* Flush )(PP_Resource video_decoder, struct PP_CompletionCallback callback)
int32_t(* Reset )(PP_Resource video_decoder, struct PP_CompletionCallback callback)

Detailed Description

Video decoder interface.

Typical usage:

  • Call Create() to create a new video decoder resource.
  • Call Initialize() to initialize it with a 3d graphics context and the desired codec profile.
  • Call Decode() continuously (waiting for each previous call to complete) to push bitstream buffers to the decoder.
  • Call GetPicture() continuously (waiting for each previous call to complete) to pull decoded pictures from the decoder.
  • Call Flush() to signal end of stream to the decoder and perform shutdown when it completes.
  • Call Reset() to quickly stop the decoder (e.g. to implement Seek) and wait for the callback before restarting decoding at another point.
  • To destroy the decoder, the plugin should release all of its references to it. Any pending callbacks will abort before the decoder is destroyed.

Available video codecs vary by platform. All: theora, vorbis, vp8. Chrome and ChromeOS: aac, h264. ChromeOS: mpeg4.


Field Documentation

Creates a new video decoder resource.

Parameters:
[in]instanceA PP_Instance identifying the instance with the video decoder.
Returns:
A PP_Resource corresponding to a video decoder if successful or 0 otherwise.
int32_t(* PPB_VideoDecoder::Decode)(PP_Resource video_decoder, uint32_t decode_id, uint32_t size, const void *buffer, struct PP_CompletionCallback callback)

Decodes a bitstream buffer.

Copies |size| bytes of data from the plugin's |buffer|. The plugin should wait until the decoder signals completion by returning PP_OK or by running |callback| before calling Decode() again.

In general, each bitstream buffer should contain a demuxed bitstream frame for the selected video codec. For example, H264 decoders expect to receive one AnnexB NAL unit, including the 4 byte start code prefix, while VP8 decoders expect to receive a bitstream frame without the IVF frame header.

If the call to Decode() eventually results in a picture, the |decode_id| parameter is copied into the returned picture. The plugin can use this to associate decoded pictures with Decode() calls (e.g. to assign timestamps or frame numbers to pictures.) This value is opaque to the API so the plugin is free to pass any value.

Parameters:
[in]video_decoderA PP_Resource identifying the video decoder.
[in]decode_idAn optional value, chosen by the plugin, that can be used to associate calls to Decode() with decoded pictures returned by GetPicture().
[in]sizeBuffer size in bytes.
[in]bufferStarting address of buffer.
[in]callbackA PP_CompletionCallback to be called on completion.
Returns:
An int32_t containing an error code from pp_errors.h. Returns PP_ERROR_FAILED if the decoder isn't initialized or if a Flush() or Reset() call is pending. Returns PP_ERROR_INPROGRESS if there is another Decode() call pending. Returns PP_ERROR_NOMEMORY if a bitstream buffer can't be created. Returns PP_ERROR_ABORTED when Reset() is called while Decode() is pending.
int32_t(* PPB_VideoDecoder::Flush)(PP_Resource video_decoder, struct PP_CompletionCallback callback)

Flushes the decoder.

The plugin should call Flush() when it reaches the end of its video stream in order to stop cleanly. The decoder will run any pending Decode() call to completion. The plugin should make no further calls to the decoder other than GetPicture() and RecyclePicture() until the decoder signals completion by running |callback|. Just before completion, any pending GetPicture() call will complete by running its callback with result PP_ERROR_ABORTED to signal that no more pictures are available. Any pictures held by the plugin remain valid during and after the flush and should be recycled back to the decoder.

Parameters:
[in]video_decoderA PP_Resource identifying the video decoder.
[in]callbackA PP_CompletionCallback to be called on completion.
Returns:
An int32_t containing an error code from pp_errors.h. Returns PP_ERROR_FAILED if the decoder isn't initialized.
int32_t(* PPB_VideoDecoder::GetPicture)(PP_Resource video_decoder, struct PP_VideoPicture *picture, struct PP_CompletionCallback callback)

Gets the next picture from the decoder.

The picture is valid after the decoder signals completion by returning PP_OK or running |callback|. The plugin can call GetPicture() again after the decoder signals completion. When the plugin is finished using the picture, it should return it to the system by calling RecyclePicture().

Parameters:
[in]video_decoderA PP_Resource identifying the video decoder.
[out]pictureA PP_VideoPicture to hold the decoded picture.
[in]callbackA PP_CompletionCallback to be called on completion.
Returns:
An int32_t containing an error code from pp_errors.h. Returns PP_ERROR_FAILED if the decoder isn't initialized or if a Reset() call is pending. Returns PP_ERROR_INPROGRESS if there is another GetPicture() call pending. Returns PP_ERROR_ABORTED when Reset() is called, or if a call to Flush() completes while GetPicture() is pending.
int32_t(* PPB_VideoDecoder::Initialize)(PP_Resource video_decoder, PP_Resource graphics3d_context, PP_VideoProfile profile, PP_HardwareAcceleration acceleration, uint32_t min_picture_count, struct PP_CompletionCallback callback)

Initializes a video decoder resource.

This should be called after Create() and before any other functions.

Parameters:
[in]video_decoderA PP_Resource identifying the video decoder.
[in]graphics3d_contextA PPB_Graphics3D resource to use during decoding.
[in]profileA PP_VideoProfile specifying the video codec profile.
[in]accelerationA PP_HardwareAcceleration specifying whether to use a hardware accelerated or a software implementation.
[in]min_picture_countA count of pictures the plugin would like to have in flight. This is effectively the number of times the plugin can call GetPicture() and get a decoded frame without calling RecyclePicture(). The decoder has its own internal minimum count, and will take the larger of its internal and this value. A client that doesn't care can therefore just pass in zero for this argument.
[in]callbackA PP_CompletionCallback to be called upon completion.
Returns:
An int32_t containing an error code from pp_errors.h. Returns PP_ERROR_NOTSUPPORTED if video decoding is not available, or the requested profile is not supported. In this case, the client may call Initialize() again with different parameters to find a good configuration. Returns PP_ERROR_BADARGUMENT if the requested minimum picture count is unreasonably large.

Determines if the given resource is a video decoder.

Parameters:
[in]resourceA PP_Resource identifying a resource.
Returns:
PP_TRUE if the resource is a PPB_VideoDecoder, PP_FALSE if the resource is invalid or some other type.
void(* PPB_VideoDecoder::RecyclePicture)(PP_Resource video_decoder, const struct PP_VideoPicture *picture)

Recycles a picture that the plugin has received from the decoder.

The plugin should call this as soon as it has finished using the texture so the decoder can decode more pictures.

Parameters:
[in]video_decoderA PP_Resource identifying the video decoder.
[in]pictureA PP_VideoPicture to return to the decoder.
int32_t(* PPB_VideoDecoder::Reset)(PP_Resource video_decoder, struct PP_CompletionCallback callback)

Resets the decoder as quickly as possible.

The plugin can call Reset() to skip to another position in the video stream. After Reset() returns, any pending calls to Decode() and GetPicture()) abort, causing their callbacks to run with PP_ERROR_ABORTED. The plugin should not make further calls to the decoder other than RecyclePicture() until the decoder signals completion by running |callback|. Any pictures held by the plugin remain valid during and after the reset and should be recycled back to the decoder.

Parameters:
[in]video_decoderA PP_Resource identifying the video decoder.
[in]callbackA PP_CompletionCallback to be called on completion.
Returns:
An int32_t containing an error code from pp_errors.h. Returns PP_ERROR_FAILED if the decoder isn't initialized.

The documentation for this struct was generated from the following file: