media/mojo/interfaces/video_decoder.mojom

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module media.mojom;

import "media/mojo/interfaces/media_types.mojom";

interface VideoDecoder {
  // Initialize the decoder. This must be called before any other method.
  //
  // |decoder_buffer_pipe| will be used to transfer encoded data for each
  // DecoderBuffer.
  //
  // TODO(sandersd): Rename to Initialize() if/when
  // media::VideoDecoder::Initialize() is renamed to Configure().
  Construct(associated VideoDecoderClient client,
            handle<data_pipe_consumer> decoder_buffer_pipe);

  // Configure (or reconfigure) the decoder. This must be called before decoding
  // any frames, and must not be called while there are pending Initialize(),
  // Decode(), or Reset() requests.
  //
  // If |low_delay| is true, the decoder must output frames as soon as possible;
  // in particular, it must not wait for another Decode() request, except as
  // required for frame reordering. Implementations must fail initialization if
  // they cannot satisfy this requirement.
  //
  // On completion, the callback also includes |needs_bitstream_conversion|,
  // indicating whether decode buffers need bitstream conversion, and
  // |max_decode_requests|, the maximum number of concurrent Decode() requests
  // the implementation supports.
  Initialize(VideoDecoderConfig config, bool low_delay) =>
      (bool success, bool needs_bitstream_conversion,
       int32 max_decode_requests);

  // Request decoding of exactly one frame or an EOS buffer. This must not be
  // called while there are pending Initialize(), Reset(), or Decode(EOS)
  // requests.
  //
  // Implementations must eventually execute the callback, even if Decode() is
  // not called again. It is not required that the decode status match the
  // actual result of decoding the buffer, only that decode errors are
  // eventually reported (such as at EOS).
  //
  // If |buffer| is an EOS buffer, implementations must execute all other
  // pending Decode() callbacks and output all pending frames before executing
  // the Decode(EOS) callback. (That is, they must flush.)
  Decode(DecoderBuffer buffer) => (DecodeStatus status);

  // Reset the decoder. All ongoing Decode() requests must be completed or
  // aborted before executing the callback. This must not be called while there
  // is a pending Initialize() request.
  Reset() => ();
};

interface VideoDecoderClient {
  // Output a decoded frame. Frames must be output in presentation order.
  OnVideoFrameDecoded(VideoFrame frame);
};