src/media/audio/audio_core/audio_renderer_format_info.cc

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/media/audio/audio_core/audio_renderer_format_info.h"

#include "src/lib/fxl/logging.h"
#include "src/media/audio/audio_core/mixer/constants.h"

namespace media::audio {

AudioRendererFormatInfo::AudioRendererFormatInfo(fuchsia::media::AudioStreamType format)
    : format_(format) {
  // Precompute some useful timing/format stuff.
  //
  // Start with the ratio between frames and nanoseconds.
  frames_per_ns_ = TimelineRate(format_.frames_per_second, ZX_SEC(1));

  // Figure out the rate we need to scale by in order to produce our fixed point timestamps.
  frame_to_media_ratio_ = TimelineRate(1 << kPtsFractionalBits, 1);

  // Figure out the total number of bytes in a packed frame.
  switch (format_.sample_format) {
    case fuchsia::media::AudioSampleFormat::UNSIGNED_8:
      bytes_per_frame_ = 1;
      break;

    case fuchsia::media::AudioSampleFormat::SIGNED_16:
      bytes_per_frame_ = 2;
      break;

    case fuchsia::media::AudioSampleFormat::SIGNED_24_IN_32:
    case fuchsia::media::AudioSampleFormat::FLOAT:
      bytes_per_frame_ = 4;
      break;

    default:
      // Format filtering was supposed to happen during AudioRendererImpl::SetStreamType.  It should
      // never be attempting to create a FormatInfo structure with a sample format that we do not
      // understand.
      FXL_CHECK(false) << "unrecognized sample format";
      bytes_per_frame_ = 2;
      break;
  }

  bytes_per_frame_ *= format_.channels;
}

// static
fbl::RefPtr<AudioRendererFormatInfo> AudioRendererFormatInfo::Create(
    fuchsia::media::AudioStreamType format) {
  return fbl::AdoptRef(new AudioRendererFormatInfo(format));
}

}  // namespace media::audio