92 lines
2.6 KiB
C++
92 lines
2.6 KiB
C++
// Copyright (c) 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "packager/base/logging.h"
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#include "packager/media/formats/webm/opus_packet_builder.h"
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#include "packager/media/formats/webm/webm_cluster_parser.h"
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namespace edash_packager {
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namespace media {
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OpusPacket::OpusPacket(uint8_t config, uint8_t frame_count, bool is_VBR) {
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DCHECK_GE(config, 0);
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DCHECK_LT(config, kNumPossibleOpusConfigs);
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DCHECK_GE(frame_count, kMinOpusPacketFrameCount);
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DCHECK_LE(frame_count, kMaxOpusPacketFrameCount);
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duration_ms_ = frame_count *
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WebMClusterParser::kOpusFrameDurationsMu[config] /
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static_cast<float>(1000);
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uint8_t frame_count_code;
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uint8_t frame_count_byte;
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if (frame_count == 1) {
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frame_count_code = 0;
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} else if (frame_count == 2) {
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frame_count_code = is_VBR ? 2 : 1;
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} else {
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frame_count_code = 3;
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frame_count_byte = (is_VBR ? 1 << 7 : 0) | frame_count;
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}
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// All opus packets must have TOC byte.
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uint8_t opus_toc_byte = (config << 3) | frame_count_code;
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data_.push_back(opus_toc_byte);
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// For code 3 packets, the number of frames is signaled in the "frame
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// count byte".
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if (frame_count_code == 3) {
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data_.push_back(frame_count_byte);
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}
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// Packet will only conform to layout specification for the TOC byte
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// and optional frame count bytes appended above. This last byte
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// is purely dummy padding where frame size data or encoded data might
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// otherwise start.
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data_.push_back(static_cast<uint8_t>(0));
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}
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OpusPacket::~OpusPacket() {
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}
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const uint8_t* OpusPacket::data() const {
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return &(data_[0]);
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}
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int OpusPacket::size() const {
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return data_.size();
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}
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double OpusPacket::duration_ms() const {
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return duration_ms_;
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}
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ScopedVector<OpusPacket> BuildAllOpusPackets() {
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ScopedVector<OpusPacket> opus_packets;
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for (int frame_count = kMinOpusPacketFrameCount;
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frame_count <= kMaxOpusPacketFrameCount; frame_count++) {
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for (int opus_config_num = 0; opus_config_num < kNumPossibleOpusConfigs;
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opus_config_num++) {
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bool is_VBR = false;
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opus_packets.push_back(
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new OpusPacket(opus_config_num, frame_count, is_VBR));
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if (frame_count >= 2) {
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// Add another packet with VBR flag toggled. For frame counts >= 2,
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// VBR triggers changes to packet framing.
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is_VBR = true;
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opus_packets.push_back(
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new OpusPacket(opus_config_num, frame_count, is_VBR));
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}
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}
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}
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return opus_packets.Pass();
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}
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} // namespace media
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} // namespace edash_packager
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