ZLMediaKit/ext-codec/AACRtp.cpp
2024-06-16 09:34:39 +08:00

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/*
* Copyright (c) 2016-present The ZLMediaKit project authors. All Rights Reserved.
*
* This file is part of ZLMediaKit(https://github.com/ZLMediaKit/ZLMediaKit).
*
* Use of this source code is governed by MIT-like license that can be found in the
* LICENSE file in the root of the source tree. All contributing project authors
* may be found in the AUTHORS file in the root of the source tree.
*/
#include "AACRtp.h"
namespace mediakit{
bool AACRtpEncoder::inputFrame(const Frame::Ptr &frame) {
auto ptr = (char *)frame->data() + frame->prefixSize();
auto size = frame->size() - frame->prefixSize();
auto remain_size = size;
auto max_size = getRtpInfo().getMaxSize() - 4;
while (remain_size > 0) {
if (remain_size <= max_size) {
outputRtp(ptr, remain_size, size, true, frame->dts());
break;
}
outputRtp(ptr, max_size, size, false, frame->dts());
ptr += max_size;
remain_size -= max_size;
}
return true;
}
void AACRtpEncoder::outputRtp(const char *data, size_t len, size_t total_len, bool mark, uint64_t stamp) {
auto rtp = getRtpInfo().makeRtp(TrackAudio, nullptr, len + 4, mark, stamp);
auto payload = rtp->data() + RtpPacket::kRtpTcpHeaderSize + RtpPacket::kRtpHeaderSize;
payload[0] = 0;
payload[1] = 16;
payload[2] = ((total_len) >> 5) & 0xFF;
payload[3] = ((total_len & 0x1F) << 3) & 0xFF;
memcpy(payload + 4, data, len);
RtpCodec::inputRtp(std::move(rtp), false);
}
/////////////////////////////////////////////////////////////////////////////////////
AACRtpDecoder::AACRtpDecoder() {
obtainFrame();
}
void AACRtpDecoder::obtainFrame() {
//从缓存池重新申请对象,防止覆盖已经写入环形缓存的对象
_frame = FrameImp::create();
_frame->_codec_id = CodecAAC;
}
bool AACRtpDecoder::inputRtp(const RtpPacket::Ptr &rtp, bool key_pos) {
auto payload_size = rtp->getPayloadSize();
if (payload_size <= 0) {
// 无实际负载
return false;
}
auto stamp = rtp->getStampMS();
// rtp数据开始部分
auto ptr = rtp->getPayload();
// rtp数据末尾
auto end = ptr + payload_size;
// 首2字节表示Au-Header的个数单位bit所以除以16得到Au-Header个数
auto au_header_count = ((ptr[0] << 8) | ptr[1]) >> 4;
if (!au_header_count) {
// 问题issue: https://github.com/ZLMediaKit/ZLMediaKit/issues/1869
WarnL << "invalid aac rtp au_header_count";
return false;
}
// 记录au_header起始指针
auto au_header_ptr = ptr + 2;
ptr = au_header_ptr + au_header_count * 2;
if (end < ptr) {
// 数据不够
return false;
}
if (!_last_dts) {
// 记录第一个时间戳
_last_dts = stamp;
}
// 每个audio unit时间戳增量
auto dts_inc = (stamp - _last_dts) / au_header_count;
if (dts_inc < 0 || dts_inc > 100) {
// 时间戳增量异常,忽略
dts_inc = 0;
}
for (auto i = 0u; i < (size_t)au_header_count; ++i) {
// 之后的2字节是AU_HEADER,其中高13位表示一帧AAC负载的字节长度低3位无用
auto size = ((au_header_ptr[0] << 8) | au_header_ptr[1]) >> 3;
auto len = std::min<int>(size, end - ptr);
if (len <= 0) {
break;
}
_frame->_buffer.append((char *)ptr, len);
ptr += len;
au_header_ptr += 2;
if (_frame->size() >= (size_t)size) {
// 设置当前audio unit时间戳
_frame->_dts = _last_dts + i * dts_inc;
flushData();
}
}
// 记录上次时间戳
_last_dts = stamp;
return false;
}
void AACRtpDecoder::flushData() {
auto ptr = reinterpret_cast<const uint8_t *>(_frame->data());
if ((ptr[0] == 0xFF && (ptr[1] & 0xF0) == 0xF0) && _frame->size() > ADTS_HEADER_LEN) {
// adts头打入了rtp包不符合规范兼容EasyPusher的bug
_frame->_prefix_size = ADTS_HEADER_LEN;
}
RtpCodec::inputFrame(_frame);
obtainFrame();
}
}//namespace mediakit