video-pc/AvRecorder/encoder/audio_encoder.cpp

#include "audio_encoder.h"

#include <QDebug>
#include <algorithm>

std::vector<std::string> Encoder<MediaType::AUDIO>::_usableEncoders;

const std::vector<std::string>& Encoder<MediaType::AUDIO>::GetUsableEncoders()
{
    if (_usableEncoders.empty()) {
        _FindUsableEncoders();
    }
    return _usableEncoders;
}

void Encoder<MediaType::AUDIO>::_FindUsableEncoders()
{
    qDebug() << "AudioEncoder: Finding usable encoders...";

    Param param;
    param.bitRate = 128000; // 128 kbps
    Encoder encoder;
    AVFormatContext* fmtCtx = nullptr;
    __CheckNo(avformat_alloc_output_context2(&fmtCtx, nullptr, nullptr, "test.mp4") >= 0);

    for (const auto& name : _encoderNames) {
        param.name = name;
        qDebug() << "AudioEncoder: Testing encoder:" << name;
        if (encoder.Open(param, fmtCtx)) {
            _usableEncoders.push_back(name);
            qDebug() << "AudioEncoder: Encoder" << name << "is usable";
        } else {
            qDebug() << "AudioEncoder: Encoder" << name << "failed to open";
        }
        encoder.Close();
    }

    // 简单的优先级排序：AAC优先，其次Opus，最后MP3
    if (!_usableEncoders.empty()) {
        auto priority = [](const std::string& n) -> int {
            if (n == "aac" || n == "libfdk_aac") return 0; // 与mp4/flv/rtmp兼容性最好
            if (n == "libopus" || n == "opus") return 1;  // 需容器/推流支持
            if (n == "libmp3lame") return 2;               // 一般不用于flv
            return 100;
        };
        std::sort(_usableEncoders.begin(), _usableEncoders.end(), [&](const std::string& a, const std::string& b) {
            int pa = priority(a);
            int pb = priority(b);
            if (pa != pb) return pa < pb;
            return a < b;
        });
    }

    qDebug() << "AudioEncoder: Found" << _usableEncoders.size() << "usable encoders";
    Free(fmtCtx, [&fmtCtx] { avformat_free_context(fmtCtx); });
}

bool Encoder<MediaType::AUDIO>::Open(const Param& audioParam, AVFormatContext* fmtCtx)
{
    Close();
    _isOpen = false;
    
    qDebug() << "AudioEncoder::Open: Initializing audio encoder with bitrate" << audioParam.bitRate
             << ", name:" << (audioParam.name.empty() ? "<auto>" : audioParam.name.c_str());
    
    if (!_Init(audioParam, fmtCtx)) {
        qDebug() << "AudioEncoder::Open failed: Audio encoder initialization failed";
        return false;
    }
    
    int ret = avcodec_open2(_codecCtx, _codec, nullptr);
    if (ret < 0) {
        char errbuf[AV_ERROR_MAX_STRING_SIZE];
        av_strerror(ret, errbuf, AV_ERROR_MAX_STRING_SIZE);
        qDebug() << "AudioEncoder::Open failed: Cannot open audio codec. Error:" << errbuf << "(" << ret << ")";
        qDebug() << "Codec name:" << _codec->name << "ID:" << _codec->id;
        qDebug() << "Sample rate:" << _codecCtx->sample_rate << "Channels:" << _codecCtx->ch_layout.nb_channels;
        return false;
    }
    
    _isOpen = true;
    qDebug() << "AudioEncoder::Open: Audio encoder opened successfully";
    return true;
}

void Encoder<MediaType::AUDIO>::Close()
{
    if (_codecCtx != nullptr) {
        avcodec_free_context(&_codecCtx);
    }
    Free(_codecCtx, [this] { avcodec_free_context(&_codecCtx); });
}

bool Encoder<MediaType::AUDIO>::_Init(const Param& audioParam, AVFormatContext* fmtCtx)
{
    // codec 选择：优先按名称，其次回退到容器默认音频编码器，再次回退到AAC
    if (!audioParam.name.empty()) {
        _codec = avcodec_find_encoder_by_name(audioParam.name.c_str());
    }
    if (!_codec && fmtCtx && fmtCtx->oformat && fmtCtx->oformat->audio_codec != AV_CODEC_ID_NONE) {
        _codec = avcodec_find_encoder(fmtCtx->oformat->audio_codec);
    }
    if (!_codec) {
        _codec = avcodec_find_encoder(AV_CODEC_ID_AAC);
    }
    __CheckBool(_codec);
    // codeccontext
    __CheckBool(_codecCtx = avcodec_alloc_context3(_codec));
    _codecCtx->sample_fmt = AV_SAMPLE_FMT_FLTP;
    _codecCtx->bit_rate = audioParam.bitRate;
    _codecCtx->sample_rate = AUDIO_SAMPLE_RATE;
    AVChannelLayout layout;
    layout.order = AV_CHANNEL_ORDER_NATIVE;
    layout.nb_channels = AUDIO_CHANNEL;
    layout.u.mask = (AUDIO_CHANNEL == 1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO);
    av_channel_layout_copy(&_codecCtx->ch_layout, &layout);
    if (fmtCtx->oformat->flags & AVFMT_GLOBALHEADER) {
        _codecCtx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    }
    return true;
}

bool Encoder<MediaType::AUDIO>::PushFrame(AVFrame* frame, bool isEnd, uint64_t pts)
{
    if (!isEnd) {
        __CheckBool(frame);
    } else {
        frame = nullptr;
    }
    if (frame != nullptr) {
        frame->pts = pts;
    }
    __CheckBool(avcodec_send_frame(_codecCtx, frame) >= 0);
    return true;
}