QT下使用ffmpeg+SDL实现音视频播放器，支持录像截图功能，提供工程源码下载

#include "cvideoplayer.h" QMutex g_lock; // 音频处理回调函数。读队列获取音频包，解码，播放 // 此函数被SDL按需调用，此函数不在用户主线程中，因此数据需要保护 // \param[in] userdata用户在注册回调函数时指定的参数 // \param[out] stream 音频数据缓冲区地址，将解码后的音频数据填入此缓冲区 // \param[out] len 音频数据缓冲区大小，单位字节 // 回调函数返回后，stream指向的音频缓冲区将变为无效 void sdl_audio_callback(void *userdata, uint8_t *stream, int len) { cVideoPlayer *pPlayer = (cVideoPlayer*)userdata; SDL_memset(stream, 0, len); if(pPlayer && pPlayer->m_adq.size() > 0) { QMutexLocker guard(&g_lock); audio_data_t* pAudioData = pPlayer->m_adq.dequeue(); if(pAudioData->size == 0) return; len = (len>pAudioData->size?pAudioData->size:len); SDL_MixAudio(stream, (uint8_t *)pAudioData->data, len, SDL_MIX_MAXVOLUME); delete pAudioData; } } cVideoPlayer::cVideoPlayer(QWidget *parent, int nWidth, int nHeight) : QWidget(parent), m_nSDLWidth(nWidth), m_nSDLHeight(nHeight) { this->resize(nWidth, nHeight); } cVideoPlayer::~cVideoPlayer() { m_bRun = false; MY_DEBUG << "~cVideoPlayer 000"; if(nullptr != m_pSurface) { SDL_FreeSurface(m_pSurface); m_pSurface = nullptr; } if(nullptr != m_pTexture) { SDL_DestroyTexture(m_pTexture); m_pTexture = nullptr; } MY_DEBUG << "~cVideoPlayer 111"; if(nullptr != m_pRenderer) { SDL_DestroyRenderer(m_pRenderer); m_pRenderer = nullptr; } MY_DEBUG << "~cVideoPlayer 222"; if(nullptr != m_pWindow) { SDL_DestroyWindow(m_pWindow); m_pWindow = nullptr; } MY_DEBUG << "~cVideoPlayer 333"; SDL_CloseAudio(); SDL_Quit(); MY_DEBUG << "~cVideoPlayer 444"; if(nullptr != m_pFrame) { av_frame_free(&m_pFrame); m_pFrame = nullptr; } if(nullptr != m_pYuvFrame) { av_frame_free(&m_pYuvFrame); m_pYuvFrame = nullptr; } MY_DEBUG << "~cVideoPlayer 555"; if(nullptr != m_pVideoCodecCxt) { avcodec_close(m_pVideoCodecCxt); //m_pVideoCodecCxt = nullptr; //设置为nullptr会导致崩溃 } MY_DEBUG << "~cVideoPlayer 666"; if(m_pFormatCtx) { avformat_close_input(&m_pFormatCtx); avformat_free_context(m_pFormatCtx); m_pFormatCtx = nullptr; } MY_DEBUG << "~cVideoPlayer 777"; if(nullptr != m_pSwsCtx) { sws_freeContext(m_pSwsCtx); m_pSwsCtx = nullptr; } MY_DEBUG << "~cVideoPlayer 888"; if(nullptr != m_pDstBuffer) { av_free(m_pDstBuffer); } MY_DEBUG << "~cVideoPlayer end"; } bool cVideoPlayer::loadVideo(const QString &sUrl) { avformat_network_init(); if(sUrl.contains("rtsp://") || sUrl.contains("http://")) //实时流 m_nPlayWay = MEDIA_PLAY_STREAM; else m_nPlayWay = MEDIA_PLAY_FILE; m_pFormatCtx = avformat_alloc_context(); if (avformat_open_input(&m_pFormatCtx, sUrl.toStdString().c_str(), nullptr, nullptr) != 0) { MY_DEBUG << "Failed to open video file"; return false; } if (avformat_find_stream_info(m_pFormatCtx, nullptr) < 0) { MY_DEBUG << "Failed to find stream information"; return false; } /* m_nVideoIndex = -1; for (unsigned int i = 0; i < m_pFormatCtx->nb_streams; i++) { if (m_pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) { m_nVideoIndex = i; break; } }*/ m_nVideoIndex = av_find_best_stream(m_pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0); m_nAudioIndex = av_find_best_stream(m_pFormatCtx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0); if (m_nVideoIndex == -1) { MY_DEBUG << "Failed to find video stream"; return false; } //查找并打开视频解码器 m_pVideoCodecCxt = avcodec_alloc_context3(nullptr); if (avcodec_parameters_to_context(m_pVideoCodecCxt, m_pFormatCtx->streams[m_nVideoIndex]->codecpar) != 0) { MY_DEBUG << "Failed to copy codec parameters to codec context"; return false; } const AVCodec *codec = avcodec_find_decoder(m_pVideoCodecCxt->codec_id); if (codec == nullptr) { MY_DEBUG << "Failed to find video decoder"; return false; } if (avcodec_open2(m_pVideoCodecCxt, codec, nullptr) < 0) { MY_DEBUG << "Failed to open video decoder"; return false; } m_CodecId = codec->id; //查找并打开音频解码器 if(m_nAudioIndex > 0) { //查找音频解码器 const AVCodec *pAVCodec = avcodec_find_decoder(m_pFormatCtx->streams[m_nAudioIndex]->codecpar->codec_id); if(!pAVCodec) { MY_DEBUG << "audio decoder not found"; return false; } m_AudioCodecId = pAVCodec->id; //音频解码器参数配置 if (!m_pAudioCodecCxt) m_pAudioCodecCxt = avcodec_alloc_context3(nullptr); if(nullptr == m_pAudioCodecCxt) { MY_DEBUG << "avcodec_alloc_context3 error m_pAudioCodecCxt=nullptr"; return false; } avcodec_parameters_to_context(m_pAudioCodecCxt, m_pFormatCtx->streams[m_nAudioIndex]->codecpar); //打开音频解码器 int nRet = avcodec_open2(m_pAudioCodecCxt, pAVCodec, nullptr); if(nRet < 0) { avcodec_close(m_pAudioCodecCxt); MY_DEBUG << "avcodec_open2 error m_pAudioCodecCxt"; return false; } //音频重采样初始化 if (nullptr == m_pAudioSwrContext) { if(m_pAudioCodecCxt->channel_layout <= 0 || m_pAudioCodecCxt->channel_layout > 3) m_pAudioCodecCxt->channel_layout = 1; MY_DEBUG << "m_audioCodecContext->channel_layout:" << m_pAudioCodecCxt->channel_layout; MY_DEBUG << "m_audioCodecContext->channels:" << m_pAudioCodecCxt->channels; m_pAudioSwrContext = swr_alloc_set_opts(0, m_pAudioCodecCxt->channel_layout, AV_SAMPLE_FMT_S16, m_pAudioCodecCxt->sample_rate, av_get_default_channel_layout(m_pAudioCodecCxt->channels), m_pAudioCodecCxt->sample_fmt, m_pAudioCodecCxt->sample_rate, 0, 0); auto nRet = swr_init(m_pAudioSwrContext); if(nRet < 0) { MY_DEBUG << "swr_init error"; return false; } } m_nAudioSampleRate = m_pAudioCodecCxt->sample_rate; m_audioSpec.freq = m_nAudioSampleRate; // 采样率 m_audioSpec.format = AUDIO_S16SYS; // S表带符号，16是采样深度，SYS表采用系统字节序 m_audioSpec.channels = m_pAudioCodecCxt->channels; // 声道数 m_audioSpec.silence = 0; // 静音值 m_audioSpec.samples = m_pAudioCodecCxt->frame_size; // SDL声音缓冲区尺寸，单位是单声道采样点尺寸x通道数 m_audioSpec.callback = sdl_audio_callback; // 回调函数，若为NULL，则应使