直接上代码吧:
RecordingThread.h#ifndef RECORDINGTHREAD_H
#define RECORDINGTHREAD_H
#include "QTimer"
#include <QObject>
#include <QImage>
#include <QQueue>extern "C"{//因为FFmpeg是c语言,QT里面调用的话需要extern "C"#include "libavcodec/avcodec.h"#include "libavformat/avformat.h"#include "libswscale/swscale.h"#include "libavdevice/avdevice.h"#include "libavformat/avio.h"#include "libavutil/imgutils.h"
}class RecordingThread : public QObject
{Q_OBJECTpublic:void FFmpegInit();void saveMp4(QImage image);void stopMp4();void setImage(QImage image);public slots:void recordInit();signals:void send(QString);private:AVFormatContext* formatContext;AVCodecParameters* codecParameters;const AVCodec* codec;AVCodecContext* codecContext;AVStream* stream;const AVPixelFormat* pixFmt;int num = 0;QQueue<QImage> gQdata;int isRecord = -1;};#endif // RECORDINGTHREAD_H
#include "recordingthread.h"
#include <QPainter>
#include <cmath>
#include <QPainterPath>
#include <QDebug>
#include <QTimer>
#include <QDateTime>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>void RecordingThread::FFmpegInit(){isRecord = -1;int ret;// 初始化 FFmpegqDebug()<<"avdevice_register_all()";avdevice_register_all(); //初始化所有设备qDebug()<<"formatContext = avformat_alloc_context()";formatContext = avformat_alloc_context();//分配format上下文qint64 timeT = QDateTime::currentMSecsSinceEpoch();//毫秒级时间戳QString outputFileName = QString("/sdcard/").append("ffmpeg").append(QString::number(timeT)).append(".mp4");//第三个参数可以直接使用nullptr 根据outputFileName的后缀自动识别qDebug()<<"avformat_alloc_output_context2(&formatContext, nullptr, \"mp4\", outputFileName.toUtf8().constData())";ret = avformat_alloc_output_context2(&formatContext, nullptr, nullptr, outputFileName.toUtf8().constData());qDebug()<<"ret===="<<ret;qDebug()<<"formatContext===="<<formatContext;qDebug()<<"formatContext->oformat = av_guess_format(nullptr, outputFileName.toUtf8().constData(), nullptr);";formatContext->oformat = av_guess_format(nullptr, outputFileName.toUtf8().constData(), nullptr);qDebug() << "avio_open(&formatContext->pb, outputFileName.toUtf8().constData(), AVIO_FLAG_WRITE) < 0";// 打开输出文件if (avio_open(&formatContext->pb, outputFileName.toUtf8().constData(), AVIO_FLAG_WRITE) < 0) {qDebug() << "Failed to open output file";return;}qDebug() << "AVStream* stream = avformat_new_stream(formatContext, nullptr);";// 创建一个AVStream对象stream = avformat_new_stream(formatContext, nullptr);if (!stream) {qDebug() << "Failed to create output stream";return;}qDebug() << "AVCodecParameters* codecParameters = stream->codecpar;";// 配置AVCodecContextcodecParameters = stream->codecpar;codecParameters->codec_type = AVMEDIA_TYPE_VIDEO;codecParameters->codec_id = AV_CODEC_ID_H264; // 使用H.264编码器codecParameters->width = 400;codecParameters->height = 400;qDebug() << " const AVCodec* codec = avcodec_find_encoder(codecParameters->codec_id);";// 打开编解码器codec = avcodec_find_encoder(codecParameters->codec_id);codecContext = avcodec_alloc_context3(codec);codecContext->width = 400;codecContext->height = 400;codecContext->pix_fmt = AV_PIX_FMT_YUV420P;codecContext->time_base = {1, 25}; // 设置编码器的时间基为 1秒/30帧codecContext->framerate = {25, 1}; // 设置编码器的帧率为 30fps//codecContext->thread_count = 4;qDebug() << "AV_PIX_FMT_YUV420P====="<<AV_PIX_FMT_YUV420P;qDebug() << "codecContext->pix_fmt====="<<codecContext->pix_fmt;qDebug() << "avcodec_open2(codecContext, codec, nullptr);";//设置完成编码格式以后要立刻打开,要不然调用avcodec_parameters_to_context的时候会重置编码ret = avcodec_open2(codecContext, codec, nullptr);if(ret < 0){qDebug() << "Failed to avcodec_open2";return;}qDebug() << "avcodec_parameters_to_context(codecContext, codecParameters);";// 将编码器参数复制到输出流avcodec_parameters_to_context(codecContext, codecParameters);// 检查编解码器支持的像素格式pixFmt = codec->pix_fmts;qDebug() << "while";while (*pixFmt != AV_PIX_FMT_NONE) {qDebug() << av_get_pix_fmt_name(*pixFmt);++pixFmt;}qDebug() << " avformat_write_header(formatContext, nullptr);";// 写入头部信息avformat_write_header(formatContext, nullptr);
}
void RecordingThread::saveMp4(QImage image){int imagewidth = image.width();int imageheight = image.height();int ret;//qDebug() << " AVFrame* frame = av_frame_alloc();";// 逐个写入图像帧AVFrame* frame = av_frame_alloc();if (!frame) {qDebug() << "Failed to allocate frame.";return;}//qDebug() << "frame->format = AV_PIX_FMT_YUV420P";frame->format = AV_PIX_FMT_YUV420P;frame->width = imagewidth;frame->height = imageheight;// 在循环中设置每一帧的时间戳 如果没有这个可能就是0秒视频frame->pts = (((AV_TIME_BASE / 25))/10 * num);// qDebug() << "frame->pts===========" << frame->pts;if (av_frame_get_buffer(frame, 0) < 0) {qDebug() << "Failed to allocate frame buffer.";av_frame_free(&frame);return;}// 图像格式转换SwsContext* swsContext = sws_getContext(imagewidth, imageheight, AV_PIX_FMT_RGB32,frame->width, frame->height, AV_PIX_FMT_YUV420P,SWS_BICUBIC, nullptr, nullptr, nullptr);if (!swsContext) {qDebug() << "Failed to create SwsContext.";av_frame_free(&frame);return;}uint8_t* destData[4] = {frame->data[0], frame->data[1], frame->data[2], nullptr};int destLinesize[4] = {frame->linesize[0], frame->linesize[1], frame->linesize[2], 0};//av_image_fill_arrays(frame->data, frame->linesize, destData[0], codecContext->pix_fmt, codecContext->width, codecContext->height, 1);image = image.convertToFormat(QImage::Format_RGB32);const uchar* bits = image.constBits();int bytesPerLine = image.bytesPerLine();// 函数返回的值是转换后的图像的输出行数。输出的图像高度为图像像素。ret = sws_scale(swsContext, &bits, &bytesPerLine, 0, image.height(), destData, destLinesize);//qDebug() << "sws_scale ret==="<<ret;//函数用于释放由 sws_getContext 函数创建的图像格式转换上下文sws_freeContext(swsContext);//qDebug() << "AVPacket packet;";// 编码并写入视频帧AVPacket packet;av_init_packet(&packet);packet.data = nullptr;packet.size = 0;int code = -1;// 接收输出包while (code < 0) {ret = avcodec_send_frame(codecContext, frame);// qDebug() << "avcodec_send_frame ret===="<<ret;code = avcodec_receive_packet(codecContext, &packet);//qDebug() << "while avcodec_receive_packet====" << code;if(code == 0){// 处理输出包ret = av_interleaved_write_frame(formatContext, &packet);// qDebug() << "av_interleaved_write_frame==================" << ret;av_packet_unref(&packet); // 释放输出包} else if (code == AVERROR(EAGAIN)) {// 当输出队列为空时，需要重新发送帧进行编码continue;} else {qDebug() << "Error encoding frame: " << code;break;}}//qDebug() << "av_frame_free(&frame);";av_frame_free(&frame);//qDebug()<<"num==============================================="<<num;++num;
}
void RecordingThread::stopMp4(){isRecord = 0;
}void RecordingThread::setImage(QImage image){isRecord = 1;gQdata.push_back(image);
}void RecordingThread::recordInit(){while (1) {if(!gQdata.isEmpty() && gQdata.size()>0){QImage qimage = gQdata.dequeue();saveMp4(qimage);}else{if(isRecord == 0){isRecord = -1;num = 0;//写入尾部信息qDebug() << "av_write_trailer(formatContext)"; int ret = av_write_trailer(formatContext);qDebug() << "av_write_trailer(formatContext) ret==="<<ret; emit send("stopRecode");} }usleep(5000);}
}我这里是专门搞了个类封装,我把这个类当成线程使用了,在启动程序的时候直接当线程启动recordInit():比如这样
然后我在需要合成视频的时候先调用初始化:
mRecordingThread->FFmpegInit();再传入QImage:
mRecordingThread->setImage(rotatedImage);停止的时候再调用:mRecordingThread->stopMp4();这样就不会造成卡死主线程的情况
我在使用FFmpeg的时候主要出现两个比较明显的情况:
1.pix_fmt为-1的情况,原因是
设置完成编码格式以后要立刻打开,要不然调用avcodec_parameters_to_context的时候会重置编码
2.合成的视频只有一帧的情况
//主要是因为这个参数导致的,你们可以根据自己的需求微调 // 在循环中设置每一帧的时间戳 如果没有这个可能就是0秒视频 frame->pts = ((baseTimestamp + (num * (AV_TIME_BASE / 30)))/10);
