【FFMPEG】从视频文件中抽取aac数据写成文件_市场资讯

【FFMPEG】从视频文件中抽取aac数据写成文件

admin

2024-02-06 14:29:05

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这篇博客主要记录的是

如何打开视频文件
如何写文件
如何从AVFormatContext中抽取aac数据
如何写出AAC数据
如何生成AAC Header

extern "C" {#include #include #include #include }#include #include int buildAdtsHeader(char *const header, const int dataLength, const int profile, const int samplerate, const int channels) {//采样率编号std::map samplerateMap;samplerateMap.insert(std::make_pair(96000, 0x0));samplerateMap.insert(std::make_pair(88200, 0x1));samplerateMap.insert(std::make_pair(64000, 0x2));samplerateMap.insert(std::make_pair(48000, 0x3));samplerateMap.insert(std::make_pair(44100, 0x4));samplerateMap.insert(std::make_pair(32000, 0x5));samplerateMap.insert(std::make_pair(24000, 0x6));samplerateMap.insert(std::make_pair(22050, 0x7));samplerateMap.insert(std::make_pair(16000, 0x8));samplerateMap.insert(std::make_pair(12000, 0x9));samplerateMap.insert(std::make_pair(11025, 0xa));samplerateMap.insert(std::make_pair(8000, 0xb));int samplerateCode = samplerateMap.find(samplerate)->second;//生成Headerint frameLength = dataLength + 7;header[0] = 0xff;  //syncword:0xffheader[1] = 0xf0;header[1] |= (0 << 3);  //MPEG Version: 0 MPEG-4, 1 MPEG-2, 1bitheader[1] |= (0 << 1);  //Layer: 0, 2bitheader[1] |= 1;  //protection absent: 1, 1bitheader[2] = (profile) << 6;  //profile: aac profile, 2bitheader[2] |= (samplerateCode & 0x0f) << 2;  //samplerate, 4bitheader[2] |= (0 << 1);  //private bit: 0, 1bitheader[2] |= (channels & 0x04) >> 2;  //channels, 1bitheader[3] = (channels & 0x03) << 6;  //channels, 2bitheader[3] |= (0 << 5);  //original: 0, 1bitheader[3] |= (0 << 4);  //home: 0, 1bitheader[3] |= (0 << 3);  //copyright id bit: 0, 1bitheader[3] |= (0 << 2);  //copyright id start: 0, 1bitheader[3] |= ((frameLength & 0x1800) >> 11);  //frame length part1, 2bitheader[4] = (uint8_t)((frameLength & 0x7f8) >> 3);  //frame length part2, 8bitheader[5] = (uint8_t)((frameLength & 0x7) << 5);  //frame length part3, 3bitheader[5] |= 0x1f;  //buffer fullness part1, 5bitheader[6] = 0xfc;  //‭buffer fullness part2, 6bitreturn 0;}int main() {char *inputFile = "G:/src.mp4";char *outputFile = "G:/dst.aac";FILE *aacFile = fopen(outputFile, "wb+");//打开视频文件AVFormatContext *avFormatContext = NULL;avformat_open_input(&avFormatContext, inputFile, NULL, NULL);//探测流信息avformat_find_stream_info(avFormatContext, NULL);//获取音频流int audioStreamIndex = av_find_best_stream(avFormatContext, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);AVStream *audioStream = avFormatContext->streams[audioStreamIndex];//创建并初始化AVPacketAVPacket *packet = av_packet_alloc();av_init_packet(packet);//读取文件，把aac数据写入文件while (av_read_frame(avFormatContext, packet) >= 0) {if (packet->stream_index != audioStreamIndex)continue;//创建AVPacket对应的头部char header[7] = {};buildAdtsHeader(header, packet->size, audioStream->codecpar->profile, audioStream->codecpar->sample_rate, audioStream->codecpar->channels);//写入AVPacket的Header和Body//如果是TS流的数据话，AVPacket本身已经携带Header了，不需要再写入fwrite(header, 1, 7, aacFile);fwrite(packet->data, 1, packet->size, aacFile);//解除一个引用计数av_packet_unref(packet);}//关闭和释放资源av_free_packet(packet);if (avFormatContext)avformat_close_input(&avFormatContext);if (aacFile)fclose(aacFile);return 0;}

词库加载错误:未能找到文件“E:\highferrum_mysql\Configuration\Dict_Stopwords.txt”。

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【FFMPEG】从视频文件中抽取aac数据写成文件

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