// VideoProcessing.cpp // #pragma once using namespace std; #include <iostream> extern "C" { #include <libavcodec/avcodec.h> #include <libavdevice/avdevice.h> #include <libavformat/avformat.h> #include <libavfilter/avfilter.h> #include <libavutil/avutil.h> #include <libswscale/swscale.h> #pragma comment(lib, "avcodec.lib") #pragma comment(lib, "avdevice.lib") #pragma comment(lib, "avformat.lib") #pragma comment(lib, "avfilter.lib") #pragma comment(lib, "avutil.lib") #pragma comment(lib, "swscale.lib") } void SaveToJPEG(AVFrame* pFrame, const char * folderName, int index) { // Setup Output Path char outFile[256] = { 0 }; sprintf_s(outFile, sizeof(outFile)/sizeof(outFile[0]), "%s\\OutputImages-%d.jpg", folderName, index); AVFormatContext* pFormatCtx = avformat_alloc_context(); // Setup the output format pFormatCtx->oformat = av_guess_format("mjpeg", NULL, NULL); // Initializext if (avio_open(&pFormatCtx->pb, outFile, AVIO_FLAG_READ_WRITE) < 0) { printf("Couldn't open output file."); return; } // Get a new Stream from the indicated format context AVStream* pAVStream = avformat_new_stream(pFormatCtx, 0); if (pAVStream == NULL) { return; } // Find encoder from the codec identifier. AVCodec* pCodec = avcodec_find_encoder(pFormatCtx->oformat->video_codec); if (!pCodec) { printf("Codec not found."); return; } // Setup the codec context AVCodecContext* codecCtx = avcodec_alloc_context3(pCodec); codecCtx->codec_id = pFormatCtx->oformat->video_codec; codecCtx->codec_type = AVMEDIA_TYPE_VIDEO; codecCtx->pix_fmt = AV_PIX_FMT_YUVJ420P; codecCtx->width = pFrame->width; codecCtx->height = pFrame->height; codecCtx->time_base = AVRational{ 1,25 }; // Open the codec if (avcodec_open2(codecCtx, pCodec, NULL) < 0) { printf("Could not open codec."); return; } // assign the codec context to the stream parameters. avcodec_parameters_from_context(pAVStream->codecpar, codecCtx); //Write Header avformat_write_header(pFormatCtx, NULL); int y_size = (codecCtx->width) * (codecCtx->height); // assign large enough space AVPacket pkt; av_new_packet(&pkt, y_size); int got_picture = 0; // Use avcodec_send_frame()/avcodec_receive_packet() instead int ret = avcodec_send_frame(codecCtx, pFrame); if (ret < 0) { printf("Encode Error.\n"); return; } else { ret = avcodec_receive_packet(codecCtx, &pkt); ret = av_write_frame(pFormatCtx, &pkt); } av_packet_unref(&pkt); //Write Trailer av_write_trailer(pFormatCtx); printf("Encode Successful.\n"); avcodec_close(codecCtx); avio_close(pFormatCtx->pb); avformat_free_context(pFormatCtx); avcodec_free_context(&codecCtx); } int main(int argc, char * argv[]) { if (argc < 2) { cout << "You need to specify a media file." << endl; cout << "Command line : VideoProcessing.exe [input_video_path] [output_folder]" << endl; return -1; } AVFormatContext* pFormatContext = avformat_alloc_context(); if (!pFormatContext) { cout << "ERROR could not allocate memory for Format Context" << endl; return -1; } if (avformat_open_input(&pFormatContext, argv[1], NULL, NULL) != 0) { cout << "ERROR could not open the file" << endl; return -1; } if (avformat_find_stream_info(pFormatContext, NULL) < 0) { cout << "ERROR could not get the stream info" << endl; return -1; } // Initialize the codec, paramters for subsequent useage. AVCodec* pCodec = NULL; AVCodecParameters* pCodecParameters = NULL; int videoStreamIndex = -1; for (int i = 0; i < pFormatContext->nb_streams; i++) { AVCodecParameters* pLocalCodecParameters = NULL; // Read the codec parameters corresponding to each stream. pLocalCodecParameters = pFormatContext->streams[i]->codecpar; AVCodec* pLocalCodec = NULL; pLocalCodec = avcodec_find_decoder(pLocalCodecParameters->codec_id); if (pLocalCodec == NULL) { cout << "[ERROR] Cannot find the codec" << endl; } if (pLocalCodecParameters->codec_type == AVMEDIA_TYPE_VIDEO) { if (videoStreamIndex == -1) { videoStreamIndex = i; pCodec = pLocalCodec; pCodecParameters = pLocalCodecParameters; } } } AVCodecContext* pCodecContext = avcodec_alloc_context3(pCodec); if (pCodecContext == NULL) { cout << "Fail to allocate the memoery to the Codec Context." << endl; return -1; } if (avcodec_parameters_to_context(pCodecContext, pCodecParameters) < 0) { cout << "failed to copy codec params to codec context" << endl; return -1; } if (avcodec_open2(pCodecContext, pCodec, NULL) < 0) { cout << "failed to open codec through avcodec_open2" << endl; return -1; } AVFrame* pFrame = av_frame_alloc(); if (!pFrame) { cout << "failed to allocated memory for AVFrame" << endl; return -1; } AVPacket* pPacket = av_packet_alloc(); if (!pPacket) { cout << "failed to allocated memory for AVPacket" << endl; return -1; } int indexOfFrame = 0; while (av_read_frame(pFormatContext, pPacket) >= 0) { // if it's the video stream if (pPacket->stream_index == videoStreamIndex) { int response = avcodec_send_packet(pCodecContext, pPacket); if (response < 0) { break; } else { response = avcodec_receive_frame(pCodecContext, pFrame); if (response >= 0) { indexOfFrame++; SaveToJPEG(pFrame, argv[2], indexOfFrame); } } } av_packet_unref(pPacket); // Limit the number of output frame to be 5. if (indexOfFrame == 5) { break; } } // https://ffmpeg.org/doxygen/trunk/group__lavc__packet.html#ga63d5a489b419bd5d45cfd09091cbcbc2 avformat_close_input(&pFormatContext); av_frame_free(&pFrame); avcodec_free_context(&pCodecContext); }Reference:
2020年6月25日 星期四
FFMPEG: Decode and then encode frames to JPEG images
I've used FFMPEG library for a while. Actually, the FFMPEG library's decoding process flow can be described as the following picture. If you want to read the videos and then save to jpeg file, you can take a look on my programming code (tested on FFMPEG ver. 4 library).
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