FFmpeg菜鸡互啄#第5篇#视频帧格式转换

关键步骤

int rgbsize &＃61; avpicture_get_size(PIX_FMT_RGB24, pVCodecCtx->width, pVCodecCtx->height);//算出该格式和分辨率下一帧图像的数据大小//uint8_t* rgbBuffer &＃61; (uint8_t *)av_malloc(rgbsize * sizeof(uint8_t));//分配保存图像的内存//avpicture_fill((AVPicture *)&rgbFrame, rgbBuffer, PIX_FMT_RGB24, pVCodecCtx->width, pVCodecCtx->height);//将自己分配的内存绑定到rgbFrame的data数据区avpicture_alloc((AVPicture *)&rgbFrame, PIX_FMT_RGB24, pVCodecCtx->width, pVCodecCtx->height);//为rgbFrame的data分配内存&＃xff0c;不用自己分配SwsContext *img_convert_ctx &＃61; sws_getContext(pVCodecCtx->width, pVCodecCtx->height, AV_PIX_FMT_YUV420P, pVCodecCtx->width, pVCodecCtx->height, PIX_FMT_RGB24, SWS_FAST_BILINEAR, NULL, NULL, NULL);//转换上下文sws_scale(img_convert_ctx, (uint8_t const* const *)Frame.data, Frame.linesize, 0, pVCodecCtx->height, rgbFrame.data, rgbFrame.linesize);//转换

avpicture_get_size 算出某格式和分辨率下一帧图像的数据大小
avpicture_fill 将自己分配的内存绑定到AVFrame帧的data数据区
avpicture_alloc 为AVFrame帧的data分配内存&＃xff0c;不用自己分配
sws_getContext 创建从一种格式到另一种格式的转换上下文
sws_scale 转换
以上的每一个函数都没有对AFrame的linesize进行有效处理&＃xff0c;使用data的内存大小要用avpicture_get_size算出

Code

#define _CRT_SECURE_NO_WARNINGS
#include /*
#define __STDC_CONSTANT_MACROS
#ifndef INT64_C
#define INT64_C(c) (c ## LL)
#define UINT64_C(c) (c ## ULL)
#endif
*/extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
}#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avdevice.lib")
#pragma comment(lib, "avfilter.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "postproc.lib")
#pragma comment(lib, "swresample.lib")
#pragma comment(lib, "swscale.lib")#define INPUT "in.flv"
#define OUTVIDEO "video.yuv"
#define OUTAUDIO "audio.pcm"
#define OUTRGB "video.rgb"int main()
{int res &＃61; 0;int videoStream &＃61; -1;//标记视频流的编号int audioStream &＃61; -1;//标记音频流的编号char errBuf[BUFSIZ] &＃61; { 0 };FILE* fp_video &＃61; fopen(OUTVIDEO, "wb&＃43;");FILE* fp_audio &＃61; fopen(OUTAUDIO, "wb&＃43;");FILE* fp_rgb &＃61; fopen(OUTRGB, "wb&＃43;");//初始化FFMPEG 调用了这个才能正常适用编码器和解码器av_register_all();printf("FFmpeg&＃39;s version is: %d\n", avcodec_version());//FFMPEG所有的操作都要通过这个AVFormatContext来进行AVFormatContext* pFormatCtx &＃61; NULL;//打开输入视频文件//Open an input stream and read the header. The codecs are not opened.if ((res &＃61; avformat_open_input(&pFormatCtx, INPUT, NULL, NULL)) <0){av_strerror(res, errBuf, sizeof(errBuf));printf("%s\n", errBuf);return -1;}//Read packets of a media file to get stream information. This is useful for file formats with no headers such as MPEG.//相当于对输入进行 “预处理”avformat_find_stream_info(pFormatCtx, NULL);av_dump_format(pFormatCtx, 0, NULL, 0); //输出视频流的信息//查找流for (int i &＃61; 0; i nb_streams; &＃43;&＃43;i){if (pFormatCtx->streams[i]->codec->codec_type &＃61;&＃61; AVMEDIA_TYPE_VIDEO)videoStream &＃61; i;else if (pFormatCtx->streams[i]->codec->codec_type &＃61;&＃61; AVMEDIA_TYPE_AUDIO)audioStream &＃61; i;}if (videoStream &＃61;&＃61; -1){printf("Didn&＃39;t find a video stream.\n");return -1;}if (audioStream &＃61;&＃61; -1){printf("Didn&＃39;t find a audio stream.\n");return -1;}///查找解码器 AVCodecContext* pVCodecCtx &＃61; pFormatCtx->streams[videoStream]->codec;AVCodec* pVCodec &＃61; avcodec_find_decoder(pVCodecCtx->codec_id);if (pVCodec &＃61;&＃61; NULL){printf("Video Codec not found.\n");return -1;}AVCodecContext* pACodecCtx &＃61; pFormatCtx->streams[audioStream]->codec;AVCodec* pACodec &＃61; avcodec_find_decoder(pACodecCtx->codec_id);if (pACodec &＃61;&＃61; NULL){printf("Audio Codec not found.\n");return -1;}///打开解码器if (avcodec_open2(pVCodecCtx, pVCodec, NULL) <0){printf("Could not open Video codec.\n");return -1;}if (avcodec_open2(pACodecCtx, pACodec, NULL) <0){printf("Could not open Audio codec.\n");return -1;}AVFrame Frame &＃61; { 0 };//不初始化&＃xff0c;avcodec_decode_video2会报错AVFrame rgbFrame;AVPacket packet;int got_picture;int rgbsize &＃61; avpicture_get_size(PIX_FMT_RGB24, pVCodecCtx->width, pVCodecCtx->height);//算出该格式和分辨率下一帧图像的数据大小//uint8_t* rgbBuffer &＃61; (uint8_t *)av_malloc(rgbsize * sizeof(uint8_t));//分配保存图像的内存//avpicture_fill((AVPicture *)&rgbFrame, rgbBuffer, PIX_FMT_RGB24, pVCodecCtx->width, pVCodecCtx->height);//将自己分配的内存绑定到rgbFrame的data数据区avpicture_alloc((AVPicture *)&rgbFrame, PIX_FMT_RGB24, pVCodecCtx->width, pVCodecCtx->height);//为rgbFrame的data分配内存&＃xff0c;不用自己分配SwsContext *img_convert_ctx &＃61; sws_getContext(pVCodecCtx->width, pVCodecCtx->height, AV_PIX_FMT_YUV420P, pVCodecCtx->width, pVCodecCtx->height, PIX_FMT_RGB24, SWS_FAST_BILINEAR, NULL, NULL, NULL);//转换上下文while (1){//读取视频帧//return 0 if OK, <0 on error or end of fileif (av_read_frame(pFormatCtx, &packet) <0){break; //这里认为视频读取完了}if (packet.stream_index &＃61;&＃61; videoStream){//解码视频帧if (avcodec_decode_video2(pVCodecCtx, &Frame, &got_picture, &packet) <0){printf("decode Video error.\n");return -1;}if (got_picture){if (Frame.format &＃61;&＃61; PIX_FMT_YUV420P){//解码后YUV格式的视频像素数据保存在AVFrame的data[0]、data[1]、data[2]中。//但是这些像素值并不是连续存储的&＃xff0c;每行有效像素之后存储了一些无效像素。//以亮度Y数据为例&＃xff0c;data[0]中一共包含了linesize[0] * height个数据。//但是出于优化等方面的考虑&＃xff0c;linesize[0]实际上并不等于宽度width&＃xff0c;而是一个比宽度大一些的值。fwrite(Frame.data[0], Frame.linesize[0] * Frame.height, 1, fp_video);fwrite(Frame.data[1], Frame.linesize[1] * Frame.height / 2, 1, fp_video);fwrite(Frame.data[2], Frame.linesize[2] * Frame.height / 2, 1, fp_video);sws_scale(img_convert_ctx, (uint8_t const* const *)Frame.data, Frame.linesize, 0, pVCodecCtx->height, rgbFrame.data, rgbFrame.linesize);//转换fwrite(rgbFrame.data[0], rgbsize, 1, fp_rgb);}}}else if (packet.stream_index &＃61;&＃61; audioStream){//解码音频帧if (avcodec_decode_audio4(pACodecCtx, &Frame, &got_picture, &packet) <0){printf("decode Audio error.\n");return -1;}if (got_picture){if (Frame.format &＃61;&＃61; AV_SAMPLE_FMT_S16P)//signed 16 bits, planar 16位 平面数据{//AV_SAMPLE_FMT_S16P//代表每个data[]的数据是连续的&＃xff08;planar&＃xff09;&＃xff0c;每个单位是16bitsfor (int i &＃61; 0; i 0]; i &＃43;&＃61; 2){//如果是多通道的话&＃xff0c;保存成c1低位、c1高位、c2低位、c2高位...for (int j &＃61; 0; j 2, 1, fp_audio);}}else if (Frame.format &＃61;&＃61; AV_SAMPLE_FMT_FLTP){for (int i &＃61; 0; i 0]; i &＃43;&＃61; 4){for (int j &＃61; 0; j 4, 1, fp_audio);}}}}av_free_packet(&packet);//清除packet里面指向的缓冲区}fclose(fp_video);fclose(fp_audio);fclose(fp_rgb);avpicture_free((AVPicture*)&rgbFrame);//释放avpicture_alloc分配的内存avcodec_close(pVCodecCtx);//关闭解码器avcodec_close(pACodecCtx);avformat_close_input(&pFormatCtx);//关闭输入视频文件。avformat_free_context(pFormatCtx);就不需要了return 0;
}

Github

https://github.com/gongluck/FFmpegTest.git