ffmpeg学习日记121-视频-各种图片转yuv

Author: wencoo
Bloghttps://wencoo.blog.csdn.net/
Date: 24/04/2023
Details:

这其中有一个功能点需要注意不同的图片格式封装算法不同所以解码使用的解码器也不同我现在不清楚什么格式对应什么解码器所以采用通过id的方式来查找解码器是一种靠谱的行为。

实现功能

将png图片转换为yuv数据,示例代码如下

#include <iostream>
#include <fstream>
#include <sstream>
#include <jsoncpp/json/json.h>
#include <tuple>


extern "C"
{
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <libavcodec/avcodec.h>

#include <libavformat/avformat.h>
#include <libavformat/avio.h>

#include <libavutil/audio_fifo.h>
#include <libavutil/avassert.h>
#include <libavutil/avstring.h>
#include <libavutil/dict.h>
#include <libavutil/frame.h>
#include <libavutil/imgutils.h>
#include <libavutil/opt.h>
#include <libavutil/pixdesc.h>
#include <libavutil/samplefmt.h>
#include <libavutil/time.h>
#include <libavutil/timestamp.h>

#include <libavfilter/buffersink.h>
#include <libavfilter/buffersrc.h>
#include <libavfilter/avfilter.h>

#include <libswresample/swresample.h>
}

int main()
{
	std::cout << "Hello World!" << std::endl;
	printf("ffmpeg version:%s\n", av_version_info());

	int ret = 0;

	// input yuv
	//打开png图片
	// png转换为yuv指令为ffmpeg -i %4d.png -pix_fmt yuv420p -s 1984x1344 out.yuv

	FILE *inFile = NULL;
	const char *inFileName = "bg.png";
	inFile = fopen(inFileName, "rb+");
	if (!inFile)
	{
		printf("Fail to open file\n");
		return -1;
	}

	int in_width = 48;
	int in_height = 48;

	// output yuv
	FILE *outFile = NULL;
	const char *outFileName = "output.yuv";
	outFile = fopen( outFileName, "wb");
	if (!outFile)
	{
		printf("Fail to create file for output\n");
		return -1;
	}

	AVFormatContext  *pFormatCtx = NULL;
	if (avformat_open_input(&pFormatCtx, inFileName, NULL, NULL) != 0)
	{
		fprintf(stderr, "Couldn't open input filen");
		return -1;
	}

	if (avformat_find_stream_info(pFormatCtx,0) < 0){
		fprintf(stderr ,"av_find_stream_info ERRORn");
		return -1;
	}

	int videoStream = -1;
	for (int i = 0; i < pFormatCtx->nb_streams; i++)
	{
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			videoStream = i;
			fprintf(stderr ,"the first video stream index: videoStream = %d\n", videoStream);
			break;
		}
	}
	if (videoStream == -1)
		return -1; // Didn't find a video stream

	AVCodecContext *codeCtx = pFormatCtx->streams[videoStream]->codec;
	if (!codeCtx)
	{
		fprintf(stderr, "Could not allocate video codec context\n");
		exit(1);
	}

	std::cout << "pix_fmt:" << codeCtx->pix_fmt << std::endl;

	//打开mp4文件
	const AVCodec *codec = avcodec_find_decoder(codeCtx->codec_id);
	if (!codec)
	{
		fprintf(stderr, "Codec not found\n");
		exit(1);
	}

	if (avcodec_open2(codeCtx, codec, NULL) < 0)
	{
		fprintf(stderr, "Could not open codec\n");
		exit(1);
	}

	AVFrame *frame = av_frame_alloc();
	if (!frame)
	{
		fprintf(stderr, "Could not allocate video frame\n");
		exit(1);
	}

	AVPacket *pkt = av_packet_alloc();
	if (!pkt){
		fprintf(stderr, "Could not allocate video packet\n");
		exit(1);
	}

	uint8_t *video_dst_data[4] = {NULL};
	int video_dst_linesize[4] = {0};
	ret = av_image_alloc(video_dst_data, video_dst_linesize, in_width, in_height, codeCtx->pix_fmt,1);
	if (ret < 0){

	}
	int video_dst_bufsize = ret;

	int indexNum = 1;
	while (av_read_frame(pFormatCtx, pkt) >= 0)
	{
		if (pkt->stream_index == videoStream){
			ret = avcodec_send_packet(codeCtx,pkt);

			while(ret >= 0){
				ret = avcodec_receive_frame(codeCtx,frame);
				if (ret < 0 || ret == AVERROR_EOF || ret == AVERROR(EAGAIN))
				{
					break;
				}

				if (codeCtx->codec->type == AVMEDIA_TYPE_VIDEO){
					//获取到了yuv视频帧
					av_image_copy(video_dst_data, video_dst_linesize,
								  (const uint8_t **)(frame->data), frame->linesize,
								  codeCtx->pix_fmt, in_width, in_height);
					char tmpstr[100] = {};
					sprintf(tmpstr, "yuv-%d.yuv", indexNum);
					FILE *f1;
					f1 = fopen(tmpstr, "wb");
					fwrite(video_dst_data[0], 1, video_dst_bufsize, f1);
					fclose(f1);
					indexNum++;
				}
			}
		}
		av_packet_unref(pkt);
		if (ret < 0)
			break;
	}

	fclose(inFile);
	fclose(outFile);
	return 0;
}

查看转换结果

使用ffplay进行播放查看需指定格式

ffplay.exe -f rawvideo -video_size 48x48 -pix_fmt rgba -i .\yuv-1.yuv

参考

• FFmpeg开发实战六jpeg转换为yuv格式图像