FFmpeg —— 13.示例程序（七）：视频编码器（YUV编码为H265）

Love The Way You Lie 2021-09-24 04:26 933阅读 0赞

此程序和上一篇[YUN编码为H264][YUN_H264]类似，仅仅是修改几个参数

# 程序源码 #

/*
     *
     * 本程序实现了YUV像素数据编码为视频码流（H264）
     *
     */
    
    #include <stdio.h>
    
    #define __STDC_CONSTANT_MACROS
    
    extern "C"
    {
    #include "libavdevice/avdevice.h"
    #include "libavutil/imgutils.h"
    #include "libavutil/opt.h"
    #include "libavcodec/avcodec.h"
    #include "libavformat/avformat.h"
    #include "libswscale/swscale.h"
    };
    
    
    int flush_encoder(AVFormatContext *fmtCtx,unsigned int streamIndex){
    	int ret;
    	int got_frame;
    	AVPacket enc_pkt;
    
    	if (!(fmtCtx->streams[streamIndex]->codec->codec->capabilities & AV_CODEC_CAP_DELAY))
    	{
    		return 0;
    	}
    
    	while (1)
    	{
    		enc_pkt.data = NULL;
    		enc_pkt.size = 0;
    		av_init_packet(&enc_pkt);
    		ret = avcodec_encode_video2 (fmtCtx->streams[streamIndex]->codec, &enc_pkt,
    			NULL, &got_frame);
    		av_frame_free(NULL);
    		if (ret < 0)
    			break;
    		if (!got_frame){
    			ret=0;
    			break;
    		}
    		printf("Flush Encoder: Succeed to encode 1 frame!\tsize:%5d\n",enc_pkt.size);
    		/* mux encoded frame */
    		ret = av_write_frame(fmtCtx, &enc_pkt);
    		if (ret < 0)
    			break;
    	}
    
    	return ret;
    }
    
    int main(int argc, char *argv[])
    {
    	AVFormatContext *pFormatCtx = NULL;
    	AVCodecContext *pCodecCtx = NULL;
    	AVCodec *pCodec = NULL;
    	AVOutputFormat *pOutFmt = NULL;
    
    	const char *inFilename = "input.yuv";
    //	const char *outFilename = "output.h264";
    	const char *outFilename = "output.hevc";
    
    
    	//1.注册组件：编解码器等
    	avdevice_register_all();
    
    	//2.初始化封装格式上下文
    	//方法一：
    //	pFormatCtx = avformat_alloc_context();
    //	pOutFmt = av_guess_format(NULL, outFilename, NULL);
    //	pFormatCtx->oformat = pOutFmt;
    
    	//方法二：
    	avformat_alloc_output_context2(&pFormatCtx, NULL, NULL, outFilename);
    	pOutFmt = pFormatCtx->oformat;
    
    	//3.打开输出文件
    	if (avio_open(&pFormatCtx->pb, outFilename, AVIO_FLAG_WRITE) < 0)
    	{
    		printf("can't open output file\n");
    		return -1;
    	}
    
    	//4.创建输出码流
    	AVStream *pOutStream = avformat_new_stream(pFormatCtx, NULL);
    	if (!pOutStream)
    	{
    		printf("can't allocate new stream\n");
    		return -1;
    	}
    
    	//5.查找视频编码器
    	//获取编码器上下文
    //	avcodec_parameters_to_context(pCodecCtx, pOutStream->codecpar);
    	pCodecCtx = pOutStream->codec;
    
    	//设置编码器上下文参数
    	pCodecCtx->codec_id = pOutFmt->video_codec;
    	pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
    	pCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P;
    	//视频的宽度和高度：确保等于输入文件的宽度和高度
    	pCodecCtx->width = 960;
    	pCodecCtx->height = 544;
    	//设置帧率25fps
    	pCodecCtx->time_base.num = 1;
    	pCodecCtx->time_base.den = 25;
    	//设置码率
    	pCodecCtx->bit_rate = 400000;
    	//设置GOP
    	pCodecCtx->gop_size = 250;
    	//设置量化参数
    	pCodecCtx->qmin = 10;
    	pCodecCtx->qmax = 51;
    //	pCodecCtx->max_b_frames = 0;
    
    
    	//6.查找编码器
    	pCodec = avcodec_find_encoder(pCodecCtx->codec_id);
    	if (!pCodec)
    	{
    		printf("can't find encoder\n");
    		return -1;
    	}
    
    	printf("pCodec.name = %s\n", pCodec->name);
    
    	//若是H264编码器，要设置一些参数
    	AVDictionary *param = NULL;
    	if (pCodecCtx->codec_id == AV_CODEC_ID_H264)
    	{
    		av_dict_set(&param, "preset", "slow", 0);
    		av_dict_set(&param, "tune", "zerolatency", 0);
    	}
    
    	//H.265
    	if(pCodecCtx->codec_id == AV_CODEC_ID_H265){
    //		av_dict_set(&param, "x265-params", "qp=20", 0);
    		av_dict_set(&param, "preset", "ultrafast", 0);
    		av_dict_set(&param, "tune", "zero-latency", 0);
    	}
    
    	//7.打开编码器
    	if (avcodec_open2(pCodecCtx, pCodec, &param) < 0)
    	{
    		printf("can't open encoder\n");
    		return -1;
    	}
    
    	//8.写入头文件信息
    	avformat_write_header(pFormatCtx, NULL);
    
    	//9.循环编码YUV文件为H264
    	//(1)开辟缓冲区
    	int bufSize = av_image_get_buffer_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, 1);
    	int ySize = pCodecCtx->width * pCodecCtx->height;
    	uint8_t *outBuffer = (uint8_t *)av_malloc(bufSize);
    
    	FILE *inFile = fopen(inFilename, "rb");
    	if (!inFile)
    	{
    		printf("can't find input file\n");
    		return -1;
    	}
    
    	//(2) 内容空间填充
    	AVFrame *pFrame = av_frame_alloc();
    	//设置真的格式、宽度和高度，否则会出现
    	//1.AVFrame.format is not set
    	//AVFrame.width or height is not set
    	pFrame->format = pCodecCtx->pix_fmt;
    	pFrame->width = pCodecCtx->width;
    	pFrame->height = pCodecCtx->height;
    
    	av_image_fill_arrays(pFrame->data,
    			pFrame->linesize,
    			outBuffer,
    			pCodecCtx->pix_fmt,
    			pCodecCtx->width,
    			pCodecCtx->height,
    			1);
    
    	//(3)开辟packet
    	AVPacket *pPacket = (AVPacket *)av_malloc(bufSize);
    
    	int i = 0, frameIndex = 0;
    
    	//(4)循环编码
    	while(1)
    	{
    		//从YUV文件里面读取缓冲区
    		//读取大小：ySize * 3 / 2
    		if (fread(outBuffer, 1, ySize * 3 / 2, inFile) <= 0)
    		{
    			printf("finished to read data\n");
    			break;
    		}
    		else if (feof(inFile))
    		{
    			break;
    		}
    
    		//将缓冲区数据转换成AVFrame类型
    		pFrame->data[0] = outBuffer;			//Y值
    		pFrame->data[1] = outBuffer + ySize;	//U值
    		pFrame->data[2] = outBuffer + ySize * 5 / 4;	//V值
    
    		pFrame->pts = i * (pOutStream->time_base.den) / (pOutStream->time_base.num * 25);
    
    
    		//10.视频编码处理
    		//（1）发送一帧视频像素数据
    		if (avcodec_send_frame(pCodecCtx, pFrame) < 0)
    		{
    			printf("failed to encoder\n");
    			return -1;
    		}
    		//(2)接收一帧视频压缩数据格式（像素数据编码而来）
    		if (avcodec_receive_packet(pCodecCtx, pPacket) >= 0)
    		{
    			//编码成功
    			//11.将视频写入到输出文件
    			pPacket->stream_index = pOutStream->index;
    			if (av_write_frame(pFormatCtx, pPacket) < 0)
    			{
    				printf("failed to write frame\n");
    				return -1;
    			}
    			printf("succeed to write frame: %d\tsize:%d\n", frameIndex++, pPacket->size);
    		}
    
    		av_packet_unref(pPacket);
    
    	}
    
        //写入剩余帧数据->可能没有
        flush_encoder(pFormatCtx, 0);
    
        //写入文件尾部信息
        av_write_trailer(pFormatCtx);
    
        //释放内存
        avcodec_close(pCodecCtx);
        av_free(pFrame);
        av_free(outBuffer);
        av_packet_free(&pPacket);
        avio_close(pFormatCtx->pb);
        avformat_free_context(pFormatCtx);
        fclose(inFile);
    
        return 0;
    }

# 问题总结 #

## 出错问题1：Lookahead depth must be greater than the max consecutive bframe count ##

解决办法1：关闭B帧

//    pCodecCtx->max\_b\_frames = 0;

解决办法2：不设置zero-latency

//        av\_dict\_set(&param, "tune", "zero-latency", 0);

以上2种方法二选一即可

[YUN_H264]: https://blog.csdn.net/guoyunfei123/article/details/105606500