FFmepg--mp4文件合成3--main函数实现（C++实现）

本文主要是介绍FFmepg--mp4文件合成3--main函数实现（C++实现），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

文章目录

- - 流程
  - 计算
  - main.c

yuv 和 pcm 输出mp4文件，主函数实现

流程

打开yuv pcm文件
初始化编码器

2.1 初始化video，初始化编码器，分配yuv buf
2.2 初始化audio，初始化音频编码器，分配pcm buf，初始化重采样
mp4初始化包括新建流，open io, send header
在while循环读取yuv、pcm进行编码然后发送给MP4 muxer，计算时间戳

计算

y u v 帧大小计算
y_frame_size = yuv_width * yuv_height;
u_frame_size = yuv_width * yuv_height /4;
v_frame_size = yuv_width * yuv_height /4;
yuv_frame_size = y_frame_size + u_frame_size + v_frame_size；
y u v 分量采用420类型，4个y分量对应一个u分量和一个v分量
每帧PCM数据大小：
采样点 = 采样率 * 采样时间
pcm_frame_size=单个采样点字节 * 通道数量 * 每个通道采用点
时间戳计算
音频帧时间间隔 = 采样点/采样率（采样时间）* 时间基
audio_frame_duration = audio_encoder.GetFrameSize()/pcm_sample_rateaudio_time_base;
如：每帧1024个采样点，采样率为44.1kz
采样时间为 1024/44.11000 * 10^6 （s转化为us） = 23,219.9 us
audio_time_base: 110^6 us
写每帧音频时,audio_frame_duration进行叠加，初始audio_pts为0
…
视频时间间隔 = 帧率（每秒中画面数量）时间基
video_frame_duration = =yuv_fps * video_time_base;

main.c

命令行参数： in.yuv in.pcm out.mp4

#include <iostream>#include "audioencoder.h"
#include "audioresampler.h"
#include "videoencoder.h"
#include "muxer.h"
using namespace std;#define YUV_WIDTH 720
#define YUV_HEIGHT 576
#define YUV_FPS  25#define VIDEO_BIT_RATE 500*1024#define PCM_SAMPLE_FORMAT AV_SAMPLE_FMT_S16
#define PCM_SAMPLE_RATE 44100
#define PCM_CHANNELS 2#define AUDIO_BIT_RATE 128*1024#define AUDIO_TIME_BASE 1000000
#define VIDEO_TIME_BASE 1000000
//ffmpeg -i sound_in_sync_test.mp4 -pix_fmt yuv420p 720x576_yuv420p.yuv
//ffmpeg -i sound_in_sync_test.mp4 -vn -ar 44100 -ac 2 -f s16le 44100_2_s16le.pcm
// 执行文件  yuv文件 pcm文件 输出mp4文件
int main(int argc, char **argv)
{if(argc != 4) {printf("usage -> exe in.yuv in.pcm out.mp4");return -1;}// 1. 打开yuv pcm文件char *in_yuv_name = argv[1];char *in_pcm_name = argv[2];char *out_mp4_name = argv[3];FILE *in_yuv_fd = NULL;FILE *in_pcm_fd = NULL;//1. 打开测试文件// 打开YUV文件in_yuv_fd = fopen(in_yuv_name, "rb");if( !in_yuv_fd ){printf("Failed to open %s file\n", in_yuv_name);return -1;}// 打开PCM文件in_pcm_fd = fopen(in_pcm_name, "rb");if( !in_pcm_fd ){printf("Failed to open %s file\n", in_pcm_name);return -1;}int ret = 0;// 2. 初始化编码器，包括视频、音频编码器, 分配yuv、pcm的帧buffer// 2.1 初始化video// 初始化编码器int yuv_width = YUV_WIDTH;int yuv_height = YUV_HEIGHT;int yuv_fps = YUV_FPS;int video_bit_rate = VIDEO_BIT_RATE;VideoEncoder video_encoder;ret = video_encoder.InitH264(yuv_width, yuv_height, yuv_fps, video_bit_rate);if(ret < 0){printf("video_encoder.InitH264 failed\n");return -1;}// 分配yuv bufint y_frame_size = yuv_width * yuv_height;int u_frame_size = yuv_width * yuv_height /4;int v_frame_size = yuv_width * yuv_height /4;int yuv_frame_size = y_frame_size + u_frame_size + v_frame_size;uint8_t *yuv_frame_buf = (uint8_t *)malloc(yuv_frame_size);if(!yuv_frame_buf){printf("malloc(yuv_frame_size)\n");return -1;}// 2.2 初始化audio// 初始化音频编码器int pcm_channels= PCM_CHANNELS;int pcm_sample_rate = PCM_SAMPLE_RATE;int pcm_sample_format = PCM_SAMPLE_FORMAT;int audio_bit_rate = AUDIO_BIT_RATE;AudioEncoder audio_encoder;ret = audio_encoder.InitAAC(pcm_channels, pcm_sample_rate, audio_bit_rate);if(ret < 0){printf("audio_encoder.InitAAC failed\n");return -1;}// 分配pcm buf// pcm_frame_size  = 单个采样点占用的字节 * 通道数量 * 每个通道有多少给采用点int pcm_frame_size = av_get_bytes_per_sample((AVSampleFormat)pcm_sample_format)*pcm_channels * audio_encoder.GetFrameSize();if(pcm_frame_size <= 0) {printf("pcm_frame_size <= 0\n");return -1;}uint8_t *pcm_frame_buf = (uint8_t *)malloc(pcm_frame_size);if(!pcm_frame_buf){printf("malloc(pcm_frame_size)\n");return -1;}// 初始化重采样AudioResampler audio_resampler;ret = audio_resampler.InitFromS16ToFLTP(pcm_channels, pcm_sample_rate,audio_encoder.GetChannels(), audio_encoder.GetSampleRate());if(ret < 0){printf("audio_resampler.InitFromS16ToFLTP failed\n");return -1;}// 3. mp4初始化 包括新建流，open io, send headerMuxer mp4_muxer;ret = mp4_muxer.Init(out_mp4_name);if(ret < 0){printf("mp4_muxer.Init failed\n");return -1;}ret = mp4_muxer.AddStream(video_encoder.GetCodecContext());if(ret < 0){printf("mp4_muxer.AddStream video failed\n");return -1;}ret = mp4_muxer.AddStream(audio_encoder.GetCodecContext());if(ret < 0){printf("mp4_muxer.AddStream audio failed\n");return -1;}ret = mp4_muxer.Open();if(ret < 0){printf("mp4_muxer.Open failed\n");return -1;}ret = mp4_muxer.SendHeader();if(ret < 0){printf("mp4_muxer.SendHeader failed\n");return -1;}// 4. 在while循环读取yuv、pcm进行编码然后发送给MP4 muxer// 4.1 时间戳相关int64_t audio_time_base = AUDIO_TIME_BASE;int64_t video_time_base = VIDEO_TIME_BASE;double audio_pts = 0;double video_pts = 0;// yuv_fps 每秒画面数，刷新率double audio_frame_duration = 1.0 * audio_encoder.GetFrameSize()/pcm_sample_rate*audio_time_base;double video_frame_duration = 1.0/yuv_fps * video_time_base;int audio_finish = 0;   // 两者都为0的时候才结束while循环int video_finish = 0;size_t read_len = 0;AVPacket *packet =  NULL;int audio_index = mp4_muxer.GetAudioStreamIndex();int video_index = mp4_muxer.GetVideoStreamIndex();while (1) {if(audio_finish && video_finish) {break;}printf("apts:%0.0lf vpts:%0.0lf\n", audio_pts/1000, video_pts/1000);if((video_finish != 1 && audio_pts > video_pts)   // audio和vidoe都还有数据，优先audio（audio_pts > video_pts）||  (video_finish != 1 && audio_finish == 1)) {read_len = fread(yuv_frame_buf, 1, yuv_frame_size, in_yuv_fd);if(read_len < yuv_frame_size) {video_finish = 1;printf("fread yuv_frame_buf finish\n");}if(video_finish != 1) {packet = video_encoder.Encode(yuv_frame_buf, yuv_frame_size, video_index,video_pts, video_time_base);}else {packet = video_encoder.Encode(NULL, 0, video_index,video_pts, video_time_base);}video_pts += video_frame_duration;  // 叠加ptsif(packet) {mp4_muxer.SendPacket(packet);}} else if(audio_finish != 1) {read_len = fread(pcm_frame_buf, 1, pcm_frame_size, in_pcm_fd);if(read_len < pcm_frame_size) {audio_finish = 1;printf("fread pcm_frame_buf finish\n");}if(audio_finish != 1) {AVFrame *fltp_frame = AllocFltpPcmFrame(pcm_channels, audio_encoder.GetFrameSize());ret = audio_resampler.ResampleFromS16ToFLTP(pcm_frame_buf, fltp_frame);if(ret < 0)printf("ResampleFromS16ToFLTP error\n");packet = audio_encoder.Encode(fltp_frame, audio_index,audio_pts, audio_time_base);FreePcmFrame(fltp_frame);}else {packet = audio_encoder.Encode(NULL,video_index,audio_pts, audio_time_base);}audio_pts += audio_frame_duration;  // 叠加ptsif(packet) {mp4_muxer.SendPacket(packet);}}}ret = mp4_muxer.SendTrailer();if(ret < 0){printf("mp4_muxer.SendTrailer failed\n");}printf("write mp4 finish\n");if(yuv_frame_buf)free(yuv_frame_buf);if(pcm_frame_buf)free(pcm_frame_buf);if(in_yuv_fd)fclose(in_yuv_fd);if(in_pcm_fd)fclose(in_pcm_fd);return 0;
}