ffmpeg C代码实现 视频添加文字
盗用的一张流程图
雷神博客地址 https://blog.****.net/leixiaohua1020/article/details/29368911
流程中的关键函数如下所示:
avfilter_register_all():注册所有AVFilter。
avfilter_graph_alloc():为FilterGraph分配内存。
avfilter_graph_create_filter():创建并向FilterGraph中添加一个Filter。
avfilter_graph_parse_ptr():将一串通过字符串描述的Graph添加到FilterGraph中。
avfilter_graph_config():检查FilterGraph的配置。
av_buffersrc_add_frame():向FilterGraph中加入一个AVFrame。
av_buffersink_get_frame():从FilterGraph中取出一个AVFrame。
#include <stdlib.h>
#include <stdio.h>
//封装格式
#include "libavformat/avformat.h"
//解码
#include "libavcodec/avcodec.h"
//缩放
#include "libswscale/swscale.h"
#include "libswresample/swresample.h"
//滤镜
#include "libavfilter/avfilter.h"
#include "libavutil/log.h"
#include <libavutil/opt.h>
#include "libavfilter/buffersrc.h"
#include "libavfilter/buffersink.h"
AVFormatContext * context = NULL;
AVFormatContext* outputContext;
int64_t lastPts = 0;
int64_t lastDts = 0;
int64_t lastFrameRealtime = 0;
int64_t firstPts = AV_NOPTS_VALUE;
int64_t startTime = 0;
AVCodecContext* outPutEncContext = NULL;
AVCodecContext *decoderContext = NULL;
#define SrcWidth 1920
#define SrcHeight 1080
#define DstWidth 640
#define DstHeight 480
struct SwsContext* pSwsContext;
AVFilterGraph * filter_graph = NULL;
AVFilterContext *buffersink_ctx = NULL;;
AVFilterContext *buffersrc_ctx = NULL;;
int interrupt_cb(void *ctx)
{
return 0;
}
void Init()
{
av_register_all();
avfilter_register_all();
avformat_network_init();
av_log_set_level(AV_LOG_ERROR);
}
int open_input_context(char *fileName)
{
context = avformat_alloc_context();
context->interrupt_callback.callback = interrupt_cb;
AVDictionary *format_opts = NULL;
int ret = avformat_open_input(&context, fileName, NULL, &format_opts);
if(ret < 0)
{
return ret;
}
ret = avformat_find_stream_info(context,NULL);
av_dump_format(context, 0, fileName, 0);
if(ret >= 0)
{
printf("open input stream successfully \n");
}
return ret;
}
AVPacket* ReadPacketFromSource()
{
AVPacket* packet = av_packet_alloc();
int ret = av_read_frame(context, packet);
if(ret >= 0)
{
return packet;
}
else
{
return NULL;
}
}
int open_output_context(char *fileName)
{
int ret = 0;
ret = avformat_alloc_output_context2(&outputContext, NULL, "mpegts", fileName);
if(ret < 0)
{
goto Error;
}
ret = avio_open2(&outputContext->pb, fileName, AVIO_FLAG_READ_WRITE,NULL, NULL);
if(ret < 0)
{
goto Error;
}
for(int i = 0; i < context->nb_streams; i++)
{
AVStream * stream = avformat_new_stream(outputContext, outPutEncContext->codec);
stream->codec = outPutEncContext;
if(ret < 0)
{
goto Error;
}
}
av_dump_format(outputContext, 0, fileName, 1);
ret = avformat_write_header(outputContext, NULL);
if(ret < 0)
{
goto Error;
}
if(ret >= 0)
printf("open output stream successfully\n");
return ret ;
Error:
if(outputContext)
{
avformat_close_input(&outputContext);
}
return ret ;
}
void close_input()
{
if(context != NULL)
{
avformat_close_input(&context);
}
}
void close_output()
{
if(outputContext != NULL)
{
for(int i = 0 ; i < outputContext->nb_streams; i++)
{
AVCodecContext *codecContext = outputContext->streams[i]->codec;
avcodec_close(codecContext);
}
avformat_close_input(&outputContext);
}
}
int init_encode_codec( int iWidth, int iHeight)
{
AVCodec * pH264Codec = avcodec_find_encoder(AV_CODEC_ID_H264);
if(NULL == pH264Codec)
{
printf("%s \n", "avcodec_find_encoder failed");
return -1;
}
outPutEncContext = avcodec_alloc_context3(pH264Codec);
outPutEncContext->gop_size = 30;
outPutEncContext->has_b_frames = 0;
outPutEncContext->max_b_frames = 0;
outPutEncContext->codec_id = pH264Codec->id;
outPutEncContext->time_base.num =context->streams[0]->codec->time_base.num;
outPutEncContext->time_base.den = context->streams[0]->codec->time_base.den;
outPutEncContext->pix_fmt = *pH264Codec->pix_fmts;
outPutEncContext->width = iWidth;
outPutEncContext->height = iHeight;
outPutEncContext->me_subpel_quality = 0;
outPutEncContext->refs = 1;
outPutEncContext->scenechange_threshold = 0;
outPutEncContext->trellis = 0;
AVDictionary *options = NULL;
outPutEncContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
int ret = avcodec_open2(outPutEncContext, pH264Codec, &options);
if (ret < 0)
{
printf("%s", "open codec failed");
return ret;
}
return 1;
}
int init_decode_codec()
{
decoderContext = context->streams[0]->codec;
if (!decoderContext) {
printf( "Could not allocate video codec context\n");
exit(1);
}else{
printf("success \n");
}
enum AVCodecID codecId = decoderContext->codec_id;
AVCodec* codec = avcodec_find_decoder(codecId);
if(!codec)
{
return -1;
}else{
printf("success \n");
}
int ret = avcodec_open2(decoderContext, codec, NULL);
return ret;
}
int decode_video(AVPacket* packet, AVFrame* frame)
{
int gotFrame = 0;
int hr = avcodec_decode_video2(decoderContext, frame, &gotFrame, packet);
if(hr >= 0 && gotFrame != 0)
{
return 1;
}
return -1;
}
int init_filter(AVCodecContext * codecContext)
{
char args[512];
int ret = 0;
AVFilter *buffersrc = avfilter_get_by_name("buffer");
AVFilter *buffersink = avfilter_get_by_name("buffersink");
AVFilterInOut *outputs = avfilter_inout_alloc();
AVFilterInOut *inputs = avfilter_inout_alloc();
// char* filters_descr ="drawtext=fontfile=D\\\\:FreeSerif.ttf:fontsize=100:text=hello world:x=100:y=100";
char* filters_descr = "drawtext=fontfile=/System/Library/Fonts/Courier.dfont:fontsize=40:text=hello world:x=100:y=100:fontcolor=green";
enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV420P};
filter_graph = avfilter_graph_alloc();
if (!outputs || !inputs || !filter_graph) {
ret = AVERROR(ENOMEM);
goto end;
}
/* buffer video source: the decoded frames from the decoder will be inserted here. */
snprintf(args, sizeof(args),
"video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
codecContext->width, codecContext->height, codecContext->pix_fmt,
codecContext->time_base.num, codecContext->time_base.den,
codecContext->sample_aspect_ratio.num, codecContext->sample_aspect_ratio.den);
ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
args, NULL, filter_graph);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
goto end;
}
/* buffer video sink: to terminate the filter chain. */
ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
NULL, NULL, filter_graph);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
goto end;
}
ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
AV_PIX_FMT_YUV420P, AV_OPT_SEARCH_CHILDREN);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
goto end;
}
/* Endpoints for the filter graph. */
outputs->name = av_strdup("in");
outputs->filter_ctx = buffersrc_ctx;
outputs->pad_idx = 0;
outputs->next = NULL;
inputs->name = av_strdup("out");
inputs->filter_ctx = buffersink_ctx;
inputs->pad_idx = 0;
inputs->next = NULL;
if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
&inputs, &outputs, NULL)) < 0)
goto end;
if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
goto end;
return ret;
end:
avfilter_inout_free(&inputs);
avfilter_inout_free(&outputs);
return ret;
}
int main(int argc, char* argv[])
{
//注意:视频是只有视频流的,没有音频流
char* fileInput = "./jichi_no_audio.ts";
char* fileOutput = "./jichi22.ts";
Init();
if(open_input_context(fileInput) < 0)
{
printf( "Open file Input failed!\n");
return 0;
}
int ret = init_decode_codec();
if(ret <0)
{
printf( "init_decode_codec failed!\n");
return 0;
}else
{
printf("init_decode_codec success \n");
}
ret = init_encode_codec(decoderContext->width,decoderContext->height);
if(ret < 0)
{
printf( "open eccoder failed ret is %d\n",ret);
printf( "init_encode_codec failed!\n");
return 0;
}else{
printf("init_encode_codec success \n");
}
if(open_output_context(fileOutput) < 0)
{
printf( "Open file Output failed!\n");
return 0;
}else{
printf("open_output_context success \n");
}
ret = init_filter(outPutEncContext);
if(ret < 0){
printf("init_filter failed \n");
return 0;
}else{
printf("init_filter success \n");
}
AVFrame* pSrcFrame = av_frame_alloc();
AVFrame* filterFrame = av_frame_alloc();
int got_output = 0;
int64_t timeRecord = 0;
int64_t firstPacketTime = 0;
int64_t outLastTime = av_gettime();
int64_t inLastTime = av_gettime();
int64_t videoCount = 0;
while(1)
{
outLastTime = av_gettime();
AVPacket* packet = ReadPacketFromSource();
if(packet)
{
if(timeRecord == 0)
{
firstPacketTime = av_gettime();
timeRecord++;
}
if(decode_video(packet,pSrcFrame))
{
if (av_buffersrc_add_frame_flags(buffersrc_ctx, pSrcFrame, AV_BUFFERSRC_FLAG_KEEP_REF) >= 0)
{
if (av_buffersink_get_frame(buffersink_ctx, filterFrame) >= 0)
{
AVPacket *pTmpPkt = (AVPacket *)av_malloc(sizeof(AVPacket));
av_init_packet(pTmpPkt);
pTmpPkt->data = NULL;
pTmpPkt->size = 0;
ret = avcodec_encode_video2(outPutEncContext, pTmpPkt, filterFrame, &got_output);
if (ret >= 0 && got_output)
{
int ret = av_write_frame(outputContext, pTmpPkt);
av_packet_unref(pTmpPkt);
}
}
}
}
}
else break;
}
printf("Transcode file end!\n");
_end:
close_input();
close_output();
return 0;
}