ffmpeg代码实现自定义encoder

Posted 2020-10-02 DoubleLi

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1、概述

本文主要讲述如何用ffmpeg代码实现自己的encoder。

2、代码

[cpp] view plain copy

/*
*本程序主要实现一个自己的encoder并加入到encoder链中去,供api调用
*作者：缪国凯（MK）
*[email protected]
*2015-6-4
*/
#include "stdafx.h"
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/pixdesc.h>
#
#ifdef __cplusplus
};
#endif
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avutil.lib")
//#pragma comment(lib, "avdevice.lib")
//#pragma comment(lib, "avfilter.lib")
//#pragma comment(lib, "postproc.lib")
//#pragma comment(lib, "swresample.lib")
//#pragma comment(lib, "swscale.lib")
static av_cold int mk_encode_init(AVCodecContext *avctx)
{
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
avctx->coded_frame = av_frame_alloc();
avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
avctx->bits_per_coded_sample = av_get_bits_per_pixel(desc);
if(!avctx->codec_tag)
avctx->codec_tag = avcodec_pix_fmt_to_codec_tag(avctx->pix_fmt);
return 0;
}
static int mk_encode(AVCodecContext *avctx, AVPacket *pkt,
const AVFrame *frame, int *got_packet)
{
int ret = avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height);
if (ret < 0)
return ret;
if (pkt->data == NULL && pkt->size == 0)
{
av_new_packet(pkt,ret);
pkt->size = ret;
}
// if ((ret = ff_alloc_packet2(avctx, pkt, ret)) < 0)
// return ret;
if ((ret = avpicture_layout((const AVPicture *)frame, avctx->pix_fmt, avctx->width,
avctx->height, pkt->data, pkt->size)) < 0)
return ret;
// if(avctx->codec_tag == AV_RL32("yuv2") && ret > 0 &&
// avctx->pix_fmt == AV_PIX_FMT_YUYV422)
// {
// int x;
// for(x = 1; x < avctx->height*avctx->width*2; x += 2)
// pkt->data[x] ^= 0x80;
// }
pkt->flags |= AV_PKT_FLAG_KEY;
*got_packet = 1;
return 0;
}
static av_cold int mk_close(AVCodecContext *avctx)
{
av_frame_free(&avctx->coded_frame);
return 0;
}
AVCodec ff_mkvideo_encoder = {
/*.name = */"mkvideo",
/*.long_name = */"mk video",
/*.type = */AVMEDIA_TYPE_VIDEO,
/*.id = */AV_CODEC_ID_MKVIDEO,
/*.capabilities = */0,
/*.supported_framerates = */NULL,
/*.pix_fmts = */NULL,
/*.supported_samplerates = */NULL,
/*.sample_fmts = */NULL,
/*.channel_layouts = */NULL,
/*.max_lowres = */0,
/*.priv_class = */NULL,
/*.profiles = */NULL,
/*.priv_data_size = */0,
/*.next = */NULL,
/*.init_thread_copy = */NULL,
/*.update_thread_context = */NULL,
/*.defaults = */NULL,
/*.init_static_data = */NULL,
/*.init = */mk_encode_init,
/*.encode_sub = */NULL,
/*.encode2 = */mk_encode,
/*.decode = */NULL,
/*.close = */mk_close,
};
void help()
{
printf("**********************************************\n");
printf("Usage:\n");
printf(" MyMuxer [inputfile] [outputfile] \n");
printf("\n");
printf("Examples: \n");
printf(" MyMuxer a.avi a.yuv \n");
printf("**********************************************\n");
}
int _tmain(int argc, _TCHAR* argv[])
{
if(argc < 3 || (!strcmp(argv[1],"--help")))
{
help();
return 0;
}
av_register_all();
avcodec_register(&ff_mkvideo_encoder);
AVFormatContext *in_fxt = NULL, *out_fxt = NULL;
AVStream *out_stream = NULL;
int video_index = -1;
if (avformat_open_input(&in_fxt, argv[1], NULL, NULL) < 0)
{
printf("can not open the input file context!\n");
goto end;
}
if (avformat_find_stream_info(in_fxt, NULL) < 0)
{
printf("can not find the stream info!\n");
goto end;
}
if(avformat_alloc_output_context2(&out_fxt, NULL, NULL, argv[2]) < 0)
{
printf("can not alloc output context!\n");
goto end;
}
for (int i = 0; i < in_fxt->nb_streams; i++)
{
if (in_fxt->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
{
//open decoder
if(0 > avcodec_open2(in_fxt->streams[i]->codec, avcodec_find_decoder(in_fxt->streams[i]->codec->codec_id), NULL))
{
printf("can not find or open decoder!\n");
goto end;
}
video_index = i;
//new stream
out_stream = avformat_new_stream(out_fxt, NULL);
if (!out_stream)
{
printf("can not new stream for output!\n");
goto end;
}
//set codec context param
out_stream->codec->codec = avcodec_find_encoder(/*out_fxt->oformat->video_codec*/AV_CODEC_ID_MKVIDEO);
out_stream->codec->height = in_fxt->streams[i]->codec->height;
out_stream->codec->width = in_fxt->streams[i]->codec->width;
out_stream->codec->time_base = in_fxt->streams[i]->time_base;
//out_stream->codec->time_base.den = 25;
out_stream->codec->sample_aspect_ratio = in_fxt->streams[i]->codec->sample_aspect_ratio;
out_stream->codec->pix_fmt = in_fxt->streams[i]->codec->pix_fmt;
out_stream->avg_frame_rate.den = out_stream->codec->time_base.num;
out_stream->avg_frame_rate.num = out_stream->codec->time_base.den;
if (!out_stream->codec->codec)
{
printf("can not find the encoder!\n");
goto end;
}
if ((avcodec_open2(out_stream->codec, out_stream->codec->codec, NULL)) < 0)
{
printf("can not open the encoder\n");
goto end;
}
if (out_fxt->oformat->flags & AVFMT_GLOBALHEADER)
out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
break;
}
}
if (-1 == video_index)
{
printf("found no video stream in input file!\n");
goto end;
}
if (!(out_fxt->oformat->flags & AVFMT_NOFILE))
{
if(avio_open(&out_fxt->pb, argv[2], AVIO_FLAG_WRITE) < 0)
{
printf("can not open output file handle!\n");
goto end;
}
}
if(avformat_write_header(out_fxt, NULL) < 0)
{
printf("can not write the header of the output file!\n");
goto end;
}
AVPacket pkt_in, pkt_out;
AVFrame *frame;
frame = av_frame_alloc();
av_init_packet(&pkt_in);
av_init_packet(&pkt_out);
int got_frame, got_picture;
int i = 0, frame_index = 0;
while(1)
{
got_frame = -1;
got_picture = -1;
if (av_read_frame(in_fxt, &pkt_in) < 0)
{
break;
}
if (avcodec_decode_video2(in_fxt->streams[video_index]->codec, frame, &got_frame, &pkt_in) < 0)
{
printf("can not decoder a frame");
break;
}
av_free_packet(&pkt_in);
if (got_frame)
{
frame->pts = i++;
pkt_out.data = NULL;//主要这里必须自己初始化，或者必须置为null，不然ff_alloc_packet2函数会报错
pkt_out.size = 0;
if (avcodec_encode_video2(out_stream->codec, &pkt_out, frame, &got_picture) < 0)
{
printf("can not encode a frame!\n");
break;
}
if (got_picture)
{
printf("Succeed to encode frame: %5d\tsize:%5d\n",frame_index,pkt_out.size);
pkt_out.stream_index = out_stream->index;
frame_index++;
av_write_frame(out_fxt, &pkt_out);
av_free_packet(&pkt_out);
}
}
}
av_frame_free(&frame);
av_write_trailer(out_fxt);
//clean
avcodec_close(out_stream->codec);
avcodec_close(out_fxt->streams[video_index]->codec);
end:
avformat_close_input(&in_fxt);
if (out_fxt && !(out_fxt->oformat->flags & AVFMT_NOFILE))
{
avio_close(out_fxt->pb);
}
avformat_free_context(out_fxt);
return 0;
}

3、解释

原理和前面的自定义的muxer、demuxer一样，在这里就不多说了。

from:http://blog.csdn.net/dancing_night/article/details/46360851

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