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ffmpeg封装H246为MP4
2016-09-09 09:21:13         来源:画梁佳的专栏  
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前言

文章主要对H264视频流封装为MP4格式文件的讲述,有实时H264视频流的封装和h264文件的封装,本文主要针对飞思卡尔I.MX6Q-vpu视频编码后的视频封装,所以没涉及到音频,

一、h264视频文件的封装

这部分代码主要是从雷博那里借鉴过来的,雷博的文章是音频和视频封装,我这里只实现视频的封装,具体实现方法差不多,就是少了音频这一路,代码如下:

#include 
#define __STDC_CONSTANT_MACROS
#include 
/*

FIX: H.264 in some container format (FLV, MP4, MKV etc.) need 

"h264_mp4toannexb" bitstream filter (BSF)

  *Add SPS,PPS in front of IDR frame

  *Add start code ("0,0,0,1") in front of NALU

H.264 in some container (MPEG2TS) don't need this BSF.

*/

//'1': Use H.264 Bitstream Filter 

#define USE_H264BSF 0
/*

FIX:AAC in some container format (FLV, MP4, MKV etc.) need 

"aac_adtstoasc" bitstream filter (BSF)

*/

//'1': Use AAC Bitstream Filter 

#define USE_AACBSF 0
int main(int argc, char* argv[])

{

	AVOutputFormat *ofmt = NULL;
	//Input AVFormatContext and Output AVFormatContext
	AVFormatContext *ifmt_ctx_v = NULL, *ifmt_ctx_a = NULL,*ofmt_ctx = NULL;
	AVPacket pkt;
	int ret, i;
	int videoindex_v=0,videoindex_out=0;
	int frame_index=0;
	int64_t cur_pts_v=0,cur_pts_a=0;
	//const char *in_filename_v = "cuc_ieschool.ts";//Input file URL
	const char *in_filename_v = "vpu.h264";
	//const char *in_filename_a = "cuc_ieschool.mp3";
	//const char *in_filename_a = "gowest.m4a";
	//const char *in_filename_a = "gowest.aac";
	const char *in_filename_a = "huoyuanjia.mp3";
	const char *out_filename = "vpu.mp4";//Output file URL
	av_register_all();
	//Input
	if ((ret = avformat_open_input(&ifmt_ctx_v, in_filename_v, 0, 0)) < 0) {
		printf( "Could not open input file.");
		goto end;

	}
	if ((ret = avformat_find_stream_info(ifmt_ctx_v, 0)) < 0) {
		printf( "Failed to retrieve input stream information");
		goto end;
	}
	/*if ((ret = avformat_open_input(&ifmt_ctx_a, in_filename_a, 0, 0)) < 0) {
		printf( "Could not open input file.");
		goto end;
	}
	if ((ret = avformat_find_stream_info(ifmt_ctx_a, 0)) < 0) {
		printf( "Failed to retrieve input stream information");
		goto end;
	}*/
	printf("===========Input Information==========\n");
	av_dump_format(ifmt_ctx_v, 0, in_filename_v, 0);
	//av_dump_format(ifmt_ctx_a, 0, in_filename_a, 0);
	printf("======================================\n");
	//Output
	avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
	if (!ofmt_ctx) {
		printf( "Could not create output context\n");
		ret = AVERROR_UNKNOWN;
		goto end;
	}
	ofmt = ofmt_ctx->oformat;
	printf("ifmt_ctx_v->nb_streams=%d\n",ifmt_ctx_v->nb_streams);
	for (i = 0; i < ifmt_ctx_v->nb_streams; i++) {
		//Create output AVStream according to input AVStream
		//if(ifmt_ctx_v->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
		{
			AVStream *in_stream = ifmt_ctx_v->streams[i];
			AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
			videoindex_v=i;
			if (!out_stream) {
				printf( "Failed allocating output stream\n");
				ret = AVERROR_UNKNOWN;
				goto end;
			}
			videoindex_out=out_stream->index;
			//Copy the settings of AVCodecContext
			if (avcodec_copy_context(out_stream->codec, in_stream->codec) < 0) {
				printf( "Failed to copy context from input to output stream codec context\n");
				goto end;
			}
			out_stream->codec->codec_tag = 0;
			if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
				out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
			//break;
		}
	}
/*
	for (i = 0; i < ifmt_ctx_a->nb_streams; i++) {
		//Create output AVStream according to input AVStream
		if(ifmt_ctx_a->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){
			AVStream *in_stream = ifmt_ctx_a->streams[i];
			AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
			audioindex_a=i;
			if (!out_stream) {
				printf( "Failed allocating output stream\n");
				ret = AVERROR_UNKNOWN;
				goto end;
			}
			audioindex_out=out_stream->index;
			//Copy the settings of AVCodecContext
			if (avcodec_copy_context(out_stream->codec, in_stream->codec) < 0) {
				printf( "Failed to copy context from input to output stream codec context\n");
				goto end;
			}
			out_stream->codec->codec_tag = 0;
			if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
				out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
			break;
		}
	}
*/
	printf("==========Output Information==========\n");
	av_dump_format(ofmt_ctx, 0, out_filename, 1);
	printf("======================================\n");
	//Open output file
	if (!(ofmt->flags & AVFMT_NOFILE)) {
		if (avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE) < 0) {
			printf( "Could not open output file '%s'", out_filename);
			goto end;
		}
	}
	//Write file header
	if (avformat_write_header(ofmt_ctx, NULL) < 0) {
		printf( "Error occurred when opening output file\n");
		goto end;
	}
	//FIX
#if USE_H264BSF
	AVBitStreamFilterContext* h264bsfc =  av_bitstream_filter_init("h264_mp4toannexb"); 
#endif
#if USE_AACBSF
	AVBitStreamFilterContext* aacbsfc =  av_bitstream_filter_init("aac_adtstoasc"); 
#endif
	while (1) {
		AVFormatContext *ifmt_ctx;
		int stream_index=0;
		AVStream *in_stream, *out_stream;
		//Get an AVPacket
		//if(av_compare_ts(cur_pts_v,ifmt_ctx_v->streams[videoindex_v]->time_base,cur_pts_a,ifmt_ctx_a->streams[audioindex_a]->time_base) <= 0)
		{
			ifmt_ctx=ifmt_ctx_v;
			stream_index=videoindex_out;
			if(av_read_frame(ifmt_ctx, &pkt) >= 0){
				do{
					in_stream  = ifmt_ctx->streams[pkt.stream_index];
					out_stream = ofmt_ctx->streams[stream_index];
					printf("stream_index==%d,pkt.stream_index==%d,videoindex_v=%d\n", stream_index,pkt.stream_index,videoindex_v);
					if(pkt.stream_index==videoindex_v){
						//FIX:No PTS (Example: Raw H.264)
						//Simple Write PTS
						if(pkt.pts==AV_NOPTS_VALUE){
							printf("frame_index==%d\n",frame_index);
							//Write PTS
							AVRational time_base1=in_stream->time_base;
							//Duration between 2 frames (us)
							int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(in_stream->r_frame_rate);
							//Parameters
							pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE);
							pkt.dts=pkt.pts;
							pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE);
							frame_index++;
						}
						cur_pts_v=pkt.pts;
						break;
					}
				}while(av_read_frame(ifmt_ctx, &pkt) >= 0);
			}else{
				break;
			}
		}
		/*else
		{
			ifmt_ctx=ifmt_ctx_a;
			stream_index=audioindex_out;
			if(av_read_frame(ifmt_ctx, &pkt) >= 0){
				do{
					in_stream  = ifmt_ctx->streams[pkt.stream_index];
					out_stream = ofmt_ctx->streams[stream_index];
					if(pkt.stream_index==audioindex_a){
						//FIX:No PTS
						//Simple Write PTS
						if(pkt.pts==AV_NOPTS_VALUE){
							//Write PTS
							AVRational time_base1=in_stream->time_base;
							//Duration between 2 frames (us)
							int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(in_stream->r_frame_rate);
							//Parameters
							pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE);
							pkt.dts=pkt.pts;
							pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE);
							frame_index++;
						}
						cur_pts_a=pkt.pts;
						break;
					}
				}while(av_read_frame(ifmt_ctx, &pkt) >= 0);
			}else{
				break;
			}
		}*/
		//FIX:Bitstream Filter
#if USE_H264BSF
		av_bitstream_filter_filter(h264bsfc, in_stream->codec, NULL, &pkt.data, &pkt.size, pkt.data, pkt.size, 0);
#endif
#if USE_AACBSF
		av_bitstream_filter_filter(aacbsfc, out_stream->codec, NULL, &pkt.data, &pkt.size, pkt.data, pkt.size, 0);
#endif
		//Convert PTS/DTS
		pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
		pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
		pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
		pkt.pos = -1;
		pkt.stream_index=stream_index;
		printf("Write 1 Packet. size:%5d\tpts:%lld\n",pkt.size,pkt.pts);
		//Write
		if (av_interleaved_write_frame(ofmt_ctx, &pkt) < 0) {
			printf( "Error muxing packet\n");
			break;
		}
		av_free_packet(&pkt);
	}
	//Write file trailer
	av_write_trailer(ofmt_ctx);
#if USE_H264BSF
	av_bitstream_filter_close(h264bsfc);
#endif
#if USE_AACBSF
	av_bitstream_filter_close(aacbsfc);
#endif
end:
	avformat_close_input(&ifmt_ctx_v);
	//avformat_close_input(&ifmt_ctx_a);
	/* close output */
	if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
		avio_close(ofmt_ctx->pb);
	avformat_free_context(ofmt_ctx);
	if (ret < 0 && ret != AVERROR_EOF) {
		printf( "Error occurred.\n");
		return -1;
	}
	return 0;
}

二、h264视频实时流的封装

大体思路和上面文件操作是差不多的,区别在于不能像上面一样可以获取文件中视频流的信息,这样你就的自己去设置这些参数,下面程序是根据我自己的视频流设置的,如果你的不同,需要修改;具体参数如下:

enum AVMediaType codec_type:编解码器的类型(视频,音频...)

struct AVCodec *codec:采用的解码器AVCodec(H.264,MPEG2...)

int bit_rate:平均比特率

uint8_t *extradata;int extradata_size:针对特定编码器包含的附加信息(例如对于H.264解码器来说,存储SPS,PPS等)

AVRational time_base:根据该参数,可以把PTS转化为实际的时间(单位为秒s)

int width, height:如果是视频的话,代表宽和高

int refs:运动估计参考帧的个数(H.264的话会有多帧,MPEG2这类的一般就没有了)

int sample_rate:采样率(音频)

int channels:声道数(音频)

enum AVSampleFormat sample_fmt:采样格式

int profile:型(H.264里面就有,其他编码标准应该也有)

int level:级(和profile差不太多)

还有一个结构体参数也需要去设置,在AVPacket结构体中,重要的变量有以下几个:

uint8_t *data:压缩编码的数据。

例如对于H.264来说。1个AVPacket的data通常对应一个NAL。

注意:在这里只是对应,而不是一模一样。

因此在使用FFMPEG进行视音频处理的时候,常常可以将得到的AVPacket的data数据直接写成文件,从而得到视音频的码流文件。

int size:data的大小

int64_t pts:显示时间戳

int64_t dts:解码时间戳

int stream_index:标识该AVPacket所属的视频/音频流。

总体代码如下:

#include"ffmpeg_mp4.h"

int getVopType( const void *p, int len )
{
    if ( !p || 6 >= len )
        return -1;
    unsigned char *b = (unsigned char*)p;
    // Verify NAL marker
    if ( b[ 0 ] || b[ 1 ] || 0x01 != b[ 2 ] )
    {   b++;
		if ( b[ 0 ] || b[ 1 ] || 0x01 != b[ 2 ] )
			return -1;
    } // end if
    b += 3;
    // Verify VOP id
    if ( 0xb6 == *b )
    {   
		b++;
		return ( *b & 0xc0 ) >> 6;
    } // end if
    switch( *b )
    {  
		case 0x65 : return 0;
		case 0x61 : return 1;
		case 0x01 : return 2;
    } // end switch
    return -1;
}
/* Add an output stream */
AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id)
{
    AVCodecContext *c;
    AVStream *st;
    /* find the encoder */
    *codec = avcodec_find_encoder(codec_id);
    if (!*codec)
    {
        printf("could not find encoder for '%s' \n", avcodec_get_name(codec_id));
        exit(1);
    }
    st = avformat_new_stream(oc, *codec);
    if (!st)
    {
        printf("could not allocate stream \n");
        exit(1);
    }
    st->id = oc->nb_streams-1;
    c = st->codec;
    vi = st->index;
    switch ((*codec)->type)
    {
    case AVMEDIA_TYPE_AUDIO:
        printf("AVMEDIA_TYPE_AUDIO\n");
        c->sample_fmt = (*codec)->sample_fmts ? (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;
        c->bit_rate = 64000;
        c->sample_rate = 44100;
        c->channels = 2;
        break;
    case AVMEDIA_TYPE_VIDEO:
        printf("AVMEDIA_TYPE_VIDEO\n");
        c->codec_id = AV_CODEC_ID_H264;
        c->bit_rate = 0;
        c->width = 1920;
        c->height = 1080;
        c->time_base.den = 50;
        c->time_base.num = 1;
        c->gop_size = 1;
        c->pix_fmt = STREAM_PIX_FMT;
        if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO)
        {
            c->max_b_frames = 2;
        }
        if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO)
        {
            c->mb_decision = 2;
        }
        break;
    default:
        break;
    }
    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
    {
        c->flags |= CODEC_FLAG_GLOBAL_HEADER;
    }
    return st;
}
void open_video(AVFormatContext *oc, AVCodec *codec, AVStream *st)
{
    int ret;
    AVCodecContext *c = st->codec;
    /* open the codec */
    ret = avcodec_open2(c, codec, NULL);
    if (ret < 0)
    {
        printf("could not open video codec");
       //exit(1);
    }
}
int CreateMp4()
{
    int ret; // 成功返回0,失败返回1
    const char* pszFileName = "/udisk/vpu.mp4";
    AVOutputFormat *fmt;
    AVCodec *video_codec;
    AVStream *m_pVideoSt;
    av_register_all();
    avformat_alloc_output_context2(&m_pOc, NULL, NULL, pszFileName);
    if (!m_pOc)
    {
        printf("Could not deduce output format from file extension: using MPEG. \n");
        avformat_alloc_output_context2(&m_pOc, NULL, "mpeg", pszFileName);
    }
    if (!m_pOc)
    {
        return 1;
    }
    fmt = m_pOc->oformat;
    if (fmt->video_codec != AV_CODEC_ID_NONE)
    {
        printf("1111111111111111add_stream\n");
        m_pVideoSt = add_stream(m_pOc, &video_codec, fmt->video_codec);
    }
    if (m_pVideoSt)
    {
        printf("1111111111111111open_video\n");
        open_video(m_pOc, video_codec, m_pVideoSt);
    }
    printf("==========Output Information==========\n");
    av_dump_format(m_pOc, 0, pszFileName, 1);
    printf("======================================\n");
    /* open the output file, if needed */
    if (!(fmt->flags & AVFMT_NOFILE))
    {
        ret = avio_open(&m_pOc->pb, pszFileName, AVIO_FLAG_WRITE);
        if (ret < 0)
        {
            printf("could not open %s\n", pszFileName);
            return 1;
        }
    }
    /* Write the stream header, if any */
    ret = avformat_write_header(m_pOc, NULL);
    if (ret < 0)
    {
        printf("Error occurred when opening output file");
        return 1;
    }
}
/* write h264 data to mp4 file

 * 创建mp4文件返回2;写入数据帧返回0 */
void WriteVideo(void* data, int nLen)
{
    int ret;
    if ( 0 > vi )
    {
       printf("vi less than 0");
        //return -1;
    }
    AVStream *pst = m_pOc->streams[ vi ];
    //printf("vi=====%d\n",vi);
    // Init packet
    AVPacket pkt;
    // 我的添加,为了计算pts
    AVCodecContext *c = pst->codec;
    av_init_packet( &pkt );
    pkt.flags |= ( 0 >= getVopType( data, nLen ) ) ? AV_PKT_FLAG_KEY : 0;
    pkt.stream_index = pst->index;
    pkt.data = (uint8_t*)data;
    pkt.size = nLen;
    // Wait for key frame
    if ( waitkey )
        if ( 0 == ( pkt.flags & AV_PKT_FLAG_KEY ) )
            return ;
        else
            waitkey = 0;
    pkt.pts = (ptsInc++) * (90000/STREAM_FRAME_RATE);
    pkt.pts = av_rescale_q((ptsInc++)*2, pst->codec->time_base,pst->time_base);
    //pkt.dts = (ptsInc++) * (90000/STREAM_FRAME_RATE);
  //  pkt.pts=av_rescale_q_rnd(pkt.pts, pst->time_base,pst->time_base,(AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
    pkt.dts=av_rescale_q_rnd(pkt.dts, pst->time_base,pst->time_base,(AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
    pkt.duration = av_rescale_q(pkt.duration,pst->time_base, pst->time_base);
    pkt.pos = -1;
    printf("pkt.size=%d\n",pkt.size);
    ret = av_interleaved_write_frame( m_pOc, &pkt );
    if (ret < 0)
    {
        printf("cannot write frame");
    }
}
void CloseMp4()
{
    waitkey = -1;
    vi = -1;
    if (m_pOc)
        av_write_trailer(m_pOc);
    if (m_pOc && !(m_pOc->oformat->flags & AVFMT_NOFILE))
        avio_close(m_pOc->pb);
    if (m_pOc)
    {
        avformat_free_context(m_pOc);
        m_pOc = NULL;
    }
}
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