音视频解封装demo：将FLV文件解封装(demux)得到文件中的H264数据和AAC数据(纯手工，不依赖第三方开源库)

1、README

前言

注意：flv是不支持h.265封装的。目前解封装功能正常，所得到的H.264文件与AAC文件均可正常播放。

a. demo使用

$ make clean && make DEBUG=1
$ 
$ $ ./flv_demux_h264_aac 
Usage: ./flv_demux_h264_aac avfile/test1.flv./flv_demux_h264_aac avfile/test2.flv

b. 参考链接

【参考文章】

• FLV格式详解_JT同学的博客-CSDN博客_flv格式**（推荐！！！）**

• FLV封装格式介绍及解析 - 简书

• 音视频封装：FLV格式详解和打包H264、AAC方案（上） - 云+社区 - 腾讯云

• 音视频封装：FLV格式详解和打包H264、AAC方案（下） - 云+社区 - 腾讯云

【参考源码】

• https://github.com/ImSjt/H.264toFLV.git

• https://github.com/rainfly123/flvmuxer

【工具下载】

• SpecialAAAC.exe：https://sourceforge.net/projects/aacstreamanalysis/

• H264BSAnalyzer.exe：https://github.com/latelee/H264BSAnalyzer/tree/master/release

• FlvParse.exe：https://github.com/ty6815/AvStackDocs/tree/master/media%20format/flv

c. demo目录架构

$ tree
.
├── aac_adts.c
├── aac_adts.h
├── avfile
│   ├── test1.aac
│   ├── test1.flv
│   ├── test1.h264
│   ├── test2.aac
│   ├── test2.flv
│   └── test2.h264
├── docs
│   ├── FLV封装格式介绍及解析 - 简书.mhtml
│   ├── FLV格式详解_JT同学的博客-CSDN博客_flv格式.mhtml
│   ├── 笔记---H.264里的SEI - 简书.mhtml
│   ├── 音视频封装：FLV格式详解和打包H264、AAC方案（上） - 云+社区 - 腾讯云.mhtml
│   └── 音视频封装：FLV格式详解和打包H264、AAC方案（下） - 云+社区 - 腾讯云.mhtml
├── flv.c
├── flv_format.h
├── flv.h
├── h264_nalu.h
├── main.c
├── Makefile
├── README.md
├── reference_code
│   └── Flv_to_h264_AAC_Demux.zip
└── tools├── FlvParse.exe├── H264BSAnalyzer.exe└── SpecialAAAC.exe

2、主要代码片段

flv_format.h

/**************************************************************** describe: Flv file format description(Mainly for H.264 & AAC)* author: linriming* e-mail: [e-mail]***************************************************************/#ifndef __FLV_FORMAT_H__
#define __FLV_FORMAT_H__#include <stdint.h>#define AUDIO_SUPPORT(x)    (x << 2)    /* bit[2] in flvheader's type_flag */
#define VIDEO_SUPPORT(x)    (x << 0)    /* bit[0] in flvheader's type_flag */#define SIZE_FLV_HEADER         sizeof(struct flvHeader)    /* 9 Bytes */
#define SIZE_FLV_TAG_HEADER     sizeof(struct flvTagHeader) /* 11 Bytes */
#define SIZE_PREVIOUS_TAG_SIZE  sizeof(uint32_t)            /* 4 Bytes *//* FLV tag type */
typedef enum{FLVTAG_TYPE_AUDIO  = 0x08,FLVTAG_TYPE_VIDEO  = 0x09,FLVTAG_TYPE_SCRIPT = 0x12,
}flvTagType;/* AMF data type in <Script Tag> */
typedef enum{AMF_DATA_TYPE_NUMBER      = 0x00,AMF_DATA_TYPE_BOOL        = 0x01,AMF_DATA_TYPE_STRING      = 0x02,AMF_DATA_TYPE_OBJECT      = 0x03,AMF_DATA_TYPE_NULL        = 0x05,AMF_DATA_TYPE_UNDEFINED   = 0x06,AMF_DATA_TYPE_REFERENCE   = 0x07,AMF_DATA_TYPE_MIXEDARRAY  = 0x08,AMF_DATA_TYPE_OBJECT_END  = 0x09,AMF_DATA_TYPE_ARRAY       = 0x0a,AMF_DATA_TYPE_DATE        = 0x0b,AMF_DATA_TYPE_LONG_STRING = 0x0c,AMF_DATA_TYPE_UNSUPPORTED = 0x0d,
} amfDataType;/* audio tag */
typedef enum{SFI_LINEAR_PCM_PLATFORM_ENDIAN = 0,SFI_ADPCM                      = 1,SFI_MP3                        = 2,SFI_LINEAR_PCM_LITTLE_ENDIAN   = 3,SFI_NELLYMOSER_16KHZ_MONO      = 4,SFI_NELLYMOSER_8KHZ_MONO       = 5,SFI_NELLYMOSER                 = 6,SFI_G711A                      = 7,SFI_G711MU                     = 8,SFI_RESERVED                   = 9,SFI_AAC                        = 10,SFI_SPEEX                      = 11,SFI_MP3_8KHZ                   = 14,SFI_DEVIVE_SPECIFIC_SOUND      = 15,
}soundFormatIndex;typedef enum{SRI_5_5KHZ = 0,SRI_11KHZ  = 1,SRI_22KHZ  = 2,SRI_44KHZ  = 3,
}soundSamplerateIndex;typedef enum{SSI_8BIT  = 0,SSI_16BIT = 1,
}soundSizeIndex;typedef enum{STI_MONO   = 0,STI_STEREO = 1,
}soundTypeIndex;#define  AAC_PACKET_TYPE_SEQUENCE_HEADER 	(0)
#define  AAC_PACKET_TYPE_RAW 				(1)typedef enum{AAC_MAIN = 1,AAC_LC   = 2,AAC_SSR  = 3,
}aacProfileIndex;typedef enum{AAC_96KHz = 0x0,AAC_88_2KHz = 0x1,AAC_64KHz = 0x2,AAC_48KHz = 0x3,AAC_44_1KHz = 0x4,AAC_32KHz = 0x5,AAC_24KHz = 0x6,AAC_22_05KHz = 0x7,AAC_16KHz  = 0x8,AAC_12KHz  = 0x9,AAC_11_025KHz  = 0xa,AAC_8KHz  = 0xb,AAC_RESERVED = 0xc,
}aacSamplerateIndex;typedef enum{AAC_CHANNEL_SPECIAL = 0x0,AAC_CHANNEL_MONO = 0x1,AAC_CHANNEL_STEREO = 0x2,AAC_CHANNEL_3 = 0x3,AAC_CHANNEL_4 = 0x4,AAC_CHANNEL_5 = 0x5,AAC_CHANNEL_5_1 = 0x6,AAC_CHANNEL_7_1 = 0x7,AAC_CHANNELRESERVED = 0x8,
}aacChannelIndex;#define  AVC_PACKET_TYPE_SEQUENCE_HEADER 			 (0)
#define  AVC_PACKET_TYPE_NALU 						 (1)
#define  AVC_PACKET_TYPE_END_OF_SEQUENCE 			 (2)/* next for video tag */
#define  VIDEOTAG_FRAMETYPE_KEYFRAME                 (1)
#define  VIDEOTAG_FRAMETYPE_INTER_FRAME              (2)
#define  VIDEOTAG_FRAMETYPE_DISPOSABLE_INTER_FRAME   (3)
#define  VIDEOTAG_FRAMETYPE_GENERATED_KEYFRAME       (4)
#define  VIDEOTAG_FRAMETYPE_VIDEO_INFO_FRAME         (5)#define  VIDEOTAG_CODECID_JPEG                       (1)
#define  VIDEOTAG_CODECID_SORENSON_H263              (2)
#define  VIDEOTAG_CODECID_SCREEN_VIDEO               (3)
#define  VIDEOTAG_CODECID_ON2_VP6                    (4)
#define  VIDEOTAG_CODECID_ON2_VP6_WITH_ALPHA_CHANNEL (5)
#define  VIDEOTAG_CODECID_SCREEN_VIDEO_VERSION_2     (6)
#define  VIDEOTAG_CODECID_AVC                        (7)#pragma pack(push)
#pragma pack(1)   /* 1 bytes align */typedef struct flvHeader{uint8_t  signature[3]; 		/* signature bytes always 'F' 'L' 'V': 0x46 0x4C 0x56 */uint8_t  version; 			/* file version, always 0x01 */uint8_t  type_flag; 		/* bit[7:3] and bit[1] always 0, bit[2] for aduio, bit[0] for video */uint32_t data_offset; 		/* size of header, 00 00 00 09(big-endian) for version 1 */
}T_FlvHeader, *PT_FlvHeader;   	    /* 9 bytes totally */typedef struct flvTagHeader{uint8_t TagType; 					/* Type of this tag. Value are 8(audio), 9(video), 18(script), other(reserved). */uint8_t DataSize[3]; 				/* Length of the data in the Data filed. */uint8_t Timestamp[3]; 				/* Time in milliseconds at which the data in this applies. 0 in first tag in the FLV file. */uint8_t TimestampExtended; 			/* Extension of Timestamp field to form a SI32 value, it is upper 8 bits. */uint8_t StreamID[3]; 				/* Always 0 */
}T_FlvTagHeader, *PT_FlvTagHeader; 	/* 11 bytes total */typedef struct flvTag{T_FlvTagHeader flvheader; 	/* tag header */uint8_t flvdata[0]; 		/* tag data index */
}T_FlvTag, *PT_FlvTag;typedef struct avcVideoPacket{T_FlvTagHeader flvheader;uint8_t flvdata[0]; 		/* flv tag data index */
}T_AvcVideoPacket, *PT_AvcVideoPacket;#pragma pack(pop)#endif /* __FLV_FORMAT_H__ */

flv.c

#include "h264_nalu.h"
#include "aac_adts.h"
#include "flv.h"int flv_demux_h264_aac(const char *flvFileName)
{FILE *fpH264 = NULL;FILE *fpAAC  = NULL;FILE *fpFLV  = NULL;uint8_t *flvBuf = NULL;// note!!!: it maybe happen the 'Segmentation fault', as 1024 is too long for 'sps', but it maybe save the 'sei' or other unused data if first nalu isn't 'sps'.uint8_t spsBuf[64] = {0};uint8_t ppsBuf[64] = {0};uint32_t spsLen = 0;uint32_t ppsLen = 0;int ret = -1;uint32_t flvTagDataSize = 0;PT_FlvTag ptFlvTag = NULL;const char *h264FileName = "out_video.h264";const char *aacFileName = "out_audio.aac";/* open file */fpFLV  = fopen(flvFileName,  "rb");if (!fpFLV){printf("open %s error!\n", flvFileName);}fpH264 = fopen(h264FileName, "wb");if (!fpH264){printf("open %s error!\n", h264FileName);}fpAAC  = fopen(aacFileName,  "wb");if (!fpAAC){printf("open %s error!\n", aacFileName);}/* alloc memory */flvBuf = (uint8_t *)malloc(MAX_FLV_BUF_SIZE);if (!flvBuf){printf("malloc for 'flvBuf' error!\n");}/* parse and save some data first. */fread(flvBuf, SIZE_FLV_HEADER, 1, fpFLV);ret = strncmp((const char *)flvBuf, "FLV", 3);if(ret != 0){printf("\033[31m It's not a FLV file!\n\033[0m");return -1;}DEBUG("\033[32m""=====================================\n""Signature: '%c' '%c' '%c'\n""Version  : 0x%02x\n""Audio    : %s\n""Video    : %s\n""=====================================\n""\033[0m",flvBuf[0], flvBuf[1], flvBuf[2], flvBuf[3], (flvBuf[4] & 0x04) ? "yes" : "no", (flvBuf[4] & 0x01) ? "yes" : "no");fread(flvBuf, SIZE_PREVIOUS_TAG_SIZE, 1, fpFLV);DEBUG("\033[37m[Pre Tag Size]: %d \033[0m\n", (flvBuf[0] << 24) |\(flvBuf[1] << 16) |\(flvBuf[2] <<  8) |\flvBuf[3]);while(1){ret = fread(flvBuf, SIZE_FLV_TAG_HEADER, 1, fpFLV);if (ret <= 0){DEBUG(">>> FLV file end! <<<\n");break;}ptFlvTag = (PT_FlvTag)flvBuf;flvTagDataSize = (ptFlvTag->flvheader.DataSize[0] << 16) |\(ptFlvTag->flvheader.DataSize[1] << 8) |\ptFlvTag->flvheader.DataSize[2];fread(ptFlvTag->flvdata, flvTagDataSize, 1, fpFLV);switch (ptFlvTag->flvheader.TagType){case FLVTAG_TYPE_SCRIPT: {DEBUG("\033[34m[Script Tag] \033[0m\n");/* nothing to do! */break;}case FLVTAG_TYPE_AUDIO: {char *packetTypeStr = NULL;int aacPacketType = ptFlvTag->flvdata[1];switch(aacPacketType){case AAC_PACKET_TYPE_SEQUENCE_HEADER:packetTypeStr = "[AAC sequence header]";/* nothing to do! */break;case AAC_PACKET_TYPE_RAW:packetTypeStr = "[AAC raw]";uint8_t headerbuf[AAC_ADTS_HEADER_SIZE] = {0};uint32_t headerbufLen = 0;uint32_t datasize = ((ptFlvTag->flvheader.DataSize[0] << 16) |\(ptFlvTag->flvheader.DataSize[1] << 8) |\ptFlvTag->flvheader.DataSize[2]);generateAdtsHeader(AAC_ADTS_HEADER_SIZE + (datasize - 2), headerbuf, &headerbufLen);fwrite(headerbuf, headerbufLen, 1, fpAAC);fwrite(&ptFlvTag->flvdata[2], datasize - 2, 1, fpAAC);break;default:printf("[%s:%d] Unknown AAC packet type!", __FUNCTION__, __LINE__);goto exit;}DEBUG("\033[36m[Audio Tag] \t %s\033[0m\n", packetTypeStr);break;}case FLVTAG_TYPE_VIDEO: {char *packetTypeStr = NULL;char *frameTypeStr = NULL;uint8_t startCode[4] = {0x00, 0x00, 0x00, 0x01};int isKeyFrame = 0;int type = 0;isKeyFrame = (ptFlvTag->flvdata[0] & 0xF0) == 0x10 ? 1 : 0;type = ptFlvTag->flvdata[1];switch(type){case AVC_PACKET_TYPE_SEQUENCE_HEADER:packetTypeStr = "[AVC squence header]";frameTypeStr = "[key frame]";spsLen = ((ptFlvTag->flvdata[11] << 8) | ptFlvTag->flvdata[12]);memcpy(spsBuf, &ptFlvTag->flvdata[13], spsLen);//printf("spsLen: %d\n", spsLen);//for(int i = 0; i < spsLen; i++)//	printf("0x%02x ", spsBuf[i]);//printf("\n");ppsLen = ((ptFlvTag->flvdata[13 + spsLen + 1] << 8) | ptFlvTag->flvdata[13+spsLen+2]);memcpy(ppsBuf, &ptFlvTag->flvdata[13 + spsLen + 3], ppsLen);//printf("ppsLen: %d\n", ppsLen);//for(int i = 0; i < ppsLen; i++)//	printf("0x%02x ", ppsBuf[i]);//printf("\n");break;case AVC_PACKET_TYPE_NALU:packetTypeStr = "[AVC NALU]";/* one or more NALU. */uint32_t naluDataSize = 0;uint32_t curPos = 0;curPos = 5;naluDataSize = (ptFlvTag->flvdata[curPos + 0] << 24) |\(ptFlvTag->flvdata[curPos + 1] << 16) |\(ptFlvTag->flvdata[curPos + 2] << 8) |\ptFlvTag->flvdata[curPos + 3];if(isKeyFrame){frameTypeStr = "[key frame]";if((ptFlvTag->flvdata[curPos + 4] & 0x1f) == NALU_TYPE_SEI &&\(ptFlvTag->flvdata[curPos + 5] & 0x1f) == 0x05/* SEI: payloadType: user_data_unregistered() */){/* has SEI *//* SEI */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(&ptFlvTag->flvdata[curPos + 4], naluDataSize, 1, fpH264);/* SPS */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(spsBuf, spsLen, 1, fpH264);/* PPS */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(ppsBuf, ppsLen, 1, fpH264);/* update the second NALU data size. */curPos += (4 + naluDataSize);naluDataSize = (ptFlvTag->flvdata[curPos + 0] << 24) |\(ptFlvTag->flvdata[curPos + 1] << 16) |\(ptFlvTag->flvdata[curPos + 2] << 8) |\ptFlvTag->flvdata[curPos + 3];/* IDR */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(&ptFlvTag->flvdata[curPos + 4], naluDataSize, 1, fpH264);}else{/* SPS */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(spsBuf, spsLen, 1, fpH264);/* PPS */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(ppsBuf, ppsLen, 1, fpH264);/* IDR */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(&ptFlvTag->flvdata[curPos + 4], naluDataSize, 1, fpH264);}}else{frameTypeStr = "[inter frame]";/* SLICE */fwrite(startCode, sizeof(startCode), 1, fpH264);fwrite(&ptFlvTag->flvdata[curPos + 4], naluDataSize, 1, fpH264);}break;case AVC_PACKET_TYPE_END_OF_SEQUENCE:packetTypeStr = "[AVC end of squence]";frameTypeStr = "[key frame]";break;default:printf("[%s:%d] Unknown AVC packet type!", __FUNCTION__, __LINE__);goto exit;}DEBUG("\033[35m[Video Tag] \t %s \t %s\033[0m\n", packetTypeStr, frameTypeStr);break;}default: {printf("\033[33m[Unknown Tag]\033[0m\n");break;}}fread(flvBuf, SIZE_PREVIOUS_TAG_SIZE, 1, fpFLV);DEBUG("\033[37m[PreTagSize] \t %d\033[0m\n", (flvBuf[0] << 24) |\(flvBuf[1] << 16) |\(flvBuf[2] <<	8) |\flvBuf[3]);}exit:if(fpFLV) 	fclose(fpFLV);if(fpH264) 	{fflush(fpH264); fclose(fpH264);}if(fpAAC) 	{fflush(fpAAC); fclose(fpAAC);}if(flvBuf)  free(flvBuf);return 0;
}

main.c

#include <stdio.h>#include "flv.h"int main(int argc, char *argv[])
{if(argc == 1){printf("Usage: \n""   %s avfile/test1.flv\n""   %s avfile/test2.flv\n",argv[0], argv[0]);return -1;}flv_demux_h264_aac(argv[1]);printf("\033[32m""Success!\n""\033[0m");return 0;
}

3、demo下载地址（任选一个）

• https://download.csdn.net/download/weixin_44498318/89526743
• https://gitee.com/linriming/av_flv_demux_h264_aac.git
• https://github.com/linriming20/av_flv_demux_h264_aac.git