FFMPEG解码海思音频数据

解码流程：
1、  读取海思g726音频数据，海思g726音频会多4个字节的海思头信息。
2、选择ffmpeg g726编码器进行解码。ffmpeg g726解码器包括：AV_CODEC_ID_ADPCM_G726、AV_CODEC_ID_ADPCM_G726LE。如果海思g726码流类型为asf时，请选择AV_CODEC_ID_ADPCM_G726解码器类型；如果海思g726码流类型为RFC3551标准时，请选择AV_CODEC_ID_ADPCM_G726LE解码器类型。
 实例代码：

解码流程：

1、  读取海思g726音频数据，海思g726音频会多4个字节的海思头信息。

2、选择ffmpeg g726编码器进行解码。ffmpeg g726解码器包括：AV_CODEC_ID_ADPCM_G726、AV_CODEC_ID_ADPCM_G726LE。如果海思g726码流类型为asf时，请选择AV_CODEC_ID_ADPCM_G726解码器类型；如果海思g726码流类型为RFC3551标准时，请选择AV_CODEC_ID_ADPCM_G726LE解码器类型。

 实例代码：

 

#define  Hisi_AUDIO_HERDER_LEN			4					//hisi 音频数据头extern "C"{#include "libavcodec/avcodec.h"#include "libavformat/avformat.h"#include "libavutil/frame.h"#include "libswscale/swscale.h"#include "libavutil/imgutils.h"}//链接 ffmpeg lib库AVCodec *codec;	AVCodecContext *c= NULL;	AVPacket avpkt;	AVFrame *decoded_frame = NULL;	avcodec_register_all();	av_init_packet(&avpkt);	/* find the mpeg audio decoder */	/*	ffmpeg g726编码器：AV_CODEC_ID_ADPCM_G726	ffmpeg g726解码器包括：AV_CODEC_ID_ADPCM_G726、AV_CODEC_ID_ADPCM_G726LE	如果海思g726码流类型为asf时，请选择AV_CODEC_ID_ADPCM_G726解码器类型	如果海思g726码流类型为RFC3551标准时，请选择AV_CODEC_ID_ADPCM_G726LE解码器类型	*/	codec = avcodec_find_decoder(AV_CODEC_ID_ADPCM_G726LE);	if (!codec) 	{		fprintf(stderr, "codec not found\n");		return;	}	c = avcodec_alloc_context3(codec);	//采样率= 8000 每个采样用的bit数= 16 通道数= 1	/*	bits_per_coded_sample:表示编码压缩bit值与采样率的bit值之比。	如果为g726音频时，表示g726码流压缩与采样率比值。比如kbps码流压缩比为：k/8k = 5，kbps码流压缩比为k/8k = 2。	*/	c->bits_per_coded_sample = 5;	c->channels = 1;	c->sample_fmt = AV_SAMPLE_FMT_S16;	c->sample_rate = 8000;	c->codec_type = AVMEDIA_TYPE_AUDIO;	//c->bit_rate = 16000;	int iRet = avcodec_open2(c, codec,NULL);	if ( iRet < 0 ) 	{		fprintf(stderr, "could not open codec\n");		return;	}	CString filePath = "";	CString newlFilePath = "";	char szFilter[] = {"g726 Files (*.g726_hisi)|*.g726_hisi||"};	CFileDialog dlg(TRUE,NULL,NULL,OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT,szFilter,NULL);	if(dlg.DoModal() == IDOK)	{		filePath = dlg.GetPathName();		newlFilePath = filePath;		newlFilePath.Replace(".g726_hisi",".hisi2ff.pcm");		BOOL bRet = 0;		FILE * fpSrc = fopen(filePath.GetBuffer(filePath.GetLength()),"rb");		FILE * fpDst = fopen(newlFilePath.GetBuffer(newlFilePath.GetLength()),"wb ");		char szData[100] = {0};		char szOutData[320] = {0};		int  nDataLen = 100;		int  nOutDataLen = 320;		int  nReadedSize = 0;		unsigned short usHisiHeader[2] = {0};		if(fpSrc != NULL)		{			while(TRUE)			{				//读取头标记				nDataLen = Hisi_AUDIO_HERDER_LEN;				nReadedSize = fread(szData,sizeof(char),nDataLen,fpSrc);				if(nReadedSize < nDataLen)				{					break;				}				memcpy(usHisiHeader,szData,Hisi_AUDIO_HERDER_LEN);				int nAudioFrameDataLen = (usHisiHeader[1] & 0x00ff) * sizeof(unsigned short);				nDataLen = nAudioFrameDataLen;				//读取音频帧数据				nReadedSize = fread(szData,sizeof(char),nDataLen,fpSrc);				if(nReadedSize < nDataLen)				{					break;				}				avpkt.data = (uint8_t *)szData;				avpkt.size = nReadedSize;				int got_frame = 0;				if (!decoded_frame) 				{					if (!(decoded_frame = avcodec_alloc_frame())) 					{						return;					}				} 				else				{					avcodec_get_frame_defaults(decoded_frame);				}				int len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt);				if (len < 0) 				{					return;				}				if (got_frame) 				{					/* if a frame has been decoded, output it */					int data_size = av_samples_get_buffer_size(NULL, c->channels,						decoded_frame->nb_samples,						c->sample_fmt, 1);					fwrite(decoded_frame->data[0], 1, data_size, fpDst);									}			}			fclose(fpSrc);			fclose(fpDst);			avcodec_close(c);			av_free(c);			av_free(decoded_frame);		}	}

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