SkeyeRTSPLive高效转码之SkeyeVideoDecoder高效软解码解决方案（附源码)

在我之前写的一篇文章《SkeyeRTSPLive传统视频监控互联网+实现利器解决方案》中提到RTSP转RTMP的转流过程，简化流程就是通过SkeyeRTSPClient拉RTSP流，获取音视频编码数据，然后再通过SkeyeRTMP推出去，流程非常简单；然后再实际开发过程中，我们发现其实这个过程并没有想象中那么简单；首先，RTSP协议支持多种音视频编码格式，如音频支持AAC,G711，G726,等，视频支持H264，H625，MJPEG, MPEG等等各种格式，而SkeyeRTMPPusher推流只支持H264（已扩展支持H265）格式，这时，音频我们可以通过SkeyeAACEncoder将音频转码成AAC格式，而视频我们可以通过SkeyeVideoDecoder解码成原始数据，然后再通过SkeyeVideoEncoder将原始数据转码成RTMP推送指定的格式，本文，我们将重点讲述SkeyeVideoDecoder的软解码流程。

1. SkeyeVideoDecoder软解码接口声明如下：

#ifndef __SKEYE_DECODER_API_H__
#define __FF_DECODER_API_H__


#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define SKEYEDECODER_API  __declspec(dllexport)
//=======================================================
//Decoder
#ifndef DECODER_H264
#define DECODER_H264			0x1C			//28
#endif
#ifndef DECODER_MPEG4
#define DECODER_MPEG4			0x0D			//13
#endif
#ifndef DECODER_MPEG2
#define DECODER_MPEG2			0x02			//2
#endif
#ifndef DECODER_MJPEG
#define DECODER_MJPEG			0x08			//8
#endif

#ifndef DECODER_MP3
#define DECODER_MP3				0x15001			//86017
#endif

#ifndef DECODER_AAC
#define DECODER_AAC				0x15002			//86018
#endif

//=======================================================
//输出格式
#ifndef OUTPUT_PIX_FMT_YUV420P
#define OUTPUT_PIX_FMT_YUV420P		0
#endif
#ifndef OUTPUT_PIX_FMT_YUYV422
#define OUTPUT_PIX_FMT_YUYV422		1
#endif
#ifndef OUTPUT_PIX_FMT_RGB565LE
#define OUTPUT_PIX_FMT_RGB565LE		44
#endif
#ifndef OUTPUT_PIX_FMT_RGBA
#define OUTPUT_PIX_FMT_RGBA			28
#endif

//=======================================================
//图像处理
//=======================================================
typedef enum __VIDEO_FILTER_TYPE
{
	VIDEO_ROTATION_90_0				=		0,	//顺时针旋转90度
	VIDEO_ROTATION_90_1,						//逆时针旋转90度
	VIDEO_ROTATION_90_0_FLIP,					//顺时针旋转90度,再水平翻转
	VIDEO_ROTATION_90_1_FLIP,					//逆时针旋转90度,再垂直翻转

	VIDEO_TEXT,

}VIDEO_FILTER_TYPE;




//=======================================================
typedef void *SKEYEDEC_HANDLE;


//=======================================================
extern "C"
{
	int	SKEYEDECODER_API	SKEYEDECODER_Init(SKEYEDEC_HANDLE *_handle);
	int	SKEYEDECODER_API	SKEYEDECODER_Deinit(SKEYEDEC_HANDLE *_handle);

	int SKEYEDECODER_API	SKEYEDECODER_SetVideoDecoderParam(SKEYEDEC_HANDLE _handle, int _width, int _height, int _decoder, int _outformat);
	int SKEYEDECODER_API	SKEYEDECODER_SetAudioDecoderParam(SKEYEDEC_HANDLE _handle, unsigned char _channel, unsigned int _sample_rate, unsigned int _decoder);

	int	SKEYEDECODER_API	SKEYEDECODER_GetVideoDecoderInfo(SKEYEDEC_HANDLE _handle, int *_decoder, int *_width, int *_height);

	int	SKEYEDECODER_API	SKEYEDECODER_DecodeVideo(SKEYEDEC_HANDLE _handle, char *pInBuf, int inputSize, char **pOutBuf, int dstW, int dstH);

	//desc:				解码后的数据，直接送到指定的内存中
	int	SKEYEDECODER_API	SKEYEDECODER_DecodeVideo2Buf(SKEYEDEC_HANDLE _handle, char *_inbuf, int _bufsize, void *_outbuf[8], int _pitch);

	int	SKEYEDECODER_API	SKEYEDECODER_DecodeVideo3(SKEYEDEC_HANDLE _handle, char *_inbuf, int _bufsize, void *yuvbuf, int dstW, int dstH);
	int	SKEYEDECODER_API	SKEYEDECODER_DecodeVideoPacket(SKEYEDEC_HANDLE _handle, char *pCodecCtx, unsigned char *avPacket, char **_outbuf);


	int	SKEYEDECODER_API	SKEYEDECODER_DecodeAudio(SKEYEDEC_HANDLE _handle, char *pInBuf, int inputSize, char *pOutBuf, int *outSize);
	int	SKEYEDECODER_API	SKEYEDECODER_DecodeAudioPacket(SKEYEDEC_HANDLE _handle, char *pCodecCtx, unsigned char *avPacket, char *pOutBuf, int *outSize);
};

#endif

2. 软解码通过ffmpeg解码实现流程

和网上大多数的ffmpeg解码示例调用相似。软解码实现分四步走，详细流程如下：

• 第一步，全局注册ffmpeg编解码器

	avcodec_register_all();/*注册所有的编码解码器*/
	av_register_all();// //注册所有可解码类型

• 第二步，初始化视频解码参数

int	InitVideoDecoder(int _width, int _height, int _videoCodec, int _outformat)
{
	if (NULL != decoderObj.pVideoCodecCtx)		return -1;	//or call DeinitVideoDecoder();

	AVCodec			*pAVCodec;
	pAVCodec = avcodec_find_decoder((AVCodecID)_videoCodec);
	if (NULL == pAVCodec)		return -1;

	decoderObj.pVideoCodecCtx = avcodec_alloc_context3(pAVCodec);
	decoderObj.pVideoCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P;
	decoderObj.pVideoCodecCtx->width   = _width;
	decoderObj.pVideoCodecCtx->height  = _height;
	//decoderObj.pVideoCodecCtx->thread_count = 2;
	//decoderObj.pVideoCodecCtx->active_thread_type = decoderObj.pVideoCodecCtx->thread_type = FF_THREAD_FRAME;

	int ret = avcodec_open2(decoderObj.pVideoCodecCtx, pAVCodec, NULL);
	if (ret < 0)				goto $fail;

	int numBytes = avpicture_get_size(AV_PIX_FMT_YUV420P, _width, _height);
	decoderObj.pBuffYuv420 = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));
	decoderObj.mVideoFrame420	= av_frame_alloc();
	if (avpicture_fill((AVPicture *)decoderObj.mVideoFrame420, decoderObj.pBuffYuv420, AV_PIX_FMT_YUV420P,
		decoderObj.width, decoderObj.height) < 0)
	{
	}
#ifdef ADD_VIDEO_FILTER
	SetVideoFilter(VIDEO_TEXT, NULL);
#endif
	av_init_packet(&decoderObj.avVidPacket);
	decoderObj.outputFormat = _outformat;
	decoderObj.codec	=	_videoCodec;
	decoderObj.width	=	_width;
	decoderObj.height	=	_height;	
	return 0;

$fail:
	{
		DeinitVideoDecoder();
		return -1;
	}
}

• 第三步，直接解码视频帧并输出指定色彩格式

int	DecodeVideo(char *_inbuf, int _bufsize, char **_outbuf, int dstW, int dstH)
{
	if (NULL == _inbuf)			return -1;
	if (1 > _bufsize)			return -1;

	//if (NULL == decoderObj.pSws_ctx)	return -2;

	if (NULL == decoderObj.mVideoFrame420)	decoderObj.mVideoFrame420 = av_frame_alloc();
	
	decoderObj.avVidPacket.size = _bufsize;
	decoderObj.avVidPacket.data	= (uint8_t*)_inbuf;

	int frameFinished = 0;
	int nDecode = avcodec_decode_video2(decoderObj.pVideoCodecCtx, decoderObj.mVideoFrame420, &frameFinished, &decoderObj.avVidPacket);//(uint8_t*)pInBuffer, inputSize);
	if (nDecode < 0)	return -3;
	if (!frameFinished)	return -4;

	if (NULL == decoderObj.pAvFrameYuv)
	{
		int numBytes = avpicture_get_size((AVPixelFormat)decoderObj.outputFormat,  dstW, dstH);
		decoderObj.pBuffYuv = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));
		decoderObj.pAvFrameYuv = av_frame_alloc();
		if (avpicture_fill((AVPicture *)decoderObj.pAvFrameYuv, decoderObj.pBuffYuv, (AVPixelFormat)decoderObj.outputFormat,
			dstW, dstH) < 0)
		{

		}
	}

	if (NULL == decoderObj.pSws_ctx)
	{
		decoderObj.pSws_ctx = sws_getCachedContext(decoderObj.pSws_ctx, decoderObj.width, decoderObj.height, (AVPixelFormat)AV_PIX_FMT_YUV420P, 
			//decoderObj.width/2, decoderObj.height/2, (PixelFormat)PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
			dstW, dstH, (AVPixelFormat)decoderObj.outputFormat, SWS_BICUBIC, NULL, NULL, NULL);
	}

	if (NULL == decoderObj.pSws_ctx)		return -1;

	sws_scale(decoderObj.pSws_ctx, decoderObj.mVideoFrame420->data, decoderObj.mVideoFrame420->linesize, 0, decoderObj.pVideoCodecCtx->height, 
		decoderObj.pAvFrameYuv->data, decoderObj.pAvFrameYuv->linesize);

	//sws_freeContext(decoderObj.pSws_ctx);
	//decoderObj.pSws_ctx = NULL;

	*_outbuf = (char*)decoderObj.pAvFrameYuv->data[0];

	return 0;
}

• 第四步，停止解码后，销毁解码器申请的资源

void DeinitVideoDecoder()
{
	if (NULL != decoderObj.mVideoFrame420)
	{
		av_frame_free(&decoderObj.mVideoFrame420);
		decoderObj.mVideoFrame420 = NULL;
	}
	if (NULL != decoderObj.pBuffYuv420)
	{
		av_free(decoderObj.pBuffYuv420);
		decoderObj.pBuffYuv420 = NULL;
	}
	if (NULL != decoderObj.pAvFrameSws)
	{
		av_frame_free(&decoderObj.pAvFrameSws);
		decoderObj.pAvFrameSws = NULL;
	}
	if (NULL != decoderObj.pAvFrameYuv)
	{
		av_frame_free(&decoderObj.pAvFrameYuv);
		decoderObj.pAvFrameYuv = NULL;
	}
	if (NULL != decoderObj.pBuffYuv)
	{
		av_free(decoderObj.pBuffYuv);
		decoderObj.pBuffYuv = NULL;
	}

	if (NULL != decoderObj.pSws_ctx)
	{
		sws_freeContext(decoderObj.pSws_ctx);
		decoderObj.pSws_ctx = NULL;
	}

	if (NULL != decoderObj.pVideoCodecCtx)
	{
		avcodec_close(decoderObj.pVideoCodecCtx);
		av_free(decoderObj.pVideoCodecCtx);
		decoderObj.pVideoCodecCtx = NULL;
	}
}

有任何技术问题，欢迎大家和我技术交流：
[email protected]

大家也可以加入SKEYEPlayer流媒体播放器 QQ群进行讨论：
102644504