H264是当今流行的视频压缩格式；ffmpeg是一个开源库，实现了对h264视频文件的解压缩。
为了降低使用ffmpeg的复杂性，尽量隐藏实现细节，我写了一个封装库。c#也可以很方便的使用此库。解压后的数据可以为yuv格式，也可以为rgb格式。同时可以对rgb格式视频做缩放。
类H264Decode实现了所有解码功能。最后，再把此类封装成c函数，以便于与c#交互。
代码下载地址 https://download.csdn.net/download/qq_29939347/10674597
下面讲述一下此类的实现细节：
1 BOOL H264Decode::Init()
初始化解码库，打开h264解码器。
BOOL H264Decode::Init()
{
if (_init)
return TRUE; _init = TRUE;
if (!_av_register)
{
_av_register = TRUE;
av_register_all();
} _pCodecContext = avcodec_alloc_context3(NULL);
_pH264VideoDecoder = avcodec_find_decoder(AV_CODEC_ID_H264);
if (_pH264VideoDecoder == NULL)
{
return FALSE;
} //初始化参数，下面的参数应该由具体的业务决定 AV_PIX_FMT_YUV420P;
_pCodecContext->time_base.num = ;
_pCodecContext->frame_number = ; //每包一个视频帧
_pCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
_pCodecContext->bit_rate = ;
_pCodecContext->time_base.den = ;//帧率
_pCodecContext->width = ;//视频宽
_pCodecContext->height = ;//视频高
_pCodecContext->pix_fmt = AV_PIX_FMT_YUVJ420P;
_pCodecContext->color_range = AVCOL_RANGE_MPEG; if (avcodec_open2(_pCodecContext, _pH264VideoDecoder, NULL) >= )
_pFrameYuv = av_frame_alloc();
else
return FALSE; return TRUE;
}
2 向解码器输入数据
INT32 H264Decode::H264_PutVideoStream(char* buffer, INT32 bufferLen)
{
AVPacket packet = { };
packet.data = (uint8_t*)buffer; //这里填入一个指向完整H264数据帧的指针
packet.size = bufferLen; //这个填入H264数据帧的大小 int ret = avcodec_send_packet(_pCodecContext, &packet);
return ret;
}
3 读取解压后的数据 yuv格式
INT32 H264Decode::H264_GetNextVideoFrame(char* buffer, INT32 bufferLen, INT32 yuFormate)
{
if (avcodec_receive_frame(_pCodecContext, _pFrameYuv) == )
{
int height = _pCodecContext->height;
int width = _pCodecContext->width; if (yuFormate == )
{
////写入数据
int yLen = height * width;
memcpy(buffer, _pFrameYuv->data[], yLen); int uLen = yLen / ;
memcpy(buffer + yLen, _pFrameYuv->data[], uLen); int vLen = uLen;
memcpy(buffer + yLen + uLen, _pFrameYuv->data[], vLen);
return ;
}
else
{
////写入数据
int yLen = height * width;
memcpy(buffer, _pFrameYuv->data[], yLen); int uLen = yLen / ;
memcpy(buffer + yLen, _pFrameYuv->data[], uLen); int vLen = uLen;
memcpy(buffer + yLen + uLen, _pFrameYuv->data[], vLen);
return ;
}
}
return -;
}
4 获取RGB格式视频；可同时，根据需要的大小，对视频做缩放。
INT32 H264Decode::H264_GetNextVideoFrame_Rgb(char* buffer, INT32 bufferLen, INT32 width, INT32 height)
{
if (avcodec_receive_frame(_pCodecContext, _pFrameYuv) == )
{
ResetRgbScale(width, height); int n = (_out_rgb_buffer_len == bufferLen); uint8_t * data[];
data[] = _pFrameYuv->data[];
data[] = _pFrameYuv->data[]; //u v 向量互换
data[] = _pFrameYuv->data[]; _dst_dataTmp[] = (uint8_t *)buffer; //少一次复制
int ret = sws_scale(_img_convert_ctx, (const unsigned char* const*)data, _pFrameYuv->linesize, , _pCodecContext->height,
_dst_dataTmp, _dst_linesize);
return ;
}
return -;
}
C语言封装接口
extern "C"
{
LibFfmpegWrapper_API INT64 H264_CreateHandle();
LibFfmpegWrapper_API INT32 H264_CloseHandle(INT64 handle); LibFfmpegWrapper_API INT32 H264_SetDefaultAlgorithm(INT32 flag);
LibFfmpegWrapper_API INT32 H264_SetAlgorithm(INT64 handle, INT32 flag); LibFfmpegWrapper_API INT32 H264_PutVideoStream(INT64 handle, char* buffer, INT32 bufferLen);
LibFfmpegWrapper_API INT32 H264_GetVideoParam(INT64 handle, INT32& width, INT32& height); LibFfmpegWrapper_API INT32 H264_GetVideoFrameSize(INT64 handle);
LibFfmpegWrapper_API INT32 H264_GetVideoFrameFormate(INT64 handle); LibFfmpegWrapper_API INT32 H264_GetNextVideoFrame(INT64 handle, char* buffer, INT32 bufferLen, INT32 yuFormate); LibFfmpegWrapper_API INT32 H264_GetVideoFrameSize_Rgb(INT64 handle);
LibFfmpegWrapper_API INT32 H264_GetNextVideoFrame_Rgb(INT64 handle, char* buffer, INT32 bufferLen); LibFfmpegWrapper_API INT32 H264_GetVideoFrameSize_Rgb2(INT64 handle,INT32 width, INT32 height);
LibFfmpegWrapper_API INT32 H264_GetNextVideoFrame_Rgb2(INT64 handle, char* buffer, INT32 bufferLen, INT32 width, INT32 height);
}
c# 调用封装
class H264Decode
{
public const int Decode_Result_OK = ; long _handleDecode = ; public static void SetDefaultAlgorithm(EN_H264Algorithm flag)
{
H264DecodeWrapper.SetDefaultAlgorithm((int)flag);
} ~H264Decode()
{
Close();
} public void Init()
{
_handleDecode = H264DecodeWrapper.CreateHandle();
} public Int32 SetAlgorithm(EN_H264Algorithm flag)
{
return H264DecodeWrapper.SetAlgorithm(_handleDecode, (int)flag);
} public void Close()
{
if (_handleDecode == )
return;
H264DecodeWrapper.CloseHandle(_handleDecode);
_handleDecode = ;
} public int PutVideoStream(byte[] buffer)
{
return PutVideoStream(buffer, buffer.Length);
} public int PutVideoStream(byte[] buffer, Int32 bufferLen)
{
return H264DecodeWrapper.PutVideoStream(_handleDecode, buffer, bufferLen);
} public int GetVideoOrgSize(out int width, out int height)
{
int result = H264DecodeWrapper.GetVideoParam(_handleDecode, out width, out height);
return result;
} public int GetVideoFrameSize()
{
int result = H264DecodeWrapper.GetVideoFrameSize(_handleDecode);
return result;
}
public AVPixelFormat GetVideoFrameFormate()
{
int result = H264DecodeWrapper.GetVideoFrameFormate(_handleDecode);
return (AVPixelFormat)result;
} public int GetNextVideoFrame(byte[] buffer, Int32 bufferLen, EN_H264_YU_Formate formate)
{
int result = H264DecodeWrapper.GetNextVideoFrame(_handleDecode, buffer, bufferLen, formate);
return result;
}
public int GetNextVideoFrame(byte[] buffer, EN_H264_YU_Formate formate)
{
int result = H264DecodeWrapper.GetNextVideoFrame(_handleDecode, buffer, buffer.Length, formate);
return result;
} public int GetVideoFrameSize_Rgb()
{
int result = H264DecodeWrapper.GetVideoFrameSize_Rgb(_handleDecode);
return result;
} public int GetNextVideoFrame_Rgb(byte[] buffer, Int32 bufferLen)
{
int result = H264DecodeWrapper.GetNextVideoFrame_Rgb(_handleDecode, buffer, bufferLen);
return result;
} public int GetVideoFrameSize_Rgb2(Int32 width, Int32 height)
{
int result = H264DecodeWrapper.GetVideoFrameSize_Rgb2(_handleDecode, width, height);
return result;
} public int GetNextVideoFrame_Rgb2(byte[] buffer, Int32 bufferLen, Int32 width, Int32 height)
{
int result = H264DecodeWrapper.GetNextVideoFrame_Rgb2(_handleDecode, buffer, bufferLen, width, height);
return result;
} } public enum EN_H264Algorithm
{
SWS_FAST_BILINEAR = ,
SWS_BILINEAR = ,
SWS_BICUBIC = ,
SWS_X = ,
SWS_POINT = 0x10,
SWS_AREA = 0x20,
SWS_BICUBLIN = 0x40,
SWS_GAUSS = 0x80,
SWS_SINC = 0x100,
SWS_LANCZOS = 0x200,
SWS_SPLINE = 0x400,
} public class H264DecodeWrapper
{
private const string DLLName = "LibFfmpegWrapper.dll"; [DllImport(DLLName, EntryPoint = "H264_CreateHandle", CallingConvention = CallingConvention.Cdecl)]
private static extern long H264_CreateHandle(); [DllImport(DLLName, EntryPoint = "H264_CloseHandle", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_CloseHandle(long handle); [DllImport(DLLName, EntryPoint = "H264_PutVideoStream", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_PutVideoStream(long handle, IntPtr buffer, Int32 bufferLen); [DllImport(DLLName, EntryPoint = "H264_GetVideoParam", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetVideoParam(long handle, IntPtr width, IntPtr height); [DllImport(DLLName, EntryPoint = "H264_GetVideoFrameSize", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetVideoFrameSize(long handle); [DllImport(DLLName, EntryPoint = "H264_GetVideoFrameFormate", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetVideoFrameFormate(long handle); [DllImport(DLLName, EntryPoint = "H264_GetNextVideoFrame", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetNextVideoFrame(long handle, IntPtr buffer, Int32 bufferLen, Int32 yuFormate); [DllImport(DLLName, EntryPoint = "H264_GetVideoFrameSize_Rgb", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetVideoFrameSize_Rgb(long handle); [DllImport(DLLName, EntryPoint = "H264_GetNextVideoFrame_Rgb", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetNextVideoFrame_Rgb(long handle, IntPtr buffer, Int32 bufferLen); [DllImport(DLLName, EntryPoint = "H264_GetVideoFrameSize_Rgb2", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetVideoFrameSize_Rgb2(long handle, Int32 width, Int32 height); [DllImport(DLLName, EntryPoint = "H264_GetNextVideoFrame_Rgb2", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_GetNextVideoFrame_Rgb2(long handle, IntPtr buffer, Int32 bufferLen, Int32 width, Int32 height); [DllImport(DLLName, EntryPoint = "H264_SetDefaultAlgorithm", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_SetDefaultAlgorithm(Int32 flag); [DllImport(DLLName, EntryPoint = "H264_SetAlgorithm", CallingConvention = CallingConvention.Cdecl)]
private static extern Int32 H264_SetAlgorithm(long handle,Int32 flag); public static long CreateHandle()
{
return H264_CreateHandle();
} public static long CloseHandle(long handle)
{
return H264_CloseHandle(handle);
} public static int PutVideoStream(long handle, byte[] buffer, Int32 bufferLen)
{
GCHandle hin = GCHandle.Alloc(buffer, GCHandleType.Pinned);
int result = H264_PutVideoStream(handle, hin.AddrOfPinnedObject(), bufferLen);
hin.Free();
return result;
} public static int GetVideoParam(long handle, out int width, out int height)
{
width = ;
height = ;
byte[] width2 = new byte[];
byte[] height2 = new byte[]; GCHandle hin_width = GCHandle.Alloc(width2, GCHandleType.Pinned);
GCHandle hin_height = GCHandle.Alloc(height2, GCHandleType.Pinned);
int result = H264_GetVideoParam(handle, hin_width.AddrOfPinnedObject(), hin_height.AddrOfPinnedObject());
hin_width.Free();
hin_height.Free(); if (result != )
{
return result;
} width = BitConverter.ToInt32(width2, );
height = BitConverter.ToInt32(height2, );
return result;
} public static int GetVideoFrameSize(long handle)
{
int result = H264_GetVideoFrameSize(handle);
return result;
}
public static int GetVideoFrameFormate(long handle)
{
int result = H264_GetVideoFrameFormate(handle);
return result;
} public static int GetNextVideoFrame(long handle, byte[] buffer, Int32 bufferLen, EN_H264_YU_Formate formate)
{
GCHandle hin = GCHandle.Alloc(buffer, GCHandleType.Pinned);
int result = H264_GetNextVideoFrame(handle, hin.AddrOfPinnedObject(), bufferLen, (int)formate);
hin.Free();
return result;
} public static int GetVideoFrameSize_Rgb(long handle)
{
int result = H264_GetVideoFrameSize_Rgb(handle);
return result;
} public static int GetNextVideoFrame_Rgb(long handle, byte[] buffer, Int32 bufferLen)
{
GCHandle hin = GCHandle.Alloc(buffer, GCHandleType.Pinned);
int result = H264_GetNextVideoFrame_Rgb(handle, hin.AddrOfPinnedObject(), bufferLen);
hin.Free();
return result;
} public static int GetVideoFrameSize_Rgb2(long handle, Int32 width, Int32 height)
{
int result = H264_GetVideoFrameSize_Rgb2(handle, width, height);
return result;
} public static Int32 SetDefaultAlgorithm(Int32 flag)
{
return H264_SetDefaultAlgorithm(flag);
} public static Int32 SetAlgorithm(long handle, Int32 flag)
{
return H264_SetAlgorithm(handle,flag);
} public static int GetNextVideoFrame_Rgb2(long handle, byte[] buffer, Int32 bufferLen, Int32 width, Int32 height)
{
GCHandle hin = GCHandle.Alloc(buffer, GCHandleType.Pinned);
int result = H264_GetNextVideoFrame_Rgb2(handle, hin.AddrOfPinnedObject(), bufferLen, width, height);
hin.Free();
return result;
} public enum EN_H264_YU_Formate
{
Y_U_V = ,
Y_V_U = ,
}
}
