分享一段代码,基于 ffmpeg 的视频转化为图片

代码如下:

function Video2Bmp(const strVideoFileName, strSavePath: string): Boolean; var   pfc1          : PAVFormatContext;   pfc2          : PAVFormatContext;   intVideoStreamIndex: Integer;   pps          : PPAVStream;   III          : Integer;   pcc          : PAVCodecContext;   pCodec          : PAVCodec;   pFrameVdo          : PAVFrame;   pFrameRGB          : PAVFrame;   psc          : PSwsContext;   avp          : TAVPacket;   intRemain          : Integer;   bFirst          : Boolean;   intDecoded         : Integer;   intFrameFinished   : Integer;   bmp          : TBitmap; label   lbexit; begin   Result := False;    { 1. 注册所有容器格式和CODEC }   av_register_all();    { 2. 打开文件 }   pfc1 := nil;   if avformat_open_input(pfc1, PAnsiChar(AnsiString(strVideoFileName)), nil, nil) <> 0 then   begin     ShowMessage('打开文件失败，请检查你的文件！');     Exit;   end;    { 3. 从文件中提取流信息 }   if avformat_find_stream_info(pfc1, nil) < 0 then   begin     ShowMessage('不存在任何音频或视频流！');     Exit;   end;    { 4. 穷举所有的流，查找是否包含视频流 }   intVideoStreamIndex := -1;   pfc2          := pfc1;   pps          := pfc1^.streams;   for III          := 0 to pfc1^.nb_streams - 1 do   begin     if pps^.codec.codec_type = AVMEDIA_TYPE_VIDEO then     begin       intVideoStreamIndex := III;     end;     inc(pps);   end;    if intVideoStreamIndex = -1 then   begin     ShowMessage('不存在视频流！');     Exit;   end;    { 5. 定位到视频流 }   inc(pfc1^.streams, intVideoStreamIndex);   pcc    := pfc1^.streams^.codec;   pCodec := avcodec_find_decoder(pcc^.codec_id);   if pCodec = nil then   begin     ShowMessage('找不到视频流!');     Exit;   end;    { 6. 修正视频流 }   if (pCodec^.capabilities and CODEC_CAP_TRUNCATED) = CODEC_CAP_TRUNCATED then     pcc^.flags := pcc.flags or CODEC_FLAG_TRUNCATED;   if avcodec_open2(pcc, pCodec, nil) < 0 then   begin     ShowMessage('打开视频流发生错误!');     Exit;   end;    { 7. 视频流转化为BMP }   if (pcc^.time_base.num > 1000) and (pcc^.time_base.den = 1) then     pcc^.time_base.den := 1000;   pFrameVdo          := avcodec_alloc_frame();   pFrameRGB          := avcodec_alloc_frame;   { 按视频帧的原始大小输出图片 }   avpicture_alloc(PAVPicture(pFrameRGB), AV_PIX_FMT_RGB32, pcc^.Width, pcc^.Height);   psc       := sws_getContext(pcc^.Width, pcc^.Height, pcc^.pix_fmt, pcc^.Width, pcc^.Height, AV_PIX_FMT_RGB32, SWS_BICUBIC, nil, nil, nil);   intRemain := 0;   bFirst    := True;    { 查找视频的每一帧 }   while True do   begin     if bFirst then     begin       bFirst   := False;       avp.data := nil;     end;      while True do     begin       while intRemain > 0 do       begin         intDecoded := avcodec_decode_video2(pcc, pFrameVdo, intFrameFinished, @avp);         if intDecoded < 0 then           break;          dec(intRemain, intDecoded);          { 找到完整的一帧 }         if intFrameFinished <> 0 then         begin           { 按原图输出 }           sws_scale(psc, @pFrameVdo^.data, @pFrameVdo^.linesize, 0, pcc^.Height, @pFrameRGB^.data, @pFrameRGB^.linesize);            { 输出位图 }           bmp := TBitmap.Create;           try           bmp.PixelFormat := pf32bit;           bmp.Width       := pcc^.Width;           bmp.Height      := pcc^.Height;           for III         := 0 to bmp.Height - 1 do           begin           CopyMemory(bmp.ScanLine[III], Pointer(Integer(pFrameRGB.data[0]) + bmp.Width * 4 * III), bmp.Width * 4);           end;           bmp.SaveToFile(Format('%s/%d.bmp', [strSavePath, GetTickCount]));           finally           bmp.free;           end;            { 寻找下一帧 }           Continue;         end;       end;        repeat         if av_read_frame(pfc2, @avp) < 0 then           goto lbexit;        until avp.stream_index = intVideoStreamIndex;       intRemain := avp.size;     end;      lbexit:     avcodec_decode_video2(pcc, pFrameVdo, intFrameFinished, @avp);      if avp.data <> nil then       av_free_packet(@avp);      if intFrameFinished = 0 then       break;   end;    { 8. 释放资源 }   sws_freeContext(psc);   avpicture_free(PAVPicture(pFrameRGB));   av_free(pFrameRGB);   av_free(pFrameVdo);   avcodec_close(pcc);   avformat_close_input(pfc1);    { 9. 返回成功 }   Result := True; end;