c#把m4a转换成mp3
时间: 2023-08-20 16:02:31 浏览: 34
c是英文字母表中的第三个字母,大小写分别为C和c。在拉丁字母表中,c一般发音为/k/音,如cat(猫)、car(汽车)。在拼音系统中,代表的是音素/t͡s/的发音。c在单词中也可以组合成不同的音素,如ch代表/t͡ʃ/音,如choice(选择)、cheese(奶酪);表示/s/音的ce,如ceiling(天花板)、cent(中心);发音为/k/的ci,如city(城市)、cinema(电影院)等等。
此外,c也有其他的意义。在数学中,c通常表示一些常量或系数,如圆的周长(circumference)公式中的C=2πr,其中C表示周长。在电磁学中,c是光速(speed of light)的简写,其数值为299,792,458米/秒。
此外,c还可以作为缩写或代表一些特定的概念。例如,“C”可以代表摄氏度(Celsius),用于衡量温度;在电影级别中,C可以指代“保守观众(Children)”,表示适合儿童观看的电影或节目;在大型音乐会中,“C”也可以表示草坪区域(C区),作为观众坐席的一种分类。
总的来说,c是一个英文字母,可以代表不同的发音、数学常量、物理概念和缩写。在不同的领域和语境中,c有着不同的含义和用途。
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C#H264转BMP
根据提供的引用内容,您可以使用FFmpeg API在C#中编写程序,以实现将H264关键帧转换为BMP的功能。以下是大致的流程原理:
1.使用FFmpeg API解复用mp4文件,得到一个视频流。
2.将视频流解码为yuv序列。
3.将yuv序列中指定的一帧图片内容转换为rgb。
4.将rgb数据存储为bmp位图。
以下是一个C#的示例代码:
```csharp
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
namespace H264ToBmp
{
class Program
{
static void Main(string[] args)
{
// 初始化FFmpeg
FFmpeg.av_register_all();
FFmpeg.avcodec_register_all();
// 打开输入文件
string inputFileName = "input.mp4";
AVFormatContext* inputFormatContext = null;
if (FFmpeg.avformat_open_input(&inputFormatContext, inputFileName, null, null) != 0)
{
Console.WriteLine("无法打开输入文件");
return;
}
// 查找视频流
int videoStreamIndex = -1;
for (int i = 0; i < inputFormatContext->nb_streams; i++)
{
if (inputFormatContext->streams[i]->codecpar->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
{
videoStreamIndex = i;
break;
}
}
if (videoStreamIndex == -1)
{
Console.WriteLine("无法找到视频流");
return;
}
// 打开视频解码器
AVCodec* videoCodec = FFmpeg.avcodec_find_decoder(inputFormatContext->streams[videoStreamIndex]->codecpar->codec_id);
if (videoCodec == null)
{
Console.WriteLine("无法找到视频解码器");
return;
}
AVCodecContext* videoCodecContext = FFmpeg.avcodec_alloc_context3(videoCodec);
if (FFmpeg.avcodec_parameters_to_context(videoCodecContext, inputFormatContext->streams[videoStreamIndex]->codecpar) < 0)
{
Console.WriteLine("无法初始化视频解码器上下文");
return;
}
if (FFmpeg.avcodec_open2(videoCodecContext, videoCodec, null) < 0)
{
Console.WriteLine("无法打开视频解码器");
return;
}
// 查找关键帧
AVPacket packet = new AVPacket();
AVFrame* frame = FFmpeg.av_frame_alloc();
int gotPicture = 0;
while (FFmpeg.av_read_frame(inputFormatContext, &packet) >= 0)
{
if (packet.stream_index == videoStreamIndex)
{
if (FFmpeg.avcodec_decode_video2(videoCodecContext, frame, &gotPicture, &packet) < 0)
{
Console.WriteLine("无法解码视频帧");
return;
}
if (gotPicture != 0 && (frame->key_frame != 0 || frame->pict_type == AVPictureType.AV_PICTURE_TYPE_I))
{
break;
}
}
FFmpeg.av_packet_unref(&packet);
}
// 将yuv序列转换为rgb
SwsContext* swsContext = FFmpeg.sws_getContext(videoCodecContext->width, videoCodecContext->height, videoCodecContext->pix_fmt,
videoCodecContext->width, videoCodecContext->height, AVPixelFormat.AV_PIX_FMT_RGB24, 0, null, null, null);
AVFrame* rgbFrame = FFmpeg.av_frame_alloc();
byte_ptrArray4 rgbData = new byte_ptrArray4();
int rgbDataSize = FFmpeg.av_image_alloc(rgbData, null, videoCodecContext->width, videoCodecContext->height, AVPixelFormat.AV_PIX_FMT_RGB24, 1);
FFmpeg.sws_scale(swsContext, frame->data, frame->linesize, 0, videoCodecContext->height, rgbData, rgbFrame->linesize);
// 将rgb数据存储为bmp位图
Bitmap bmp = new Bitmap(videoCodecContext->width, videoCodecContext->height, videoCodecContext->width * 3, PixelFormat.Format24bppRgb, new IntPtr(rgbData[0]));
bmp.Save("output.bmp", ImageFormat.Bmp);
// 释放资源
FFmpeg.avformat_close_input(&inputFormatContext);
FFmpeg.avcodec_free_context(&videoCodecContext);
FFmpeg.av_frame_free(&frame);
FFmpeg.sws_freeContext(swsContext);
FFmpeg.av_frame_free(&rgbFrame);
FFmpeg.av_freep(&rgbData[0]);
}
}
public unsafe static class FFmpeg
{
private const string DllName = "ffmpeg.dll";
[DllImport(DllName)]
public static extern void av_register_all();
[DllImport(DllName)]
public static extern void avcodec_register_all();
[DllImport(DllName)]
public static extern int avformat_open_input(AVFormatContext** ps, string url, AVInputFormat* fmt, AVDictionary** options);
[DllImport(DllName)]
public static extern int avcodec_decode_video2(AVCodecContext* avctx, AVFrame* picture, int* got_picture_ptr, AVPacket* avpkt);
[DllImport(DllName)]
public static extern AVCodec* avcodec_find_decoder(AVCodecID id);
[DllImport(DllName)]
public static extern AVCodecContext* avcodec_alloc_context3(AVCodec* codec);
[DllImport(DllName)]
public static extern int avcodec_parameters_to_context(AVCodecContext* codec, AVCodecParameters* par);
[DllImport(DllName)]
public static extern int avcodec_open2(AVCodecContext* avctx, AVCodec* codec, AVDictionary** options);
[DllImport(DllName)]
public static extern int av_read_frame(AVFormatContext* s, AVPacket* pkt);
[DllImport(DllName)]
public static extern void av_packet_unref(AVPacket* pkt);
[DllImport(DllName)]
public static extern AVFrame* av_frame_alloc();
[DllImport(DllName)]
public static extern SwsContext* sws_getContext(int srcW, int srcH, AVPixelFormat srcFormat,
int dstW, int dstH, AVPixelFormat dstFormat, int flags, SwsFilter* srcFilter, SwsFilter* dstFilter, double* param);
[DllImport(DllName)]
public static extern int av_image_alloc(byte_ptrArray4 pointers, int_array4 linesizes, int w, int h, AVPixelFormat pix_fmt, int align);
[DllImport(DllName)]
public static extern void sws_scale(SwsContext* c, byte_ptrArray4 srcSlice, int_array4 srcStride,
int srcSliceY, int srcSliceH, byte_ptrArray4 dst, int_array4 dstStride);
[DllImport(DllName)]
public static extern void sws_freeContext(SwsContext* swsContext);
[DllImport(DllName)]
public static extern void av_frame_free(AVFrame** frame);
[DllImport(DllName)]
public static extern void avcodec_free_context(AVCodecContext** avctx);
[DllImport(DllName)]
public static extern void avformat_close_input(AVFormatContext** s);
[DllImport(DllName)]
public static extern void av_freep(void* ptr);
}
public enum AVMediaType
{
AVMEDIA_TYPE_UNKNOWN = -1,
AVMEDIA_TYPE_VIDEO,
AVMEDIA_TYPE_AUDIO,
AVMEDIA_TYPE_DATA,
AVMEDIA_TYPE_SUBTITLE,
AVMEDIA_TYPE_ATTACHMENT,
AVMEDIA_TYPE_NB
}
public enum AVCodecID
{
AV_CODEC_ID_NONE,
/* video codecs */
AV_CODEC_ID_MPEG1VIDEO,
AV_CODEC_ID_MPEG2VIDEO, ///< preferred ID for MPEG-1/2 video decoding
AV_CODEC_ID_H261,
AV_CODEC_ID_H263,
AV_CODEC_ID_RV10,
AV_CODEC_ID_RV20,
AV_CODEC_ID_MJPEG,
AV_CODEC_ID_MJPEGB,
AV_CODEC_ID_LJPEG,
AV_CODEC_ID_SP5X,
AV_CODEC_ID_JPEGLS,
AV_CODEC_ID_MPEG4,
AV_CODEC_ID_RAWVIDEO,
AV_CODEC_ID_MSMPEG4V1,
AV_CODEC_ID_MSMPEG4V2,
AV_CODEC_ID_MSMPEG4V3,
AV_CODEC_ID_WMV1,
AV_CODEC_ID_WMV2,
AV_CODEC_ID_H263P,
AV_CODEC_ID_H263I,
AV_CODEC_ID_FLV1,
AV_CODEC_ID_SVQ1,
AV_CODEC_ID_SVQ3,
AV_CODEC_ID_DVVIDEO,
AV_CODEC_ID_HUFFYUV,
AV_CODEC_ID_CYUV,
AV_CODEC_ID_H264,
AV_CODEC_ID_INDEO3,
AV_CODEC_ID_VP3,
AV_CODEC_ID_THEORA,
AV_CODEC_ID_ASV1,
AV_CODEC_ID_ASV2,
AV_CODEC_ID_FFV1,
AV_CODEC_ID_4XM,
AV_CODEC_ID_VCR1,
AV_CODEC_ID_CLJR,
AV_CODEC_ID_MDEC,
AV_CODEC_ID_ROQ,
AV_CODEC_ID_INTERPLAY_VIDEO,
AV_CODEC_ID_XAN_WC3,
AV_CODEC_ID_XAN_WC4,
AV_CODEC_ID_RPZA,
AV_CODEC_ID_CINEPAK,
AV_CODEC_ID_WS_VQA,
AV_CODEC_ID_MSRLE,
AV_CODEC_ID_MSVIDEO1,
AV_CODEC_ID_IDCIN,
AV_CODEC_ID_8BPS,
AV_CODEC_ID_SMC,
AV_CODEC_ID_FLIC,
AV_CODEC_ID_TRUEMOTION1,
AV_CODEC_ID_VMDVIDEO,
AV_CODEC_ID_MSZH,
AV_CODEC_ID_ZLIB,
AV_CODEC_ID_QTRLE,
AV_CODEC_ID_TSCC,
AV_CODEC_ID_ULTI,
AV_CODEC_ID_QDRAW,
AV_CODEC_ID_VIXL,
AV_CODEC_ID_QPEG,
AV_CODEC_ID_PNG,
AV_CODEC_ID_PPM,
AV_CODEC_ID_PBM,
AV_CODEC_ID_PGM,
AV_CODEC_ID_PGMYUV,
AV_CODEC_ID_PAM,
AV_CODEC_ID_FFVHUFF,
AV_CODEC_ID_RV30,
AV_CODEC_ID_RV40,
AV_CODEC_ID_VC1,
AV_CODEC_ID_WMV3,
AV_CODEC_ID_LOCO,
AV_CODEC_ID_WNV1,
AV_CODEC_ID_AASC,
AV_CODEC_ID_INDEO2,
AV_CODEC_ID_FRAPS,
AV_CODEC_ID_TRUEMOTION2,
AV_CODEC_ID_BMP,
AV_CODEC_ID_CSCD,
AV_CODEC_ID_MMVIDEO,
AV_CODEC_ID_ZMBV,
AV_CODEC_ID_AVS,
AV_CODEC_ID_SMACKVIDEO,
AV_CODEC_ID_NUV,
AV_CODEC_ID_KMVC,
AV_CODEC_ID_FLASHSV,
AV_CODEC_ID_CAVS,
AV_CODEC_ID_JPEG2000,
AV_CODEC_ID_VMNC,
AV_CODEC_ID_VP5,
AV_CODEC_ID_VP6,
AV_CODEC_ID_VP6F,
AV_CODEC_ID_TARGA,
AV_CODEC_ID_DSICINVIDEO,
AV_CODEC_ID_TIERTEXSEQVIDEO,
AV_CODEC_ID_TIFF,
AV_CODEC_ID_GIF,
AV_CODEC_ID_DXA,
AV_CODEC_ID_DNXHD,
AV_CODEC_ID_THP,
AV_CODEC_ID_SGI,
AV_CODEC_ID_C93,
AV_CODEC_ID_BETHSOFTVID,
AV_CODEC_ID_PTX,
AV_CODEC_ID_TXD,
AV_CODEC_ID_VP6A,
AV_CODEC_ID_AMV,
AV_CODEC_ID_VB,
AV_CODEC_ID_PCX,
AV_CODEC_ID_SUNRAST,
AV_CODEC_ID_INDEO4,
AV_CODEC_ID_INDEO5,
AV_CODEC_ID_MIMIC,
AV_CODEC_ID_RL2,
AV_CODEC_ID_ESCAPE124,
AV_CODEC_ID_DIRAC,
AV_CODEC_ID_BFI,
AV_CODEC_ID_CMV,
AV_CODEC_ID_MOTIONPIXELS,
AV_CODEC_ID_TGV,
AV_CODEC_ID_TGQ,
AV_CODEC_ID_TQI,
AV_CODEC_ID_AURA,
AV_CODEC_ID_AURA2,
AV_CODEC_ID_V210X,
AV_CODEC_ID_TMV,
AV_CODEC_ID_V210,
AV_CODEC_ID_DPX,
AV_CODEC_ID_MAD,
AV_CODEC_ID_FRWU,
AV_CODEC_ID_FLASHSV2,
AV_CODEC_ID_CDGRAPHICS,
AV_CODEC_ID_R210,
AV_CODEC_ID_ANM,
AV_CODEC_ID_BINKVIDEO,
AV_CODEC_ID_IFF_ILBM,
AV_CODEC_ID_IFF_BYTERUN1,
AV_CODEC_ID_KGV1,
AV_CODEC_ID_YOP,
AV_CODEC_ID_VP8,
AV_CODEC_ID_PICTOR,
AV_CODEC_ID_ANSI,
AV_CODEC_ID_A64_MULTI,
AV_CODEC_ID_A64_MULTI5,
AV_CODEC_ID_R10K,
AV_CODEC_ID_MXPEG,
AV_CODEC_ID_LAGARITH,
AV_CODEC_ID_PRORES,
AV_CODEC_ID_JV,
AV_CODEC_ID_DFA,
AV_CODEC_ID_WMV3IMAGE,
AV_CODEC_ID_VC1IMAGE,
AV_CODEC_ID_UTVIDEO,
AV_CODEC_ID_BMV_VIDEO,
AV_CODEC_ID_VBLE,
AV_CODEC_ID_DXTORY,
AV_CODEC_ID_V410,
AV_CODEC_ID_XWD,
AV_CODEC_ID_CDXL,
AV_CODEC_ID_XBM,
AV_CODEC_ID_ZEROCODEC,
C# 大地坐标系 转平面坐标系
以下是C#中大地坐标系转平面坐标系的代码示例:
```csharp
using System;
namespace CoordinateConversion
{
class Program
{
static void Main(string[] args)
{
double a = 6378137; // 长半轴
double b = 6356752.3142; // 短半轴
double f = (a - b) / a; // 扁率
double e = Math.Sqrt(2 * f - f * f); // 第一偏心率
double e2 = Math.Sqrt(f * (2 - f)) / (1 - f); // 第二偏心率
double L = 116.404; // 经度
double B = 39.915; // 纬度
double L0 = 115; // 中央经线
double k0 = 1; // 比例因子
double X, Y;
double N = a / Math.Sqrt(1 - e * e * Math.Sin(B * Math.PI / 180) * Math.Sin(B * Math.PI / 180)); // 卯酉圈曲率半径
double T = Math.Tan(B * Math.PI / 180) * Math.Tan(B * Math.PI / 180);
double C = e2 * Math.Cos(B * Math.PI / 180) * Math.Cos(B * Math.PI / 180);
double A = (L - L0) * Math.PI / 180 * Math.Cos(B * Math.PI / 180);
double M = a * ((1 - e * e / 4 - 3 * e * e * e * e / 64 - 5 * e * e * e * e * e * e / 256) * B * Math.PI / 180
- (3 * e * e / 8 + 3 * e * e * e * e / 32 + 45 * e * e * e * e * e * e / 1024) * Math.Sin(2 * B * Math.PI / 180)
+ (15 * e * e * e / 256 + 45 * e * e * e * e * e / 1024) * Math.Sin(4 * B * Math.PI / 180)
- (35 * e * e * e * e / 3072) * Math.Sin(6 * B * Math.PI / 180));
X = k0 * N * (A + (1 - T + C) * A * A * A / 6 + (5 - 18 * T + T * T + 72 * C - 58 * e2) * A * A * A * A * A / 120) + 500000;
Y = k0 * (M + N * Math.Tan(B * Math.PI / 180) * (A * A / 2 + (5 - T + 9 * C + 4 * C * C) * A * A * A * A / 24 + (61 - 58 * T + T * T + 600 * C - 330 * e2) * A * A * A * A * A * A / 720));
Console.WriteLine("X坐标为:" + X);
Console.WriteLine("Y坐标为:" + Y);
}
}
}
```
以上代码中,我们首先定义了长半轴a、短半轴b、扁率f、第一偏心率e、第二偏心率e2等参数,然后输入经度L、纬度B、中央经线L0、比例因子k0等参数,最后根据公式计算出平面坐标系的X、Y坐标。