fwrite | 易学教程

iphone利用AudioQueue播放wav(PCM码)

阅读更多关于 iphone利用AudioQueue播放wav(PCM码)

续上一篇 iphone利用AudioQueue播放音频文件(mp3,aac,caf,wav等）绝对原创，转载请注明出处： http://www.cnblogs.com/xuanyuanchen/admin/EditPosts.aspx?postid=2450169 1、ffmpeg解码音频流并且保存成wav文件。　这一步比较简单，只要熟悉ffmpeg解码音频的流程，将解码出的pcm码，保存到本地文件中，并实时统计解码的pcm的字节长度，最后解码完成之后再添加44字节的wav文件头。 save_audio.c View Code 1 #include <stdio.h> 2 #include "libavformat/avformat.h" 3 #include "libavcodec/avcodec.h" 4 #include "libavutil/avutil.h" 5 static void writeWavHeader(AVCodecContext *pCodecCtx,AVFormatContext *pFormatCtx,FILE *audioFile) { 6 int8_t *data; 7 int32_t long_temp; 8 int16_t short_temp; 9 int16_t BlockAlign; 10 int bits=16; 11 int32

fwrite() not working to write integer in binary file

阅读更多关于 fwrite() not working to write integer in binary file

问题 Can someone tell my why won't this function work? I just can't get it... void writeRegister(FILE *arq, Book *L){ //writes in actual file position char c = '|'; int sizeRegWrite = reglen(L); //reglen() returns the size of Book fwrite(&sizeRegWrite, sizeof(int), 1, arq); fwrite(L->TITLE, sizeof(char), strlen(L->TITLE), arq); fwrite(&c, sizeof(char), 1, arq); //writing delimiter fwrite(L->AUTHOR, sizeof(char), strlen(L->AUTHOR), arq); fwrite(&c, sizeof(char), 1, arq); //writing delimiter fwrite

How can i specify encode in fwrite() for export csv file R?

阅读更多关于 How can i specify encode in fwrite() for export csv file R?

问题 Since fwrite() cannot apply encoding argument , how can i export csv file in specific encode as fast as fwrite() ? ( fwrite() is the fastest function within my acknowledgement so far) fwrite(DT,"DT.csv",encoding = "UTF-8") Error in fwrite(DT, "DT.csv", encoding = "UTF-8") : unused argument (encoding = "UTF-8") 回答1: You should post a reproducible example, but I would guess you could do this by making sure the data in DT is in UTF-8 within R, then setting the encoding of each column to "unknown

用来获取豆瓣网上电影信息的简介

阅读更多关于用来获取豆瓣网上电影信息的简介

<?php //搜索链接 function search_link($moviename) { //构造url，其中max-results可根据需要更改 $urlString = 'http://api.douban.com/movie/subjects?q='.$moviename.'&start-index=1&max-results=1&alt=json'; //print_r($urlString); $urlString=mb_convert_encoding($urlString, "UTF-8", "GBK");//将Url转换为utf-8编码 $r = new HttpRequest($urlString,HttpRequest::METH_GET);//请求 $response = $r->send(); $result = $r->getResponseBody(); $obj = json_decode($result);//解析成json格式 if($entry = @$obj->{'entry'}){ //搜索链接并存在数组中返回 for($i = 0;$i<sizeof($entry);$i++){ $link=$entry[$i]->{'link'}; for($j = 0;$j<sizeof($link);$j++){ $arr = (array)

Security vulnerabilities in php fwrite?

阅读更多关于 Security vulnerabilities in php fwrite?

问题 I recently transitioned my companies website over to our in-house servers (Apache) from a hosting companies (IIS). The group that originally built the site did a piss poor job and the entire thing was a mess to migrate. While the move went fairly smoothly, looking at the error_log there are still some missing pages. Rather than having to continually grep through the error_log for "File does not exist" errors relating to this domain - we have about 15 or so we host on these servers - I was

多媒体文件格式（五）：PCM / WAV 格式

阅读更多关于多媒体文件格式（五）：PCM / WAV 格式

一、名词解析 PCM(Pulse Code Modulation)也被称为脉码编码调制，PCM中的声音数据没有被压缩，它是由模拟信号经过采样、量化、编码转换成的标准的数字音频数据。采样转换方式参考下图进行了解：音频采样包含以下几大要素： 1. 采样率采样率表示音频信号每秒的数字快照数。该速率决定了音频文件的频率范围。采样率越高，数字波形的形状越接近原始模拟波形。低采样率会限制可录制的频率范围，这可导致录音表现原始声音的效果不佳。根据奈奎斯特采样定理，为了重现给定频率，采样率必须至少是该频率的两倍。例如，一般CD唱片的采样率为每秒 44,100 个采样，因此可重现最高为 22,050 Hz 的频率，此频率刚好超过人类的听力极限 20,000 Hz。图中A是低采样率的音频信号，其效果已经将原始声波进行了扭曲，B则是完全重现原始声波的高采样率的音频信号。数字音频常用的采样率如下： 2. 位深度位深度决定动态范围。采样声波时，为每个采样指定最接近原始声波振幅的振幅值。较高的位深度可提供更多可能的振幅值，产生更大的动态范围、更低的噪声基准和更高的保真度。位深度越高，提供的动态范围越大。二、PCM 在上面的名词解析中我们应该对PCM有了一定的理解和认识，下面我们将对PCM做更多的讲解。 1. PCM音频数据存储方式如果是单声道的文件，采样数据按时间的先后顺序依次存入

Getting a segmentation fault while trying to write a struct instance to a file

阅读更多关于 Getting a segmentation fault while trying to write a struct instance to a file

问题 I am trying to write a struct to a file, but am getting a segmentation fault at run time: #include<stdio.h> //just a struct for purposes of demonstration struct my_struct{ int prop1; int prop2; }; //writes dummy struct to filename.dat void writeStruct(){ FILE *file_pointer; file_pointer = fopen("filename.dat","w"); //define and assign variables to a quick dummy struct struct my_struct *this_struct; this_struct->prop1=0; //seg faults here! this_struct->prop2=1; //write struct to file fwrite

《PHP和MySQL Web开发》学习之二--数据的存储与检索

阅读更多关于《PHP和MySQL Web开发》学习之二--数据的存储与检索

最近这段时间主要将时间和精力花在看《代码大全》和《Clean Code》上了，今晚操作了一下久违的PHP，现将第二章的主要内容摘要如下。书很久之前就看了，一直没有写笔记，突然发现很多语法已经有些生疏，看来学习一门新的语言还是要通过练习，练习再练习。当然，写笔记的过程也是一个记忆的过程，俗话说：好记心当不得烂笔头是也。存储数据有两种基本方法：保存到普通文件，或者保存到数据库中。 1.文件处理将数据写入文件的三个步骤：（1）打开这个文件，如果不存在则创建；（2）将数据写入文件；（3）关闭文件从文件中读取数据的三个步骤：（1）打开这个文件，如果文件不存在则正确的退出；（2）从文件中读取数据；（3）关闭文件。 2.打开文件 (1)使用fopen()来打开文件如要将一个顾客订单写入Bob订单文件，可以使用如下语句打开该文件： $fp = fopen("%DOCUMENT_ROOT/../orders/orders.txt", 'w'); 上面代码中，使用了内置变量$_SERVER['DOCUMENT_ROOT']，指向web服务器文档树的根。用".."表示文档根目录的父目录。在Unix系统中，根目录是/，在windows系统中，根目录是C:\。在Unix环境下，目录中的间隔符是正斜线（/）。windows平台下可以使用正斜线或者反斜线，如果使用反斜线，则需要使用转义字符

fwrite() succeeded after fclose()

阅读更多关于 fwrite() succeeded after fclose()

问题 I've encountered a strange behavior that is fwrite() succeeds after I close the stream with fclose() but the file is not overwritten as fflush() fails. My code is: int main(int argc, char* argv[]) { FILE* file = fopen("file.txt", "w"); if(!file) perror("Cannot open the file.\n"); char text[] = "1234567"; fclose(file); int count_of_written_objects = fwrite(text, sizeof(text),1, file); printf("Count of written objects into the file: %d \n", count_of_written_objects); if(count_of_written_objects

fwrite() succeeded after fclose()

阅读更多关于 fwrite() succeeded after fclose()

订阅 fwrite