bogen pcm

The creation framework for PCM device has been written before, so let's look at how PCM device is created.A SND_PCM type of PCM device is created when the snd_pcm_new is called.struct SND_PCM {struct Snd_card *card;//pcm device says the sound card is mountedstruct List_head list;//A card may have multiple

Audio this aspect is very profound, I certainly can not speak what advanced things, at most also just some basic knowledge, first, we want to introduce Android he provided the recording class, in fact, he has two, one is Mediarecorder, There is another one that we are going to use today, what is the difference between them? Audiorecord I. Distinction Mediarecorder and Audiorecord can record audio, the difference is Mediarecorder recorded audio files are compressed, you need to set the encoder.

Summary of the online G711 codec, it has been to the Andorid system, through the JNI to G711 and PCM, because of the two formats do not have in-depth understanding, so if you want to understand them can Baidu, here is just to achieve such a function. G711.C contains encoding and decoding methods http://www.easydarwin.org/article/Streaming/38.html Reference Article//HTTPS://GITHUB.COM/EASYDARWIN/EASYAACENCODER/BL Ob/master/g711.cpp//http://www.oschina

The previous article recorded the RGB/YUV video pixel data processing method, this article continues the previous article the content, records the PCM audio sampling data processing method. The location of the audio sample data in the video player's decoding process is shown.This paper introduces several PCM audio sampling data processing functions as follows:Separating the left and right channels of the Pc

The principle of increasing or decreasing PCM audio data is primarily to multiply the sampled data by a number or divide by a number, but pay attention to overflow handling. Implementation of the following C language implementation #define OLD_FILE_PATH "FILE.PCM" #define Vol_file_path "VOL.PCM" int volume_adjust (short * in_buf, short * out_buf, FL Oat in_vol) {int i, TMP; In_vol[0] float = in_vol-98; if ( -98 In the above program

[TOC] Introduction A simple Save the PCM demo, note to save there for the two-channel processing, because the PCM pair of two channels is alternately stored code /* * A simple Save the PCM demo, note to save there for the two-channel processing, because the PCM pair of channels are alternately stored * Miu *MK (8214860

business type that require high service quality and stability. At the same time, these users are also in relatively developed areas, close to the DDN nodes already laid. So how can we effectively extend and expand the DDN Network range to meet the requirements of more users? PCM devices are a good solution.Chapter 2: PCM device is an effective solution for DDN Network ExtensionAs a traditional concept,

During voice communication, you often encounter situations where you need to convert audio signals of a certain format into audio signals of another format and mix two or more audio signals. For more information, see the information found on the Internet, I made an example. ProgramThis program can convert two 8-bit 8000 sample 1 channel pcm a-Law audio files into 16-bit 8000 sample 1 channel PCM line audio

I have previously written an audio-driven codec analysis. At that time, I ignored the most basic concepts. To understand something, you must first understand what it serves, and then better analyze its workflow. So here we mention:Codec: audio chip control, such as mute, turn on (off) ADC (DAC), set ADC (DAC) gain, and earphone mode detection.I2S: digital audio interface, used to transmit raw data of digital audio streams between the CPU and codec. When there is a playback or record operation, s

This document records the techniques used by directsound to play audio. Directsound is the most common Audio Playback Technology in windows. Currently, most audio playback applications use directsound. This article records an example of using directsound to play PCM. Note: A dear friend has reminded me that directsound is planned to be replaced by xaudio2. Later, I found that this was the case. Therefore, in the next update, consider adding xaudio2 to

Android audio and video goes deep into an AudioRecord recording to generate pcm into wav (with source code download), androidaudiorecord This project address is named AudioRecord recording (can be paused, convert pch to wav ).Https://github.com/979451341/Audio-and-video-learning-materialsHere is an official description1. AndioRecord Overview The main function of the AndioRecord class is to allow various JAVA applications to manage audio resources so t

on.ChannelconfigChannel settings: Android supports two-channel stereo and mono. Mono mono, stereo stereoAudioformatencoding format and sample size: The data collected is of course used PCM encoding (pulse code modulation encoding, PCM encoding. PCM converts a continuously varying analog signal to a digital encoding by sampling, quantization, and coding in three

Brief Introduction to PCM File Format PCM file: the analog audio signal is directly formed by Analog-to-analog conversion (A/D conversion ).Binary SequenceThe file does not have an additional file header and end mark. Windows convert can convert PCM audio files to Microsoft wav files.To digitize audio is actually to digitize sound. The most common method is to mo

PCM (pulse codemodulation----Pulse Code modulated recording). The so-called PCM recording is the sound and other analog signals into the symbolic pulse column, and then recorded. PCM signal is a digital signal composed of [1], [0] and other symbols, without any coding and compression processing. Compared with analog signal, it is not susceptible to the clutter an

Transferred from: http://blog.csdn.net/nogodoss/article/details/10399243 Http://blog.csdn.net/kindyb/archive/2005/10/13/503024.aspx First, overview: This paper describes how to convert from IMA-ADPCM file to PCM file by IMA-ADPCM compression and decompression algorithm. The main contents include: The internal structure of PCM and IMA-ADPCM wave files, IMA-ADPCM compression and decompression algorithm, and

1 Perl script On the Peking University Chinese forum, a netizen asked how to play the PCM data from the end. I used to encounter 8 K sampled PCM data at work. At that time, I was not clear about the wav file format. The Perl module has an audio: WAV module that can write wav files, a Perl script is written: use Audio::Wav;my $wav = new Audio::Wav;my $sample_rate = 8000;my $bits_sample = 16;my $details = {

This document records the Audio Playback Technology of SDL. The version used here is sdl2. In fact, SDL does not provide the video/audio playback function. It only encapsulates the underlying API for video/audio playback. On Windows, SDL encapsulates direct3d APIs for video playback and directsound APIs for audio playback. Because SDL is designed to simplify the development of video and audio playback, it is very easy to Use SDL to play video (YUV/RGB) and audio (