bogen pcm

PCM Definition PCM Chinese called pulse code modulation, composed of. rivers proposed in 1937 that this concept laid the foundation for digital communication. In 1960s, it began to be applied to the local telephone network to expand the capacity, so that the transmission capacity of most existing audio cable core lines was increased by 24 ~ 48 times. By the middle and end of 1970s, various countries have s

Record PCM lock information in GRD It is located in the SGA of each instance However, each instance only contains part of GRD, And the GRD of all instances is a complete GRD. PCM lock has three main attributes: Mode, Role, and PI. ① Mode -- S -- X -- NULL For S and X lock modes, we will not repeat them here NULL indicates that the corresponding memory space can be reused. Before being reused, the instance c

Using System; Using System.IO; Using System.Text; Using System.Windows.Forms; Using System.Runtime.InteropServices; namespace TRAIN.WAV2PCM {public partial class Frmmain:form {/// There is nothing to do today, write a wav "= =" PCM file conversion program. Let's announce that we learn together. The PCM file is not played and is not known to be successful. only when studying.

Another product of the company, when monitoring CTI, the recording format is PCM.To play in IE, You need to convert it into a standard WAV. previously, I used a com library for conversion. Now I can't use that library for various reasons (64-bit support is not good), So I implemented it in Java. The basic code is as follows.In fact, WAV is only a PCM file with the relevant file header and description information, not complicated. This program referenc

Document directory Notes: General discussion of riff files: References: The wave file format is a subset of Microsoft's Riff specification for the storage of multimedia files. A riff file starts out with a file header followed by a sequence of data chunks. A wave file is often just a riff file with a single "wave" chunk which consists of two sub-Chunks -- a "FMT" chunk specifying the data format and a "data" chunk ining the actual sample data. call this form the "canonical form ". who kno

Another product of the company, when monitoring CTI, the format of recording is PCM.In order to be able to play in IE, you need to convert to a standard WAV. Used to be a COM library to do the conversion, now for a variety of reasons can not use the library (64-bit support is not good, etc.), the implementation of a java. The basic code is as follows.In fact, WAV is only PCM file plus related file headers and descriptive information, not complicated.

This article is similar to the principle of using WINDOWSAPI to obtain audio recordings, and no longer details the parameters of functions and structures1. Waveoutgetnumdevs2. Waveoutgetdevcaps3. Waveoutopencallback functionvoid CALLBACK

Pcm2mp3.c #include #include #include #define INBUFSIZE 4096 #define MP3BUFSIZE (int ) (1.25 * inbufsize) + 7200 int encode (char* inpath, char* outpath) {int status = 0; Lame_global_flags* GFP; int Ret_code; File* INFP; File* OUTFP; short*

100644--- a/pcm.c+++ b/pcm.c@@ -691,7 +691,7 @@ struct pcm *pcm_open(unsigned int card, unsigned int device, memset(sparams, 0, sizeof(sparams));- sparams.tstamp_mode = SNDRV_PCM_TSTAMP_ENABLE;+ sparams.tstamp_mode = SNDRV_PCM_TSTAMP_NONE; sparams.period_step = 1; if (!config->start_threshold) { If the specific parameters are incorrect or inappropriate, the Android driver engineer needs to check the hardware design and chip manua

-------Sound Driver----------------------------------HardwareAt this point, the application will invoke the interface provided by the Esd,pulseaudio and other mixer. For ESD, a lot of program support, such as MPlayer. For PulseAudio, there are corresponding patch.Alsa itself also offers mixed-tone plugin,dmix.App1 APP2---------------Alsa-lib (dmix) User space-------------------------------------Alsa Kernel Space-------Sound Driver----------------------------------HardwareThis schema and schema 1

sound card documentation, it may be because the driver does not support all functions. ALSA cards and sound card hardware correspond one by one. ALSA cards stores the list of devices on each card. A card can be represented by an ID (string) or a number starting from 0. Most ALSA hardware accesses occur at the device level. You can enumerate the devices of each card from 0. Different devices can be opened and used independently. Typically, sound cards and devices are sufficient to determine wher

. The main focus is on PCM interface programming, including examples of programs you can automate.The reason you're using alsa may be because it's new, but it's not the only sound API available. Alsa is a good choice if you want to perform low-level sound operations to maximize control of sound and maximize performance, or if you use features that are not available in other sound APIs. If you have already written an audio program, you may want to add

Introduction and comparison of common audio protocols for conference TV white PaperFirst, the digital audio principle: The sound is actually a kind of energy wave, therefore also has the frequency and the amplitude characteristic, the frequency corresponds to the time axis, the amplitude corresponds to the level axis. Usually the ear can be heard in the frequency of 20Hz to 20KHz of sound waves known as audible, less than 20Hz to become infrasound, higher than 20KHz for ultrasound, multimedia te

(reprint) Common Audio Protocol IntroductionIntroduction and comparison of common audio protocols for conference TV white PaperFirst, the digital audio principle: The sound is actually a kind of energy wave, therefore also has the frequency and the amplitude characteristic, the frequency corresponds to the time axis, the amplitude corresponds to the level axis. Usually the ear can be heard in the frequency of 20Hz to 20KHz of sound waves known as audible, less than 20Hz to become infrasound, hig

file or directoryE/alsalib (1767): external/ALSA-lib/src/control. C: 902 :( snd_ctl_open_noupdate) invalid CTL androidoutW/audiohardwarealsa (1767): Unable to attach mixer to device androidin: no such file or directoryE/alsalib (1767): external/ALSA-lib/src/control. C: 902 :( snd_ctl_open_noupdate) invalid CTL androidinE/alsalib (1767): external/ALSA-lib/src/PCM. C: 2210 :( snd_pcm_open_noupdate) unknown PCM