mirrors/alsa-lib
1
0
Fork 0
mirror of https://github.com/alsa-project/alsa-lib.git synced 2025-11-01 22:58:49 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Changed PCM intro

Browse source
This commit is contained in:
Jaroslav Kysela 2002-02-13 23:19:29 +00:00
parent 1bd2ac6dd4
commit d91e0649c9
1 changed files with 26 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

27
src/pcm/pcm.c
View file

@ -42,7 +42,32 @@
understanding it as general digital audio processing with volume samples
generated in continuous time periods.</P>
<P>Write some description about digital audio here.</P>
<P>The analog signal is recorded via analog to digital converters (ADC).
The digital value (de-facto a volume at a specific time) obtained
from ADC can be further processed. The following picture shows a perfect
sinus waveform:</P>
<BR>
\image html wave1.gif
<P>Next image shows digitized representation:</P>
<BR>
\image html wave2.gif
<P>As you may see, the quality of digital audio signal depends on the time
(recording rate) and voltage resolution (usually in an linear integer
representation with basic unit one bit).</P>
<P>The stored digital signal can be converted back to voltage (analog)
representation via digital to analog converters (DAC).</P>
<P>One digital value is called sample. More samples are collected to frames
(frame is terminology for ALSA) depending on count of converters used at one
specific time. One frame might contain one sample (when only one converter is
used - mono) or more samples (for example: stereo has signals from two converters
recorded at same time). Digital audio stream contains collection of frames
recorded at boundaries of continous time periods.</P>
\section pcm_general_overview General overview