EAB 3043 DIGITAL SIGNAL PROCESSING
DIGITAL SIGNAL PROCESSING PROJECT
RECORDED VOICE AND VARIOUS PLAYBACK
MOHAMED ME MEERA HU HUSSIEN IEN B. B. JA JAWHAR SA SATHIK
15093 5093
AZMEER B. ABDUL MAJID
15136
OBJECTIVE
1. This project record audio signal from the computer/audio cd , then plays it back with various playback such as reverse, delayed and fast forward conditions.
2. To apply these playbacks in our daily life for audio/music purpose.
INTRODUCTION
In this new technology era, speech recognition has become popular research topic. Many Researches had been done to improvise this technology. The application is not only limited for calls, however it can be used to simply human daily chaos. As an example, voice recorded is embedded in the security system and in mobile application. Moreover, dvd player, ipod and computer a lso use these features to simplify the audio function system in our daily life. The main idea of this project is to record the audio file from the computer or audio CD by recognizing the audio data using DSK6713 board. The buffer is continually overwritten with
new values until recording is halted manually. Voice activated recording is used with Audio file input and will start recording when the switch for record is press. For the output of this project, there will be three outputs that is Reverse, Slow and Fast forward playbacks. These outputs are produce with the concept of frequency sampling and inverse that satisfy the formula Fs>2Fo to avoid aliasing effect.
REVERSE PLAYBACK
INPUT
SLOW PLAYBACK
OUTPUT
FAST FORWARD PLAYBACK
FIGURE 1: Concept of this project on how the input being manipulated to produce three different types of
output (Reverse, Slow and Fasforward) condition. METHOD
For this project, Matlab software is used for testing purpose. However, the real programme is applied in DSK kit using C language. In analyzing the input signal, time shifting, frequency response and quantization are applied to produce the desired outcome. Moreover, the Frequency sampling need to satisfy the formula Fs>2Fo to avoid aliasing effect. Below is the Matlab code and flow chart.
Matlab code
record_mic.m recObj = audiorecorder(44100, 16, 1); get(recObj) % Record your voice for seconds. recObj = audiorecorder; disp('Start speaking.') recordblocking(recObj, sec); disp('End of Recording.'); % Play back the recording. play(recObj); % Store data in double-precision array. myRecording = getaudiodata(recObj); wavLink = 'C:\record_chunk.wav'; wavwrite(myRecording,wavLink); % Plot the waveform. plot(myRecording); title('Record Sound Waveform (RAW)'); y = wavread('C:\Users\Public\Music\Sample Music\Austin_Powers_danger.wav'); %normal playback Fs=8192; sound(y); %fipped playback y2=flipud(y); soundsc(y2); wavwrite(y2,'C:\Users\Public\Music\Sample Music\Austin_Powers_danger_reverse.wav'); %delayed playback y1 = wavread('C:\Users\Public\Music\Sample Music\Austin_Powers_danger.wav'); Fs = 5000;
soundsc(y1,Fs); wavwrite(y1,Fs,'C:\Users\Public\Music\Sample Music\Austin_Powers_danger_slow.wav'); %fast playback y3 = wavread('C:\Users\Public\Music\Sample Music\Austin_Powers_danger.wav'); Fs = 19000; soundsc(y3,Fs); wavwrite(y3,Fs,'C:\Users\Public\Music\Sample Music\Austin_Powers_danger_fast.wav');
Flowchart for Matlab
start
Set the sampling frequency of audio input
Start Recording
Record signal until time = 0sec
Stop Recording 'End of
Playback the record audio with three types of outputs (Reverse,slow,fastforward)
end
DSK6713
For the DSK board, the value for frequency sample is set to 8Khz and the buffer length for recorded audio is set to 2400000(300secs) which equal to about 1 song for a playback. For this project we use polling technique to determine the three outputs(Reverse,Fastforward and slow playbacks). The switches on the DSK board were assign to SW3=Recording SW2=Fasforwad/Slow SW1=Reverse SW0=Original audio. Moreover, LED function were included as the switch turn ‘0’ or ‘1’ to show the signal playback. Below is the source code for the project. Source code
//record.c record/play input using external memory
#include "dsk6713_aic23.h"
//codec support
Uint32 fs=DSK6713_AIC23_FREQ_8KHZ;
//set sampling rate
#define DSK6713_AIC23_INPUT_MIC 0x0015 #define DSK6713_AIC23_INPUT_LINE 0x0011 Uint16 inputsource=DSK6713_AIC23_INPUT_LINE; // select input #define N
2400000
//large buffer size 300 secs
long i,j; short buffer[N],delay; #pragma DATA_SECTION(buffer,".EXT_RAM") //buffer ->external memory short DIP_Mask = 20; short newMask = 0; void main() {
short recording = 0; short playing = 0; for (i=0 ; i
//any DIP SW value except 0-15
comm_poll(); while(1)
//init DSK, codec, McBSP //infinite loop
{ if(DSK6713_DIP_get(3) == 0)
//if SW#3 is pressed
{ for (i=0; i
//turn on LED#3
if (i2000) if (DSK6713_DIP_get(3) == 1) { j=i; //last buffer index recording = 0; DSK6713_LED_off(3); }
//LED#3 off when buffer full
} // while (recording == 1) } //if if(DSK6713_DIP_get(0)==0) //if SW#0 pressed { i=0; playing = 1; while (playing == 1) { DSK6713_LED_on(0);
//turn on LED#0
output_left_sample(buffer[i++]); //input data
if (i>=j) i=0; if (i>2000) if (DSK6713_DIP_get(0) == 1) { playing = 0; DSK6713_LED_off(0); }
//LED#3 off when buffer full
} // while (playing == 1) }
if(DSK6713_DIP_get(1)==0)
// if SW#1 pressed, play backward
{ i=j; playing = 1; while (playing == 1) { DSK6713_LED_on(1);
//turn on LED#1
output_left_sample(buffer[i--]);
//input data
if(i<=0) i=j; if (DSK6713_DIP_get(1) == 1) { playing = 0; DSK6713_LED_off(1); } }//while (playing == 1) } /*
if(DSK6713_DIP_get(2)==0) { i=0;
// if SW#1 pressed, play fast forward
playing = 1; while (playing == 1) { DSK6713_LED_on(2);
//turn on LED#0
buffer[i++]=output_left_sample(buffer[i++]); output_left_sample(buffer[i++]);
//equation for fast forward s peed
//input
if (i>=j) i=0; if (i>2000) if (DSK6713_DIP_get(2) == 1) { playing = 0; DSK6713_LED_off(2); }
//LED#3 off when buffer full
} }*/
if(DSK6713_DIP_get(2)==0)
// if SW#1 pressed, play slow
{ i=0; playing = 1; delay = 0; while (playing == 1) { DSK6713_LED_on(2);
//turn on LED#0
delay= output_left_sample(buffer[i++]); output_left_sample(delay); if (i>=j) i=0; if (i>2000) if (DSK6713_DIP_get(2) == 1)
//input
//equation for slow playback
{ playing = 0; DSK6713_LED_off(2); }
//LED#3 off when buffer full
} }
} }
.
Flowchart for CCS
Start
Set the sampling frequency of audio input
Test switch 3 if press??
no
yes
Test switch 0 if press?? Yes
Record signal until time = 0sec
Playback the record audio with three types of outputs (Reverse,slow,fastforward)
end
Discussion
From the project, we manage to get 3 outputs that are original audio, reverse and fast forward playback using DSK6713 board. The frequency were set at 8KHz and the buffer length is 2400000(300secs) which equal to about for 1 song. All of the outputs have been test in Matlab and it works. After success in Matlab, we do the programming in Code Composer Studio to get the output using DSK6713 board using polling technique. As we tried using interrupt technique for this project , the switch function works fine but when we try to record the were no audio recorded. So we used the polling method instead. Four switches used for recording, original, reverse fast forward and slow playbacks. However for the slow playback the ouput that we determine have certain noise. This occurs because of the formula used are not suitable with the program/source code.
Conclusion
As what we learn in our lab for DSP, we manage to implement it in our project Voice Recorded and Various Playback. The project works fine in Matlab and DSK6713. This project can be implemented in our audio system to help human daily life. From the project done, we are capable of handling certain techniques in Matlab as well as CCS that helps to understand in depth about Digital Signal Processing.
