Link / use external library in QtCreator - c++

Question

With mingw's Msys tool I've successfully build the opus-codec from source 1.1.tar.gz. The build produced some files, amongst which are libopus.a and libopus-0.dll. Now I want to try the trivial-example.c in QtCreator. I added the lib to my .pro-file and included opus.h in my main file. The compiler complains that it can't find the headers that are included in opus.h Shouldn't these be included within the lib? How do I need to setup my application to run the "trivial-example"?
My folder structure is:
main.cpp
opus_lib_test.pro
opus_lib_test.pro.user
include [folder]
opus.h (from the source include folder)
libs [folder]
libopus.a
libopus-0.dll
My .pro-file looks like
QT += core
QT -= gui
TARGET = opus_lib_test
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app
INCLUDEPATH += $$PWD/include
LIBS += -L"C:/Qt/Qt5.2.1/Tools/QtCreator/bin/opus_lib_test/libs/" -llibopus
SOURCES += main.cpp
HEADERS += include/opus.h
and my main.cpp is here:
//#include <QCoreApplication>
#include "opus.h"
int main(int argc, char *argv[])
{
// QCoreApplication a(argc, argv);
// return a.exec();
// ----------------------------- trivial_example.c
char *inFile;
FILE *fin;
char *outFile;
FILE *fout;
opus_int16 in[FRAME_SIZE*CHANNELS];
opus_int16 out[MAX_FRAME_SIZE*CHANNELS];
unsigned char cbits[MAX_PACKET_SIZE];
int nbBytes;
/*Holds the state of the encoder and decoder */
OpusEncoder *encoder;
OpusDecoder *decoder;
int err;
if (argc != 3)
{
fprintf(stderr, "usage: trivial_example input.pcm output.pcm\n");
fprintf(stderr, "input and output are 16-bit little-endian raw files\n");
return EXIT_FAILURE;
}
/*Create a new encoder state */
encoder = opus_encoder_create(SAMPLE_RATE, CHANNELS, APPLICATION, &err);
if (err<0)
{
fprintf(stderr, "failed to create an encoder: %s\n", opus_strerror(err));
return EXIT_FAILURE;
}
/* Set the desired bit-rate. You can also set other parameters if needed.
The Opus library is designed to have good defaults, so only set
parameters you know you need. Doing otherwise is likely to result
in worse quality, but better. */
err = opus_encoder_ctl(encoder, OPUS_SET_BITRATE(BITRATE));
if (err<0)
{
fprintf(stderr, "failed to set bitrate: %s\n", opus_strerror(err));
return EXIT_FAILURE;
}
inFile = argv[1];
fin = fopen(inFile, "r");
if (fin==NULL)
{
fprintf(stderr, "failed to open file: %s\n", strerror(errno));
return EXIT_FAILURE;
}
/* Create a new decoder state. */
decoder = opus_decoder_create(SAMPLE_RATE, CHANNELS, &err);
if (err<0)
{
fprintf(stderr, "failed to create decoder: %s\n", opus_strerror(err));
return EXIT_FAILURE;
}
outFile = argv[2];
fout = fopen(outFile, "w");
if (fout==NULL)
{
fprintf(stderr, "failed to open file: %s\n", strerror(errno));
return EXIT_FAILURE;
}
while (1)
{
int i;
unsigned char pcm_bytes[MAX_FRAME_SIZE*CHANNELS*2];
int frame_size;
/* Read a 16 bits/sample audio frame. */
fread(pcm_bytes, sizeof(short)*CHANNELS, FRAME_SIZE, fin);
if (feof(fin))
break;
/* Convert from little-endian ordering. */
for (i=0;i<CHANNELS*FRAME_SIZE;i++)
in[i]=pcm_bytes[2*i+1]<<8|pcm_bytes[2*i];
/* Encode the frame. */
nbBytes = opus_encode(encoder, in, FRAME_SIZE, cbits, MAX_PACKET_SIZE);
if (nbBytes<0)
{
fprintf(stderr, "encode failed: %s\n", opus_strerror(nbBytes));
return EXIT_FAILURE;
}
/* Decode the data. In this example, frame_size will be constant because
the encoder is using a constant frame size. However, that may not
be the case for all encoders, so the decoder must always check
the frame size returned. */
frame_size = opus_decode(decoder, cbits, nbBytes, out, MAX_FRAME_SIZE, 0);
if (frame_size<0)
{
fprintf(stderr, "decoder failed: %s\n", opus_strerror(err));
return EXIT_FAILURE;
}
/* Convert to little-endian ordering. */
for(i=0;i<CHANNELS*frame_size;i++)
{
pcm_bytes[2*i]=out[i]&0xFF;
pcm_bytes[2*i+1]=(out[i]>>8)&0xFF;
}
/* Write the decoded audio to file. */
fwrite(pcm_bytes, sizeof(short), frame_size*CHANNELS, fout);
}
/*Destroy the encoder state*/
opus_encoder_destroy(encoder);
opus_decoder_destroy(decoder);
fclose(fin);
fclose(fout);
return EXIT_SUCCESS;
}

Answer 1

The header files referenced in opus.h:
#include "opus_types.h"
#include "opus_defines.h"
They are both from source include folder, the same as opus.h. I think your problem will be solved if you copy all .h files (5 including opus.h) from source include folder into include [folder] in your folder structure.
Header files are not included in lib, only cpp files are included. You need to specify header files separately.