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Fix reading wav samples

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Wave samples are stored as a 16 bit little endian signed integer, and
then converted to floats by dividing by 32768. I was reading in numbers
as unsigned.
This commit is contained in:
Brandon Skari 2017-06-15 01:29:48 -06:00
parent b7826adc22
commit cc0d5e2baf
1 changed files with 5 additions and 7 deletions
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12
src/python/_rpitxmodule.c
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@ -5,7 +5,6 @@
#include <unistd.h>
#include "../RpiTx.h"
#include "../RpiGpio.h"
#define COUNT_OF(x) ((sizeof(x)/sizeof(0[x])) / ((size_t)(!(sizeof(x) % sizeof(0[x])))))
@ -28,10 +27,10 @@ typedef struct {
uint32_t waitForThisSample;
} samplerf_t;
static size_t read_float(int streamFileNo, float* wavBuffer, const size_t count);
static size_t readFloat(int streamFileNo, float* wavBuffer, const size_t count);
/**
* Formats a chunk of an array of a mono 48k wav at a time and outputs IQ
* Formats a chunk of an array of a mono 48k wav at a time and outputs RF
* formatted array for broadcast.
*/
static ssize_t formatRfWrapper(void* const outBuffer, const size_t count) {
@ -64,7 +63,7 @@ static ssize_t formatRfWrapper(void* const outBuffer, const size_t count) {
assert(wavOffset <= wavFilled);
if (wavOffset == wavFilled) {
wavFilled = read_float(streamFileNo, wavBuffer, COUNT_OF(wavBuffer));
wavFilled = readFloat(streamFileNo, wavBuffer, COUNT_OF(wavBuffer));
if (wavFilled == 0) {
// End of file
return numBytesWritten;
@ -74,9 +73,9 @@ static ssize_t formatRfWrapper(void* const outBuffer, const size_t count) {
}
return numBytesWritten;
}
static size_t read_float(int streamFileNo, float* wavBuffer, const size_t count) {
static size_t readFloat(int streamFileNo, float* wavBuffer, const size_t count) {
// Samples are stored as 16 bit signed integers in range of -32768 to 32767
uint16_t sample;
int16_t sample;
int i;
for (i = 0; i < count; ++i) {
const int byteCount = read(streamFileNo, &sample, sizeof(sample));
@ -106,7 +105,6 @@ _rpitx_broadcast_fm(PyObject* self, PyObject* args) {
if (!PyArg_ParseTuple(args, "if", &streamFileNo, &frequency)) {
RETURN_ERROR("Invalid arguments");
return NULL;
}
union {