From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Sat, 28 Jan 2017 21:12:19 +0000 (+0000)
Subject: simple linear interpolator
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=03600d7b91438c5b0760f1896cf31083b5a79122;p=freetel-svn-tracking.git

simple linear interpolator

git-svn-id: https://svn.code.sf.net/p/freetel/code@3004 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/unittest/tlininterp.c b/codec2-dev/unittest/tlininterp.c
new file mode 100644
index 00000000..1c5b2905
--- /dev/null
+++ b/codec2-dev/unittest/tlininterp.c
@@ -0,0 +1,79 @@
+/*
+   tlininterp.c
+   David Rowe
+   Jan 2017
+
+   Linear interpolator, CPU effecient way of getting large oversample
+   ratios, if the input is already limited to a fraction of the
+   input sampling rate.
+
+   build: gcc tlininterp.c -o tlininterp -Wall -O2
+
+*/
+
+#include <assert.h>
+#include <getopt.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define N    10000                   /* processing buffer size */
+
+void display_help(void) {
+    fprintf(stderr, "\nusage: tlininterp inputRawFile OutputRawFile OverSampleRatio [-c]\n");
+    fprintf(stderr, "\nUse - for stdin/stdout\n\n");
+    fprintf(stderr, "-c complex (two channel) resampling\n\n");
+}
+
+int main(int argc, char *argv[]) {
+    FILE       *fin, *fout;
+    short       left, right, out;
+    float       oversample, t;
+
+    if (argc < 3) {
+	display_help();
+	exit(1);
+    }
+
+    if (strcmp(argv[1], "-") == 0) 
+        fin = stdin;
+    else
+        fin = fopen(argv[1], "rb");
+    assert(fin != NULL);
+
+    if (strcmp(argv[2], "-") == 0) 
+        fout = stdout;
+    else
+        fout = fopen(argv[2], "wb");
+    assert(fout != NULL);
+
+    oversample = atof(argv[3]);
+
+    int channels = 1;
+    int opt;
+    while ((opt = getopt(argc, argv, "c")) != -1) {
+        switch (opt) {
+        case 'c': channels = 2; break;
+        default:
+            display_help();
+            exit(1);
+        }
+    }
+
+    left = 0;
+    t = 0.0;
+    while(fread(&right, sizeof(short), 1, fin) == 1) {
+        while (t < 1.0) {
+            out = (1.0 - t)*left + t*right;
+            fwrite(&out, sizeof(short), 1, fout);
+            t += 1.0/oversample;
+        }
+        t -= 1.0;
+        left = right;
+    }
+
+    fclose(fout);
+    fclose(fin);
+
+    return 0;
+}