possible uninitialised memory in lpc_to_lsp()

[DaveBerkeley]

I built the codec and ran under valgrind on a linux pc. I see occasional uninitialised memory errors in lpc_to_lsp()

If I zero the freq[i] data at the start of the loop this warning goes away, but I don't know if this also breaks the encoding. The uninitialised data could be copied from somewhere else : the error occurs at the "freq[i] = acosf(freq[i]);" stage.

diff --git a/src/lsp.c b/src/lsp.c
index aa7bac3..fcb33e5 100644
--- a/src/lsp.c
+++ b/src/lsp.c
@@ -184,6 +184,7 @@ int lpc_to_lsp(float *a, int order, float freq, int nb, float delta)
xl = 1.0; / start at point xl = 1 */

for (j = 0; j < order; j++) {
+// freq[j] = 0;
if (j % 2) /* determines whether P' or Q' is eval. */
pt = qx;
else

[drowe67]

hi @DaveBerkeley - can you please provide the steps to reproduce the issue consistently using the codec2 command line tools?

[DaveBerkeley]

I'm using a generated sine wave as an input file. My test program has a lot of extra code in it, so it is hard to simplify the example. I'm reading a stereo WAV file in my code.

When I convert this to a RAW file using SOX it runs without error using the CLI tools. However, if I use the WAV file as if it was RAW then I get the error. I know this is less than ideal, and not a real audio file, but it does trigger the issue.

The python code I use to generate the WAV file is :

#!/bin/env python

import math
import struct
import wave

name = "sine.wav"

f = wave.open(name, "wb")

f.setnchannels(2)
f.setsampwidth(2)
f.setframerate(48000)

gain = 0x4000

for i in range(10000000):
    angle = i * 0.1
    s = math.sin(angle) * gain
    sample = int(s)

    # Little endian. of course it is.
    b = struct.pack("<hh", sample, sample)
    f.writeframes(b)

f.close()

So running :

valgrind demo/c2demo sine.wav /tmp/o.raw

causes the error :

==63686== at 0x4BFB365: acosf (w_acosf_compat.c:30)
==63686== by 0x487E9CE: lpc_to_lsp (lsp.c:240)
==63686== by 0x488BD70: speech_to_uq_lsps (quantise.c:686)
==63686== by 0x48715BE: codec2_encode_1300 (codec2.c:1115)
==63686== by 0x109335: main (c2demo.c:67)

I hope this is useful. I realise that the input is not exactly speech.