opus - Dec 2016 - A potential error in opus-1.1.3

Hi, 


I downloaded the source code of opus-1.1.3.tar.gz, and statically analyzed the
code by a static analysis tool. Many potential false alarms are reported. I
checked manually and selected a potential error which is described as follow.
Could you please check it?


In file ‘src/opus_encoder.c’, function ‘opus_encode_native’, the piece of code
is:


…
Line 1802: if (frame_size == 2*st->Fs/25)  /* 80 ms -> 2x 40 ms */
Line 1803:   enc_frame_size = st->Fs/25;
Line 1804: if (frame_size == 3*st->Fs/25)  /* 120 ms -> 2x 60 ms */
Line 1805:   enc_frame_size = 3*st->Fs/50;
Line 1806: else                            /* 100 ms -> 5x 20 ms */
Line 1807:   enc_frame_size = st->Fs/50; 
…


In the above code, Line 1802 and 1803 may be not useful. Because the result of
variable ‘enc_frame_size’ is not read and used. After executing Line 1805 or
Line 1807, the value of ‘enc_frame_size’ is overwritten.


Looking forward to your reply.


Best,
Zhendong
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Hi Zhendong,

Thanks for reporting this. Turns out there was indeed a bug. Not dead
code, but a missing "else" in the chain. It's fixed in master now.

Cheers,

	Jean-Marc

On 05/12/16 08:14 AM, Zhendong Wu wrote:
> Hi, 
> 
> I downloaded the source code of opus-1.1.3.tar.gz, and statically
> analyzed the code by a static analysis tool. Many potential false alarms
> are reported. I checked manually and selected a potential error which is
> described as follow. Could you please check it?
> 
> In file ‘src/opus_encoder.c’, function ‘opus_encode_native’, the piece
> of code is:
> 
> …
> Line 1802: if (frame_size == 2*st->Fs/25)  /* 80 ms -> 2x 40 ms */
> Line 1803:   enc_frame_size = st->Fs/25;
> Line 1804: if (frame_size == 3*st->Fs/25)  /* 120 ms -> 2x 60 ms */
> Line 1805:   enc_frame_size = 3*st->Fs/50;
> Line 1806: else                            /* 100 ms -> 5x 20 ms */
> Line 1807:   enc_frame_size = st->Fs/50; 
> …
> 
> In the above code, Line 1802 and 1803 may be not useful. Because the
> result of variable ‘enc_frame_size’ is not read and used. After
> executing Line 1805 or Line 1807, the value of ‘enc_frame_size’ is
> overwritten. 
> 
> Looking forward to your reply.
> 
> Best,
> Zhendong
> 
> 
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>