[linux-audio-dev] libsndfile breakage

[Erik de Castro Lopo]

On Wed, 11 Feb 2004 21:32:03 +0000
james at dis-dot-dat.net wrote:

> Well, I've stopped the crashing.
> 
> It was my bad, but still a bit confusing.
> 
> Here's what I was doing
> 
> 
>        samples=info->frames*info->channels;
>        sound=(sample_t *) malloc (samples * sizeof(sample_t));
>        sf_readf_float(f,sound,samples);
> 
> Which (I now realise) isn't quite right because I'm trying to read
> twice as many frames as there are in the file (assuming a stereo
> file).

The cause of this is rather subtle. If you use the sndfile-info 
program in the file x_kick.wav that you posted, you will notice 
that there is non-audio data following the audio data. The 
problem is that using sf_readf_float() is attempting to read this
data as audio data.
  
> Changing to sf_read_float does the trick, but I still don't understand
> why some stereo files worked, while others didn't.  

The problem free files did not have the trailing non-audio data.

> Opening them in
> something wlse and saving them again in exactly the same format made
> them work!

Saving the file probably removed that trailing non-audio data. Use 
the sndfile-info program to verify this.

> Also, shouldn't sf_readf_float handle being asked to read too many
> frames?

Yes, thats a bug. Fix in progress.

Erik
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