[linux-audio-dev] libsndfile breakage

[james at dis-dot-dat.net]

On Thu, 12 Feb, 2004 at 08:59PM +1100, Erik de Castro Lopo spake thus:
> 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.

Ahhh.
   
> > 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.

Thanks, that's great.

> > Also, shouldn't sf_readf_float handle being asked to read too many
> > frames?
> 
> Yes, thats a bug. Fix in progress.

Heh!  I didn't realise I was talking to the author.

Sorry if that last line sounded whiney and/or ungrateful - what I
should have said was : thanks so much for libsndfile.

James

> Erik