sndfile-waveform: 6-channel input => Channel 6 missing from generated PNG

[wolfgangw]

Hi Erik,

sndfile-waveform apparently drops channel 6 from a 6-channel input audiofile, at least from the ones I've been throwing at it (24 bps, 48 kHz).

The command I've used:

sndfile-waveform -c -1 -l -g 1280x980 <input> <output>

See https://github.com/wolfgangw/blobs/tree/master/sndfile-waveform-material to reproduce. The 6-channel audiofile contains -- in temporal sequence -- 1 tone per channel in center (ch 3), left (ch 1), right (ch 2), left surround (ch 5), right surround (ch 6) and LFE (ch 4).

[x42]

the channel parameter starts counting at 1 for the 1st channel (0 means downmix to mono).
Fix:

--- a/src/waveform.c
+++ b/src/waveform.c
@@ -151,7 +151,7 @@ calc_peak (SNDFILE *infile, SF_INFO *info, double width, int channel, AGC *agc)
        float* data ;
        long f_offset = 0 ;

-       if (channel < 0 || channel >= info->channels)
+       if (channel < 0 || channel > info->channels)
        {       printf ("invalid channel\n") ;
                return ;
                } ;
@@ -232,7 +232,7 @@ render_waveform (cairo_surface_t * surface, RENDER *render, SNDFILE *infile, SF_
        float* data ;
        long f_offset = 0 ;

-       if (channel < 0 || channel >= info->channels)
+       if (channel < 0 || channel > info->channels)
        {       printf ("invalid channel\n") ;
                return ;
                } ;

[erikd]

Fixed in the above commit.