At Tue, 30 Jun 2009 11:40:20 -0300,
Guilherme wrote:
>
> Tks takashi....
>
> The doubt comes from this block of code:
>
> for (chn = 0; chn < channels; chn++) {
> if ((areas[chn].first % 8) != 0) {
> printf("areas[%i].first == %i, abortando...\n", chn,
> areas[chn].first);
> exit(EXIT_FAILURE);
> }
> //pega endereço e offset da area
> samples[chn] = /*(signed short *)*/(((unsigned char
> *)areas[chn].addr) + (areas[chn].first / 8));
>
> if ((areas[chn].step % 16) != 0) {
> printf("areas[%i].step == %i, aborting...\n", chn,
> areas[chn].step);
> exit(EXIT_FAILURE);
> }
>
> steps[chn] = areas[chn].step / 8;
> samples[chn] += offset * steps[chn];
> }
>
> first:
>
> areas[chn].first % 8 ( I am using chn = 1). So for the only area that
> I have, if I get the value of the parameter 'first' isn't divisible by
> 8, the program exits.
> The same doubt happens with "areas[chn].step % 16" and
> "areas[chn].step / 8".
>
> This is the parameter I am using:
>
> static snd_pcm_format_t format = SND_PCM_FORMAT_S16; //sample format
> unsigned 16 bit endian
>
> Perhaps with this practical example I can understand better.
Oops, I wrote wrongly. The first and step fields are not in bytes but
bits. That's why 8 and 16 appear there, corresponding to 1 byte and 2
bytes.
Takashi
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