Hello,

I am currently implementing LAME gapless support into XMMS2's mad-decoder. I have some questions and I hope that someone here can help me clarify some issues.

This is what I currently do:

In the Xing parser I parse the normal Xing tag and then I read the LAME tag, like this:

CODE

if (strncmp ((gchar *)ptr.byte, "LAME", 4) == 0) {
  mad_bit_skip (&ptr, 8 * 20);
  mad_bit_skip (&ptr, 16);
  lame->peak_amplitude = mad_bit_read (&ptr, 32);
  lame->radio_gain = mad_bit_read (&ptr, 16);
  lame->audiophile_gain = mad_bit_read (&ptr, 16);
  mad_bit_skip (&ptr, 16);
  lame->encoder_delay_start = mad_bit_read (&ptr, 12);
  lame->encoder_delay_stop = mad_bit_read (&ptr, 12);
  mad_bit_skip (&ptr, 8);
  lame->mp3_gain = mad_bit_read (&ptr, 8);
}


Then I use these numbers in the mp3 decoder to do something like this:

CODE

data->samples_to_skip = lame->encoder_delay_start;
data->samples_to_skip_end = lame->encoder_delay_stop;
data->samples_to_play = (guint64)(((guint64)xmms_xing_get_frames (data->xing) * (guint64)1152) - (guint64)lame->encoder_delay_stop);


And then in the decoding phase:

CODE

        if (data->synthpos < data->synth.pcm.length) {
            if (data->samples_to_skip <= 0 && data->samples_to_play >= 0) {
                out[j++] = scale_linear (data->synth.pcm.samples[0][data->synthpos]);
                if (data->channels == 2) {
                    out[j++] = scale_linear (data->synth.pcm.samples[1][data->synthpos]);
                    read += 2 * xmms_sample_size_get (XMMS_SAMPLE_FORMAT_S16);
                    data->samples_to_play -= 2;
                } else {
                    read += xmms_sample_size_get (XMMS_SAMPLE_FORMAT_S16);
                    data->samples_to_play --;
                }
            } else {
                if (data->channels == 2) {
                    data->samples_to_skip -= 2;
                } else {
                    data->samples_to_skip --;
                }
            }
            data->synthpos++;
            continue;
        }


Still have some clicks between songs that play beautifully in foobar2000. Am I understanding something wrong? Any tips would be helpful.

The full code is available here:

http://git.xmms.se/?p=xmms2-devel.git;a=tr...src/plugins/mad

Thanks in advance.

// Tobias - xmms2 developer