static av_cold void set_bandwidth(AC3EncodeContext *s, int cutoff) { int ch, bw_code; if (cutoff) { /* calculate bandwidth based on user-specified cutoff frequency */ int fbw_coeffs; cutoff = av_clip(cutoff, 1, s->sample_rate >> 1); fbw_coeffs = cutoff * 2 * AC3_MAX_COEFS / s->sample_rate; bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60); } else { /* use default bandwidth setting */ /* XXX: should compute the bandwidth according to the frame size, so that we avoid annoying high frequency artifacts */ bw_code = 50; } /* set number of coefficients for each channel */ for (ch = 0; ch < s->fbw_channels; ch++) { s->bandwidth_code[ch] = bw_code; s->nb_coefs[ch] = bw_code * 3 + 73; } if (s->lfe_on) s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */ }