+ }
+
+ /* set optional output params */
+ if (num_bands)
+ *num_bands = n_bands;
+ if (band_sizes)
+ memcpy(band_sizes, bnd_sz, n_bands);
+}
+
+static inline int spx_strategy(AC3DecodeContext *s, int blk)
+{
+ GetBitContext *bc = &s->gbc;
+ int fbw_channels = s->fbw_channels;
+ int dst_start_freq, dst_end_freq, src_start_freq,
+ start_subband, end_subband, ch;
+
+ /* determine which channels use spx */
+ if (s->channel_mode == AC3_CHMODE_MONO) {
+ s->channel_uses_spx[1] = 1;
+ } else {
+ for (ch = 1; ch <= fbw_channels; ch++)
+ s->channel_uses_spx[ch] = get_bits1(bc);
+ }
+
+ /* get the frequency bins of the spx copy region and the spx start
+ and end subbands */
+ dst_start_freq = get_bits(bc, 2);
+ start_subband = get_bits(bc, 3) + 2;
+ if (start_subband > 7)
+ start_subband += start_subband - 7;
+ end_subband = get_bits(bc, 3) + 5;
+ if (end_subband > 7)
+ end_subband += end_subband - 7;
+ dst_start_freq = dst_start_freq * 12 + 25;
+ src_start_freq = start_subband * 12 + 25;
+ dst_end_freq = end_subband * 12 + 25;
+
+ /* check validity of spx ranges */
+ if (start_subband >= end_subband) {
+ av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
+ "range (%d >= %d)\n", start_subband, end_subband);
+ return AVERROR_INVALIDDATA;
+ }
+ if (dst_start_freq >= src_start_freq) {
+ av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
+ "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
+ return AVERROR_INVALIDDATA;
+ }
+
+ s->spx_dst_start_freq = dst_start_freq;
+ s->spx_src_start_freq = src_start_freq;
+ s->spx_dst_end_freq = dst_end_freq;
+
+ decode_band_structure(bc, blk, s->eac3, 0,
+ start_subband, end_subband,
+ ff_eac3_default_spx_band_struct,
+ &s->num_spx_bands,
+ s->spx_band_sizes);
+
+ return 0;
+}
+
+static inline void spx_coordinates(AC3DecodeContext *s)
+{
+ GetBitContext *bc = &s->gbc;
+ int fbw_channels = s->fbw_channels;
+ int ch, bnd;
+
+ for (ch = 1; ch <= fbw_channels; ch++) {
+ if (s->channel_uses_spx[ch]) {
+ if (s->first_spx_coords[ch] || get_bits1(bc)) {
+ float spx_blend;
+ int bin, master_spx_coord;
+
+ s->first_spx_coords[ch] = 0;
+ spx_blend = get_bits(bc, 5) * (1.0f / 32);
+ master_spx_coord = get_bits(bc, 2) * 3;
+
+ bin = s->spx_src_start_freq;
+ for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
+ int bandsize;
+ int spx_coord_exp, spx_coord_mant;
+ float nratio, sblend, nblend, spx_coord;
+
+ /* calculate blending factors */
+ bandsize = s->spx_band_sizes[bnd];
+ nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
+ nratio = av_clipf(nratio, 0.0f, 1.0f);
+ nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
+ // to give unity variance
+ sblend = sqrtf(1.0f - nratio);
+ bin += bandsize;
+
+ /* decode spx coordinates */
+ spx_coord_exp = get_bits(bc, 4);
+ spx_coord_mant = get_bits(bc, 2);
+ if (spx_coord_exp == 15) spx_coord_mant <<= 1;
+ else spx_coord_mant += 4;
+ spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
+ spx_coord = spx_coord_mant * (1.0f / (1 << 23));
+
+ /* multiply noise and signal blending factors by spx coordinate */
+ s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
+ s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
+ }
+ }
+ } else {
+ s->first_spx_coords[ch] = 1;