- ff_mdct_init(&sbr->mdct, 7, 1, 1.0/64);
- ff_rdft_init(&sbr->rdft, 6, IDFT_R2C);
+ /* SBR requires samples to be scaled to +/-32768.0 to work correctly.
+ * mdct scale factors are adjusted to scale up from +/-1.0 at analysis
+ * and scale back down at synthesis. */
+ mdct_scale = ac->avctx->sample_fmt == AV_SAMPLE_FMT_FLT ? 32768.0f : 1.0f;
+ ff_mdct_init(&sbr->mdct, 7, 1, 1.0 / (64 * mdct_scale));
+ ff_mdct_init(&sbr->mdct_ana, 7, 1, -2.0 * mdct_scale);
+ ff_ps_ctx_init(&sbr->ps);