+ ctx->const_block = av_malloc (sizeof(*ctx->const_block) * num_buffers);
+ ctx->shift_lsbs = av_malloc (sizeof(*ctx->shift_lsbs) * num_buffers);
+ ctx->opt_order = av_malloc (sizeof(*ctx->opt_order) * num_buffers);
+ ctx->store_prev_samples = av_malloc(sizeof(*ctx->store_prev_samples) * num_buffers);