libavcodec/ra288.c
Go to the documentation of this file.
00001 /*
00002  * RealAudio 2.0 (28.8K)
00003  * Copyright (c) 2003 the ffmpeg project
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avcodec.h"
00023 #include "internal.h"
00024 #define BITSTREAM_READER_LE
00025 #include "get_bits.h"
00026 #include "ra288.h"
00027 #include "lpc.h"
00028 #include "celp_math.h"
00029 #include "celp_filters.h"
00030 #include "dsputil.h"
00031 
00032 #define MAX_BACKWARD_FILTER_ORDER  36
00033 #define MAX_BACKWARD_FILTER_LEN    40
00034 #define MAX_BACKWARD_FILTER_NONREC 35
00035 
00036 #define RA288_BLOCK_SIZE        5
00037 #define RA288_BLOCKS_PER_FRAME 32
00038 
00039 typedef struct {
00040     AVFrame frame;
00041     DSPContext dsp;
00042     DECLARE_ALIGNED(16, float,   sp_lpc)[FFALIGN(36, 8)];   
00043     DECLARE_ALIGNED(16, float, gain_lpc)[FFALIGN(10, 8)];   
00044 
00048     float sp_hist[111];
00049 
00051     float sp_rec[37];
00052 
00056     float gain_hist[38];
00057 
00059     float gain_rec[11];
00060 } RA288Context;
00061 
00062 static av_cold int ra288_decode_init(AVCodecContext *avctx)
00063 {
00064     RA288Context *ractx = avctx->priv_data;
00065     avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
00066     dsputil_init(&ractx->dsp, avctx);
00067 
00068     avcodec_get_frame_defaults(&ractx->frame);
00069     avctx->coded_frame = &ractx->frame;
00070 
00071     return 0;
00072 }
00073 
00074 static void convolve(float *tgt, const float *src, int len, int n)
00075 {
00076     for (; n >= 0; n--)
00077         tgt[n] = ff_dot_productf(src, src - n, len);
00078 
00079 }
00080 
00081 static void decode(RA288Context *ractx, float gain, int cb_coef)
00082 {
00083     int i;
00084     double sumsum;
00085     float sum, buffer[5];
00086     float *block = ractx->sp_hist + 70 + 36; // current block
00087     float *gain_block = ractx->gain_hist + 28;
00088 
00089     memmove(ractx->sp_hist + 70, ractx->sp_hist + 75, 36*sizeof(*block));
00090 
00091     /* block 46 of G.728 spec */
00092     sum = 32.;
00093     for (i=0; i < 10; i++)
00094         sum -= gain_block[9-i] * ractx->gain_lpc[i];
00095 
00096     /* block 47 of G.728 spec */
00097     sum = av_clipf(sum, 0, 60);
00098 
00099     /* block 48 of G.728 spec */
00100     /* exp(sum * 0.1151292546497) == pow(10.0,sum/20) */
00101     sumsum = exp(sum * 0.1151292546497) * gain * (1.0/(1<<23));
00102 
00103     for (i=0; i < 5; i++)
00104         buffer[i] = codetable[cb_coef][i] * sumsum;
00105 
00106     sum = ff_dot_productf(buffer, buffer, 5) * ((1<<24)/5.);
00107 
00108     sum = FFMAX(sum, 1);
00109 
00110     /* shift and store */
00111     memmove(gain_block, gain_block + 1, 9 * sizeof(*gain_block));
00112 
00113     gain_block[9] = 10 * log10(sum) - 32;
00114 
00115     ff_celp_lp_synthesis_filterf(block, ractx->sp_lpc, buffer, 5, 36);
00116 }
00117 
00130 static void do_hybrid_window(RA288Context *ractx,
00131                              int order, int n, int non_rec, float *out,
00132                              float *hist, float *out2, const float *window)
00133 {
00134     int i;
00135     float buffer1[MAX_BACKWARD_FILTER_ORDER + 1];
00136     float buffer2[MAX_BACKWARD_FILTER_ORDER + 1];
00137     LOCAL_ALIGNED_16(float, work, [FFALIGN(MAX_BACKWARD_FILTER_ORDER +
00138                                            MAX_BACKWARD_FILTER_LEN   +
00139                                            MAX_BACKWARD_FILTER_NONREC, 8)]);
00140 
00141     ractx->dsp.vector_fmul(work, window, hist, FFALIGN(order + n + non_rec, 8));
00142 
00143     convolve(buffer1, work + order    , n      , order);
00144     convolve(buffer2, work + order + n, non_rec, order);
00145 
00146     for (i=0; i <= order; i++) {
00147         out2[i] = out2[i] * 0.5625 + buffer1[i];
00148         out [i] = out2[i]          + buffer2[i];
00149     }
00150 
00151     /* Multiply by the white noise correcting factor (WNCF). */
00152     *out *= 257./256.;
00153 }
00154 
00158 static void backward_filter(RA288Context *ractx,
00159                             float *hist, float *rec, const float *window,
00160                             float *lpc, const float *tab,
00161                             int order, int n, int non_rec, int move_size)
00162 {
00163     float temp[MAX_BACKWARD_FILTER_ORDER+1];
00164 
00165     do_hybrid_window(ractx, order, n, non_rec, temp, hist, rec, window);
00166 
00167     if (!compute_lpc_coefs(temp, order, lpc, 0, 1, 1))
00168         ractx->dsp.vector_fmul(lpc, lpc, tab, FFALIGN(order, 8));
00169 
00170     memmove(hist, hist + n, move_size*sizeof(*hist));
00171 }
00172 
00173 static int ra288_decode_frame(AVCodecContext * avctx, void *data,
00174                               int *got_frame_ptr, AVPacket *avpkt)
00175 {
00176     const uint8_t *buf = avpkt->data;
00177     int buf_size = avpkt->size;
00178     float *out;
00179     int i, ret;
00180     RA288Context *ractx = avctx->priv_data;
00181     GetBitContext gb;
00182 
00183     if (buf_size < avctx->block_align) {
00184         av_log(avctx, AV_LOG_ERROR,
00185                "Error! Input buffer is too small [%d<%d]\n",
00186                buf_size, avctx->block_align);
00187         return AVERROR_INVALIDDATA;
00188     }
00189 
00190     /* get output buffer */
00191     ractx->frame.nb_samples = RA288_BLOCK_SIZE * RA288_BLOCKS_PER_FRAME;
00192     if ((ret = ff_get_buffer(avctx, &ractx->frame)) < 0) {
00193         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00194         return ret;
00195     }
00196     out = (float *)ractx->frame.data[0];
00197 
00198     init_get_bits(&gb, buf, avctx->block_align * 8);
00199 
00200     for (i=0; i < RA288_BLOCKS_PER_FRAME; i++) {
00201         float gain = amptable[get_bits(&gb, 3)];
00202         int cb_coef = get_bits(&gb, 6 + (i&1));
00203 
00204         decode(ractx, gain, cb_coef);
00205 
00206         memcpy(out, &ractx->sp_hist[70 + 36], RA288_BLOCK_SIZE * sizeof(*out));
00207         out += RA288_BLOCK_SIZE;
00208 
00209         if ((i & 7) == 3) {
00210             backward_filter(ractx, ractx->sp_hist, ractx->sp_rec, syn_window,
00211                             ractx->sp_lpc, syn_bw_tab, 36, 40, 35, 70);
00212 
00213             backward_filter(ractx, ractx->gain_hist, ractx->gain_rec, gain_window,
00214                             ractx->gain_lpc, gain_bw_tab, 10, 8, 20, 28);
00215         }
00216     }
00217 
00218     *got_frame_ptr   = 1;
00219     *(AVFrame *)data = ractx->frame;
00220 
00221     return avctx->block_align;
00222 }
00223 
00224 AVCodec ff_ra_288_decoder = {
00225     .name           = "real_288",
00226     .type           = AVMEDIA_TYPE_AUDIO,
00227     .id             = CODEC_ID_RA_288,
00228     .priv_data_size = sizeof(RA288Context),
00229     .init           = ra288_decode_init,
00230     .decode         = ra288_decode_frame,
00231     .capabilities   = CODEC_CAP_DR1,
00232     .long_name      = NULL_IF_CONFIG_SMALL("RealAudio 2.0 (28.8K)"),
00233 };