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libavcodec/ra144dec.c

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00001 /*
00002  * Real Audio 1.0 (14.4K)
00003  *
00004  * Copyright (c) 2008 Vitor Sessak
00005  * Copyright (c) 2003 Nick Kurshev
00006  *     Based on public domain decoder at http://www.honeypot.net/audio
00007  *
00008  * This file is part of Libav.
00009  *
00010  * Libav is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * Libav is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with Libav; if not, write to the Free Software
00022  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00023  */
00024 
00025 #include "libavutil/intmath.h"
00026 #include "avcodec.h"
00027 #include "get_bits.h"
00028 #include "ra144.h"
00029 
00030 
00031 static av_cold int ra144_decode_init(AVCodecContext * avctx)
00032 {
00033     RA144Context *ractx = avctx->priv_data;
00034 
00035     ractx->avctx = avctx;
00036 
00037     ractx->lpc_coef[0] = ractx->lpc_tables[0];
00038     ractx->lpc_coef[1] = ractx->lpc_tables[1];
00039 
00040     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00041 
00042     avcodec_get_frame_defaults(&ractx->frame);
00043     avctx->coded_frame = &ractx->frame;
00044 
00045     return 0;
00046 }
00047 
00048 static void do_output_subblock(RA144Context *ractx, const uint16_t  *lpc_coefs,
00049                                int gval, GetBitContext *gb)
00050 {
00051     int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
00052     int gain    = get_bits(gb, 8);
00053     int cb1_idx = get_bits(gb, 7);
00054     int cb2_idx = get_bits(gb, 7);
00055 
00056     ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, gval,
00057                           gain);
00058 }
00059 
00061 static int ra144_decode_frame(AVCodecContext * avctx, void *data,
00062                               int *got_frame_ptr, AVPacket *avpkt)
00063 {
00064     const uint8_t *buf = avpkt->data;
00065     int buf_size = avpkt->size;
00066     static const uint8_t sizes[LPC_ORDER] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
00067     unsigned int refl_rms[NBLOCKS];           // RMS of the reflection coefficients
00068     uint16_t block_coefs[NBLOCKS][LPC_ORDER]; // LPC coefficients of each sub-block
00069     unsigned int lpc_refl[LPC_ORDER];         // LPC reflection coefficients of the frame
00070     int i, j;
00071     int ret;
00072     int16_t *samples;
00073     unsigned int energy;
00074 
00075     RA144Context *ractx = avctx->priv_data;
00076     GetBitContext gb;
00077 
00078     /* get output buffer */
00079     ractx->frame.nb_samples = NBLOCKS * BLOCKSIZE;
00080     if ((ret = avctx->get_buffer(avctx, &ractx->frame)) < 0) {
00081         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00082         return ret;
00083     }
00084     samples = (int16_t *)ractx->frame.data[0];
00085 
00086     if(buf_size < FRAMESIZE) {
00087         av_log(avctx, AV_LOG_ERROR,
00088                "Frame too small (%d bytes). Truncated file?\n", buf_size);
00089         *got_frame_ptr = 0;
00090         return buf_size;
00091     }
00092     init_get_bits(&gb, buf, FRAMESIZE * 8);
00093 
00094     for (i = 0; i < LPC_ORDER; i++)
00095         lpc_refl[i] = ff_lpc_refl_cb[i][get_bits(&gb, sizes[i])];
00096 
00097     ff_eval_coefs(ractx->lpc_coef[0], lpc_refl);
00098     ractx->lpc_refl_rms[0] = ff_rms(lpc_refl);
00099 
00100     energy = ff_energy_tab[get_bits(&gb, 5)];
00101 
00102     refl_rms[0] = ff_interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
00103     refl_rms[1] = ff_interp(ractx, block_coefs[1], 2,
00104                             energy <= ractx->old_energy,
00105                             ff_t_sqrt(energy*ractx->old_energy) >> 12);
00106     refl_rms[2] = ff_interp(ractx, block_coefs[2], 3, 0, energy);
00107     refl_rms[3] = ff_rescale_rms(ractx->lpc_refl_rms[0], energy);
00108 
00109     ff_int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
00110 
00111     for (i=0; i < NBLOCKS; i++) {
00112         do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
00113 
00114         for (j=0; j < BLOCKSIZE; j++)
00115             *samples++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
00116     }
00117 
00118     ractx->old_energy = energy;
00119     ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
00120 
00121     FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
00122 
00123     *got_frame_ptr   = 1;
00124     *(AVFrame *)data = ractx->frame;
00125 
00126     return FRAMESIZE;
00127 }
00128 
00129 AVCodec ff_ra_144_decoder = {
00130     .name           = "real_144",
00131     .type           = AVMEDIA_TYPE_AUDIO,
00132     .id             = CODEC_ID_RA_144,
00133     .priv_data_size = sizeof(RA144Context),
00134     .init           = ra144_decode_init,
00135     .decode         = ra144_decode_frame,
00136     .capabilities   = CODEC_CAP_DR1,
00137     .long_name      = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
00138 };
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