155 lines
5.2 KiB
C
155 lines
5.2 KiB
C
/*
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* Copyright (c) CMU 1993 Computer Science, Speech Group
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* Chengxiang Lu and Alex Hauptmann
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* Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
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* Copyright (c) 2009 Kenan Gillet
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* Copyright (c) 2010 Martin Storsjo
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* G.722 ADPCM audio decoder
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*
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* This G.722 decoder is a bit-exact implementation of the ITU G.722
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* specification for all three specified bitrates - 64000bps, 56000bps
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* and 48000bps. It passes the ITU tests.
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*
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* @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits
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* respectively of each byte are ignored.
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*/
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#include "libavutil/channel_layout.h"
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#include "libavutil/opt.h"
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#include "avcodec.h"
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#include "get_bits.h"
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#include "g722.h"
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#include "internal.h"
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#define OFFSET(x) offsetof(G722Context, x)
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#define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
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static const AVOption options[] = {
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{ "bits_per_codeword", "Bits per G722 codeword", OFFSET(bits_per_codeword), AV_OPT_TYPE_FLAGS, { .i64 = 8 }, 6, 8, AD },
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{ NULL }
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};
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static const AVClass g722_decoder_class = {
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.class_name = "g722 decoder",
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.item_name = av_default_item_name,
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.option = options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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static av_cold int g722_decode_init(AVCodecContext * avctx)
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{
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G722Context *c = avctx->priv_data;
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avctx->channels = 1;
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avctx->channel_layout = AV_CH_LAYOUT_MONO;
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avctx->sample_fmt = AV_SAMPLE_FMT_S16;
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c->band[0].scale_factor = 8;
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c->band[1].scale_factor = 2;
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c->prev_samples_pos = 22;
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avcodec_get_frame_defaults(&c->frame);
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avctx->coded_frame = &c->frame;
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return 0;
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}
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static const int16_t low_inv_quant5[32] = {
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-35, -35, -2919, -2195, -1765, -1458, -1219, -1023,
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-858, -714, -587, -473, -370, -276, -190, -110,
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2919, 2195, 1765, 1458, 1219, 1023, 858, 714,
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587, 473, 370, 276, 190, 110, 35, -35
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};
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static const int16_t *low_inv_quants[3] = { ff_g722_low_inv_quant6,
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low_inv_quant5,
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ff_g722_low_inv_quant4 };
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static int g722_decode_frame(AVCodecContext *avctx, void *data,
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int *got_frame_ptr, AVPacket *avpkt)
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{
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G722Context *c = avctx->priv_data;
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int16_t *out_buf;
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int j, ret;
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const int skip = 8 - c->bits_per_codeword;
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const int16_t *quantizer_table = low_inv_quants[skip];
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GetBitContext gb;
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/* get output buffer */
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c->frame.nb_samples = avpkt->size * 2;
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if ((ret = ff_get_buffer(avctx, &c->frame)) < 0) {
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av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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return ret;
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}
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out_buf = (int16_t *)c->frame.data[0];
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init_get_bits(&gb, avpkt->data, avpkt->size * 8);
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for (j = 0; j < avpkt->size; j++) {
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int ilow, ihigh, rlow, rhigh, dhigh;
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int xout1, xout2;
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ihigh = get_bits(&gb, 2);
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ilow = get_bits(&gb, 6 - skip);
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skip_bits(&gb, skip);
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rlow = av_clip((c->band[0].scale_factor * quantizer_table[ilow] >> 10)
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+ c->band[0].s_predictor, -16384, 16383);
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ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));
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dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;
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rhigh = av_clip(dhigh + c->band[1].s_predictor, -16384, 16383);
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ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);
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c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;
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c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;
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ff_g722_apply_qmf(c->prev_samples + c->prev_samples_pos - 24,
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&xout1, &xout2);
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*out_buf++ = av_clip_int16(xout1 >> 11);
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*out_buf++ = av_clip_int16(xout2 >> 11);
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if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
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memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,
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22 * sizeof(c->prev_samples[0]));
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c->prev_samples_pos = 22;
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}
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}
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*got_frame_ptr = 1;
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*(AVFrame *)data = c->frame;
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return avpkt->size;
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}
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AVCodec ff_adpcm_g722_decoder = {
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.name = "g722",
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.type = AVMEDIA_TYPE_AUDIO,
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.id = AV_CODEC_ID_ADPCM_G722,
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.priv_data_size = sizeof(G722Context),
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.init = g722_decode_init,
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.decode = g722_decode_frame,
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.capabilities = CODEC_CAP_DR1,
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.long_name = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),
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.priv_class = &g722_decoder_class,
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};
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