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libavcodec/adxdec.c

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00001 /*
00002  * ADX ADPCM codecs
00003  * Copyright (c) 2001,2003 BERO
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 "libavutil/intreadwrite.h"
00023 #include "avcodec.h"
00024 #include "adx.h"
00025 #include "get_bits.h"
00026 
00036 static av_cold int adx_decode_init(AVCodecContext *avctx)
00037 {
00038     ADXContext *c = avctx->priv_data;
00039     int ret, header_size;
00040 
00041     if (avctx->extradata_size >= 24) {
00042         if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,
00043                                             avctx->extradata_size, &header_size,
00044                                             c->coeff)) < 0) {
00045             av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
00046             return AVERROR_INVALIDDATA;
00047         }
00048         c->channels      = avctx->channels;
00049         c->header_parsed = 1;
00050     }
00051 
00052     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00053 
00054     avcodec_get_frame_defaults(&c->frame);
00055     avctx->coded_frame = &c->frame;
00056 
00057     return 0;
00058 }
00059 
00067 static int adx_decode(ADXContext *c, int16_t *out, const uint8_t *in, int ch)
00068 {
00069     ADXChannelState *prev = &c->prev[ch];
00070     GetBitContext gb;
00071     int scale = AV_RB16(in);
00072     int i;
00073     int s0, s1, s2, d;
00074 
00075     /* check if this is an EOF packet */
00076     if (scale & 0x8000)
00077         return -1;
00078 
00079     init_get_bits(&gb, in + 2, (BLOCK_SIZE - 2) * 8);
00080     s1 = prev->s1;
00081     s2 = prev->s2;
00082     for (i = 0; i < BLOCK_SAMPLES; i++) {
00083         d  = get_sbits(&gb, 4);
00084         s0 = ((d << COEFF_BITS) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;
00085         s2 = s1;
00086         s1 = av_clip_int16(s0);
00087         *out = s1;
00088         out += c->channels;
00089     }
00090     prev->s1 = s1;
00091     prev->s2 = s2;
00092 
00093     return 0;
00094 }
00095 
00096 static int adx_decode_frame(AVCodecContext *avctx, void *data,
00097                             int *got_frame_ptr, AVPacket *avpkt)
00098 {
00099     int buf_size        = avpkt->size;
00100     ADXContext *c       = avctx->priv_data;
00101     int16_t *samples;
00102     const uint8_t *buf  = avpkt->data;
00103     int num_blocks, ch, ret;
00104 
00105     if (c->eof) {
00106         *got_frame_ptr = 0;
00107         return buf_size;
00108     }
00109 
00110     if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {
00111         int header_size;
00112         if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,
00113                                             c->coeff)) < 0) {
00114             av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
00115             return AVERROR_INVALIDDATA;
00116         }
00117         c->channels      = avctx->channels;
00118         c->header_parsed = 1;
00119         if (buf_size < header_size)
00120             return AVERROR_INVALIDDATA;
00121         buf      += header_size;
00122         buf_size -= header_size;
00123     }
00124     if (!c->header_parsed)
00125         return AVERROR_INVALIDDATA;
00126 
00127     /* calculate number of blocks in the packet */
00128     num_blocks = buf_size / (BLOCK_SIZE * c->channels);
00129 
00130     /* if the packet is not an even multiple of BLOCK_SIZE, check for an EOF
00131        packet */
00132     if (!num_blocks || buf_size % (BLOCK_SIZE * avctx->channels)) {
00133         if (buf_size >= 4 && (AV_RB16(buf) & 0x8000)) {
00134             c->eof = 1;
00135             *got_frame_ptr = 0;
00136             return avpkt->size;
00137         }
00138         return AVERROR_INVALIDDATA;
00139     }
00140 
00141     /* get output buffer */
00142     c->frame.nb_samples = num_blocks * BLOCK_SAMPLES;
00143     if ((ret = avctx->get_buffer(avctx, &c->frame)) < 0) {
00144         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00145         return ret;
00146     }
00147     samples = (int16_t *)c->frame.data[0];
00148 
00149     while (num_blocks--) {
00150         for (ch = 0; ch < c->channels; ch++) {
00151             if (adx_decode(c, samples + ch, buf, ch)) {
00152                 c->eof = 1;
00153                 buf = avpkt->data + avpkt->size;
00154                 break;
00155             }
00156             buf_size -= BLOCK_SIZE;
00157             buf      += BLOCK_SIZE;
00158         }
00159         samples += BLOCK_SAMPLES * c->channels;
00160     }
00161 
00162     *got_frame_ptr   = 1;
00163     *(AVFrame *)data = c->frame;
00164 
00165     return buf - avpkt->data;
00166 }
00167 
00168 static void adx_decode_flush(AVCodecContext *avctx)
00169 {
00170     ADXContext *c = avctx->priv_data;
00171     memset(c->prev, 0, sizeof(c->prev));
00172     c->eof = 0;
00173 }
00174 
00175 AVCodec ff_adpcm_adx_decoder = {
00176     .name           = "adpcm_adx",
00177     .type           = AVMEDIA_TYPE_AUDIO,
00178     .id             = CODEC_ID_ADPCM_ADX,
00179     .priv_data_size = sizeof(ADXContext),
00180     .init           = adx_decode_init,
00181     .decode         = adx_decode_frame,
00182     .flush          = adx_decode_flush,
00183     .capabilities   = CODEC_CAP_DR1,
00184     .long_name      = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),
00185 };
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