152 lines
4 KiB
C
152 lines
4 KiB
C
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/*
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* HCOM audio decoder
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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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#include "libavutil/intreadwrite.h"
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#include "avcodec.h"
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#include "get_bits.h"
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#include "internal.h"
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typedef struct HEntry {
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int16_t l, r;
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} HEntry;
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typedef struct HCOMContext {
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AVCodecContext *avctx;
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uint8_t first_sample;
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uint8_t sample;
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int dict_entries;
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int dict_entry;
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int delta_compression;
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HEntry *dict;
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} HCOMContext;
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static av_cold int hcom_init(AVCodecContext *avctx)
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{
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HCOMContext *s = avctx->priv_data;
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if (avctx->channels != 1) {
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av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
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return AVERROR_INVALIDDATA;
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}
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if (avctx->extradata_size <= 7)
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return AVERROR_INVALIDDATA;
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s->dict_entries = AV_RB16(avctx->extradata);
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if (avctx->extradata_size < s->dict_entries * 4 + 7 ||
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s->dict_entries == 0)
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return AVERROR_INVALIDDATA;
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s->delta_compression = AV_RB32(avctx->extradata + 2);
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s->sample = s->first_sample = avctx->extradata[avctx->extradata_size - 1];
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s->dict = av_calloc(s->dict_entries, sizeof(*s->dict));
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if (!s->dict)
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return AVERROR(ENOMEM);
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for (int i = 0; i < s->dict_entries; i++) {
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s->dict[i].l = AV_RB16(avctx->extradata + 6 + 4 * i);
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s->dict[i].r = AV_RB16(avctx->extradata + 6 + 4 * i + 2);
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if (s->dict[i].l >= 0 &&
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(s->dict[i].l >= s->dict_entries ||
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s->dict[i].r >= s->dict_entries ||
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s->dict[i].r < 0 )) {
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av_freep(&s->dict);
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return AVERROR_INVALIDDATA;
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}
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}
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if (s->dict[0].l < 0) {
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av_freep(&s->dict);
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return AVERROR_INVALIDDATA;
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}
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avctx->sample_fmt = AV_SAMPLE_FMT_U8;
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s->dict_entry = 0;
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return 0;
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}
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static int hcom_decode(AVCodecContext *avctx, void *data,
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int *got_frame, AVPacket *pkt)
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{
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HCOMContext *s = avctx->priv_data;
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AVFrame *frame = data;
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GetBitContext gb;
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int ret, n = 0;
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if (pkt->size > INT16_MAX)
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return AVERROR_INVALIDDATA;
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frame->nb_samples = pkt->size * 8;
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if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
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return ret;
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if ((ret = init_get_bits8(&gb, pkt->data, pkt->size)) < 0)
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return ret;
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while (get_bits_left(&gb) > 0) {
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if (get_bits1(&gb))
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s->dict_entry = s->dict[s->dict_entry].r;
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else
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s->dict_entry = s->dict[s->dict_entry].l;
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if (s->dict[s->dict_entry].l < 0) {
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int16_t datum;
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datum = s->dict[s->dict_entry].r;
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if (!s->delta_compression)
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s->sample = 0;
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s->sample = (s->sample + datum) & 0xFF;
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frame->data[0][n++] = s->sample;
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s->dict_entry = 0;
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}
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}
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frame->nb_samples = n;
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*got_frame = 1;
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return pkt->size;
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}
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static av_cold int hcom_close(AVCodecContext *avctx)
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{
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HCOMContext *s = avctx->priv_data;
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av_freep(&s->dict);
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return 0;
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}
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AVCodec ff_hcom_decoder = {
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.name = "hcom",
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.long_name = NULL_IF_CONFIG_SMALL("HCOM Audio"),
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.type = AVMEDIA_TYPE_AUDIO,
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.id = AV_CODEC_ID_HCOM,
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.priv_data_size = sizeof(HCOMContext),
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.init = hcom_init,
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.close = hcom_close,
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.decode = hcom_decode,
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.capabilities = AV_CODEC_CAP_DR1,
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};
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