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| 1 | +/* |
| 2 | + * HCOM audio decoder |
| 3 | + * |
| 4 | + * This file is part of FFmpeg. |
| 5 | + * |
| 6 | + * FFmpeg is free software; you can redistribute it and/or |
| 7 | + * modify it under the terms of the GNU Lesser General Public |
| 8 | + * License as published by the Free Software Foundation; either |
| 9 | + * version 2.1 of the License, or (at your option) any later version. |
| 10 | + * |
| 11 | + * FFmpeg is distributed in the hope that it will be useful, |
| 12 | + * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | + * Lesser General Public License for more details. |
| 15 | + * |
| 16 | + * You should have received a copy of the GNU Lesser General Public |
| 17 | + * License along with FFmpeg; if not, write to the Free Software |
| 18 | + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | + */ |
| 20 | + |
| 21 | +#include "libavutil/intreadwrite.h" |
| 22 | + |
| 23 | +#include "avcodec.h" |
| 24 | +#include "get_bits.h" |
| 25 | +#include "internal.h" |
| 26 | + |
| 27 | +typedef struct HEntry { |
| 28 | + int16_t l, r; |
| 29 | +} HEntry; |
| 30 | + |
| 31 | +typedef struct HCOMContext { |
| 32 | + AVCodecContext *avctx; |
| 33 | + |
| 34 | + uint8_t first_sample; |
| 35 | + uint8_t sample; |
| 36 | + int dict_entries; |
| 37 | + int dict_entry; |
| 38 | + int delta_compression; |
| 39 | + |
| 40 | + HEntry *dict; |
| 41 | +} HCOMContext; |
| 42 | + |
| 43 | +static av_cold int hcom_init(AVCodecContext *avctx) |
| 44 | +{ |
| 45 | + HCOMContext *s = avctx->priv_data; |
| 46 | + |
| 47 | + if (avctx->channels != 1) { |
| 48 | + av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n"); |
| 49 | + return AVERROR_INVALIDDATA; |
| 50 | + } |
| 51 | + |
| 52 | + if (avctx->extradata_size <= 7) |
| 53 | + return AVERROR_INVALIDDATA; |
| 54 | + s->dict_entries = AV_RB16(avctx->extradata); |
| 55 | + if (avctx->extradata_size < s->dict_entries * 4 + 7) |
| 56 | + return AVERROR_INVALIDDATA; |
| 57 | + s->delta_compression = AV_RB32(avctx->extradata + 2); |
| 58 | + s->sample = s->first_sample = avctx->extradata[avctx->extradata_size - 1]; |
| 59 | + |
| 60 | + s->dict = av_calloc(s->dict_entries, sizeof(*s->dict)); |
| 61 | + if (!s->dict) |
| 62 | + return AVERROR(ENOMEM); |
| 63 | + for (int i = 0; i < s->dict_entries; i++) { |
| 64 | + s->dict[i].l = AV_RB16(avctx->extradata + 6 + 4 * i); |
| 65 | + s->dict[i].r = AV_RB16(avctx->extradata + 6 + 4 * i + 2); |
| 66 | + } |
| 67 | + |
| 68 | + avctx->sample_fmt = AV_SAMPLE_FMT_U8; |
| 69 | + s->dict_entry = 0; |
| 70 | + |
| 71 | + return 0; |
| 72 | +} |
| 73 | + |
| 74 | +static int hcom_decode(AVCodecContext *avctx, void *data, |
| 75 | + int *got_frame, AVPacket *pkt) |
| 76 | +{ |
| 77 | + HCOMContext *s = avctx->priv_data; |
| 78 | + AVFrame *frame = data; |
| 79 | + GetBitContext gb; |
| 80 | + int ret, n = 0; |
| 81 | + |
| 82 | + if (pkt->size > INT16_MAX) |
| 83 | + return AVERROR_INVALIDDATA; |
| 84 | + |
| 85 | + frame->nb_samples = pkt->size * 8; |
| 86 | + if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
| 87 | + return ret; |
| 88 | + |
| 89 | + if ((ret = init_get_bits8(&gb, pkt->data, pkt->size)) < 0) |
| 90 | + return ret; |
| 91 | + |
| 92 | + while (get_bits_left(&gb) > 0) { |
| 93 | + if (get_bits1(&gb)) { |
| 94 | + s->dict_entry = s->dict[s->dict_entry].r; |
| 95 | + } else { |
| 96 | + s->dict_entry = s->dict[s->dict_entry].l; |
| 97 | + } |
| 98 | + |
| 99 | + if (s->dict[s->dict_entry].l < 0) { |
| 100 | + int16_t datum; |
| 101 | + |
| 102 | + datum = s->dict[s->dict_entry].r; |
| 103 | + |
| 104 | + if (!s->delta_compression) |
| 105 | + s->sample = 0; |
| 106 | + s->sample = (s->sample + datum) & 0xFF; |
| 107 | + |
| 108 | + frame->data[0][n++] = s->sample; |
| 109 | + |
| 110 | + s->dict_entry = 0; |
| 111 | + } |
| 112 | + } |
| 113 | + |
| 114 | + frame->nb_samples = n; |
| 115 | + |
| 116 | + *got_frame = 1; |
| 117 | + |
| 118 | + return pkt->size; |
| 119 | +} |
| 120 | + |
| 121 | +static av_cold int hcom_close(AVCodecContext *avctx) |
| 122 | +{ |
| 123 | + HCOMContext *s = avctx->priv_data; |
| 124 | + |
| 125 | + av_freep(&s->dict); |
| 126 | + |
| 127 | + return 0; |
| 128 | +} |
| 129 | + |
| 130 | +AVCodec ff_hcom_decoder = { |
| 131 | + .name = "hcom", |
| 132 | + .long_name = NULL_IF_CONFIG_SMALL("HCOM Audio"), |
| 133 | + .type = AVMEDIA_TYPE_AUDIO, |
| 134 | + .id = AV_CODEC_ID_HCOM, |
| 135 | + .priv_data_size = sizeof(HCOMContext), |
| 136 | + .init = hcom_init, |
| 137 | + .close = hcom_close, |
| 138 | + .decode = hcom_decode, |
| 139 | + .capabilities = AV_CODEC_CAP_DR1, |
| 140 | +}; |