| /* |
| * HCOM audio decoder |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/intreadwrite.h" |
| |
| #include "avcodec.h" |
| #include "get_bits.h" |
| #include "internal.h" |
| |
| typedef struct HEntry { |
| int16_t l, r; |
| } HEntry; |
| |
| typedef struct HCOMContext { |
| AVCodecContext *avctx; |
| |
| uint8_t first_sample; |
| uint8_t sample; |
| int dict_entries; |
| int dict_entry; |
| int delta_compression; |
| |
| HEntry *dict; |
| } HCOMContext; |
| |
| static av_cold int hcom_init(AVCodecContext *avctx) |
| { |
| HCOMContext *s = avctx->priv_data; |
| |
| if (avctx->channels != 1) { |
| av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n"); |
| return AVERROR_INVALIDDATA; |
| } |
| |
| if (avctx->extradata_size <= 7) |
| return AVERROR_INVALIDDATA; |
| s->dict_entries = AV_RB16(avctx->extradata); |
| if (avctx->extradata_size < s->dict_entries * 4 + 7 || |
| s->dict_entries == 0) |
| return AVERROR_INVALIDDATA; |
| s->delta_compression = AV_RB32(avctx->extradata + 2); |
| s->sample = s->first_sample = avctx->extradata[avctx->extradata_size - 1]; |
| |
| s->dict = av_calloc(s->dict_entries, sizeof(*s->dict)); |
| if (!s->dict) |
| return AVERROR(ENOMEM); |
| for (int i = 0; i < s->dict_entries; i++) { |
| s->dict[i].l = AV_RB16(avctx->extradata + 6 + 4 * i); |
| s->dict[i].r = AV_RB16(avctx->extradata + 6 + 4 * i + 2); |
| if (s->dict[i].l >= 0 && |
| (s->dict[i].l >= s->dict_entries || |
| s->dict[i].r >= s->dict_entries || |
| s->dict[i].r < 0 )) |
| return AVERROR_INVALIDDATA; |
| } |
| if (s->dict[0].l < 0) |
| return AVERROR_INVALIDDATA; |
| |
| avctx->sample_fmt = AV_SAMPLE_FMT_U8; |
| s->dict_entry = 0; |
| |
| return 0; |
| } |
| |
| static int hcom_decode(AVCodecContext *avctx, void *data, |
| int *got_frame, AVPacket *pkt) |
| { |
| HCOMContext *s = avctx->priv_data; |
| AVFrame *frame = data; |
| GetBitContext gb; |
| int ret, n = 0; |
| |
| if (pkt->size > INT16_MAX) |
| return AVERROR_INVALIDDATA; |
| |
| frame->nb_samples = pkt->size * 8; |
| if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
| return ret; |
| |
| if ((ret = init_get_bits8(&gb, pkt->data, pkt->size)) < 0) |
| return ret; |
| |
| while (get_bits_left(&gb) > 0) { |
| if (get_bits1(&gb)) |
| s->dict_entry = s->dict[s->dict_entry].r; |
| else |
| s->dict_entry = s->dict[s->dict_entry].l; |
| |
| if (s->dict[s->dict_entry].l < 0) { |
| int16_t datum; |
| |
| datum = s->dict[s->dict_entry].r; |
| |
| if (!s->delta_compression) |
| s->sample = 0; |
| s->sample = (s->sample + datum) & 0xFF; |
| |
| frame->data[0][n++] = s->sample; |
| |
| s->dict_entry = 0; |
| } |
| } |
| |
| frame->nb_samples = n; |
| |
| *got_frame = 1; |
| |
| return pkt->size; |
| } |
| |
| static av_cold int hcom_close(AVCodecContext *avctx) |
| { |
| HCOMContext *s = avctx->priv_data; |
| |
| av_freep(&s->dict); |
| |
| return 0; |
| } |
| |
| AVCodec ff_hcom_decoder = { |
| .name = "hcom", |
| .long_name = NULL_IF_CONFIG_SMALL("HCOM Audio"), |
| .type = AVMEDIA_TYPE_AUDIO, |
| .id = AV_CODEC_ID_HCOM, |
| .priv_data_size = sizeof(HCOMContext), |
| .init = hcom_init, |
| .close = hcom_close, |
| .decode = hcom_decode, |
| .capabilities = AV_CODEC_CAP_DR1, |
| .caps_internal = FF_CODEC_CAP_INIT_CLEANUP, |
| }; |