diff options
Diffstat (limited to 'libavcodec/dfpwmdec.c')
| -rw-r--r-- | libavcodec/dfpwmdec.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/libavcodec/dfpwmdec.c b/libavcodec/dfpwmdec.c new file mode 100644 index 0000000000..05f79448ef --- /dev/null +++ b/libavcodec/dfpwmdec.c @@ -0,0 +1,134 @@ +/* + * DFPWM decoder + * Copyright (c) 2022 Jack Bruienne + * Copyright (c) 2012, 2016 Ben "GreaseMonkey" Russell + * + * 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 + */ + +/** + * @file + * DFPWM1a decoder + */ + +#include "libavutil/internal.h" +#include "avcodec.h" +#include "codec_id.h" +#include "internal.h" + +typedef struct { + int fq, q, s, lt; +} DFPWMState; + +// DFPWM codec from https://github.com/ChenThread/dfpwm/blob/master/1a/ +// Licensed in the public domain + +static void au_decompress(DFPWMState *state, int fs, int len, uint8_t *outbuf, uint8_t *inbuf) +{ + unsigned d; + for (int i = 0; i < len; i++) { + // get bits + d = *(inbuf++); + for (int j = 0; j < 8; j++) { + int nq, lq, st, ns, ov; + // set target + int t = ((d&1) ? 127 : -128); + d >>= 1; + + // adjust charge + nq = state->q + ((state->s * (t-state->q) + 512)>>10); + if(nq == state->q && nq != t) + nq += (t == 127 ? 1 : -1); + lq = state->q; + state->q = nq; + + // adjust strength + st = (t != state->lt ? 0 : 1023); + ns = state->s; + if(ns != st) + ns += (st != 0 ? 1 : -1); + if(ns < 8) ns = 8; + state->s = ns; + + // FILTER: perform antijerk + ov = (t != state->lt ? (nq+lq+1)>>1 : nq); + + // FILTER: perform LPF + state->fq += ((fs*(ov-state->fq) + 0x80)>>8); + ov = state->fq; + + // output sample + *(outbuf++) = ov + 128; + + state->lt = t; + } + } +} + +static av_cold int dfpwm_dec_init(struct AVCodecContext *ctx) +{ + DFPWMState *state = ctx->priv_data; + + if (ctx->channels <= 0) { + av_log(ctx, AV_LOG_ERROR, "Invalid number of channels\n"); + return AVERROR(EINVAL); + } + + state->fq = 0; + state->q = 0; + state->s = 0; + state->lt = -128; + + ctx->sample_fmt = AV_SAMPLE_FMT_U8; + ctx->bits_per_raw_sample = 8; + + return 0; +} + +static int dfpwm_dec_frame(struct AVCodecContext *ctx, void *data, + int *got_frame, struct AVPacket *packet) +{ + DFPWMState *state = ctx->priv_data; + AVFrame *frame = data; + int ret; + + frame->nb_samples = packet->size * 8 / ctx->channels; + if (frame->nb_samples <= 0) { + av_log(ctx, AV_LOG_ERROR, "invalid number of samples in packet\n"); + return AVERROR_INVALIDDATA; + } + + if ((ret = ff_get_buffer(ctx, frame, 0)) < 0) + return ret; + + au_decompress(state, 140, packet->size, frame->data[0], packet->data); + + *got_frame = 1; + return packet->size; +} + +const AVCodec ff_dfpwm_decoder = { + .name = "dfpwm", + .long_name = NULL_IF_CONFIG_SMALL("DFPWM1a audio"), + .type = AVMEDIA_TYPE_AUDIO, + .id = AV_CODEC_ID_DFPWM, + .priv_data_size = sizeof(DFPWMState), + .init = dfpwm_dec_init, + .decode = dfpwm_dec_frame, + .capabilities = AV_CODEC_CAP_DR1, + .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE, +}; |