122 lines
3.5 KiB
C
122 lines
3.5 KiB
C
/*
|
|
* DFPWM encoder
|
|
* 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 encoder
|
|
*/
|
|
|
|
#include "libavutil/internal.h"
|
|
#include "avcodec.h"
|
|
#include "codec_id.h"
|
|
#include "codec_internal.h"
|
|
#include "encode.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
|
|
|
|
// note, len denotes how many compressed bytes there are (uncompressed bytes / 8).
|
|
static void au_compress(DFPWMState *state, int len, uint8_t *outbuf, const uint8_t *inbuf)
|
|
{
|
|
unsigned d = 0;
|
|
for (int i = 0; i < len; i++) {
|
|
for (int j = 0; j < 8; j++) {
|
|
int nq, st, ns;
|
|
// get sample
|
|
int v = *(inbuf++) - 128;
|
|
// set bit / target
|
|
int t = (v > state->q || (v == state->q && v == 127) ? 127 : -128);
|
|
d >>= 1;
|
|
if(t > 0)
|
|
d |= 0x80;
|
|
|
|
// adjust charge
|
|
nq = state->q + ((state->s * (t-state->q) + 512)>>10);
|
|
if(nq == state->q && nq != t)
|
|
nq += (t == 127 ? 1 : -1);
|
|
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;
|
|
|
|
state->lt = t;
|
|
}
|
|
|
|
// output bits
|
|
*(outbuf++) = d;
|
|
}
|
|
}
|
|
|
|
static av_cold int dfpwm_enc_init(struct AVCodecContext *ctx)
|
|
{
|
|
DFPWMState *state = ctx->priv_data;
|
|
|
|
state->fq = 0;
|
|
state->q = 0;
|
|
state->s = 0;
|
|
state->lt = -128;
|
|
|
|
ctx->bits_per_coded_sample = 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dfpwm_enc_frame(struct AVCodecContext *ctx, struct AVPacket *packet,
|
|
const struct AVFrame *frame, int *got_packet)
|
|
{
|
|
DFPWMState *state = ctx->priv_data;
|
|
int size = frame->nb_samples * frame->ch_layout.nb_channels / 8 + (frame->nb_samples % 8 > 0 ? 1 : 0);
|
|
int ret = ff_get_encode_buffer(ctx, packet, size, 0);
|
|
|
|
if (ret) {
|
|
*got_packet = 0;
|
|
return ret;
|
|
}
|
|
|
|
au_compress(state, size, packet->data, frame->data[0]);
|
|
|
|
*got_packet = 1;
|
|
return 0;
|
|
}
|
|
|
|
const FFCodec ff_dfpwm_encoder = {
|
|
.p.name = "dfpwm",
|
|
CODEC_LONG_NAME("DFPWM1a audio"),
|
|
.p.type = AVMEDIA_TYPE_AUDIO,
|
|
.p.id = AV_CODEC_ID_DFPWM,
|
|
.priv_data_size = sizeof(DFPWMState),
|
|
.init = dfpwm_enc_init,
|
|
FF_CODEC_ENCODE_CB(dfpwm_enc_frame),
|
|
.p.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_U8, AV_SAMPLE_FMT_NONE},
|
|
.p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_VARIABLE_FRAME_SIZE |
|
|
AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
|
|
};
|