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4243da4ff4
This is possible, because every given FFCodec has to implement exactly one of these. Doing so decreases sizeof(FFCodec) and therefore decreases the size of the binary. Notice that in case of position-independent code the decrease is in .data.rel.ro, so that this translates to decreased memory consumption. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
122 lines
3.5 KiB
C
122 lines
3.5 KiB
C
/*
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* DFPWM encoder
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* Copyright (c) 2022 Jack Bruienne
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* Copyright (c) 2012, 2016 Ben "GreaseMonkey" Russell
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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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/**
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* @file
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* DFPWM1a encoder
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*/
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#include "libavutil/internal.h"
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#include "avcodec.h"
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#include "codec_id.h"
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#include "codec_internal.h"
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#include "encode.h"
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typedef struct {
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int fq, q, s, lt;
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} DFPWMState;
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// DFPWM codec from https://github.com/ChenThread/dfpwm/blob/master/1a/
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// Licensed in the public domain
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// note, len denotes how many compressed bytes there are (uncompressed bytes / 8).
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static void au_compress(DFPWMState *state, int len, uint8_t *outbuf, uint8_t *inbuf)
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{
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unsigned d = 0;
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for (int i = 0; i < len; i++) {
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for (int j = 0; j < 8; j++) {
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int nq, st, ns;
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// get sample
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int v = *(inbuf++) - 128;
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// set bit / target
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int t = (v > state->q || (v == state->q && v == 127) ? 127 : -128);
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d >>= 1;
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if(t > 0)
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d |= 0x80;
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// adjust charge
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nq = state->q + ((state->s * (t-state->q) + 512)>>10);
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if(nq == state->q && nq != t)
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nq += (t == 127 ? 1 : -1);
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state->q = nq;
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// adjust strength
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st = (t != state->lt ? 0 : 1023);
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ns = state->s;
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if(ns != st)
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ns += (st != 0 ? 1 : -1);
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if(ns < 8) ns = 8;
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state->s = ns;
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state->lt = t;
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}
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// output bits
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*(outbuf++) = d;
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}
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}
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static av_cold int dfpwm_enc_init(struct AVCodecContext *ctx)
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{
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DFPWMState *state = ctx->priv_data;
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state->fq = 0;
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state->q = 0;
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state->s = 0;
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state->lt = -128;
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ctx->bits_per_coded_sample = 1;
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return 0;
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}
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static int dfpwm_enc_frame(struct AVCodecContext *ctx, struct AVPacket *packet,
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const struct AVFrame *frame, int *got_packet)
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{
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DFPWMState *state = ctx->priv_data;
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int size = frame->nb_samples * frame->ch_layout.nb_channels / 8 + (frame->nb_samples % 8 > 0 ? 1 : 0);
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int ret = ff_get_encode_buffer(ctx, packet, size, 0);
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if (ret) {
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*got_packet = 0;
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return ret;
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}
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au_compress(state, size, packet->data, frame->data[0]);
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*got_packet = 1;
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return 0;
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}
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const FFCodec ff_dfpwm_encoder = {
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.p.name = "dfpwm",
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.p.long_name = NULL_IF_CONFIG_SMALL("DFPWM1a audio"),
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.p.type = AVMEDIA_TYPE_AUDIO,
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.p.id = AV_CODEC_ID_DFPWM,
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.priv_data_size = sizeof(DFPWMState),
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.init = dfpwm_enc_init,
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FF_CODEC_ENCODE_CB(dfpwm_enc_frame),
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.p.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_U8, AV_SAMPLE_FMT_NONE},
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.p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_VARIABLE_FRAME_SIZE,
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.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
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};
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