1/*
2 * Copyright (c) 2020 Marton Balint
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 "bsf.h"
22#include "bsf_internal.h"
23#include "libavutil/avassert.h"
24#include "libavutil/opt.h"
25
26typedef struct PCMContext {
27    const AVClass *class;
28
29    int nb_out_samples;
30    int pad;
31    AVRational frame_rate;
32
33    AVPacket *in_pkt;
34    AVPacket *out_pkt;
35    int sample_size;
36    int64_t n;
37} PCMContext;
38
39static int init(AVBSFContext *ctx)
40{
41    PCMContext *s = ctx->priv_data;
42    AVRational sr = av_make_q(ctx->par_in->sample_rate, 1);
43    int64_t min_samples;
44
45    if (ctx->par_in->ch_layout.nb_channels <= 0 || ctx->par_in->sample_rate <= 0)
46        return AVERROR(EINVAL);
47
48    ctx->time_base_out = av_inv_q(sr);
49    s->sample_size = ctx->par_in->ch_layout.nb_channels *
50                     av_get_bits_per_sample(ctx->par_in->codec_id) / 8;
51
52    if (s->frame_rate.num) {
53        min_samples = av_rescale_q_rnd(1, sr, s->frame_rate, AV_ROUND_DOWN);
54    } else {
55        min_samples = s->nb_out_samples;
56    }
57    if (min_samples <= 0 || min_samples > INT_MAX / s->sample_size - 1)
58        return AVERROR(EINVAL);
59
60    s->in_pkt  = av_packet_alloc();
61    s->out_pkt = av_packet_alloc();
62    if (!s->in_pkt || !s->out_pkt)
63        return AVERROR(ENOMEM);
64
65    return 0;
66}
67
68static void uninit(AVBSFContext *ctx)
69{
70    PCMContext *s = ctx->priv_data;
71    av_packet_free(&s->in_pkt);
72    av_packet_free(&s->out_pkt);
73}
74
75static void flush(AVBSFContext *ctx)
76{
77    PCMContext *s = ctx->priv_data;
78    av_packet_unref(s->in_pkt);
79    av_packet_unref(s->out_pkt);
80    s->n = 0;
81}
82
83static int send_packet(PCMContext *s, int nb_samples, AVPacket *pkt)
84{
85    pkt->duration = nb_samples;
86    s->n++;
87    return 0;
88}
89
90static void drain_packet(AVPacket *pkt, int drain_data, int drain_samples)
91{
92    pkt->size -= drain_data;
93    pkt->data += drain_data;
94    if (pkt->dts != AV_NOPTS_VALUE)
95        pkt->dts += drain_samples;
96    if (pkt->pts != AV_NOPTS_VALUE)
97        pkt->pts += drain_samples;
98}
99
100static int get_next_nb_samples(AVBSFContext *ctx)
101{
102    PCMContext *s = ctx->priv_data;
103    if (s->frame_rate.num) {
104        AVRational sr = av_make_q(ctx->par_in->sample_rate, 1);
105        return av_rescale_q(s->n + 1, sr, s->frame_rate) - av_rescale_q(s->n, sr, s->frame_rate);
106    } else {
107        return s->nb_out_samples;
108    }
109}
110
111static int rechunk_filter(AVBSFContext *ctx, AVPacket *pkt)
112{
113    PCMContext *s = ctx->priv_data;
114    int nb_samples = get_next_nb_samples(ctx);
115    int data_size = nb_samples * s->sample_size;
116    int ret;
117
118    do {
119        if (s->in_pkt->size) {
120            if (s->out_pkt->size || s->in_pkt->size < data_size) {
121                int drain = FFMIN(s->in_pkt->size, data_size - s->out_pkt->size);
122                if (!s->out_pkt->size) {
123                    ret = av_new_packet(s->out_pkt, data_size);
124                    if (ret < 0)
125                        return ret;
126                    ret = av_packet_copy_props(s->out_pkt, s->in_pkt);
127                    if (ret < 0) {
128                        av_packet_unref(s->out_pkt);
129                        return ret;
130                    }
131                    s->out_pkt->size = 0;
132                }
133                memcpy(s->out_pkt->data + s->out_pkt->size, s->in_pkt->data, drain);
134                s->out_pkt->size += drain;
135                drain_packet(s->in_pkt, drain, drain / s->sample_size);
136                if (!s->in_pkt->size)
137                    av_packet_unref(s->in_pkt);
138                if (s->out_pkt->size == data_size) {
139                    av_packet_move_ref(pkt, s->out_pkt);
140                    return send_packet(s, nb_samples, pkt);
141                }
142            } else if (s->in_pkt->size > data_size) {
143                ret = av_packet_ref(pkt, s->in_pkt);
144                if (ret < 0)
145                    return ret;
146                pkt->size = data_size;
147                drain_packet(s->in_pkt, data_size, nb_samples);
148                return send_packet(s, nb_samples, pkt);
149            } else {
150                av_assert0(s->in_pkt->size == data_size);
151                av_packet_move_ref(pkt, s->in_pkt);
152                return send_packet(s, nb_samples, pkt);
153            }
154        }
155
156        ret = ff_bsf_get_packet_ref(ctx, s->in_pkt);
157        if (ret == AVERROR_EOF && s->out_pkt->size) {
158            if (s->pad) {
159                memset(s->out_pkt->data + s->out_pkt->size, 0, data_size - s->out_pkt->size);
160                s->out_pkt->size = data_size;
161            } else {
162                nb_samples = s->out_pkt->size / s->sample_size;
163            }
164            av_packet_move_ref(pkt, s->out_pkt);
165            return send_packet(s, nb_samples, pkt);
166        }
167        if (ret >= 0)
168            av_packet_rescale_ts(s->in_pkt, ctx->time_base_in, ctx->time_base_out);
169    } while (ret >= 0);
170
171    return ret;
172}
173
174#define OFFSET(x) offsetof(PCMContext, x)
175#define FLAGS (AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_BSF_PARAM)
176static const AVOption options[] = {
177    { "nb_out_samples", "set the number of per-packet output samples", OFFSET(nb_out_samples),   AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, FLAGS },
178    { "n",              "set the number of per-packet output samples", OFFSET(nb_out_samples),   AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, FLAGS },
179    { "pad",            "pad last packet with zeros",                  OFFSET(pad),             AV_OPT_TYPE_BOOL, {.i64=1} ,   0,       1, FLAGS },
180    { "p",              "pad last packet with zeros",                  OFFSET(pad),             AV_OPT_TYPE_BOOL, {.i64=1} ,   0,       1, FLAGS },
181    { "frame_rate",     "set number of packets per second",            OFFSET(frame_rate),  AV_OPT_TYPE_RATIONAL, {.dbl=0},    0, INT_MAX, FLAGS },
182    { "r",              "set number of packets per second",            OFFSET(frame_rate),  AV_OPT_TYPE_RATIONAL, {.dbl=0},    0, INT_MAX, FLAGS },
183    { NULL },
184};
185
186static const AVClass pcm_rechunk_class = {
187    .class_name = "pcm_rechunk_bsf",
188    .item_name  = av_default_item_name,
189    .option     = options,
190    .version    = LIBAVUTIL_VERSION_INT,
191};
192
193static const enum AVCodecID codec_ids[] = {
194    AV_CODEC_ID_PCM_S16LE,
195    AV_CODEC_ID_PCM_S16BE,
196    AV_CODEC_ID_PCM_S8,
197    AV_CODEC_ID_PCM_S32LE,
198    AV_CODEC_ID_PCM_S32BE,
199    AV_CODEC_ID_PCM_S24LE,
200    AV_CODEC_ID_PCM_S24BE,
201    AV_CODEC_ID_PCM_F32BE,
202    AV_CODEC_ID_PCM_F32LE,
203    AV_CODEC_ID_PCM_F64BE,
204    AV_CODEC_ID_PCM_F64LE,
205    AV_CODEC_ID_PCM_S64LE,
206    AV_CODEC_ID_PCM_S64BE,
207    AV_CODEC_ID_PCM_F16LE,
208    AV_CODEC_ID_PCM_F24LE,
209    AV_CODEC_ID_NONE,
210};
211
212const FFBitStreamFilter ff_pcm_rechunk_bsf = {
213    .p.name         = "pcm_rechunk",
214    .p.codec_ids    = codec_ids,
215    .p.priv_class   = &pcm_rechunk_class,
216    .priv_data_size = sizeof(PCMContext),
217    .filter         = rechunk_filter,
218    .init           = init,
219    .flush          = flush,
220    .close          = uninit,
221};
222