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 
26 typedef 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 
init(AVBSFContext *ctx)39 static 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 
uninit(AVBSFContext *ctx)68 static 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 
flush(AVBSFContext *ctx)75 static 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 
send_packet(PCMContext *s, int nb_samples, AVPacket *pkt)83 static int send_packet(PCMContext *s, int nb_samples, AVPacket *pkt)
84 {
85     pkt->duration = nb_samples;
86     s->n++;
87     return 0;
88 }
89 
drain_packet(AVPacket *pkt, int drain_data, int drain_samples)90 static 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 
get_next_nb_samples(AVBSFContext *ctx)100 static 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 
rechunk_filter(AVBSFContext *ctx, AVPacket *pkt)111 static 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)
176 static 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 
186 static 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 
193 static 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 
212 const 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