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astenc.c
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1 /*
2  * AST muxer
3  * Copyright (c) 2012 James Almer
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "avformat.h"
23 #include "avio_internal.h"
24 #include "internal.h"
25 #include "ast.h"
26 #include "libavutil/mathematics.h"
27 #include "libavutil/opt.h"
28 
29 typedef struct ASTMuxContext {
30  AVClass *class;
31  int64_t size;
32  int64_t samples;
33  int64_t loopstart;
34  int64_t loopend;
35  int fbs;
36 } ASTMuxContext;
37 
38 #define CHECK_LOOP(type) \
39  if (ast->loop ## type > 0) { \
40  ast->loop ## type = av_rescale_rnd(ast->loop ## type, enc->sample_rate, 1000, AV_ROUND_DOWN); \
41  if (ast->loop ## type < 0 || ast->loop ## type > UINT_MAX) { \
42  av_log(s, AV_LOG_ERROR, "Invalid loop" #type " value\n"); \
43  return AVERROR(EINVAL); \
44  } \
45  }
46 
47 static int ast_write_header(AVFormatContext *s)
48 {
49  ASTMuxContext *ast = s->priv_data;
50  AVIOContext *pb = s->pb;
51  AVCodecContext *enc;
52  unsigned int codec_tag;
53 
54  if (s->nb_streams == 1) {
55  enc = s->streams[0]->codec;
56  } else {
57  av_log(s, AV_LOG_ERROR, "only one stream is supported\n");
58  return AVERROR(EINVAL);
59  }
60 
61  if (enc->codec_id == AV_CODEC_ID_ADPCM_AFC) {
62  av_log(s, AV_LOG_ERROR, "muxing ADPCM AFC is not implemented\n");
63  return AVERROR_PATCHWELCOME;
64  }
65 
66  codec_tag = ff_codec_get_tag(ff_codec_ast_tags, enc->codec_id);
67  if (!codec_tag) {
68  av_log(s, AV_LOG_ERROR, "unsupported codec\n");
69  return AVERROR(EINVAL);
70  }
71 
72  if (ast->loopend > 0 && ast->loopstart >= ast->loopend) {
73  av_log(s, AV_LOG_ERROR, "loopend can't be less or equal to loopstart\n");
74  return AVERROR(EINVAL);
75  }
76 
77  /* Convert milliseconds to samples */
78  CHECK_LOOP(start)
79  CHECK_LOOP(end)
80 
81  ffio_wfourcc(pb, "STRM");
82 
83  ast->size = avio_tell(pb);
84  avio_wb32(pb, 0); /* File size minus header */
85  avio_wb16(pb, codec_tag);
86  avio_wb16(pb, 16); /* Bit depth */
87  avio_wb16(pb, enc->channels);
88  avio_wb16(pb, 0); /* Loop flag */
89  avio_wb32(pb, enc->sample_rate);
90 
91  ast->samples = avio_tell(pb);
92  avio_wb32(pb, 0); /* Number of samples */
93  avio_wb32(pb, 0); /* Loopstart */
94  avio_wb32(pb, 0); /* Loopend */
95  avio_wb32(pb, 0); /* Size of first block */
96 
97  /* Unknown */
98  avio_wb32(pb, 0);
99  avio_wl32(pb, 0x7F);
100  avio_wb64(pb, 0);
101  avio_wb64(pb, 0);
102  avio_wb32(pb, 0);
103 
104  avio_flush(pb);
105 
106  return 0;
107 }
108 
109 static int ast_write_packet(AVFormatContext *s, AVPacket *pkt)
110 {
111  AVIOContext *pb = s->pb;
112  ASTMuxContext *ast = s->priv_data;
113  AVCodecContext *enc = s->streams[0]->codec;
114  int size = pkt->size / enc->channels;
115 
116  if (enc->frame_number == 1)
117  ast->fbs = size;
118 
119  ffio_wfourcc(pb, "BLCK");
120  avio_wb32(pb, size); /* Block size */
121 
122  /* padding */
123  avio_wb64(pb, 0);
124  avio_wb64(pb, 0);
125  avio_wb64(pb, 0);
126 
127  avio_write(pb, pkt->data, pkt->size);
128 
129  return 0;
130 }
131 
132 static int ast_write_trailer(AVFormatContext *s)
133 {
134  AVIOContext *pb = s->pb;
135  ASTMuxContext *ast = s->priv_data;
136  AVCodecContext *enc = s->streams[0]->codec;
137  int64_t file_size = avio_tell(pb);
138  int64_t samples = (file_size - 64 - (32 * enc->frame_number)) / enc->block_align; /* PCM_S16BE_PLANAR */
139 
140  av_log(s, AV_LOG_DEBUG, "total samples: %"PRId64"\n", samples);
141 
142  if (s->pb->seekable) {
143  /* Number of samples */
144  avio_seek(pb, ast->samples, SEEK_SET);
145  avio_wb32(pb, samples);
146 
147  /* Loopstart if provided */
148  if (ast->loopstart > 0) {
149  if (ast->loopstart >= samples) {
150  av_log(s, AV_LOG_WARNING, "Loopstart value is out of range and will be ignored\n");
151  ast->loopstart = -1;
152  avio_skip(pb, 4);
153  } else
154  avio_wb32(pb, ast->loopstart);
155  } else
156  avio_skip(pb, 4);
157 
158  /* Loopend if provided. Otherwise number of samples again */
159  if (ast->loopend && ast->loopstart >= 0) {
160  if (ast->loopend > samples) {
161  av_log(s, AV_LOG_WARNING, "Loopend value is out of range and will be ignored\n");
162  ast->loopend = samples;
163  }
164  avio_wb32(pb, ast->loopend);
165  } else {
166  avio_wb32(pb, samples);
167  }
168 
169  /* Size of first block */
170  avio_wb32(pb, ast->fbs);
171 
172  /* File size minus header */
173  avio_seek(pb, ast->size, SEEK_SET);
174  avio_wb32(pb, file_size - 64);
175 
176  /* Loop flag */
177  if (ast->loopstart >= 0) {
178  avio_skip(pb, 6);
179  avio_wb16(pb, 0xFFFF);
180  }
181 
182  avio_seek(pb, file_size, SEEK_SET);
183  avio_flush(pb);
184  }
185  return 0;
186 }
187 
188 #define OFFSET(obj) offsetof(ASTMuxContext, obj)
189 static const AVOption options[] = {
190  { "loopstart", "Loopstart position in milliseconds.", OFFSET(loopstart), AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
191  { "loopend", "Loopend position in milliseconds.", OFFSET(loopend), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
192  { NULL },
193 };
194 
195 static const AVClass ast_muxer_class = {
196  .class_name = "AST muxer",
197  .item_name = av_default_item_name,
198  .option = options,
199  .version = LIBAVUTIL_VERSION_INT,
200 };
201 
202 AVOutputFormat ff_ast_muxer = {
203  .name = "ast",
204  .long_name = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
205  .extensions = "ast",
206  .priv_data_size = sizeof(ASTMuxContext),
207  .audio_codec = AV_CODEC_ID_PCM_S16BE_PLANAR,
208  .video_codec = AV_CODEC_ID_NONE,
209  .write_header = ast_write_header,
210  .write_packet = ast_write_packet,
211  .write_trailer = ast_write_trailer,
212  .priv_class = &ast_muxer_class,
213  .codec_tag = (const AVCodecTag* const []){ff_codec_ast_tags, 0},
214 };
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