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flacenc.c
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1 /*
2  * raw FLAC muxer
3  * Copyright (c) 2006-2009 Justin Ruggles
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 
23 #include "libavutil/opt.h"
24 #include "libavcodec/flac.h"
25 #include "avformat.h"
26 #include "avio_internal.h"
27 #include "flacenc.h"
28 #include "vorbiscomment.h"
29 #include "libavcodec/bytestream.h"
30 
31 
32 typedef struct FlacMuxerContext {
33  const AVClass *class;
35 
36  /* updated streaminfo sent by the encoder at the end */
39 
40 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,
41  int last_block)
42 {
43  avio_w8(pb, last_block ? 0x81 : 0x01);
44  avio_wb24(pb, n_padding_bytes);
45  ffio_fill(pb, 0, n_padding_bytes);
46  return 0;
47 }
48 
50  int last_block, int bitexact)
51 {
52  const char *vendor = bitexact ? "ffmpeg" : LIBAVFORMAT_IDENT;
53  unsigned int len;
54  uint8_t *p, *p0;
55 
57 
58  len = ff_vorbiscomment_length(*m, vendor);
59  p0 = av_malloc(len+4);
60  if (!p0)
61  return AVERROR(ENOMEM);
62  p = p0;
63 
64  bytestream_put_byte(&p, last_block ? 0x84 : 0x04);
65  bytestream_put_be24(&p, len);
66  ff_vorbiscomment_write(&p, m, vendor);
67 
68  avio_write(pb, p0, len+4);
69  av_freep(&p0);
70  p = NULL;
71 
72  return 0;
73 }
74 
75 static int flac_write_header(struct AVFormatContext *s)
76 {
77  int ret;
78  int padding = s->metadata_header_padding;
79  AVCodecContext *codec = s->streams[0]->codec;
81 
82  if (!c->write_header)
83  return 0;
84 
85  if (s->nb_streams > 1) {
86  av_log(s, AV_LOG_ERROR, "only one stream is supported\n");
87  return AVERROR(EINVAL);
88  }
89  if (codec->codec_id != AV_CODEC_ID_FLAC) {
90  av_log(s, AV_LOG_ERROR, "unsupported codec\n");
91  return AVERROR(EINVAL);
92  }
93 
94  if (padding < 0)
95  padding = 8192;
96  /* The FLAC specification states that 24 bits are used to represent the
97  * size of a metadata block so we must clip this value to 2^24-1. */
98  padding = av_clip_c(padding, 0, 16777215);
99 
100  ret = ff_flac_write_header(s->pb, codec->extradata,
101  codec->extradata_size, 0);
102  if (ret)
103  return ret;
104 
105  /* add the channel layout tag */
106  if (codec->channel_layout &&
107  !(codec->channel_layout & ~0x3ffffULL) &&
109  AVDictionaryEntry *chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK",
110  NULL, 0);
111 
112  if (chmask) {
113  av_log(s, AV_LOG_WARNING, "A WAVEFORMATEXTENSIBLE_CHANNEL_MASK is "
114  "already present, this muxer will not overwrite it.\n");
115  } else {
116  uint8_t buf[32];
117  snprintf(buf, sizeof(buf), "0x%"PRIx64, codec->channel_layout);
118  av_dict_set(&s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", buf, 0);
119  }
120  }
121 
122  ret = flac_write_block_comment(s->pb, &s->metadata, !padding,
124  if (ret)
125  return ret;
126 
127  /* The command line flac encoder defaults to placing a seekpoint
128  * every 10s. So one might add padding to allow that later
129  * but there seems to be no simple way to get the duration here.
130  * So just add the amount requested by the user. */
131  if (padding)
132  flac_write_block_padding(s->pb, padding, 1);
133 
134  return ret;
135 }
136 
138 {
139  AVIOContext *pb = s->pb;
140  int64_t file_size;
142  uint8_t *streaminfo = c->streaminfo ? c->streaminfo :
143  s->streams[0]->codec->extradata;
144 
145  if (!c->write_header || !streaminfo)
146  return 0;
147 
148  if (pb->seekable) {
149  /* rewrite the STREAMINFO header block data */
150  file_size = avio_tell(pb);
151  avio_seek(pb, 8, SEEK_SET);
152  avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
153  avio_seek(pb, file_size, SEEK_SET);
154  avio_flush(pb);
155  } else {
156  av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
157  }
158 
159  av_freep(&c->streaminfo);
160 
161  return 0;
162 }
163 
165 {
167  uint8_t *streaminfo;
168  int streaminfo_size;
169 
170  /* check for updated streaminfo */
172  &streaminfo_size);
173  if (streaminfo && streaminfo_size == FLAC_STREAMINFO_SIZE) {
174  av_freep(&c->streaminfo);
175 
177  if (!c->streaminfo)
178  return AVERROR(ENOMEM);
179  memcpy(c->streaminfo, streaminfo, FLAC_STREAMINFO_SIZE);
180  }
181 
182  if (pkt->size)
183  avio_write(s->pb, pkt->data, pkt->size);
184  return 0;
185 }
186 
187 static const AVOption flacenc_options[] = {
188  { "write_header", "Write the file header", offsetof(FlacMuxerContext, write_header), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
189  { NULL },
190 };
191 
192 static const AVClass flac_muxer_class = {
193  .class_name = "flac muxer",
194  .item_name = av_default_item_name,
195  .option = flacenc_options,
196  .version = LIBAVUTIL_VERSION_INT,
197 };
198 
200  .name = "flac",
201  .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),
202  .priv_data_size = sizeof(FlacMuxerContext),
203  .mime_type = "audio/x-flac",
204  .extensions = "flac",
205  .audio_codec = AV_CODEC_ID_FLAC,
206  .video_codec = AV_CODEC_ID_NONE,
211  .priv_class = &flac_muxer_class,
212 };