Libav
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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/opt.h"
23 #include "libavcodec/flac.h"
24 #include "avformat.h"
25 #include "flacenc.h"
26 #include "vorbiscomment.h"
27 #include "libavcodec/bytestream.h"
28 
29 
30 typedef struct FlacMuxerContext {
31  const AVClass *class;
34 
35 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,
36  int last_block)
37 {
38  avio_w8(pb, last_block ? 0x81 : 0x01);
39  avio_wb24(pb, n_padding_bytes);
40  while (n_padding_bytes > 0) {
41  avio_w8(pb, 0);
42  n_padding_bytes--;
43  }
44  return 0;
45 }
46 
48  int last_block, int bitexact)
49 {
50  const char *vendor = bitexact ? "Libav" : LIBAVFORMAT_IDENT;
51  unsigned int len, count;
52  uint8_t *p, *p0;
53 
55 
56  len = ff_vorbiscomment_length(*m, vendor, &count);
57  p0 = av_malloc(len+4);
58  if (!p0)
59  return AVERROR(ENOMEM);
60  p = p0;
61 
62  bytestream_put_byte(&p, last_block ? 0x84 : 0x04);
63  bytestream_put_be24(&p, len);
64  ff_vorbiscomment_write(&p, m, vendor, count);
65 
66  avio_write(pb, p0, len+4);
67  av_freep(&p0);
68  p = NULL;
69 
70  return 0;
71 }
72 
73 static int flac_write_header(struct AVFormatContext *s)
74 {
75  int ret;
76  AVCodecContext *codec = s->streams[0]->codec;
78 
79  if (!c->write_header)
80  return 0;
81 
82  ret = ff_flac_write_header(s->pb, codec, 0);
83  if (ret)
84  return ret;
85 
86  ret = flac_write_block_comment(s->pb, &s->metadata, 0,
87  codec->flags & CODEC_FLAG_BITEXACT);
88  if (ret)
89  return ret;
90 
91  /* The command line flac encoder defaults to placing a seekpoint
92  * every 10s. So one might add padding to allow that later
93  * but there seems to be no simple way to get the duration here.
94  * So let's try the flac default of 8192 bytes */
95  flac_write_block_padding(s->pb, 8192, 1);
96 
97  return ret;
98 }
99 
100 static int flac_write_trailer(struct AVFormatContext *s)
101 {
102  AVIOContext *pb = s->pb;
103  uint8_t *streaminfo;
104  enum FLACExtradataFormat format;
105  int64_t file_size;
106  FlacMuxerContext *c = s->priv_data;
107 
108  if (!c->write_header)
109  return 0;
110 
111  if (!avpriv_flac_is_extradata_valid(s->streams[0]->codec, &format, &streaminfo))
112  return -1;
113 
114  if (pb->seekable) {
115  /* rewrite the STREAMINFO header block data */
116  file_size = avio_tell(pb);
117  avio_seek(pb, 8, SEEK_SET);
118  avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
119  avio_seek(pb, file_size, SEEK_SET);
120  avio_flush(pb);
121  } else {
122  av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
123  }
124  return 0;
125 }
126 
127 static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)
128 {
129  avio_write(s->pb, pkt->data, pkt->size);
130  return 0;
131 }
132 
133 static const AVOption flacenc_options[] = {
134  { "write_header", "Write the file header", offsetof(FlacMuxerContext, write_header), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
135  { NULL },
136 };
137 
138 static const AVClass flac_muxer_class = {
139  .class_name = "flac muxer",
140  .item_name = av_default_item_name,
141  .option = flacenc_options,
142  .version = LIBAVUTIL_VERSION_INT,
143 };
144 
146  .name = "flac",
147  .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),
148  .priv_data_size = sizeof(FlacMuxerContext),
149  .mime_type = "audio/x-flac",
150  .extensions = "flac",
151  .audio_codec = AV_CODEC_ID_FLAC,
152  .video_codec = AV_CODEC_ID_NONE,
157  .priv_class = &flac_muxer_class,
158 };