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 "libavcodec/flac.h"
23 #include "avformat.h"
24 #include "flacenc.h"
25 #include "vorbiscomment.h"
26 #include "libavcodec/bytestream.h"
27 
28 
29 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,
30  int last_block)
31 {
32  avio_w8(pb, last_block ? 0x81 : 0x01);
33  avio_wb24(pb, n_padding_bytes);
34  while (n_padding_bytes > 0) {
35  avio_w8(pb, 0);
36  n_padding_bytes--;
37  }
38  return 0;
39 }
40 
42  int last_block, int bitexact)
43 {
44  const char *vendor = bitexact ? "Libav" : LIBAVFORMAT_IDENT;
45  unsigned int len, count;
46  uint8_t *p, *p0;
47 
49 
50  len = ff_vorbiscomment_length(*m, vendor, &count);
51  p0 = av_malloc(len+4);
52  if (!p0)
53  return AVERROR(ENOMEM);
54  p = p0;
55 
56  bytestream_put_byte(&p, last_block ? 0x84 : 0x04);
57  bytestream_put_be24(&p, len);
58  ff_vorbiscomment_write(&p, m, vendor, count);
59 
60  avio_write(pb, p0, len+4);
61  av_freep(&p0);
62  p = NULL;
63 
64  return 0;
65 }
66 
67 static int flac_write_header(struct AVFormatContext *s)
68 {
69  int ret;
70  AVCodecContext *codec = s->streams[0]->codec;
71 
72  ret = ff_flac_write_header(s->pb, codec, 0);
73  if (ret)
74  return ret;
75 
76  ret = flac_write_block_comment(s->pb, &s->metadata, 0,
77  codec->flags & CODEC_FLAG_BITEXACT);
78  if (ret)
79  return ret;
80 
81  /* The command line flac encoder defaults to placing a seekpoint
82  * every 10s. So one might add padding to allow that later
83  * but there seems to be no simple way to get the duration here.
84  * So let's try the flac default of 8192 bytes */
85  flac_write_block_padding(s->pb, 8192, 1);
86 
87  return ret;
88 }
89 
90 static int flac_write_trailer(struct AVFormatContext *s)
91 {
92  AVIOContext *pb = s->pb;
93  uint8_t *streaminfo;
94  enum FLACExtradataFormat format;
95  int64_t file_size;
96 
97  if (!avpriv_flac_is_extradata_valid(s->streams[0]->codec, &format, &streaminfo))
98  return -1;
99 
100  if (pb->seekable) {
101  /* rewrite the STREAMINFO header block data */
102  file_size = avio_tell(pb);
103  avio_seek(pb, 8, SEEK_SET);
104  avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
105  avio_seek(pb, file_size, SEEK_SET);
106  avio_flush(pb);
107  } else {
108  av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
109  }
110  return 0;
111 }
112 
113 static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)
114 {
115  avio_write(s->pb, pkt->data, pkt->size);
116  avio_flush(s->pb);
117  return 0;
118 }
119 
121  .name = "flac",
122  .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),
123  .mime_type = "audio/x-flac",
124  .extensions = "flac",
125  .audio_codec = CODEC_ID_FLAC,
126  .video_codec = CODEC_ID_NONE,
127  .write_header = flac_write_header,
128  .write_packet = flac_write_packet,
129  .write_trailer = flac_write_trailer,
130  .flags= AVFMT_NOTIMESTAMPS,
131 };