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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 
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 ? "ffmpeg" : 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  if (s->nb_streams > 1) {
73  av_log(s, AV_LOG_ERROR, "only one stream is supported\n");
74  return AVERROR(EINVAL);
75  }
76  if (codec->codec_id != AV_CODEC_ID_FLAC) {
77  av_log(s, AV_LOG_ERROR, "unsupported codec\n");
78  return AVERROR(EINVAL);
79  }
80 
81  ret = ff_flac_write_header(s->pb, codec, 0);
82  if (ret)
83  return ret;
84 
85  ret = flac_write_block_comment(s->pb, &s->metadata, 0,
86  codec->flags & CODEC_FLAG_BITEXACT);
87  if (ret)
88  return ret;
89 
90  /* The command line flac encoder defaults to placing a seekpoint
91  * every 10s. So one might add padding to allow that later
92  * but there seems to be no simple way to get the duration here.
93  * So let's try the flac default of 8192 bytes */
94  flac_write_block_padding(s->pb, 8192, 1);
95 
96  return ret;
97 }
98 
99 static int flac_write_trailer(struct AVFormatContext *s)
100 {
101  AVIOContext *pb = s->pb;
102  uint8_t *streaminfo;
103  enum FLACExtradataFormat format;
104  int64_t file_size;
105 
106  if (!avpriv_flac_is_extradata_valid(s->streams[0]->codec, &format, &streaminfo))
107  return -1;
108 
109  if (pb->seekable) {
110  /* rewrite the STREAMINFO header block data */
111  file_size = avio_tell(pb);
112  avio_seek(pb, 8, SEEK_SET);
113  avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
114  avio_seek(pb, file_size, SEEK_SET);
115  avio_flush(pb);
116  } else {
117  av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
118  }
119  return 0;
120 }
121 
123 {
124  avio_write(s->pb, pkt->data, pkt->size);
125  avio_flush(s->pb);
126  return 0;
127 }
128 
130  .name = "flac",
131  .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),
132  .mime_type = "audio/x-flac",
133  .extensions = "flac",
134  .audio_codec = AV_CODEC_ID_FLAC,
135  .video_codec = AV_CODEC_ID_NONE,
136  .write_header = flac_write_header,
137  .write_packet = flac_write_packet,
138  .write_trailer = flac_write_trailer,
139  .flags = AVFMT_NOTIMESTAMPS,
140 };