FFmpeg  2.6.9
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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  int64_t len;
54  uint8_t *p, *p0;
55 
57 
58  len = ff_vorbiscomment_length(*m, vendor);
59  if (len >= ((1<<24) - 4))
60  return AVERROR(EINVAL);
61  p0 = av_malloc(len+4);
62  if (!p0)
63  return AVERROR(ENOMEM);
64  p = p0;
65 
66  bytestream_put_byte(&p, last_block ? 0x84 : 0x04);
67  bytestream_put_be24(&p, len);
68  ff_vorbiscomment_write(&p, m, vendor);
69 
70  avio_write(pb, p0, len+4);
71  av_freep(&p0);
72  p = NULL;
73 
74  return 0;
75 }
76 
77 static int flac_write_header(struct AVFormatContext *s)
78 {
79  int ret;
80  int padding = s->metadata_header_padding;
81  AVCodecContext *codec = s->streams[0]->codec;
83 
84  if (!c->write_header)
85  return 0;
86 
87  if (s->nb_streams > 1) {
88  av_log(s, AV_LOG_ERROR, "only one stream is supported\n");
89  return AVERROR(EINVAL);
90  }
91  if (codec->codec_id != AV_CODEC_ID_FLAC) {
92  av_log(s, AV_LOG_ERROR, "unsupported codec\n");
93  return AVERROR(EINVAL);
94  }
95 
96  if (padding < 0)
97  padding = 8192;
98  /* The FLAC specification states that 24 bits are used to represent the
99  * size of a metadata block so we must clip this value to 2^24-1. */
100  padding = av_clip_uintp2(padding, 24);
101 
102  ret = ff_flac_write_header(s->pb, codec->extradata,
103  codec->extradata_size, 0);
104  if (ret)
105  return ret;
106 
107  /* add the channel layout tag */
108  if (codec->channel_layout &&
109  !(codec->channel_layout & ~0x3ffffULL) &&
111  AVDictionaryEntry *chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK",
112  NULL, 0);
113 
114  if (chmask) {
115  av_log(s, AV_LOG_WARNING, "A WAVEFORMATEXTENSIBLE_CHANNEL_MASK is "
116  "already present, this muxer will not overwrite it.\n");
117  } else {
118  uint8_t buf[32];
119  snprintf(buf, sizeof(buf), "0x%"PRIx64, codec->channel_layout);
120  av_dict_set(&s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", buf, 0);
121  }
122  }
123 
124  ret = flac_write_block_comment(s->pb, &s->metadata, !padding,
126  if (ret)
127  return ret;
128 
129  /* The command line flac encoder defaults to placing a seekpoint
130  * every 10s. So one might add padding to allow that later
131  * but there seems to be no simple way to get the duration here.
132  * So just add the amount requested by the user. */
133  if (padding)
134  flac_write_block_padding(s->pb, padding, 1);
135 
136  return ret;
137 }
138 
140 {
141  AVIOContext *pb = s->pb;
142  int64_t file_size;
144  uint8_t *streaminfo = c->streaminfo ? c->streaminfo :
145  s->streams[0]->codec->extradata;
146 
147  if (!c->write_header || !streaminfo)
148  return 0;
149 
150  if (pb->seekable) {
151  /* rewrite the STREAMINFO header block data */
152  file_size = avio_tell(pb);
153  avio_seek(pb, 8, SEEK_SET);
154  avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
155  avio_seek(pb, file_size, SEEK_SET);
156  avio_flush(pb);
157  } else {
158  av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
159  }
160 
161  av_freep(&c->streaminfo);
162 
163  return 0;
164 }
165 
167 {
169  uint8_t *streaminfo;
170  int streaminfo_size;
171 
172  /* check for updated streaminfo */
174  &streaminfo_size);
175  if (streaminfo && streaminfo_size == FLAC_STREAMINFO_SIZE) {
176  av_freep(&c->streaminfo);
177 
179  if (!c->streaminfo)
180  return AVERROR(ENOMEM);
181  memcpy(c->streaminfo, streaminfo, FLAC_STREAMINFO_SIZE);
182  }
183 
184  if (pkt->size)
185  avio_write(s->pb, pkt->data, pkt->size);
186  return 0;
187 }
188 
189 static const AVOption flacenc_options[] = {
190  { "write_header", "Write the file header", offsetof(FlacMuxerContext, write_header), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
191  { NULL },
192 };
193 
194 static const AVClass flac_muxer_class = {
195  .class_name = "flac muxer",
196  .item_name = av_default_item_name,
197  .option = flacenc_options,
198  .version = LIBAVUTIL_VERSION_INT,
199 };
200 
202  .name = "flac",
203  .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),
204  .priv_data_size = sizeof(FlacMuxerContext),
205  .mime_type = "audio/x-flac",
206  .extensions = "flac",
207  .audio_codec = AV_CODEC_ID_FLAC,
208  .video_codec = AV_CODEC_ID_NONE,
213  .priv_class = &flac_muxer_class,
214 };