FFmpeg: libavformat/flacenc.c Source File

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libavformat

flacenc.c

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1 /*

2 * raw FLAC muxer

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 */

22 #include "libavcodec/flac.h"

23 #include "avformat.h"

24 #include "avio_internal.h"

25 #include "flacenc.h"

26 #include "vorbiscomment.h"

27 #include "libavcodec/bytestream.h"

30 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,

31 int last_block)

32 {

33 avio_w8(pb, last_block ? 0x81 : 0x01);

34 avio_wb24(pb, n_padding_bytes);

35 ffio_fill(pb, 0, n_padding_bytes);

36 return 0;

37 }

39 static int flac_write_block_comment(AVIOContext *pb, AVDictionary **m,

40 int last_block, int bitexact)

41 {

42 const char *vendor = bitexact ? "ffmpeg" : LIBAVFORMAT_IDENT;

43 unsigned int len, count;

44 uint8_t *p, *p0;

46 ff_metadata_conv(m, ff_vorbiscomment_metadata_conv, NULL);

48 len = ff_vorbiscomment_length(*m, vendor, &count);

49 p0 = av_malloc(len+4);

50 if (!p0)

51 return AVERROR(ENOMEM);

52 p = p0;

54 bytestream_put_byte(&p, last_block ? 0x84 : 0x04);

55 bytestream_put_be24(&p, len);

56 ff_vorbiscomment_write(&p, m, vendor, count);

58 avio_write(pb, p0, len+4);

59 av_freep(&p0);

60 p = NULL;

62 return 0;

63 }

65 static int flac_write_header(struct AVFormatContext *s)

66 {

67 int ret;

68 AVCodecContext *codec = s->streams[0]->codec;

70 if (s->nb_streams > 1) {

71 av_log(s, AV_LOG_ERROR, "only one stream is supported\n");

72 return AVERROR(EINVAL);

73 }

74 if (codec->codec_id != AV_CODEC_ID_FLAC) {

75 av_log(s, AV_LOG_ERROR, "unsupported codec\n");

76 return AVERROR(EINVAL);

77 }

79 ret = ff_flac_write_header(s->pb, codec, 0);

80 if (ret)

81 return ret;

83 ret = flac_write_block_comment(s->pb, &s->metadata, 0,

84 codec->flags & CODEC_FLAG_BITEXACT);

85 if (ret)

86 return ret;

88 /* The command line flac encoder defaults to placing a seekpoint

89 * every 10s. So one might add padding to allow that later

90 * but there seems to be no simple way to get the duration here.

91 * So let's try the flac default of 8192 bytes */

92 flac_write_block_padding(s->pb, 8192, 1);

94 return ret;

95 }

97 static int flac_write_trailer(struct AVFormatContext *s)

98 {

99 AVIOContext *pb = s->pb;

100 uint8_t *streaminfo;

101 enum FLACExtradataFormat format;

102 int64_t file_size;

103

104 if (!avpriv_flac_is_extradata_valid(s->streams[0]->codec, &format, &streaminfo))

105 return -1;

106

107 if (pb->seekable) {

108 /* rewrite the STREAMINFO header block data */

109 file_size = avio_tell(pb);

110 avio_seek(pb, 8, SEEK_SET);

111 avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);

112 avio_seek(pb, file_size, SEEK_SET);

113 avio_flush(pb);

114 } else {

115 av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");

116 }

117 return 0;

118 }

119

120 static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)

121 {

122 avio_write(s->pb, pkt->data, pkt->size);

123 return 0;

124 }

125

126 AVOutputFormat ff_flac_muxer = {

127 .name = "flac",

128 .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),

129 .mime_type = "audio/x-flac",

130 .extensions = "flac",

131 .audio_codec = AV_CODEC_ID_FLAC,

132 .video_codec = AV_CODEC_ID_NONE,

133 .write_header = flac_write_header,

134 .write_packet = flac_write_packet,

135 .write_trailer = flac_write_trailer,

136 .flags = AVFMT_NOTIMESTAMPS,

137 };

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