FFmpeg: libavformat/bit.c Source File

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libavformat

bit.c

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1 /*

2 * G.729 bit format muxer and demuxer

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 #include "avformat.h"

22 #include "internal.h"

23 #include "libavcodec/get_bits.h"

24 #include "libavcodec/put_bits.h"

26 #define MAX_FRAME_SIZE 10

28 #define SYNC_WORD 0x6b21

29 #define BIT_0 0x7f

30 #define BIT_1 0x81

32 static int probe(AVProbeData *p)

33 {

34 int i, j;

36 if(p->buf_size < 0x40)

37 return 0;

39 for(i=0; i+3<p->buf_size && i< 10*0x50; ){

40 if(AV_RL16(&p->buf[0]) != SYNC_WORD)

41 return 0;

42 j=AV_RL16(&p->buf[2]);

43 if(j!=0x40 && j!=0x50)

44 return 0;

45 i+=j;

46 }

47 return AVPROBE_SCORE_MAX/2;

48 }

50 static int read_header(AVFormatContext *s)

51 {

52 AVStream* st;

54 st=avformat_new_stream(s, NULL);

55 if (!st)

56 return AVERROR(ENOMEM);

58 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

59 st->codec->codec_id=AV_CODEC_ID_G729;

60 st->codec->sample_rate=8000;

61 st->codec->block_align = 16;

62 st->codec->channels=1;

64 avpriv_set_pts_info(st, 64, 1, 100);

65 return 0;

66 }

68 static int read_packet(AVFormatContext *s,

69 AVPacket *pkt)

70 {

71 AVIOContext *pb = s->pb;

72 PutBitContext pbo;

73 uint16_t buf[8 * MAX_FRAME_SIZE + 2];

74 int packet_size;

75 uint16_t* src=buf;

76 int i, j, ret;

77 int64_t pos= avio_tell(pb);

79 if(url_feof(pb))

80 return AVERROR_EOF;

82 avio_rl16(pb); // sync word

83 packet_size = avio_rl16(pb) / 8;

84 if(packet_size > MAX_FRAME_SIZE)

85 return AVERROR_INVALIDDATA;

87 ret = avio_read(pb, (uint8_t*)buf, (8 * packet_size) * sizeof(uint16_t));

88 if(ret<0)

89 return ret;

90 if(ret != 8 * packet_size * sizeof(uint16_t))

91 return AVERROR(EIO);

93 if (av_new_packet(pkt, packet_size) < 0)

94 return AVERROR(ENOMEM);

96 init_put_bits(&pbo, pkt->data, packet_size);

97 for(j=0; j < packet_size; j++)

98 for(i=0; i<8;i++)

99 put_bits(&pbo,1, AV_RL16(src++) == BIT_1 ? 1 : 0);

100

101 flush_put_bits(&pbo);

102

103 pkt->duration=1;

104 pkt->pos = pos;

105 return 0;

106 }

107

108 AVInputFormat ff_bit_demuxer = {

109 .name = "bit",

110 .long_name = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),

111 .read_probe = probe,

112 .read_header = read_header,

113 .read_packet = read_packet,

114 .extensions = "bit",

115 };

116

117 #if CONFIG_MUXERS

118 static int write_header(AVFormatContext *s)

119 {

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

121

122 enc->codec_id = AV_CODEC_ID_G729;

123 enc->channels = 1;

124 enc->bits_per_coded_sample = 16;

125 enc->block_align = (enc->bits_per_coded_sample * enc->channels) >> 3;

126

127 return 0;

128 }

129

130 static int write_packet(AVFormatContext *s, AVPacket *pkt)

131 {

132 AVIOContext *pb = s->pb;

133 GetBitContext gb;

134 int i;

135

136 avio_wl16(pb, SYNC_WORD);

137 avio_wl16(pb, 8 * 10);

138

139 init_get_bits(&gb, pkt->data, 8*10);

140 for(i=0; i< 8 * 10; i++)

141 avio_wl16(pb, get_bits1(&gb) ? BIT_1 : BIT_0);

142 avio_flush(pb);

143

144 return 0;

145 }

146

147 AVOutputFormat ff_bit_muxer = {

148 .name = "bit",

149 .long_name = NULL_IF_CONFIG_SMALL("G.729 BIT file format"),

150 .mime_type = "audio/bit",

151 .extensions = "bit",

152 .audio_codec = AV_CODEC_ID_G729,

153 .video_codec = AV_CODEC_ID_NONE,

154 .write_header = write_header,

155 .write_packet = write_packet,

156 };

157 #endif

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