FFmpeg: libavcodec/mpeg4audio.c Source File

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libavcodec

mpeg4audio.c

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1 /*

2 * MPEG-4 Audio common code

5 *

6 * This file is part of FFmpeg.

7 *

8 * FFmpeg is free software; you can redistribute it and/or

9 * modify it under the terms of the GNU Lesser General Public

10 * License as published by the Free Software Foundation; either

11 * version 2.1 of the License, or (at your option) any later version.

12 *

13 * FFmpeg is distributed in the hope that it will be useful,

14 * but WITHOUT ANY WARRANTY; without even the implied warranty of

15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

16 * Lesser General Public License for more details.

17 *

18 * You should have received a copy of the GNU Lesser General Public

19 * License along with FFmpeg; if not, write to the Free Software

20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

21 */

23 #include "get_bits.h"

24 #include "put_bits.h"

25 #include "mpeg4audio.h"

27 /**

28 * Parse MPEG-4 audio configuration for ALS object type.

29 * @param[in] gb bit reader context

30 * @param[in] c MPEG4AudioConfig structure to fill

31 * @return on success 0 is returned, otherwise a value < 0

32 */

33 static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)

34 {

35 if (get_bits_left(gb) < 112)

36 return -1;

38 if (get_bits_long(gb, 32) != MKBETAG('A','L','S','0円'))

39 return -1;

41 // override AudioSpecificConfig channel configuration and sample rate

42 // which are buggy in old ALS conformance files

43 c->sample_rate = get_bits_long(gb, 32);

45 // skip number of samples

46 skip_bits_long(gb, 32);

48 // read number of channels

49 c->chan_config = 0;

50 c->channels = get_bits(gb, 16) + 1;

52 return 0;

53 }

55 /* XXX: make sure to update the copies in the different encoders if you change

56 * this table */

57 const int avpriv_mpeg4audio_sample_rates[16] = {

58 96000, 88200, 64000, 48000, 44100, 32000,

59 24000, 22050, 16000, 12000, 11025, 8000, 7350

60 };

62 const uint8_t ff_mpeg4audio_channels[8] = {

63 0, 1, 2, 3, 4, 5, 6, 8

64 };

66 static inline int get_object_type(GetBitContext *gb)

67 {

68 int object_type = get_bits(gb, 5);

69 if (object_type == AOT_ESCAPE)

70 object_type = 32 + get_bits(gb, 6);

71 return object_type;

72 }

74 static inline int get_sample_rate(GetBitContext *gb, int *index)

75 {

76 *index = get_bits(gb, 4);

77 return *index == 0x0f ? get_bits(gb, 24) :

78 avpriv_mpeg4audio_sample_rates[*index];

79 }

81 int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf,

82 int bit_size, int sync_extension)

83 {

84 GetBitContext gb;

85 int specific_config_bitindex;

87 if (bit_size <= 0 || init_get_bits(&gb, buf, bit_size) < 0)

88 return AVERROR_INVALIDDATA;

89 c->object_type = get_object_type(&gb);

90 c->sample_rate = get_sample_rate(&gb, &c->sampling_index);

91 c->chan_config = get_bits(&gb, 4);

92 if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))

93 c->channels = ff_mpeg4audio_channels[c->chan_config];

94 c->sbr = -1;

95 c->ps = -1;

96 if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&

97 // check for W6132 Annex YYYY draft MP3onMP4

98 !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {

99 if (c->object_type == AOT_PS)

100 c->ps = 1;

101 c->ext_object_type = AOT_SBR;

102 c->sbr = 1;

103 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);

104 c->object_type = get_object_type(&gb);

105 if (c->object_type == AOT_ER_BSAC)

106 c->ext_chan_config = get_bits(&gb, 4);

107 } else {

108 c->ext_object_type = AOT_NULL;

109 c->ext_sample_rate = 0;

110 }

111 specific_config_bitindex = get_bits_count(&gb);

112

113 if (c->object_type == AOT_ALS) {

114 skip_bits(&gb, 5);

115 if (show_bits_long(&gb, 24) != MKBETAG('0円','A','L','S'))

116 skip_bits_long(&gb, 24);

117

118 specific_config_bitindex = get_bits_count(&gb);

119

120 if (parse_config_ALS(&gb, c))

121 return -1;

122 }

123

124 if (c->ext_object_type != AOT_SBR && sync_extension) {

125 while (get_bits_left(&gb) > 15) {

126 if (show_bits(&gb, 11) == 0x2b7) { // sync extension

127 get_bits(&gb, 11);

128 c->ext_object_type = get_object_type(&gb);

129 if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1) {

130 c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);

131 if (c->ext_sample_rate == c->sample_rate)

132 c->sbr = -1;

133 }

134 if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)

135 c->ps = get_bits1(&gb);

136 break;

137 } else

138 get_bits1(&gb); // skip 1 bit

139 }

140 }

141

142 //PS requires SBR

143 if (!c->sbr)

144 c->ps = 0;

145 //Limit implicit PS to the HE-AACv2 Profile

146 if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)

147 c->ps = 0;

148

149 return specific_config_bitindex;

150 }

151

152 static av_always_inline unsigned int copy_bits(PutBitContext *pb,

153 GetBitContext *gb,

154 int bits)

155 {

156 unsigned int el = get_bits(gb, bits);

157 put_bits(pb, bits, el);

158 return el;

159 }

160

161 int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb)

162 {

163 int five_bit_ch, four_bit_ch, comment_size, bits;

164 int offset = put_bits_count(pb);

165

166 copy_bits(pb, gb, 10); //Tag, Object Type, Frequency

167 five_bit_ch = copy_bits(pb, gb, 4); //Front

168 five_bit_ch += copy_bits(pb, gb, 4); //Side

169 five_bit_ch += copy_bits(pb, gb, 4); //Back

170 four_bit_ch = copy_bits(pb, gb, 2); //LFE

171 four_bit_ch += copy_bits(pb, gb, 3); //Data

172 five_bit_ch += copy_bits(pb, gb, 4); //Coupling

173 if (copy_bits(pb, gb, 1)) //Mono Mixdown

174 copy_bits(pb, gb, 4);

175 if (copy_bits(pb, gb, 1)) //Stereo Mixdown

176 copy_bits(pb, gb, 4);

177 if (copy_bits(pb, gb, 1)) //Matrix Mixdown

178 copy_bits(pb, gb, 3);

179 for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)

180 copy_bits(pb, gb, 16);

181 if (bits)

182 copy_bits(pb, gb, bits);

183 avpriv_align_put_bits(pb);

184 align_get_bits(gb);

185 comment_size = copy_bits(pb, gb, 8);

186 for (; comment_size > 0; comment_size--)

187 copy_bits(pb, gb, 8);

188

189 return put_bits_count(pb) - offset;

190 }

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