FFmpeg: libavcodec/dca_parser.c Source File

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libavcodec

dca_parser.c

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1 /*

2 * DCA parser

7 *

8 * This file is part of FFmpeg.

9 *

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

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

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

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

14 *

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

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

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

18 * Lesser General Public License for more details.

19 *

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

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

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

23 */

25 #include "parser.h"

26 #include "dca.h"

27 #include "dca_parser.h"

28 #include "get_bits.h"

29 #include "put_bits.h"

31 typedef struct DCAParseContext {

32 ParseContext pc;

33 uint32_t lastmarker;

34 int size;

35 int framesize;

36 int hd_pos;

37 } DCAParseContext;

39 #define IS_MARKER(state, i, buf, buf_size) \

40 ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \

41 || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \

42 || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE || state == DCA_HD_MARKER)

44 /**

45 * Find the end of the current frame in the bitstream.

46 * @return the position of the first byte of the next frame, or -1

47 */

48 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,

49 int buf_size)

50 {

51 int start_found, i;

52 uint32_t state;

53 ParseContext *pc = &pc1->pc;

55 start_found = pc->frame_start_found;

56 state = pc->state;

58 i = 0;

59 if (!start_found) {

60 for (i = 0; i < buf_size; i++) {

61 state = (state << 8) | buf[i];

62 if (IS_MARKER(state, i, buf, buf_size)) {

63 if (!pc1->lastmarker || state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER) {

64 start_found = 1;

65 pc1->lastmarker = state;

66 break;

67 }

68 }

69 }

70 }

71 if (start_found) {

72 for (; i < buf_size; i++) {

73 pc1->size++;

74 state = (state << 8) | buf[i];

75 if (state == DCA_HD_MARKER && !pc1->hd_pos)

76 pc1->hd_pos = pc1->size;

77 if (IS_MARKER(state, i, buf, buf_size) && (state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER)) {

78 if(pc1->framesize > pc1->size)

79 continue;

80 // We have to check that we really read a full frame here, and that it isn't a pure HD frame, because their size is not constant.

81 if(!pc1->framesize && state == pc1->lastmarker && state != DCA_HD_MARKER){

82 pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;

83 }

84 pc->frame_start_found = 0;

85 pc->state = -1;

86 pc1->size = 0;

87 return i - 3;

88 }

89 }

90 }

91 pc->frame_start_found = start_found;

92 pc->state = state;

93 return END_NOT_FOUND;

94 }

96 static av_cold int dca_parse_init(AVCodecParserContext * s)

97 {

98 DCAParseContext *pc1 = s->priv_data;

100 pc1->lastmarker = 0;

101 return 0;

102 }

103

104 int ff_dca_convert_bitstream(const uint8_t *src, int src_size, uint8_t *dst,

105 int max_size)

106 {

107 uint32_t mrk;

108 int i, tmp;

109 const uint16_t *ssrc = (const uint16_t *) src;

110 uint16_t *sdst = (uint16_t *) dst;

111 PutBitContext pb;

112

113 if ((unsigned) src_size > (unsigned) max_size)

114 src_size = max_size;

115

116 mrk = AV_RB32(src);

117 switch (mrk) {

118 case DCA_MARKER_RAW_BE:

119 memcpy(dst, src, src_size);

120 return src_size;

121 case DCA_MARKER_RAW_LE:

122 for (i = 0; i < (src_size + 1) >> 1; i++)

123 *sdst++ = av_bswap16(*ssrc++);

124 return src_size;

125 case DCA_MARKER_14B_BE:

126 case DCA_MARKER_14B_LE:

127 init_put_bits(&pb, dst, max_size);

128 for (i = 0; i < (src_size + 1) >> 1; i++, src += 2) {

129 tmp = ((mrk == DCA_MARKER_14B_BE) ? AV_RB16(src) : AV_RL16(src)) & 0x3FFF;

130 put_bits(&pb, 14, tmp);

131 }

132 flush_put_bits(&pb);

133 return (put_bits_count(&pb) + 7) >> 3;

134 default:

135 return AVERROR_INVALIDDATA;

136 }

137 }

138

139 static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,

140 int *sample_rate)

141 {

142 GetBitContext gb;

143 uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };

144 int ret, sample_blocks, sr_code;

145

146 if (buf_size < 12)

147 return AVERROR_INVALIDDATA;

148

149 if ((ret = ff_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)

150 return ret;

151

152 init_get_bits(&gb, hdr, 96);

153

154 skip_bits_long(&gb, 39);

155 sample_blocks = get_bits(&gb, 7) + 1;

156 if (sample_blocks < 8)

157 return AVERROR_INVALIDDATA;

158 *duration = 256 * (sample_blocks / 8);

159

160 skip_bits(&gb, 20);

161 sr_code = get_bits(&gb, 4);

162 *sample_rate = avpriv_dca_sample_rates[sr_code];

163 if (*sample_rate == 0)

164 return AVERROR_INVALIDDATA;

165

166 return 0;

167 }

168

169 static int dca_parse(AVCodecParserContext * s,

170 AVCodecContext * avctx,

171 const uint8_t ** poutbuf, int *poutbuf_size,

172 const uint8_t * buf, int buf_size)

173 {

174 DCAParseContext *pc1 = s->priv_data;

175 ParseContext *pc = &pc1->pc;

176 int next, duration, sample_rate;

177

178 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {

179 next = buf_size;

180 } else {

181 next = dca_find_frame_end(pc1, buf, buf_size);

182

183 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

184 *poutbuf = NULL;

185 *poutbuf_size = 0;

186 return buf_size;

187 }

188 }

189

190 /* read the duration and sample rate from the frame header */

191 if (!dca_parse_params(buf, buf_size, &duration, &sample_rate)) {

192 s->duration = duration;

193 avctx->sample_rate = sample_rate;

194 } else

195 s->duration = 0;

196

197 *poutbuf = buf;

198 *poutbuf_size = buf_size;

199 return next;

200 }

201

202 AVCodecParser ff_dca_parser = {

203 .codec_ids = { AV_CODEC_ID_DTS },

204 .priv_data_size = sizeof(DCAParseContext),

205 .parser_init = dca_parse_init,

206 .parser_parse = dca_parse,

207 .parser_close = ff_parse_close,

208 };

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