FFmpeg: libavformat/avc.c Source File

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libavformat

avc.c

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1 /*

2 * AVC helper functions for muxers

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 "libavutil/intreadwrite.h"

23 #include "avformat.h"

24 #include "avio.h"

25 #include "avc.h"

27 static const uint8_t *ff_avc_find_startcode_internal(const uint8_t *p, const uint8_t *end)

28 {

29 const uint8_t *a = p + 4 - ((intptr_t)p & 3);

31 for (end -= 3; p < a && p < end; p++) {

32 if (p[0] == 0 && p[1] == 0 && p[2] == 1)

33 return p;

34 }

36 for (end -= 3; p < end; p += 4) {

37 uint32_t x = *(const uint32_t*)p;

38 // if ((x - 0x01000100) & (~x) & 0x80008000) // little endian

39 // if ((x - 0x00010001) & (~x) & 0x00800080) // big endian

40 if ((x - 0x01010101) & (~x) & 0x80808080) { // generic

41 if (p[1] == 0) {

42 if (p[0] == 0 && p[2] == 1)

43 return p;

44 if (p[2] == 0 && p[3] == 1)

45 return p+1;

46 }

47 if (p[3] == 0) {

48 if (p[2] == 0 && p[4] == 1)

49 return p+2;

50 if (p[4] == 0 && p[5] == 1)

51 return p+3;

52 }

53 }

54 }

56 for (end += 3; p < end; p++) {

57 if (p[0] == 0 && p[1] == 0 && p[2] == 1)

58 return p;

59 }

61 return end + 3;

62 }

64 const uint8_t *ff_avc_find_startcode(const uint8_t *p, const uint8_t *end){

65 const uint8_t *out= ff_avc_find_startcode_internal(p, end);

66 if(p<out && out<end && !out[-1]) out--;

67 return out;

68 }

70 int ff_avc_parse_nal_units(AVIOContext *pb, const uint8_t *buf_in, int size)

71 {

72 const uint8_t *p = buf_in;

73 const uint8_t *end = p + size;

74 const uint8_t *nal_start, *nal_end;

76 size = 0;

77 nal_start = ff_avc_find_startcode(p, end);

78 for (;;) {

79 while (nal_start < end && !*(nal_start++));

80 if (nal_start == end)

81 break;

83 nal_end = ff_avc_find_startcode(nal_start, end);

84 avio_wb32(pb, nal_end - nal_start);

85 avio_write(pb, nal_start, nal_end - nal_start);

86 size += 4 + nal_end - nal_start;

87 nal_start = nal_end;

88 }

89 return size;

90 }

92 int ff_avc_parse_nal_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)

93 {

94 AVIOContext *pb;

95 int ret = avio_open_dyn_buf(&pb);

96 if(ret < 0)

97 return ret;

99 ff_avc_parse_nal_units(pb, buf_in, *size);

100

101 av_freep(buf);

102 *size = avio_close_dyn_buf(pb, buf);

103 return 0;

104 }

105

106 int ff_isom_write_avcc(AVIOContext *pb, const uint8_t *data, int len)

107 {

108 if (len > 6) {

109 /* check for h264 start code */

110 if (AV_RB32(data) == 0x00000001 ||

111 AV_RB24(data) == 0x000001) {

112 uint8_t *buf=NULL, *end, *start;

113 uint32_t sps_size=0, pps_size=0;

114 uint8_t *sps=0, *pps=0;

115

116 int ret = ff_avc_parse_nal_units_buf(data, &buf, &len);

117 if (ret < 0)

118 return ret;

119 start = buf;

120 end = buf + len;

121

122 /* look for sps and pps */

123 while (end - buf > 4) {

124 uint32_t size;

125 uint8_t nal_type;

126 size = FFMIN(AV_RB32(buf), end - buf - 4);

127 buf += 4;

128 nal_type = buf[0] & 0x1f;

129

130 if (nal_type == 7) { /* SPS */

131 sps = buf;

132 sps_size = size;

133 } else if (nal_type == 8) { /* PPS */

134 pps = buf;

135 pps_size = size;

136 }

137

138 buf += size;

139 }

140

141 if (!sps || !pps || sps_size < 4 || sps_size > UINT16_MAX || pps_size > UINT16_MAX)

142 return AVERROR_INVALIDDATA;

143

144 avio_w8(pb, 1); /* version */

145 avio_w8(pb, sps[1]); /* profile */

146 avio_w8(pb, sps[2]); /* profile compat */

147 avio_w8(pb, sps[3]); /* level */

148 avio_w8(pb, 0xff); /* 6 bits reserved (111111) + 2 bits nal size length - 1 (11) */

149 avio_w8(pb, 0xe1); /* 3 bits reserved (111) + 5 bits number of sps (00001) */

150

151 avio_wb16(pb, sps_size);

152 avio_write(pb, sps, sps_size);

153 avio_w8(pb, 1); /* number of pps */

154 avio_wb16(pb, pps_size);

155 avio_write(pb, pps, pps_size);

156 av_free(start);

157 } else {

158 avio_write(pb, data, len);

159 }

160 }

161 return 0;

162 }

163

164 int ff_avc_write_annexb_extradata(const uint8_t *in, uint8_t **buf, int *size)

165 {

166 uint16_t sps_size, pps_size;

167 uint8_t *out;

168 int out_size;

169

170 *buf = NULL;

171 if (*size >= 4 && (AV_RB32(in) == 0x00000001 || AV_RB24(in) == 0x000001))

172 return 0;

173 if (*size < 11 || in[0] != 1)

174 return AVERROR_INVALIDDATA;

175

176 sps_size = AV_RB16(&in[6]);

177 if (11 + sps_size > *size)

178 return AVERROR_INVALIDDATA;

179 pps_size = AV_RB16(&in[9 + sps_size]);

180 if (11 + sps_size + pps_size > *size)

181 return AVERROR_INVALIDDATA;

182 out_size = 8 + sps_size + pps_size;

183 out = av_mallocz(out_size);

184 if (!out)

185 return AVERROR(ENOMEM);

186 AV_WB32(&out[0], 0x00000001);

187 memcpy(out + 4, &in[8], sps_size);

188 AV_WB32(&out[4 + sps_size], 0x00000001);

189 memcpy(out + 8 + sps_size, &in[11 + sps_size], pps_size);

190 *buf = out;

191 *size = out_size;

192 return 0;

193 }

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