FFmpeg: libavformat/pva.c Source File

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libavformat

pva.c

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1 /*

2 * TechnoTrend PVA (.pva) 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 */

22 #include "avformat.h"

23 #include "internal.h"

24 #include "mpeg.h"

26 #define PVA_MAX_PAYLOAD_LENGTH 0x17f8

27 #define PVA_VIDEO_PAYLOAD 0x01

28 #define PVA_AUDIO_PAYLOAD 0x02

29 #define PVA_MAGIC (('A' << 8) + 'V')

31 typedef struct {

32 int continue_pes;

33 } PVAContext;

35 static int pva_check(const uint8_t *p) {

36 int length = AV_RB16(p + 6);

37 if (AV_RB16(p) != PVA_MAGIC || !p[2] || p[2] > 2 || p[4] != 0x55 ||

38 (p[5] & 0xe0) || length > PVA_MAX_PAYLOAD_LENGTH)

39 return -1;

40 return length + 8;

41 }

43 static int pva_probe(AVProbeData * pd) {

44 const unsigned char *buf = pd->buf;

45 int len = pva_check(buf);

47 if (len < 0)

48 return 0;

50 if (pd->buf_size >= len + 8 &&

51 pva_check(buf + len) >= 0)

52 return AVPROBE_SCORE_EXTENSION;

54 return AVPROBE_SCORE_MAX / 4;

55 }

57 static int pva_read_header(AVFormatContext *s) {

58 AVStream *st;

60 if (!(st = avformat_new_stream(s, NULL)))

61 return AVERROR(ENOMEM);

62 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

63 st->codec->codec_id = AV_CODEC_ID_MPEG2VIDEO;

64 st->need_parsing = AVSTREAM_PARSE_FULL;

65 avpriv_set_pts_info(st, 32, 1, 90000);

66 av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);

68 if (!(st = avformat_new_stream(s, NULL)))

69 return AVERROR(ENOMEM);

70 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

71 st->codec->codec_id = AV_CODEC_ID_MP2;

72 st->need_parsing = AVSTREAM_PARSE_FULL;

73 avpriv_set_pts_info(st, 33, 1, 90000);

74 av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);

76 /* the parameters will be extracted from the compressed bitstream */

77 return 0;

78 }

80 #define pva_log if (read_packet) av_log

82 static int read_part_of_packet(AVFormatContext *s, int64_t *pts,

83 int *len, int *strid, int read_packet) {

84 AVIOContext *pb = s->pb;

85 PVAContext *pvactx = s->priv_data;

86 int syncword, streamid, reserved, flags, length, pts_flag;

87 int64_t pva_pts = AV_NOPTS_VALUE, startpos;

89 recover:

90 startpos = avio_tell(pb);

92 syncword = avio_rb16(pb);

93 streamid = avio_r8(pb);

94 avio_r8(pb); /* counter not used */

95 reserved = avio_r8(pb);

96 flags = avio_r8(pb);

97 length = avio_rb16(pb);

99 pts_flag = flags & 0x10;

100

101 if (syncword != PVA_MAGIC) {

102 pva_log(s, AV_LOG_ERROR, "invalid syncword\n");

103 return AVERROR(EIO);

104 }

105 if (streamid != PVA_VIDEO_PAYLOAD && streamid != PVA_AUDIO_PAYLOAD) {

106 pva_log(s, AV_LOG_ERROR, "invalid streamid\n");

107 return AVERROR(EIO);

108 }

109 if (reserved != 0x55) {

110 pva_log(s, AV_LOG_WARNING, "expected reserved byte to be 0x55\n");

111 }

112 if (length > PVA_MAX_PAYLOAD_LENGTH) {

113 pva_log(s, AV_LOG_ERROR, "invalid payload length %u\n", length);

114 return AVERROR(EIO);

115 }

116

117 if (streamid == PVA_VIDEO_PAYLOAD && pts_flag) {

118 pva_pts = avio_rb32(pb);

119 length -= 4;

120 } else if (streamid == PVA_AUDIO_PAYLOAD) {

121 /* PVA Audio Packets either start with a signaled PES packet or

122 * are a continuation of the previous PES packet. New PES packets

123 * always start at the beginning of a PVA Packet, never somewhere in

124 * the middle. */

125 if (!pvactx->continue_pes) {

126 int pes_signal, pes_header_data_length, pes_packet_length,

127 pes_flags;

128 unsigned char pes_header_data[256];

129

130 pes_signal = avio_rb24(pb);

131 avio_r8(pb);

132 pes_packet_length = avio_rb16(pb);

133 pes_flags = avio_rb16(pb);

134 pes_header_data_length = avio_r8(pb);

135

136 if (pes_signal != 1) {

137 pva_log(s, AV_LOG_WARNING, "expected signaled PES packet, "

138 "trying to recover\n");

139 avio_skip(pb, length - 9);

140 if (!read_packet)

141 return AVERROR(EIO);

142 goto recover;

143 }

144

145 avio_read(pb, pes_header_data, pes_header_data_length);

146 length -= 9 + pes_header_data_length;

147

148 pes_packet_length -= 3 + pes_header_data_length;

149

150 pvactx->continue_pes = pes_packet_length;

151

152 if (pes_flags & 0x80 && (pes_header_data[0] & 0xf0) == 0x20)

153 pva_pts = ff_parse_pes_pts(pes_header_data);

154 }

155

156 pvactx->continue_pes -= length;

157

158 if (pvactx->continue_pes < 0) {

159 pva_log(s, AV_LOG_WARNING, "audio data corruption\n");

160 pvactx->continue_pes = 0;

161 }

162 }

163

164 if (pva_pts != AV_NOPTS_VALUE)

165 av_add_index_entry(s->streams[streamid-1], startpos, pva_pts, 0, 0, AVINDEX_KEYFRAME);

166

167 *pts = pva_pts;

168 *len = length;

169 *strid = streamid;

170 return 0;

171 }

172

173 static int pva_read_packet(AVFormatContext *s, AVPacket *pkt) {

174 AVIOContext *pb = s->pb;

175 int64_t pva_pts;

176 int ret, length, streamid;

177

178 if (read_part_of_packet(s, &pva_pts, &length, &streamid, 1) < 0 ||

179 (ret = av_get_packet(pb, pkt, length)) <= 0)

180 return AVERROR(EIO);

181

182 pkt->stream_index = streamid - 1;

183 pkt->pts = pva_pts;

184

185 return ret;

186 }

187

188 static int64_t pva_read_timestamp(struct AVFormatContext *s, int stream_index,

189 int64_t *pos, int64_t pos_limit) {

190 AVIOContext *pb = s->pb;

191 PVAContext *pvactx = s->priv_data;

192 int length, streamid;

193 int64_t res = AV_NOPTS_VALUE;

194

195 pos_limit = FFMIN(*pos+PVA_MAX_PAYLOAD_LENGTH*8, (uint64_t)*pos+pos_limit);

196

197 while (*pos < pos_limit) {

198 res = AV_NOPTS_VALUE;

199 avio_seek(pb, *pos, SEEK_SET);

200

201 pvactx->continue_pes = 0;

202 if (read_part_of_packet(s, &res, &length, &streamid, 0)) {

203 (*pos)++;

204 continue;

205 }

206 if (streamid - 1 != stream_index || res == AV_NOPTS_VALUE) {

207 *pos = avio_tell(pb) + length;

208 continue;

209 }

210 break;

211 }

212

213 pvactx->continue_pes = 0;

214 return res;

215 }

216

217 AVInputFormat ff_pva_demuxer = {

218 .name = "pva",

219 .long_name = NULL_IF_CONFIG_SMALL("TechnoTrend PVA"),

220 .priv_data_size = sizeof(PVAContext),

221 .read_probe = pva_probe,

222 .read_header = pva_read_header,

223 .read_packet = pva_read_packet,

224 .read_timestamp = pva_read_timestamp,

225 };

Generated on Sat Jan 25 2014 19:52:04 for FFmpeg by doxygen 1.8.2