FFmpeg: libavformat/ncdec.c Source File

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libavformat

ncdec.c

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1 /*

2 * NC camera feed demuxer

4 * Edouard Auvinet

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 "libavutil/intreadwrite.h"

24 #include "avformat.h"

25 #include "internal.h"

27 #define NC_VIDEO_FLAG 0x1A5

29 static int nc_probe(AVProbeData *probe_packet)

30 {

31 int size;

33 if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)

34 return 0;

36 size = AV_RL16(probe_packet->buf + 5);

38 if (size + 20 > probe_packet->buf_size)

39 return AVPROBE_SCORE_MAX/4;

41 if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)

42 return AVPROBE_SCORE_MAX;

44 return 0;

45 }

47 static int nc_read_header(AVFormatContext *s)

48 {

49 AVStream *st = avformat_new_stream(s, NULL);

51 if (!st)

52 return AVERROR(ENOMEM);

54 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

55 st->codec->codec_id = AV_CODEC_ID_MPEG4;

56 st->need_parsing = AVSTREAM_PARSE_FULL;

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

60 return 0;

61 }

63 static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)

64 {

65 int size;

66 int ret;

68 uint32_t state=-1;

69 while (state != NC_VIDEO_FLAG) {

70 if (url_feof(s->pb))

71 return AVERROR(EIO);

72 state = (state<<8) + avio_r8(s->pb);

73 }

75 avio_r8(s->pb);

76 size = avio_rl16(s->pb);

77 avio_skip(s->pb, 9);

79 if (size == 0) {

80 av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");

81 return AVERROR(EAGAIN);

82 }

84 ret = av_get_packet(s->pb, pkt, size);

85 if (ret != size) {

86 if (ret > 0) av_free_packet(pkt);

87 return AVERROR(EIO);

88 }

90 pkt->stream_index = 0;

91 return size;

92 }

94 AVInputFormat ff_nc_demuxer = {

95 .name = "nc",

96 .long_name = NULL_IF_CONFIG_SMALL("NC camera feed"),

97 .read_probe = nc_probe,

98 .read_header = nc_read_header,

99 .read_packet = nc_read_packet,

100 .extensions = "v",

101 };

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