FFmpeg: libavformat/apc.c Source File

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libavformat

apc.c

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1 /*

2 * CRYO APC audio format 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 <string.h>

24 #include "libavutil/channel_layout.h"

25 #include "avformat.h"

27 static int apc_probe(AVProbeData *p)

28 {

29 if (!strncmp(p->buf, "CRYO_APC", 8))

30 return AVPROBE_SCORE_MAX;

32 return 0;

33 }

35 static int apc_read_header(AVFormatContext *s)

36 {

37 AVIOContext *pb = s->pb;

38 AVStream *st;

40 avio_rl32(pb); /* CRYO */

41 avio_rl32(pb); /* _APC */

42 avio_rl32(pb); /* 1.20 */

44 st = avformat_new_stream(s, NULL);

45 if (!st)

46 return AVERROR(ENOMEM);

48 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

49 st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;

51 avio_rl32(pb); /* number of samples */

52 st->codec->sample_rate = avio_rl32(pb);

54 st->codec->extradata_size = 2 * 4;

55 st->codec->extradata = av_malloc(st->codec->extradata_size +

56 FF_INPUT_BUFFER_PADDING_SIZE);

57 if (!st->codec->extradata)

58 return AVERROR(ENOMEM);

60 /* initial predictor values for adpcm decoder */

61 avio_read(pb, st->codec->extradata, 2 * 4);

63 if (avio_rl32(pb)) {

64 st->codec->channels = 2;

65 st->codec->channel_layout = AV_CH_LAYOUT_STEREO;

66 } else {

67 st->codec->channels = 1;

68 st->codec->channel_layout = AV_CH_LAYOUT_MONO;

69 }

71 st->codec->bits_per_coded_sample = 4;

72 st->codec->bit_rate = st->codec->bits_per_coded_sample * st->codec->channels

73 * st->codec->sample_rate;

74 st->codec->block_align = 1;

76 return 0;

77 }

79 #define MAX_READ_SIZE 4096

81 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)

82 {

83 if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)

84 return AVERROR(EIO);

85 pkt->flags &= ~AV_PKT_FLAG_CORRUPT;

86 pkt->stream_index = 0;

87 return 0;

88 }

90 AVInputFormat ff_apc_demuxer = {

91 .name = "apc",

92 .long_name = NULL_IF_CONFIG_SMALL("CRYO APC"),

93 .read_probe = apc_probe,

94 .read_header = apc_read_header,

95 .read_packet = apc_read_packet,

96 };

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