oss_dec.c 3.9 KB

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  1. /*
  2. * Linux audio play interface
  3. * Copyright (c) 2000, 2001 Fabrice Bellard
  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. */
  21. #include "config.h"
  22. #include <stdint.h>
  23. #if HAVE_UNISTD_H
  24. #include <unistd.h>
  25. #endif
  26. #include <fcntl.h>
  27. #include <sys/ioctl.h>
  28. #include <sys/soundcard.h>
  29. #include "libavutil/internal.h"
  30. #include "libavutil/opt.h"
  31. #include "libavutil/time.h"
  32. #include "avdevice.h"
  33. #include "libavformat/internal.h"
  34. #include "oss.h"
  35. static int audio_read_header(AVFormatContext *s1)
  36. {
  37. OSSAudioData *s = s1->priv_data;
  38. AVStream *st;
  39. int ret;
  40. st = avformat_new_stream(s1, NULL);
  41. if (!st) {
  42. return AVERROR(ENOMEM);
  43. }
  44. ret = ff_oss_audio_open(s1, 0, s1->url);
  45. if (ret < 0) {
  46. return AVERROR(EIO);
  47. }
  48. /* take real parameters */
  49. st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
  50. st->codecpar->codec_id = s->codec_id;
  51. st->codecpar->sample_rate = s->sample_rate;
  52. st->codecpar->ch_layout.nb_channels = s->channels;
  53. avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
  54. return 0;
  55. }
  56. static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
  57. {
  58. OSSAudioData *s = s1->priv_data;
  59. int ret, bdelay;
  60. int64_t cur_time;
  61. struct audio_buf_info abufi;
  62. if ((ret=av_new_packet(pkt, s->frame_size)) < 0)
  63. return ret;
  64. ret = read(s->fd, pkt->data, pkt->size);
  65. if (ret <= 0){
  66. av_packet_unref(pkt);
  67. pkt->size = 0;
  68. if (ret<0) return AVERROR(errno);
  69. else return AVERROR_EOF;
  70. }
  71. pkt->size = ret;
  72. /* compute pts of the start of the packet */
  73. cur_time = av_gettime();
  74. bdelay = ret;
  75. if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
  76. bdelay += abufi.bytes;
  77. }
  78. /* subtract time represented by the number of bytes in the audio fifo */
  79. cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->sample_size * s->channels);
  80. /* convert to wanted units */
  81. pkt->pts = cur_time;
  82. if (s->flip_left && s->channels == 2) {
  83. int i;
  84. short *p = (short *) pkt->data;
  85. for (i = 0; i < ret; i += 4) {
  86. *p = ~*p;
  87. p += 2;
  88. }
  89. }
  90. return 0;
  91. }
  92. static int audio_read_close(AVFormatContext *s1)
  93. {
  94. OSSAudioData *s = s1->priv_data;
  95. ff_oss_audio_close(s);
  96. return 0;
  97. }
  98. static const AVOption options[] = {
  99. { "sample_rate", "", offsetof(OSSAudioData, sample_rate), AV_OPT_TYPE_INT, {.i64 = 48000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
  100. { "channels", "", offsetof(OSSAudioData, channels), AV_OPT_TYPE_INT, {.i64 = 2}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
  101. { NULL },
  102. };
  103. static const AVClass oss_demuxer_class = {
  104. .class_name = "OSS indev",
  105. .item_name = av_default_item_name,
  106. .option = options,
  107. .version = LIBAVUTIL_VERSION_INT,
  108. .category = AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
  109. };
  110. const AVInputFormat ff_oss_demuxer = {
  111. .name = "oss",
  112. .long_name = NULL_IF_CONFIG_SMALL("OSS (Open Sound System) capture"),
  113. .priv_data_size = sizeof(OSSAudioData),
  114. .read_header = audio_read_header,
  115. .read_packet = audio_read_packet,
  116. .read_close = audio_read_close,
  117. .flags = AVFMT_NOFILE,
  118. .priv_class = &oss_demuxer_class,
  119. };