FFmpeg
oss_dec.c
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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 
22 #include "config.h"
23 
24 #include <stdint.h>
25 
26 #if HAVE_UNISTD_H
27 #include <unistd.h>
28 #endif
29 #include <fcntl.h>
30 #include <sys/ioctl.h>
31 #include <sys/soundcard.h>
32 
33 #include "libavutil/internal.h"
34 #include "libavutil/opt.h"
35 #include "libavutil/time.h"
36 
37 #include "libavcodec/avcodec.h"
38 
39 #include "avdevice.h"
40 #include "libavformat/internal.h"
41 
42 #include "oss.h"
43 
45 {
46  OSSAudioData *s = s1->priv_data;
47  AVStream *st;
48  int ret;
49 
50  st = avformat_new_stream(s1, NULL);
51  if (!st) {
52  return AVERROR(ENOMEM);
53  }
54 
55  ret = ff_oss_audio_open(s1, 0, s1->url);
56  if (ret < 0) {
57  return AVERROR(EIO);
58  }
59 
60  /* take real parameters */
62  st->codecpar->codec_id = s->codec_id;
64  st->codecpar->channels = s->channels;
65 
66  avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
67  return 0;
68 }
69 
71 {
72  OSSAudioData *s = s1->priv_data;
73  int ret, bdelay;
74  int64_t cur_time;
75  struct audio_buf_info abufi;
76 
77  if ((ret=av_new_packet(pkt, s->frame_size)) < 0)
78  return ret;
79 
80  ret = read(s->fd, pkt->data, pkt->size);
81  if (ret <= 0){
82  av_packet_unref(pkt);
83  pkt->size = 0;
84  if (ret<0) return AVERROR(errno);
85  else return AVERROR_EOF;
86  }
87  pkt->size = ret;
88 
89  /* compute pts of the start of the packet */
90  cur_time = av_gettime();
91  bdelay = ret;
92  if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
93  bdelay += abufi.bytes;
94  }
95  /* subtract time represented by the number of bytes in the audio fifo */
96  cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->channels);
97 
98  /* convert to wanted units */
99  pkt->pts = cur_time;
100 
101  if (s->flip_left && s->channels == 2) {
102  int i;
103  short *p = (short *) pkt->data;
104 
105  for (i = 0; i < ret; i += 4) {
106  *p = ~*p;
107  p += 2;
108  }
109  }
110  return 0;
111 }
112 
114 {
115  OSSAudioData *s = s1->priv_data;
116 
118  return 0;
119 }
120 
121 static const AVOption options[] = {
122  { "sample_rate", "", offsetof(OSSAudioData, sample_rate), AV_OPT_TYPE_INT, {.i64 = 48000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
123  { "channels", "", offsetof(OSSAudioData, channels), AV_OPT_TYPE_INT, {.i64 = 2}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
124  { NULL },
125 };
126 
127 static const AVClass oss_demuxer_class = {
128  .class_name = "OSS indev",
129  .item_name = av_default_item_name,
130  .option = options,
131  .version = LIBAVUTIL_VERSION_INT,
133 };
134 
136  .name = "oss",
137  .long_name = NULL_IF_CONFIG_SMALL("OSS (Open Sound System) capture"),
138  .priv_data_size = sizeof(OSSAudioData),
142  .flags = AVFMT_NOFILE,
143  .priv_class = &oss_demuxer_class,
144 };
#define NULL
Definition: coverity.c:32
AVOption.
Definition: opt.h:246
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4896
static const AVOption options[]
Definition: oss_dec.c:121
channels
Definition: aptx.c:30
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3960
int size
Definition: avcodec.h:1481
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
static int audio_read_header(AVFormatContext *s1)
Definition: oss_dec.c:44
static AVPacket pkt
Format I/O context.
Definition: avformat.h:1358
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
AVOptions.
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4469
int channels
Definition: oss.h:32
uint8_t * data
Definition: avcodec.h:1480
#define AVERROR_EOF
End of file.
Definition: error.h:55
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
enum AVCodecID codec_id
Definition: oss.h:34
int ff_oss_audio_open(AVFormatContext *s1, int is_output, const char *audio_device)
Definition: oss.c:40
Main libavdevice API header.
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:86
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
char * url
input or output URL.
Definition: avformat.h:1454
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3956
static int audio_read_close(AVFormatContext *s1)
Definition: oss_dec.c:113
static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
Definition: oss_dec.c:70
common internal API header
#define s(width, name)
Definition: cbs_vp9.c:257
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:530
int64_t av_gettime(void)
Get the current time in microseconds.
Definition: time.c:39
Stream structure.
Definition: avformat.h:881
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
static const AVClass oss_demuxer_class
Definition: oss_dec.c:127
sample_rate
Libavcodec external API header.
int fd
Definition: oss.h:30
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
Describe the class of an AVClass context structure.
Definition: log.h:67
int frame_size
Definition: oss.h:33
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:277
#define s1
Definition: regdef.h:38
#define flags(name, subs,...)
Definition: cbs_av1.c:561
int sample_rate
Audio only.
Definition: avcodec.h:4070
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:463
unsigned int flip_left
Definition: oss.h:35
int ff_oss_audio_close(OSSAudioData *s)
Definition: oss.c:135
void * priv_data
Format private data.
Definition: avformat.h:1386
int channels
Audio only.
Definition: avcodec.h:4066
int sample_rate
Definition: oss.h:31
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
This structure stores compressed data.
Definition: avcodec.h:1457
AVInputFormat ff_oss_demuxer
Definition: oss_dec.c:135
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1473
for(j=16;j >0;--j)