1 /*
2 * ALSA input and output
3 * Copyright (c) 2007 Luca Abeni ( lucabe72 email it )
4 * Copyright (c) 2007 Benoit Fouet ( benoit fouet free fr )
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 */
22
23 /**
24 * @file
25 * ALSA input and output: output
26 * @author Luca Abeni ( lucabe72 email it )
27 * @author Benoit Fouet ( benoit fouet free fr )
28 *
29 * This avdevice encoder can play audio to an ALSA (Advanced Linux
30 * Sound Architecture) device.
31 *
32 * The filename parameter is the name of an ALSA PCM device capable of
33 * capture, for example "default" or "plughw:1"; see the ALSA documentation
34 * for naming conventions. The empty string is equivalent to "default".
35 *
36 * The playback period is set to the lower value available for the device,
37 * which gives a low latency suitable for real-time playback.
38 */
39
40 #include <alsa/asoundlib.h>
41
44
45
49
51 {
56 int res;
57
61 }
63
70 "sample rate %d not available, nearest is %d\n",
73 }
75
76 return res;
77
81 }
82
84 {
86 int res;
89
90 size /=
s->frame_size;
94
95 if (
s->reorder_func) {
96 if (
size >
s->reorder_buf_size)
99 s->reorder_func(buf,
s->reorder_buf,
size);
100 buf =
s->reorder_buf;
101 }
102 while ((res = snd_pcm_writei(
s->h, buf,
size)) < 0) {
103 if (res == -EAGAIN) {
104
106 }
107
110 snd_strerror(res));
111
113 }
114 }
115
116 return 0;
117 }
118
121 {
124
125 /* ff_alsa_open() should have accepted only supported formats */
129 /* set only used fields */
131 pkt.
size = (*frame)->nb_samples *
s->frame_size;
132 pkt.
dts = (*frame)->pkt_dts;
135 }
136
137 static void
139 int64_t *dts, int64_t *wall)
140 {
142 snd_pcm_sframes_t delay = 0;
144 snd_pcm_delay(
s->h, &delay);
145 *dts =
s->timestamp - delay;
146 }
147
149 {
151 }
152
158 };
159
174 };