2 * Linux audio play and grab interface
3 * Copyright (c) 2000, 2001 Fabrice Bellard.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 #include <sys/soundcard.h>
27 #include <sys/ioctl.h>
31 #define AUDIO_BLOCK_SIZE 4096
37 int frame_size; /* in bytes ! */
40 uint8_t buffer[AUDIO_BLOCK_SIZE];
44 static int audio_open(AudioData *s, int is_output, const char *audio_device)
48 char *flip = getenv("AUDIO_FLIP_LEFT");
50 /* open linux audio device */
52 audio_device = "/dev/dsp";
55 audio_fd = open(audio_device, O_WRONLY);
57 audio_fd = open(audio_device, O_RDONLY);
63 if (flip && *flip == '1') {
67 /* non blocking mode */
69 fcntl(audio_fd, F_SETFL, O_NONBLOCK);
71 s->frame_size = AUDIO_BLOCK_SIZE;
73 tmp = (NB_FRAGMENTS << 16) | FRAGMENT_BITS;
74 err = ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
76 perror("SNDCTL_DSP_SETFRAGMENT");
80 /* select format : favour native format */
81 err = ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &tmp);
83 #ifdef WORDS_BIGENDIAN
84 if (tmp & AFMT_S16_BE) {
86 } else if (tmp & AFMT_S16_LE) {
92 if (tmp & AFMT_S16_LE) {
94 } else if (tmp & AFMT_S16_BE) {
103 s->codec_id = CODEC_ID_PCM_S16LE;
106 s->codec_id = CODEC_ID_PCM_S16BE;
109 fprintf(stderr, "Soundcard does not support 16 bit sample format\n");
113 err=ioctl(audio_fd, SNDCTL_DSP_SETFMT, &tmp);
115 perror("SNDCTL_DSP_SETFMT");
119 tmp = (s->channels == 2);
120 err = ioctl(audio_fd, SNDCTL_DSP_STEREO, &tmp);
122 perror("SNDCTL_DSP_STEREO");
128 tmp = s->sample_rate;
129 err = ioctl(audio_fd, SNDCTL_DSP_SPEED, &tmp);
131 perror("SNDCTL_DSP_SPEED");
134 s->sample_rate = tmp; /* store real sample rate */
143 static int audio_close(AudioData *s)
149 /* sound output support */
150 static int audio_write_header(AVFormatContext *s1)
152 AudioData *s = s1->priv_data;
157 s->sample_rate = st->codec.sample_rate;
158 s->channels = st->codec.channels;
159 ret = audio_open(s, 1, NULL);
167 static int audio_write_packet(AVFormatContext *s1, int stream_index,
168 uint8_t *buf, int size, int force_pts)
170 AudioData *s = s1->priv_data;
174 len = AUDIO_BLOCK_SIZE - s->buffer_ptr;
177 memcpy(s->buffer + s->buffer_ptr, buf, len);
178 s->buffer_ptr += len;
179 if (s->buffer_ptr >= AUDIO_BLOCK_SIZE) {
181 ret = write(s->fd, s->buffer, AUDIO_BLOCK_SIZE);
184 if (ret < 0 && (errno != EAGAIN && errno != EINTR))
195 static int audio_write_trailer(AVFormatContext *s1)
197 AudioData *s = s1->priv_data;
205 static int audio_read_header(AVFormatContext *s1, AVFormatParameters *ap)
207 AudioData *s = s1->priv_data;
211 if (!ap || ap->sample_rate <= 0 || ap->channels <= 0)
214 st = av_new_stream(s1, 0);
218 s->sample_rate = ap->sample_rate;
219 s->channels = ap->channels;
221 ret = audio_open(s, 0, ap->device);
227 /* take real parameters */
228 st->codec.codec_type = CODEC_TYPE_AUDIO;
229 st->codec.codec_id = s->codec_id;
230 st->codec.sample_rate = s->sample_rate;
231 st->codec.channels = s->channels;
233 av_set_pts_info(s1, 48, 1, 1000000); /* 48 bits pts in us */
237 static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
239 AudioData *s = s1->priv_data;
242 struct audio_buf_info abufi;
244 if (av_new_packet(pkt, s->frame_size) < 0)
251 tv.tv_usec = 30 * 1000; /* 30 msecs -- a bit shorter than 1 frame at 30fps */
256 /* This will block until data is available or we get a timeout */
257 (void) select(s->fd + 1, &fds, 0, 0, &tv);
259 ret = read(s->fd, pkt->data, pkt->size);
262 if (ret == -1 && (errno == EAGAIN || errno == EINTR)) {
267 if (!(ret == 0 || (ret == -1 && (errno == EAGAIN || errno == EINTR)))) {
274 /* compute pts of the start of the packet */
275 cur_time = av_gettime();
277 if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
278 bdelay += abufi.bytes;
280 /* substract time represented by the number of bytes in the audio fifo */
281 cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->channels);
283 /* convert to wanted units */
284 pkt->pts = cur_time & ((1LL << 48) - 1);
286 if (s->flip_left && s->channels == 2) {
288 short *p = (short *) pkt->data;
290 for (i = 0; i < ret; i += 4) {
298 static int audio_read_close(AVFormatContext *s1)
300 AudioData *s = s1->priv_data;
306 static AVInputFormat audio_in_format = {
308 "audio grab and output",
314 .flags = AVFMT_NOFILE,
317 static AVOutputFormat audio_out_format = {
319 "audio grab and output",
323 /* XXX: we make the assumption that the soundcard accepts this format */
324 /* XXX: find better solution with "preinit" method, needed also in
326 #ifdef WORDS_BIGENDIAN
335 .flags = AVFMT_NOFILE,
340 av_register_input_format(&audio_in_format);
341 av_register_output_format(&audio_out_format);