• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • File List
  • Globals

libavdevice/oss_audio.c

Go to the documentation of this file.
00001 /*
00002  * Linux audio play and grab interface
00003  * Copyright (c) 2000, 2001 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "config.h"
00023 #include <stdlib.h>
00024 #include <stdio.h>
00025 #include <stdint.h>
00026 #include <string.h>
00027 #include <errno.h>
00028 #if HAVE_SOUNDCARD_H
00029 #include <soundcard.h>
00030 #else
00031 #include <sys/soundcard.h>
00032 #endif
00033 #include <unistd.h>
00034 #include <fcntl.h>
00035 #include <sys/ioctl.h>
00036 #include <sys/time.h>
00037 #include <sys/select.h>
00038 
00039 #include "libavutil/log.h"
00040 #include "libavcodec/avcodec.h"
00041 #include "libavformat/avformat.h"
00042 
00043 #define AUDIO_BLOCK_SIZE 4096
00044 
00045 typedef struct {
00046     int fd;
00047     int sample_rate;
00048     int channels;
00049     int frame_size; /* in bytes ! */
00050     enum CodecID codec_id;
00051     unsigned int flip_left : 1;
00052     uint8_t buffer[AUDIO_BLOCK_SIZE];
00053     int buffer_ptr;
00054 } AudioData;
00055 
00056 static int audio_open(AVFormatContext *s1, int is_output, const char *audio_device)
00057 {
00058     AudioData *s = s1->priv_data;
00059     int audio_fd;
00060     int tmp, err;
00061     char *flip = getenv("AUDIO_FLIP_LEFT");
00062 
00063     if (is_output)
00064         audio_fd = open(audio_device, O_WRONLY);
00065     else
00066         audio_fd = open(audio_device, O_RDONLY);
00067     if (audio_fd < 0) {
00068         av_log(s1, AV_LOG_ERROR, "%s: %s\n", audio_device, strerror(errno));
00069         return AVERROR(EIO);
00070     }
00071 
00072     if (flip && *flip == '1') {
00073         s->flip_left = 1;
00074     }
00075 
00076     /* non blocking mode */
00077     if (!is_output)
00078         fcntl(audio_fd, F_SETFL, O_NONBLOCK);
00079 
00080     s->frame_size = AUDIO_BLOCK_SIZE;
00081 #if 0
00082     tmp = (NB_FRAGMENTS << 16) | FRAGMENT_BITS;
00083     err = ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
00084     if (err < 0) {
00085         perror("SNDCTL_DSP_SETFRAGMENT");
00086     }
00087 #endif
00088 
00089     /* select format : favour native format */
00090     err = ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &tmp);
00091 
00092 #ifdef WORDS_BIGENDIAN
00093     if (tmp & AFMT_S16_BE) {
00094         tmp = AFMT_S16_BE;
00095     } else if (tmp & AFMT_S16_LE) {
00096         tmp = AFMT_S16_LE;
00097     } else {
00098         tmp = 0;
00099     }
00100 #else
00101     if (tmp & AFMT_S16_LE) {
00102         tmp = AFMT_S16_LE;
00103     } else if (tmp & AFMT_S16_BE) {
00104         tmp = AFMT_S16_BE;
00105     } else {
00106         tmp = 0;
00107     }
00108 #endif
00109 
00110     switch(tmp) {
00111     case AFMT_S16_LE:
00112         s->codec_id = CODEC_ID_PCM_S16LE;
00113         break;
00114     case AFMT_S16_BE:
00115         s->codec_id = CODEC_ID_PCM_S16BE;
00116         break;
00117     default:
00118         av_log(s1, AV_LOG_ERROR, "Soundcard does not support 16 bit sample format\n");
00119         close(audio_fd);
00120         return AVERROR(EIO);
00121     }
00122     err=ioctl(audio_fd, SNDCTL_DSP_SETFMT, &tmp);
00123     if (err < 0) {
00124         av_log(s1, AV_LOG_ERROR, "SNDCTL_DSP_SETFMT: %s\n", strerror(errno));
00125         goto fail;
00126     }
00127 
00128     tmp = (s->channels == 2);
00129     err = ioctl(audio_fd, SNDCTL_DSP_STEREO, &tmp);
00130     if (err < 0) {
00131         av_log(s1, AV_LOG_ERROR, "SNDCTL_DSP_STEREO: %s\n", strerror(errno));
00132         goto fail;
00133     }
00134 
00135     tmp = s->sample_rate;
00136     err = ioctl(audio_fd, SNDCTL_DSP_SPEED, &tmp);
00137     if (err < 0) {
00138         av_log(s1, AV_LOG_ERROR, "SNDCTL_DSP_SPEED: %s\n", strerror(errno));
00139         goto fail;
00140     }
00141     s->sample_rate = tmp; /* store real sample rate */
00142     s->fd = audio_fd;
00143 
00144     return 0;
00145  fail:
00146     close(audio_fd);
00147     return AVERROR(EIO);
00148 }
00149 
00150 static int audio_close(AudioData *s)
00151 {
00152     close(s->fd);
00153     return 0;
00154 }
00155 
00156 /* sound output support */
00157 static int audio_write_header(AVFormatContext *s1)
00158 {
00159     AudioData *s = s1->priv_data;
00160     AVStream *st;
00161     int ret;
00162 
00163     st = s1->streams[0];
00164     s->sample_rate = st->codec->sample_rate;
00165     s->channels = st->codec->channels;
00166     ret = audio_open(s1, 1, s1->filename);
00167     if (ret < 0) {
00168         return AVERROR(EIO);
00169     } else {
00170         return 0;
00171     }
00172 }
00173 
00174 static int audio_write_packet(AVFormatContext *s1, AVPacket *pkt)
00175 {
00176     AudioData *s = s1->priv_data;
00177     int len, ret;
00178     int size= pkt->size;
00179     uint8_t *buf= pkt->data;
00180 
00181     while (size > 0) {
00182         len = AUDIO_BLOCK_SIZE - s->buffer_ptr;
00183         if (len > size)
00184             len = size;
00185         memcpy(s->buffer + s->buffer_ptr, buf, len);
00186         s->buffer_ptr += len;
00187         if (s->buffer_ptr >= AUDIO_BLOCK_SIZE) {
00188             for(;;) {
00189                 ret = write(s->fd, s->buffer, AUDIO_BLOCK_SIZE);
00190                 if (ret > 0)
00191                     break;
00192                 if (ret < 0 && (errno != EAGAIN && errno != EINTR))
00193                     return AVERROR(EIO);
00194             }
00195             s->buffer_ptr = 0;
00196         }
00197         buf += len;
00198         size -= len;
00199     }
00200     return 0;
00201 }
00202 
00203 static int audio_write_trailer(AVFormatContext *s1)
00204 {
00205     AudioData *s = s1->priv_data;
00206 
00207     audio_close(s);
00208     return 0;
00209 }
00210 
00211 /* grab support */
00212 
00213 static int audio_read_header(AVFormatContext *s1, AVFormatParameters *ap)
00214 {
00215     AudioData *s = s1->priv_data;
00216     AVStream *st;
00217     int ret;
00218 
00219     if (ap->sample_rate <= 0 || ap->channels <= 0)
00220         return -1;
00221 
00222     st = av_new_stream(s1, 0);
00223     if (!st) {
00224         return AVERROR(ENOMEM);
00225     }
00226     s->sample_rate = ap->sample_rate;
00227     s->channels = ap->channels;
00228 
00229     ret = audio_open(s1, 0, s1->filename);
00230     if (ret < 0) {
00231         av_free(st);
00232         return AVERROR(EIO);
00233     }
00234 
00235     /* take real parameters */
00236     st->codec->codec_type = CODEC_TYPE_AUDIO;
00237     st->codec->codec_id = s->codec_id;
00238     st->codec->sample_rate = s->sample_rate;
00239     st->codec->channels = s->channels;
00240 
00241     av_set_pts_info(st, 64, 1, 1000000);  /* 64 bits pts in us */
00242     return 0;
00243 }
00244 
00245 static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
00246 {
00247     AudioData *s = s1->priv_data;
00248     int ret, bdelay;
00249     int64_t cur_time;
00250     struct audio_buf_info abufi;
00251 
00252     if (av_new_packet(pkt, s->frame_size) < 0)
00253         return AVERROR(EIO);
00254     for(;;) {
00255         struct timeval tv;
00256         fd_set fds;
00257 
00258         tv.tv_sec = 0;
00259         tv.tv_usec = 30 * 1000; /* 30 msecs -- a bit shorter than 1 frame at 30fps */
00260 
00261         FD_ZERO(&fds);
00262         FD_SET(s->fd, &fds);
00263 
00264         /* This will block until data is available or we get a timeout */
00265         (void) select(s->fd + 1, &fds, 0, 0, &tv);
00266 
00267         ret = read(s->fd, pkt->data, pkt->size);
00268         if (ret > 0)
00269             break;
00270         if (ret == -1 && (errno == EAGAIN || errno == EINTR)) {
00271             av_free_packet(pkt);
00272             pkt->size = 0;
00273             pkt->pts = av_gettime();
00274             return 0;
00275         }
00276         if (!(ret == 0 || (ret == -1 && (errno == EAGAIN || errno == EINTR)))) {
00277             av_free_packet(pkt);
00278             return AVERROR(EIO);
00279         }
00280     }
00281     pkt->size = ret;
00282 
00283     /* compute pts of the start of the packet */
00284     cur_time = av_gettime();
00285     bdelay = ret;
00286     if (ioctl(s->fd, SNDCTL_DSP_GETISPACE, &abufi) == 0) {
00287         bdelay += abufi.bytes;
00288     }
00289     /* subtract time represented by the number of bytes in the audio fifo */
00290     cur_time -= (bdelay * 1000000LL) / (s->sample_rate * s->channels);
00291 
00292     /* convert to wanted units */
00293     pkt->pts = cur_time;
00294 
00295     if (s->flip_left && s->channels == 2) {
00296         int i;
00297         short *p = (short *) pkt->data;
00298 
00299         for (i = 0; i < ret; i += 4) {
00300             *p = ~*p;
00301             p += 2;
00302         }
00303     }
00304     return 0;
00305 }
00306 
00307 static int audio_read_close(AVFormatContext *s1)
00308 {
00309     AudioData *s = s1->priv_data;
00310 
00311     audio_close(s);
00312     return 0;
00313 }
00314 
00315 #if CONFIG_OSS_DEMUXER
00316 AVInputFormat oss_demuxer = {
00317     "oss",
00318     NULL_IF_CONFIG_SMALL("Open Sound System capture"),
00319     sizeof(AudioData),
00320     NULL,
00321     audio_read_header,
00322     audio_read_packet,
00323     audio_read_close,
00324     .flags = AVFMT_NOFILE,
00325 };
00326 #endif
00327 
00328 #if CONFIG_OSS_MUXER
00329 AVOutputFormat oss_muxer = {
00330     "oss",
00331     NULL_IF_CONFIG_SMALL("Open Sound System playback"),
00332     "",
00333     "",
00334     sizeof(AudioData),
00335     /* XXX: we make the assumption that the soundcard accepts this format */
00336     /* XXX: find better solution with "preinit" method, needed also in
00337        other formats */
00338 #ifdef WORDS_BIGENDIAN
00339     CODEC_ID_PCM_S16BE,
00340 #else
00341     CODEC_ID_PCM_S16LE,
00342 #endif
00343     CODEC_ID_NONE,
00344     audio_write_header,
00345     audio_write_packet,
00346     audio_write_trailer,
00347     .flags = AVFMT_NOFILE,
00348 };
00349 #endif

Generated on Sat Feb 16 2013 09:23:14 for ffmpeg by  doxygen 1.7.1