| 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 allows to 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 | |
| 42 | #include "libavutil/time.h" |
| 43 | #include "libavformat/internal.h" |
| 44 | #include "avdevice.h" |
| 45 | #include "alsa-audio.h" |
| 46 | |
| 47 | static av_cold int audio_write_header(AVFormatContext *s1) |
| 48 | { |
| 49 | AlsaData *s = s1->priv_data; |
| 50 | AVStream *st = NULL; |
| 51 | unsigned int sample_rate; |
| 52 | enum AVCodecID codec_id; |
| 53 | int res; |
| 54 | |
| 55 | if (s1->nb_streams != 1 || s1->streams[0]->codec->codec_type != AVMEDIA_TYPE_AUDIO) { |
| 56 | av_log(s1, AV_LOG_ERROR, "Only a single audio stream is supported.\n"); |
| 57 | return AVERROR(EINVAL); |
| 58 | } |
| 59 | st = s1->streams[0]; |
| 60 | |
| 61 | sample_rate = st->codec->sample_rate; |
| 62 | codec_id = st->codec->codec_id; |
| 63 | res = ff_alsa_open(s1, SND_PCM_STREAM_PLAYBACK, &sample_rate, |
| 64 | st->codec->channels, &codec_id); |
| 65 | if (sample_rate != st->codec->sample_rate) { |
| 66 | av_log(s1, AV_LOG_ERROR, |
| 67 | "sample rate %d not available, nearest is %d\n", |
| 68 | st->codec->sample_rate, sample_rate); |
| 69 | goto fail; |
| 70 | } |
| 71 | avpriv_set_pts_info(st, 64, 1, sample_rate); |
| 72 | |
| 73 | return res; |
| 74 | |
| 75 | fail: |
| 76 | snd_pcm_close(s->h); |
| 77 | return AVERROR(EIO); |
| 78 | } |
| 79 | |
| 80 | static int audio_write_packet(AVFormatContext *s1, AVPacket *pkt) |
| 81 | { |
| 82 | AlsaData *s = s1->priv_data; |
| 83 | int res; |
| 84 | int size = pkt->size; |
| 85 | uint8_t *buf = pkt->data; |
| 86 | |
| 87 | size /= s->frame_size; |
| 88 | if (pkt->dts != AV_NOPTS_VALUE) |
| 89 | s->timestamp = pkt->dts; |
| 90 | s->timestamp += pkt->duration ? pkt->duration : size; |
| 91 | |
| 92 | if (s->reorder_func) { |
| 93 | if (size > s->reorder_buf_size) |
| 94 | if (ff_alsa_extend_reorder_buf(s, size)) |
| 95 | return AVERROR(ENOMEM); |
| 96 | s->reorder_func(buf, s->reorder_buf, size); |
| 97 | buf = s->reorder_buf; |
| 98 | } |
| 99 | while ((res = snd_pcm_writei(s->h, buf, size)) < 0) { |
| 100 | if (res == -EAGAIN) { |
| 101 | |
| 102 | return AVERROR(EAGAIN); |
| 103 | } |
| 104 | |
| 105 | if (ff_alsa_xrun_recover(s1, res) < 0) { |
| 106 | av_log(s1, AV_LOG_ERROR, "ALSA write error: %s\n", |
| 107 | snd_strerror(res)); |
| 108 | |
| 109 | return AVERROR(EIO); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | return 0; |
| 114 | } |
| 115 | |
| 116 | static int audio_write_frame(AVFormatContext *s1, int stream_index, |
| 117 | AVFrame **frame, unsigned flags) |
| 118 | { |
| 119 | AlsaData *s = s1->priv_data; |
| 120 | AVPacket pkt; |
| 121 | |
| 122 | /* ff_alsa_open() should have accepted only supported formats */ |
| 123 | if ((flags & AV_WRITE_UNCODED_FRAME_QUERY)) |
| 124 | return av_sample_fmt_is_planar(s1->streams[stream_index]->codec->sample_fmt) ? |
| 125 | AVERROR(EINVAL) : 0; |
| 126 | /* set only used fields */ |
| 127 | pkt.data = (*frame)->data[0]; |
| 128 | pkt.size = (*frame)->nb_samples * s->frame_size; |
| 129 | pkt.dts = (*frame)->pkt_dts; |
| 130 | pkt.duration = av_frame_get_pkt_duration(*frame); |
| 131 | return audio_write_packet(s1, &pkt); |
| 132 | } |
| 133 | |
| 134 | static void |
| 135 | audio_get_output_timestamp(AVFormatContext *s1, int stream, |
| 136 | int64_t *dts, int64_t *wall) |
| 137 | { |
| 138 | AlsaData *s = s1->priv_data; |
| 139 | snd_pcm_sframes_t delay = 0; |
| 140 | *wall = av_gettime(); |
| 141 | snd_pcm_delay(s->h, &delay); |
| 142 | *dts = s->timestamp - delay; |
| 143 | } |
| 144 | |
| 145 | static int audio_get_device_list(AVFormatContext *h, AVDeviceInfoList *device_list) |
| 146 | { |
| 147 | return ff_alsa_get_device_list(device_list, SND_PCM_STREAM_PLAYBACK); |
| 148 | } |
| 149 | |
| 150 | static const AVClass alsa_muxer_class = { |
| 151 | .class_name = "ALSA muxer", |
| 152 | .item_name = av_default_item_name, |
| 153 | .version = LIBAVUTIL_VERSION_INT, |
| 154 | .category = AV_CLASS_CATEGORY_DEVICE_AUDIO_OUTPUT, |
| 155 | }; |
| 156 | |
| 157 | AVOutputFormat ff_alsa_muxer = { |
| 158 | .name = "alsa", |
| 159 | .long_name = NULL_IF_CONFIG_SMALL("ALSA audio output"), |
| 160 | .priv_data_size = sizeof(AlsaData), |
| 161 | .audio_codec = DEFAULT_CODEC_ID, |
| 162 | .video_codec = AV_CODEC_ID_NONE, |
| 163 | .write_header = audio_write_header, |
| 164 | .write_packet = audio_write_packet, |
| 165 | .write_trailer = ff_alsa_close, |
| 166 | .write_uncoded_frame = audio_write_frame, |
| 167 | .get_device_list = audio_get_device_list, |
| 168 | .get_output_timestamp = audio_get_output_timestamp, |
| 169 | .flags = AVFMT_NOFILE, |
| 170 | .priv_class = &alsa_muxer_class, |
| 171 | }; |