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| 4349 | Serge | 1 | /* |
| 2 | * ALSA input and output |
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| 3 | * Copyright (c) 2007 Luca Abeni ( lucabe72 email it ) |
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| 4 | * Copyright (c) 2007 Benoit Fouet ( benoit fouet free fr ) |
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| 5 | * |
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| 6 | * This file is part of FFmpeg. |
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| 7 | * |
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| 8 | * FFmpeg is free software; you can redistribute it and/or |
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| 9 | * modify it under the terms of the GNU Lesser General Public |
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| 10 | * License as published by the Free Software Foundation; either |
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| 11 | * version 2.1 of the License, or (at your option) any later version. |
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| 12 | * |
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| 13 | * FFmpeg is distributed in the hope that it will be useful, |
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| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 16 | * Lesser General Public License for more details. |
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| 17 | * |
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| 18 | * You should have received a copy of the GNU Lesser General Public |
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| 19 | * License along with FFmpeg; if not, write to the Free Software |
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| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 21 | */ |
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| 22 | |||
| 23 | /** |
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| 24 | * @file |
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| 25 | * ALSA input and output: output |
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| 26 | * @author Luca Abeni ( lucabe72 email it ) |
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| 27 | * @author Benoit Fouet ( benoit fouet free fr ) |
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| 28 | * |
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| 29 | * This avdevice encoder allows to play audio to an ALSA (Advanced Linux |
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| 30 | * Sound Architecture) device. |
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| 31 | * |
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| 32 | * The filename parameter is the name of an ALSA PCM device capable of |
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| 33 | * capture, for example "default" or "plughw:1"; see the ALSA documentation |
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| 34 | * for naming conventions. The empty string is equivalent to "default". |
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| 35 | * |
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| 36 | * The playback period is set to the lower value available for the device, |
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| 37 | * which gives a low latency suitable for real-time playback. |
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| 38 | */ |
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| 39 | |||
| 40 | #include |
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| 41 | |||
| 42 | #include "libavutil/time.h" |
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| 43 | #include "libavformat/internal.h" |
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| 44 | #include "avdevice.h" |
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| 45 | #include "alsa-audio.h" |
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| 46 | |||
| 47 | static av_cold int audio_write_header(AVFormatContext *s1) |
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| 48 | { |
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| 49 | AlsaData *s = s1->priv_data; |
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| 50 | AVStream *st; |
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| 51 | unsigned int sample_rate; |
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| 52 | enum AVCodecID codec_id; |
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| 53 | int res; |
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| 54 | |||
| 55 | st = s1->streams[0]; |
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| 56 | sample_rate = st->codec->sample_rate; |
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| 57 | codec_id = st->codec->codec_id; |
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| 58 | res = ff_alsa_open(s1, SND_PCM_STREAM_PLAYBACK, &sample_rate, |
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| 59 | st->codec->channels, &codec_id); |
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| 60 | if (sample_rate != st->codec->sample_rate) { |
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| 61 | av_log(s1, AV_LOG_ERROR, |
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| 62 | "sample rate %d not available, nearest is %d\n", |
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| 63 | st->codec->sample_rate, sample_rate); |
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| 64 | goto fail; |
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| 65 | } |
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| 66 | avpriv_set_pts_info(st, 64, 1, sample_rate); |
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| 67 | |||
| 68 | return res; |
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| 69 | |||
| 70 | fail: |
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| 71 | snd_pcm_close(s->h); |
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| 72 | return AVERROR(EIO); |
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| 73 | } |
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| 74 | |||
| 75 | static int audio_write_packet(AVFormatContext *s1, AVPacket *pkt) |
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| 76 | { |
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| 77 | AlsaData *s = s1->priv_data; |
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| 78 | int res; |
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| 79 | int size = pkt->size; |
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| 80 | uint8_t *buf = pkt->data; |
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| 81 | |||
| 82 | size /= s->frame_size; |
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| 83 | if (s->reorder_func) { |
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| 84 | if (size > s->reorder_buf_size) |
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| 85 | if (ff_alsa_extend_reorder_buf(s, size)) |
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| 86 | return AVERROR(ENOMEM); |
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| 87 | s->reorder_func(buf, s->reorder_buf, size); |
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| 88 | buf = s->reorder_buf; |
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| 89 | } |
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| 90 | while ((res = snd_pcm_writei(s->h, buf, size)) < 0) { |
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| 91 | if (res == -EAGAIN) { |
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| 92 | |||
| 93 | return AVERROR(EAGAIN); |
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| 94 | } |
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| 95 | |||
| 96 | if (ff_alsa_xrun_recover(s1, res) < 0) { |
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| 97 | av_log(s1, AV_LOG_ERROR, "ALSA write error: %s\n", |
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| 98 | snd_strerror(res)); |
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| 99 | |||
| 100 | return AVERROR(EIO); |
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| 101 | } |
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| 102 | } |
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| 103 | |||
| 104 | return 0; |
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| 105 | } |
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| 106 | |||
| 107 | static void |
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| 108 | audio_get_output_timestamp(AVFormatContext *s1, int stream, |
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| 109 | int64_t *dts, int64_t *wall) |
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| 110 | { |
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| 111 | AlsaData *s = s1->priv_data; |
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| 112 | snd_pcm_sframes_t delay = 0; |
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| 113 | *wall = av_gettime(); |
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| 114 | snd_pcm_delay(s->h, &delay); |
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| 115 | *dts = s1->streams[0]->cur_dts - delay; |
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| 116 | } |
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| 117 | |||
| 118 | AVOutputFormat ff_alsa_muxer = { |
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| 119 | .name = "alsa", |
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| 120 | .long_name = NULL_IF_CONFIG_SMALL("ALSA audio output"), |
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| 121 | .priv_data_size = sizeof(AlsaData), |
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| 122 | .audio_codec = DEFAULT_CODEC_ID, |
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| 123 | .video_codec = AV_CODEC_ID_NONE, |
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| 124 | .write_header = audio_write_header, |
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| 125 | .write_packet = audio_write_packet, |
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| 126 | .write_trailer = ff_alsa_close, |
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| 127 | .get_output_timestamp = audio_get_output_timestamp, |
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| 128 | .flags = AVFMT_NOFILE, |
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| 129 | }; |