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authorMichael Niedermayer <michaelni@gmx.at>2015-04-09 22:36:42 +0300
committerMichael Niedermayer <michaelni@gmx.at>2015-04-09 22:36:42 +0300
commitb1b58310d09297eb8e64b156e6da3406bc866cce (patch)
tree9314f08b45e3e58b6afb667d4f30a05dabe497e0 /libavdevice/alsa_dec.c
parent259fd4c7cfb8afbb022921b44fe6611fcefff3b1 (diff)
parent8d26c193fb42d08602ac93ece039d4718d029adc (diff)
Merge commit '8d26c193fb42d08602ac93ece039d4718d029adc'
* commit '8d26c193fb42d08602ac93ece039d4718d029adc': avdevice: Apply a more consistent file naming scheme Conflicts: libavdevice/Makefile libavdevice/alsa.h libavdevice/alsa_dec.c libavdevice/alsa_enc.c libavdevice/sndio_enc.c Merged-by: Michael Niedermayer <michaelni@gmx.at>
Diffstat (limited to 'libavdevice/alsa_dec.c')
-rw-r--r--libavdevice/alsa_dec.c168
1 files changed, 168 insertions, 0 deletions
diff --git a/libavdevice/alsa_dec.c b/libavdevice/alsa_dec.c
new file mode 100644
index 0000000000..286af650c7
--- /dev/null
+++ b/libavdevice/alsa_dec.c
@@ -0,0 +1,168 @@
+/*
+ * ALSA input and output
+ * Copyright (c) 2007 Luca Abeni ( lucabe72 email it )
+ * Copyright (c) 2007 Benoit Fouet ( benoit fouet free fr )
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * ALSA input and output: input
+ * @author Luca Abeni ( lucabe72 email it )
+ * @author Benoit Fouet ( benoit fouet free fr )
+ * @author Nicolas George ( nicolas george normalesup org )
+ *
+ * This avdevice decoder allows to capture audio from an ALSA (Advanced
+ * Linux Sound Architecture) device.
+ *
+ * The filename parameter is the name of an ALSA PCM device capable of
+ * capture, for example "default" or "plughw:1"; see the ALSA documentation
+ * for naming conventions. The empty string is equivalent to "default".
+ *
+ * The capture period is set to the lower value available for the device,
+ * which gives a low latency suitable for real-time capture.
+ *
+ * The PTS are an Unix time in microsecond.
+ *
+ * Due to a bug in the ALSA library
+ * (https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4308), this
+ * decoder does not work with certain ALSA plugins, especially the dsnoop
+ * plugin.
+ */
+
+#include <alsa/asoundlib.h>
+
+#include "libavutil/internal.h"
+#include "libavutil/mathematics.h"
+#include "libavutil/opt.h"
+#include "libavutil/time.h"
+
+#include "libavformat/internal.h"
+
+#include "avdevice.h"
+#include "alsa.h"
+
+static av_cold int audio_read_header(AVFormatContext *s1)
+{
+ AlsaData *s = s1->priv_data;
+ AVStream *st;
+ int ret;
+ enum AVCodecID codec_id;
+
+ st = avformat_new_stream(s1, NULL);
+ if (!st) {
+ av_log(s1, AV_LOG_ERROR, "Cannot add stream\n");
+
+ return AVERROR(ENOMEM);
+ }
+ codec_id = s1->audio_codec_id;
+
+ ret = ff_alsa_open(s1, SND_PCM_STREAM_CAPTURE, &s->sample_rate, s->channels,
+ &codec_id);
+ if (ret < 0) {
+ return AVERROR(EIO);
+ }
+
+ /* take real parameters */
+ st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
+ st->codec->codec_id = codec_id;
+ st->codec->sample_rate = s->sample_rate;
+ st->codec->channels = s->channels;
+ st->codec->frame_size = s->frame_size;
+ avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
+ /* microseconds instead of seconds, MHz instead of Hz */
+ s->timefilter = ff_timefilter_new(1000000.0 / s->sample_rate,
+ s->period_size, 1.5E-6);
+ if (!s->timefilter)
+ goto fail;
+
+ return 0;
+
+fail:
+ snd_pcm_close(s->h);
+ return AVERROR(EIO);
+}
+
+static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
+{
+ AlsaData *s = s1->priv_data;
+ int res;
+ int64_t dts;
+ snd_pcm_sframes_t delay = 0;
+
+ if (av_new_packet(pkt, s->period_size * s->frame_size) < 0) {
+ return AVERROR(EIO);
+ }
+
+ while ((res = snd_pcm_readi(s->h, pkt->data, s->period_size)) < 0) {
+ if (res == -EAGAIN) {
+ av_free_packet(pkt);
+
+ return AVERROR(EAGAIN);
+ }
+ if (ff_alsa_xrun_recover(s1, res) < 0) {
+ av_log(s1, AV_LOG_ERROR, "ALSA read error: %s\n",
+ snd_strerror(res));
+ av_free_packet(pkt);
+
+ return AVERROR(EIO);
+ }
+ ff_timefilter_reset(s->timefilter);
+ }
+
+ dts = av_gettime();
+ snd_pcm_delay(s->h, &delay);
+ dts -= av_rescale(delay + res, 1000000, s->sample_rate);
+ pkt->pts = ff_timefilter_update(s->timefilter, dts, s->last_period);
+ s->last_period = res;
+
+ pkt->size = res * s->frame_size;
+
+ return 0;
+}
+
+static int audio_get_device_list(AVFormatContext *h, AVDeviceInfoList *device_list)
+{
+ return ff_alsa_get_device_list(device_list, SND_PCM_STREAM_CAPTURE);
+}
+
+static const AVOption options[] = {
+ { "sample_rate", "", offsetof(AlsaData, sample_rate), AV_OPT_TYPE_INT, {.i64 = 48000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
+ { "channels", "", offsetof(AlsaData, channels), AV_OPT_TYPE_INT, {.i64 = 2}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
+ { NULL },
+};
+
+static const AVClass alsa_demuxer_class = {
+ .class_name = "ALSA demuxer",
+ .item_name = av_default_item_name,
+ .option = options,
+ .version = LIBAVUTIL_VERSION_INT,
+ .category = AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
+};
+
+AVInputFormat ff_alsa_demuxer = {
+ .name = "alsa",
+ .long_name = NULL_IF_CONFIG_SMALL("ALSA audio input"),
+ .priv_data_size = sizeof(AlsaData),
+ .read_header = audio_read_header,
+ .read_packet = audio_read_packet,
+ .read_close = ff_alsa_close,
+ .get_device_list = audio_get_device_list,
+ .flags = AVFMT_NOFILE,
+ .priv_class = &alsa_demuxer_class,
+};