/* * Copyright 2010 S.N. Hemanth Meenakshisundaram * Copyright 2010 Stefano Sabatini * * 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 * null audio source */ #include "libavutil/audioconvert.h" #include "libavutil/opt.h" #include "audio.h" #include "avfilter.h" #include "internal.h" typedef struct { const AVClass *class; char *channel_layout_str; uint64_t channel_layout; char *sample_rate_str; int sample_rate; int nb_samples; ///< number of samples per requested frame int64_t pts; } ANullContext; #define OFFSET(x) offsetof(ANullContext, x) static const AVOption anullsrc_options[]= { { "channel_layout", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0 }, { "cl", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0 }, { "sample_rate", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0 }, { "r", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0 }, { "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX }, { "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX }, { NULL }, }; static const char *anullsrc_get_name(void *ctx) { return "anullsrc"; } static const AVClass anullsrc_class = { "ANullSrcContext", anullsrc_get_name, anullsrc_options }; static int init(AVFilterContext *ctx, const char *args, void *opaque) { ANullContext *null = ctx->priv; int ret; null->class = &anullsrc_class; av_opt_set_defaults(null); if ((ret = (av_set_options_string(null, args, "=", ":"))) < 0) { av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args); return ret; } if ((ret = ff_parse_sample_rate(&null->sample_rate, null->sample_rate_str, ctx)) < 0) return ret; if ((ret = ff_parse_channel_layout(&null->channel_layout, null->channel_layout_str, ctx)) < 0) return ret; return 0; } static int config_props(AVFilterLink *outlink) { ANullContext *null = outlink->src->priv; char buf[128]; int chans_nb; outlink->sample_rate = null->sample_rate; outlink->channel_layout = null->channel_layout; chans_nb = av_get_channel_layout_nb_channels(null->channel_layout); av_get_channel_layout_string(buf, sizeof(buf), chans_nb, null->channel_layout); av_log(outlink->src, AV_LOG_INFO, "sample_rate:%d channel_layout:'%s' nb_samples:%d\n", null->sample_rate, buf, null->nb_samples); return 0; } static int request_frame(AVFilterLink *outlink) { ANullContext *null = outlink->src->priv; AVFilterBufferRef *samplesref; samplesref = ff_get_audio_buffer(outlink, AV_PERM_WRITE, null->nb_samples); samplesref->pts = null->pts; samplesref->pos = -1; samplesref->audio->channel_layout = null->channel_layout; samplesref->audio->sample_rate = outlink->sample_rate; ff_filter_samples(outlink, avfilter_ref_buffer(samplesref, ~0)); avfilter_unref_buffer(samplesref); null->pts += null->nb_samples; return 0; } AVFilter avfilter_asrc_anullsrc = { .name = "anullsrc", .description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."), .init = init, .priv_size = sizeof(ANullContext), .inputs = (const AVFilterPad[]) {{ .name = NULL}}, .outputs = (const AVFilterPad[]) {{ .name = "default", .type = AVMEDIA_TYPE_AUDIO, .config_props = config_props, .request_frame = request_frame, }, { .name = NULL}}, };