lavfi: add join audio filter.

It joins multiple input streams into one multi-channel output.

Changelog

@@ -28,6 +28,7 @@ version <next>:
 - RTMPT protocol support
 - iLBC encoding/decoding via libilbc
 - Microsoft Screen 1 decoder
+- join audio filter
 
 
 version 0.8:

doc/filters.texi

@@ -232,6 +232,43 @@ front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
 side_right.wav
 @end example
 
+@section join
+Join multiple input streams into one multi-channel stream.
+
+The filter accepts the following named parameters:
+@table @option
+
+@item inputs
+Number of input streams. Defaults to 2.
+
+@item channel_layout
+Desired output channel layout. Defaults to stereo.
+
+@item map
+Map channels from inputs to output. The argument is a comma-separated list of
+mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
+form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
+can be either the name of the input channel (e.g. FR for front left) or its
+index in the specified input stream. @var{out_channel} is the name of the output
+channel.
+@end table
+
+The filter will attempt to guess the mappings when those are not specified
+explicitly. It does so by first trying to find an unused matching input channel
+and if that fails it picks the first unused input channel.
+
+E.g. to join 3 inputs (with properly set channel layouts)
+@example
+avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
+@end example
+
+To build a 5.1 output from 6 single-channel streams:
+@example
+avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
+'join=inputs=6:channel_layout=5.1:map=0.0-FL\,1.0-FR\,2.0-FC\,3.0-SL\,4.0-SR\,5.0-LFE'
+out
+@end example
+
 @section resample
 Convert the audio sample format, sample rate and channel layout. This filter is
 not meant to be used directly, it is inserted automatically by libavfilter

libavfilter/Makefile

@@ -32,6 +32,7 @@ OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_ASPLIT_FILTER)                 += split.o
 OBJS-$(CONFIG_ASYNCTS_FILTER)                += af_asyncts.o
 OBJS-$(CONFIG_CHANNELSPLIT_FILTER)           += af_channelsplit.o
+OBJS-$(CONFIG_JOIN_FILTER)                   += af_join.o
 OBJS-$(CONFIG_RESAMPLE_FILTER)               += af_resample.o
 
 OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o

libavfilter/af_join.c

+/*
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Audio join filter
+ *
+ * Join multiple audio inputs as different channels in
+ * a single output
+ */
+
+#include "libavutil/audioconvert.h"
+#include "libavutil/avassert.h"
+#include "libavutil/opt.h"
+
+#include "audio.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+
+typedef struct ChannelMap {
+    int input;                ///< input stream index
+    int       in_channel_idx; ///< index of in_channel in the input stream data
+    uint64_t  in_channel;     ///< layout describing the input channel
+    uint64_t out_channel;     ///< layout describing the output channel
+} ChannelMap;
+
+typedef struct JoinContext {
+    const AVClass *class;
+
+    int inputs;
+    char *map;
+    char    *channel_layout_str;
+    uint64_t channel_layout;
+
+    int      nb_channels;
+    ChannelMap *channels;
+
+    /**
+     * Temporary storage for input frames, until we get one on each input.
+     */
+    AVFilterBufferRef **input_frames;
+
+    /**
+     *  Temporary storage for data pointers, for assembling the output buffer.
+     */
+    uint8_t **data;
+} JoinContext;
+
+/**
+ * To avoid copying the data from input buffers, this filter creates
+ * a custom output buffer that stores references to all inputs and
+ * unrefs them on free.
+ */
+typedef struct JoinBufferPriv {
+    AVFilterBufferRef **in_buffers;
+    int              nb_in_buffers;
+} JoinBufferPriv;
+
+#define OFFSET(x) offsetof(JoinContext, x)
+#define A AV_OPT_FLAG_AUDIO_PARAM
+static const AVOption join_options[] = {
+    { "inputs",         "Number of input streams.", OFFSET(inputs),             AV_OPT_TYPE_INT,    { 2 }, 1, INT_MAX,       A },
+    { "channel_layout", "Channel layout of the "
+                        "output stream.",           OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, A },
+    { "map",            "A comma-separated list of channels maps in the format "
+                        "'input_stream.input_channel-output_channel.",
+                                                    OFFSET(map),                AV_OPT_TYPE_STRING,                 .flags = A },
+    { NULL },
+};
+
+static const AVClass join_class = {
+    .class_name = "join filter",
+    .item_name  = av_default_item_name,
+    .option     = join_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static void filter_samples(AVFilterLink *link, AVFilterBufferRef *buf)
+{
+    AVFilterContext *ctx = link->dst;
+    JoinContext       *s = ctx->priv;
+    int i;
+
+    for (i = 0; i < ctx->nb_inputs; i++)
+        if (link == ctx->inputs[i])
+            break;
+    av_assert0(i < ctx->nb_inputs);
+    av_assert0(!s->input_frames[i]);
+    s->input_frames[i] = buf;
+}
+
+static int parse_maps(AVFilterContext *ctx)
+{
+    JoinContext *s = ctx->priv;
+    char *cur      = s->map;
+
+    while (cur && *cur) {
+        char *sep, *next, *p;
+        uint64_t in_channel = 0, out_channel = 0;
+        int input_idx, out_ch_idx, in_ch_idx;
+
+        next = strchr(cur, ',');
+        if (next)
+            *next++ = 0;
+
+        /* split the map into input and output parts */
+        if (!(sep = strchr(cur, '-'))) {
+            av_log(ctx, AV_LOG_ERROR, "Missing separator '-' in channel "
+                   "map '%s'\n", cur);
+            return AVERROR(EINVAL);
+        }
+        *sep++ = 0;
+
+#define PARSE_CHANNEL(str, var, inout)                                         \
+        if (!(var = av_get_channel_layout(str))) {                             \
+            av_log(ctx, AV_LOG_ERROR, "Invalid " inout " channel: %s.\n", str);\
+            return AVERROR(EINVAL);                                            \
+        }                                                                      \
+        if (av_get_channel_layout_nb_channels(var) != 1) {                     \
+            av_log(ctx, AV_LOG_ERROR, "Channel map describes more than one "   \
+                   inout " channel.\n");                                       \
+            return AVERROR(EINVAL);                                            \
+        }
+
+        /* parse output channel */
+        PARSE_CHANNEL(sep, out_channel, "output");
+        if (!(out_channel & s->channel_layout)) {
+            av_log(ctx, AV_LOG_ERROR, "Output channel '%s' is not present in "
+                   "requested channel layout.\n", sep);
+            return AVERROR(EINVAL);
+        }
+
+        out_ch_idx = av_get_channel_layout_channel_index(s->channel_layout,
+                                                         out_channel);
+        if (s->channels[out_ch_idx].input >= 0) {
+            av_log(ctx, AV_LOG_ERROR, "Multiple maps for output channel "
+                   "'%s'.\n", sep);
+            return AVERROR(EINVAL);
+        }
+
+        /* parse input channel */
+        input_idx = strtol(cur, &cur, 0);
+        if (input_idx < 0 || input_idx >= s->inputs) {
+            av_log(ctx, AV_LOG_ERROR, "Invalid input stream index: %d.\n",
+                   input_idx);
+            return AVERROR(EINVAL);
+        }
+
+        if (*cur)
+            cur++;
+
+        in_ch_idx = strtol(cur, &p, 0);
+        if (p == cur) {
+            /* channel specifier is not a number,
+             * try to parse as channel name */
+            PARSE_CHANNEL(cur, in_channel, "input");
+        }
+
+        s->channels[out_ch_idx].input      = input_idx;
+        if (in_channel)
+            s->channels[out_ch_idx].in_channel = in_channel;
+        else
+            s->channels[out_ch_idx].in_channel_idx = in_ch_idx;
+
+        cur = next;
+    }
+    return 0;
+}
+
+static int join_init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    JoinContext *s = ctx->priv;
+    int ret, i;
+
+    s->class = &join_class;
+    av_opt_set_defaults(s);
+    if ((ret = av_set_options_string(s, args, "=", ":")) < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Error parsing options string '%s'.\n", args);
+        return ret;
+    }
+
+    if (!(s->channel_layout = av_get_channel_layout(s->channel_layout_str))) {
+        av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout '%s'.\n",
+               s->channel_layout_str);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    s->nb_channels  = av_get_channel_layout_nb_channels(s->channel_layout);
+    s->channels     = av_mallocz(sizeof(*s->channels) * s->nb_channels);
+    s->data         = av_mallocz(sizeof(*s->data)     * s->nb_channels);
+    s->input_frames = av_mallocz(sizeof(*s->input_frames) * s->inputs);
+    if (!s->channels || !s->data || !s->input_frames) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    for (i = 0; i < s->nb_channels; i++) {
+        s->channels[i].out_channel = av_channel_layout_extract_channel(s->channel_layout, i);
+        s->channels[i].input       = -1;
+    }
+
+    if ((ret = parse_maps(ctx)) < 0)
+        goto fail;
+
+    for (i = 0; i < s->inputs; i++) {
+        char name[32];
+        AVFilterPad pad = { 0 };
+
+        snprintf(name, sizeof(name), "input%d", i);
+        pad.type           = AVMEDIA_TYPE_AUDIO;
+        pad.name           = av_strdup(name);
+        pad.filter_samples = filter_samples;
+
+        pad.needs_fifo = 1;
+
+        ff_insert_inpad(ctx, i, &pad);
+    }
+
+fail:
+    av_opt_free(s);
+    return ret;
+}
+
+static void join_uninit(AVFilterContext *ctx)
+{
+    JoinContext *s = ctx->priv;
+    int i;
+
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        av_freep(&ctx->input_pads[i].name);
+        avfilter_unref_buffer(s->input_frames[i]);
+    }
+
+    av_freep(&s->channels);
+    av_freep(&s->data);
+    av_freep(&s->input_frames);
+}
+
+static int join_query_formats(AVFilterContext *ctx)
+{
+    JoinContext *s = ctx->priv;
+    AVFilterChannelLayouts *layouts = NULL;
+    int i;
+
+    ff_add_channel_layout(&layouts, s->channel_layout);
+    ff_channel_layouts_ref(layouts, &ctx->outputs[0]->in_channel_layouts);
+
+    for (i = 0; i < ctx->nb_inputs; i++)
+        ff_channel_layouts_ref(ff_all_channel_layouts(),
+                               &ctx->inputs[i]->out_channel_layouts);
+
+    ff_set_common_formats    (ctx, ff_planar_sample_fmts());
+    ff_set_common_samplerates(ctx, ff_all_samplerates());
+
+    return 0;
+}
+
+static void guess_map_matching(AVFilterContext *ctx, ChannelMap *ch,
+                               uint64_t *inputs)
+{
+    int i;
+
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        AVFilterLink *link = ctx->inputs[i];
+
+        if (ch->out_channel & link->channel_layout &&
+            !(ch->out_channel & inputs[i])) {
+            ch->input      = i;
+            ch->in_channel = ch->out_channel;
+            inputs[i]     |= ch->out_channel;
+            return;
+        }
+    }
+}
+
+static void guess_map_any(AVFilterContext *ctx, ChannelMap *ch,
+                          uint64_t *inputs)
+{
+    int i;
+
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        AVFilterLink *link = ctx->inputs[i];
+
+        if ((inputs[i] & link->channel_layout) != link->channel_layout) {
+            uint64_t unused = link->channel_layout & ~inputs[i];
+
+            ch->input      = i;
+            ch->in_channel = av_channel_layout_extract_channel(unused, 0);
+            inputs[i]     |= ch->in_channel;
+            return;
+        }
+    }
+}
+
+static int join_config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    JoinContext       *s = ctx->priv;
+    uint64_t *inputs;   // nth element tracks which channels are used from nth input
+    int i, ret = 0;
+
+    /* initialize inputs to user-specified mappings */
+    if (!(inputs = av_mallocz(sizeof(*inputs) * ctx->nb_inputs)))
+        return AVERROR(ENOMEM);
+    for (i = 0; i < s->nb_channels; i++) {
+        ChannelMap *ch = &s->channels[i];
+        AVFilterLink *inlink;
+
+        if (ch->input < 0)
+            continue;
+
+        inlink = ctx->inputs[ch->input];
+
+        if (!ch->in_channel)
+            ch->in_channel = av_channel_layout_extract_channel(inlink->channel_layout,
+                                                               ch->in_channel_idx);
+
+        if (!(ch->in_channel & inlink->channel_layout)) {
+            av_log(ctx, AV_LOG_ERROR, "Requested channel %s is not present in "
+                   "input stream #%d.\n", av_get_channel_name(ch->in_channel),
+                   ch->input);
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
+
+        inputs[ch->input] |= ch->in_channel;
+    }
+
+    /* guess channel maps when not explicitly defined */
+    /* first try unused matching channels */
+    for (i = 0; i < s->nb_channels; i++) {
+        ChannelMap *ch = &s->channels[i];
+
+        if (ch->input < 0)
+            guess_map_matching(ctx, ch, inputs);
+    }
+
+    /* if the above failed, try to find _any_ unused input channel */
+    for (i = 0; i < s->nb_channels; i++) {
+        ChannelMap *ch = &s->channels[i];
+
+        if (ch->input < 0)
+            guess_map_any(ctx, ch, inputs);
+
+        if (ch->input < 0) {
+            av_log(ctx, AV_LOG_ERROR, "Could not find input channel for "
+                   "output channel '%s'.\n",
+                   av_get_channel_name(ch->out_channel));
+            goto fail;
+        }
+
+        ch->in_channel_idx = av_get_channel_layout_channel_index(ctx->inputs[ch->input]->channel_layout,
+                                                                 ch->in_channel);
+    }
+
+    /* print mappings */
+    av_log(ctx, AV_LOG_VERBOSE, "mappings: ");
+    for (i = 0; i < s->nb_channels; i++) {
+        ChannelMap *ch = &s->channels[i];
+        av_log(ctx, AV_LOG_VERBOSE, "%d.%s => %s ", ch->input,
+               av_get_channel_name(ch->in_channel),
+               av_get_channel_name(ch->out_channel));
+    }
+    av_log(ctx, AV_LOG_VERBOSE, "\n");
+
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        if (!inputs[i])
+            av_log(ctx, AV_LOG_WARNING, "No channels are used from input "
+                   "stream %d.\n", i);
+    }
+
+fail:
+    av_freep(&inputs);
+    return ret;
+}
+
+static void join_free_buffer(AVFilterBuffer *buf)
+{
+    JoinBufferPriv *priv = buf->priv;
+
+    if (priv) {
+        int i;
+
+        for (i = 0; i < priv->nb_in_buffers; i++)
+            avfilter_unref_buffer(priv->in_buffers[i]);
+
+        av_freep(&priv->in_buffers);
+        av_freep(&buf->priv);
+    }
+
+    if (buf->extended_data != buf->data)
+        av_freep(&buf->extended_data);
+    av_freep(&buf);
+}
+
+static int join_request_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    JoinContext *s       = ctx->priv;
+    AVFilterBufferRef *buf;
+    JoinBufferPriv *priv;
+    int linesize   = INT_MAX;
+    int perms      = ~0;
+    int nb_samples;
+    int i, j, ret;
+
+    /* get a frame on each input */
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        AVFilterLink *inlink = ctx->inputs[i];
+
+        if (!s->input_frames[i] &&
+            (ret = ff_request_frame(inlink)) < 0)
+            return ret;
+
+        /* request the same number of samples on all inputs */
+        if (i == 0) {
+            nb_samples = s->input_frames[0]->audio->nb_samples;
+
+            for (j = 1; !i && j < ctx->nb_inputs; j++)
+                ctx->inputs[j]->request_samples = nb_samples;
+        }
+    }
+
+    for (i = 0; i < s->nb_channels; i++) {
+        ChannelMap *ch = &s->channels[i];
+        AVFilterBufferRef *cur_buf = s->input_frames[ch->input];
+
+        s->data[i] = cur_buf->extended_data[ch->in_channel_idx];
+        linesize   = FFMIN(linesize, cur_buf->linesize[0]);
+        perms     &= cur_buf->perms;
+    }
+
+    buf = avfilter_get_audio_buffer_ref_from_arrays(s->data, linesize, perms,
+                                                    nb_samples, outlink->format,
+                                                    outlink->channel_layout);
+    if (!buf)
+        return AVERROR(ENOMEM);
+
+    buf->buf->free = join_free_buffer;
+    buf->pts       = s->input_frames[0]->pts;
+
+    if (!(priv = av_mallocz(sizeof(*priv))))
+        goto fail;
+    if (!(priv->in_buffers = av_mallocz(sizeof(*priv->in_buffers) * ctx->nb_inputs)))
+        goto fail;
+
+    for (i = 0; i < ctx->nb_inputs; i++)
+        priv->in_buffers[i] = s->input_frames[i];
+    priv->nb_in_buffers = ctx->nb_inputs;
+    buf->buf->priv      = priv;
+
+    ff_filter_samples(outlink, buf);
+
+    memset(s->input_frames, 0, sizeof(*s->input_frames) * ctx->nb_inputs);
+
+    return 0;
+
+fail:
+    avfilter_unref_buffer(buf);
+    if (priv)
+        av_freep(&priv->in_buffers);
+    av_freep(&priv);
+    return AVERROR(ENOMEM);
+}
+
+AVFilter avfilter_af_join = {
+    .name           = "join",
+    .description    = NULL_IF_CONFIG_SMALL("Join multiple audio streams into "
+                                           "multi-channel output"),
+    .priv_size      = sizeof(JoinContext),
+
+    .init           = join_init,
+    .uninit         = join_uninit,
+    .query_formats  = join_query_formats,
+
+    .inputs  = (const AVFilterPad[]){{ NULL }},
+    .outputs = (const AVFilterPad[]){{ .name          = "default",
+                                       .type          = AVMEDIA_TYPE_AUDIO,
+                                       .config_props  = join_config_output,
+                                       .request_frame = join_request_frame, },
+                                     { NULL }},
+};

libavfilter/allfilters.c

@@ -41,6 +41,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (ASPLIT,      asplit,      af);
     REGISTER_FILTER (ASYNCTS,     asyncts,     af);
     REGISTER_FILTER (CHANNELSPLIT,channelsplit,af);
+    REGISTER_FILTER (JOIN,        join,        af);
     REGISTER_FILTER (RESAMPLE,    resample,    af);
 
     REGISTER_FILTER (ANULLSRC,    anullsrc,    asrc);