lavfi: Add the af_channelmap audio channel mapping filter.

Inspired by MPlayer's af_channels filter and SoX's remix effect.

3 files changed, 404 insertions, 0 deletions

diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 5fa85cebe4..c77d450d7e 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -31,6 +31,7 @@ OBJS-$(CONFIG_AMIX_FILTER)                   += af_amix.o
 OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_ASPLIT_FILTER)                 += split.o
 OBJS-$(CONFIG_ASYNCTS_FILTER)                += af_asyncts.o
+OBJS-$(CONFIG_CHANNELMAP_FILTER)             += af_channelmap.o
 OBJS-$(CONFIG_CHANNELSPLIT_FILTER)           += af_channelsplit.o
 OBJS-$(CONFIG_JOIN_FILTER)                   += af_join.o
 OBJS-$(CONFIG_RESAMPLE_FILTER)               += af_resample.o
diff --git a/libavfilter/af_channelmap.c b/libavfilter/af_channelmap.c
new file mode 100644
index 0000000000..14c2c0cb5a
--- /dev/null
+++ b/libavfilter/af_channelmap.c
@@ -0,0 +1,402 @@
+/*
+ * Copyright (c) 2012 Google, Inc.
+ *
+ * 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 channel mapping filter
+ */
+
+#include <ctype.h>
+
+#include "libavutil/audioconvert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/mathematics.h"
+#include "libavutil/opt.h"
+#include "libavutil/samplefmt.h"
+
+#include "audio.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+
+struct ChannelMap {
+    uint64_t in_channel;
+    uint64_t out_channel;
+    int in_channel_idx;
+    int out_channel_idx;
+};
+
+enum MappingMode {
+    MAP_NONE,
+    MAP_ONE_INT,
+    MAP_ONE_STR,
+    MAP_PAIR_INT_INT,
+    MAP_PAIR_INT_STR,
+    MAP_PAIR_STR_INT,
+    MAP_PAIR_STR_STR
+};
+
+#define MAX_CH 64
+typedef struct ChannelMapContext {
+    const AVClass *class;
+    AVFilterChannelLayouts *channel_layouts;
+    char *mapping_str;
+    char *channel_layout_str;
+    uint64_t output_layout;
+    struct ChannelMap map[MAX_CH];
+    int nch;
+    enum MappingMode mode;
+} ChannelMapContext;
+
+#define OFFSET(x) offsetof(ChannelMapContext, x)
+#define A AV_OPT_FLAG_AUDIO_PARAM
+static const AVOption options[] = {
+    { "map", "A comma-separated list of input channel numbers in output order.",
+          OFFSET(mapping_str),        AV_OPT_TYPE_STRING, .flags = A },
+    { "channel_layout", "Output channel layout.",
+          OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, .flags = A },
+    { NULL },
+};
+
+static const AVClass channelmap_class = {
+    .class_name = "channel map filter",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static char* split(char *message, char delim) {
+    char *next = strchr(message, delim);
+    if (next)
+      *next++ = '\0';
+    return next;
+}
+
+static int get_channel_idx(char **map, int *ch, char delim, int max_ch)
+{
+    char *next = split(*map, delim);
+    int len;
+    int n = 0;
+    if (!next && delim == '-')
+        return AVERROR(EINVAL);
+    len = strlen(*map);
+    sscanf(*map, "%d%n", ch, &n);
+    if (n != len)
+        return AVERROR(EINVAL);
+    if (*ch < 0 || *ch > max_ch)
+        return AVERROR(EINVAL);
+    *map = next;
+    return 0;
+}
+
+static int get_channel(char **map, uint64_t *ch, char delim)
+{
+    char *next = split(*map, delim);
+    if (!next && delim == '-')
+        return AVERROR(EINVAL);
+    *ch = av_get_channel_layout(*map);
+    if (av_get_channel_layout_nb_channels(*ch) != 1)
+        return AVERROR(EINVAL);
+    *map = next;
+    return 0;
+}
+
+static av_cold int channelmap_init(AVFilterContext *ctx, const char *args,
+                                   void *opaque)
+{
+    ChannelMapContext *s = ctx->priv;
+    int ret;
+    char *mapping;
+    enum mode;
+    int map_entries = 0;
+    char buf[256];
+    enum MappingMode mode;
+    uint64_t out_ch_mask = 0;
+    int i;
+
+    if (!args) {
+        av_log(ctx, AV_LOG_ERROR, "No parameters supplied.\n");
+        return AVERROR(EINVAL);
+    }
+
+    s->class = &channelmap_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;
+    }
+
+    mapping = s->mapping_str;
+
+    if (!mapping) {
+        mode = MAP_NONE;
+    } else {
+        char *dash = strchr(mapping, '-');
+        if (!dash) {  // short mapping
+            if (isdigit(*mapping))
+                mode = MAP_ONE_INT;
+            else
+                mode = MAP_ONE_STR;
+        } else if (isdigit(*mapping)) {
+            if (isdigit(*(dash+1)))
+                mode = MAP_PAIR_INT_INT;
+            else
+                mode = MAP_PAIR_INT_STR;
+        } else {
+            if (isdigit(*(dash+1)))
+                mode = MAP_PAIR_STR_INT;
+            else
+                mode = MAP_PAIR_STR_STR;
+        }
+    }
+
+    if (mode != MAP_NONE) {
+        char *comma = mapping;
+        map_entries = 1;
+        while ((comma = strchr(comma, ','))) {
+            if (*++comma)  // Allow trailing comma
+                map_entries++;
+        }
+    }
+
+    if (map_entries > MAX_CH) {
+        av_log(ctx, AV_LOG_ERROR, "Too many channels mapped: '%d'.\n", map_entries);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    for (i = 0; i < map_entries; i++) {
+        int in_ch_idx = -1, out_ch_idx = -1;
+        uint64_t in_ch = 0, out_ch = 0;
+        static const char err[] = "Failed to parse channel map\n";
+        switch (mode) {
+        case MAP_ONE_INT:
+            if (get_channel_idx(&mapping, &in_ch_idx, ',', MAX_CH) < 0) {
+                ret = AVERROR(EINVAL);
+                av_log(ctx, AV_LOG_ERROR, err);
+                goto fail;
+            }
+            s->map[i].in_channel_idx  = in_ch_idx;
+            s->map[i].out_channel_idx = i;
+            break;
+        case MAP_ONE_STR:
+            if (!get_channel(&mapping, &in_ch, ',')) {
+                av_log(ctx, AV_LOG_ERROR, err);
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
+            s->map[i].in_channel      = in_ch;
+            s->map[i].out_channel_idx = i;
+            break;
+        case MAP_PAIR_INT_INT:
+            if (get_channel_idx(&mapping, &in_ch_idx, '-', MAX_CH) < 0 ||
+                get_channel_idx(&mapping, &out_ch_idx, ',', MAX_CH) < 0) {
+                av_log(ctx, AV_LOG_ERROR, err);
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
+            s->map[i].in_channel_idx  = in_ch_idx;
+            s->map[i].out_channel_idx = out_ch_idx;
+            break;
+        case MAP_PAIR_INT_STR:
+            if (get_channel_idx(&mapping, &in_ch_idx, '-', MAX_CH) < 0 ||
+                get_channel(&mapping, &out_ch, ',') < 0 ||
+                out_ch & out_ch_mask) {
+                av_log(ctx, AV_LOG_ERROR, err);
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
+            s->map[i].in_channel_idx  = in_ch_idx;
+            s->map[i].out_channel     = out_ch;
+            out_ch_mask |= out_ch;
+            break;
+        case MAP_PAIR_STR_INT:
+            if (get_channel(&mapping, &in_ch, '-') < 0 ||
+                get_channel_idx(&mapping, &out_ch_idx, ',', MAX_CH) < 0) {
+                av_log(ctx, AV_LOG_ERROR, err);
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
+            s->map[i].in_channel      = in_ch;
+            s->map[i].out_channel_idx = out_ch_idx;
+            break;
+        case MAP_PAIR_STR_STR:
+            if (get_channel(&mapping, &in_ch, '-') < 0 ||
+                get_channel(&mapping, &out_ch, ',') < 0 ||
+                out_ch & out_ch_mask) {
+                av_log(ctx, AV_LOG_ERROR, err);
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
+            s->map[i].in_channel = in_ch;
+            s->map[i].out_channel = out_ch;
+            out_ch_mask |= out_ch;
+            break;
+        }
+    }
+    s->mode          = mode;
+    s->nch           = map_entries;
+    s->output_layout = out_ch_mask ? out_ch_mask :
+                       av_get_default_channel_layout(map_entries);
+
+    if (s->channel_layout_str) {
+        uint64_t fmt;
+        if ((fmt = av_get_channel_layout(s->channel_layout_str)) == 0) {
+            av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout: '%s'.\n",
+                   s->channel_layout_str);
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
+        if (mode == MAP_NONE) {
+            int i;
+            s->nch = av_get_channel_layout_nb_channels(fmt);
+            for (i = 0; i < s->nch; i++) {
+                s->map[i].in_channel_idx  = i;
+                s->map[i].out_channel_idx = i;
+            }
+        } else if (out_ch_mask && out_ch_mask != fmt) {
+            av_get_channel_layout_string(buf, sizeof(buf), 0, out_ch_mask);
+            av_log(ctx, AV_LOG_ERROR,
+                   "Output channel layout '%s' does not match the list of channel mapped: '%s'.\n",
+                   s->channel_layout_str, buf);
+            ret = AVERROR(EINVAL);
+            goto fail;
+        } else if (s->nch != av_get_channel_layout_nb_channels(fmt)) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Output channel layout %s does not match the number of channels mapped %d.\n",
+                   s->channel_layout_str, s->nch);
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
+        s->output_layout = fmt;
+    }
+    ff_add_channel_layout(&s->channel_layouts, s->output_layout);
+
+    if (mode == MAP_PAIR_INT_STR || mode == MAP_PAIR_STR_STR) {
+        for (i = 0; i < s->nch; i++) {
+            s->map[i].out_channel_idx = av_get_channel_layout_channel_index(
+                s->output_layout, s->map[i].out_channel);
+        }
+    }
+
+fail:
+    av_opt_free(s);
+    return ret;
+}
+
+static int channelmap_query_formats(AVFilterContext *ctx)
+{
+    ChannelMapContext *s = ctx->priv;
+
+    ff_set_common_formats(ctx, ff_planar_sample_fmts());
+    ff_set_common_samplerates(ctx, ff_all_samplerates());
+    ff_channel_layouts_ref(ff_all_channel_layouts(), &ctx->inputs[0]->out_channel_layouts);
+    ff_channel_layouts_ref(s->channel_layouts,       &ctx->outputs[0]->in_channel_layouts);
+
+    return 0;
+}
+
+static void channelmap_filter_samples(AVFilterLink *inlink, AVFilterBufferRef *buf)
+{
+    AVFilterContext  *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    const ChannelMapContext *s = ctx->priv;
+    const int nch_in = av_get_channel_layout_nb_channels(inlink->channel_layout);
+    const int nch_out = s->nch;
+    int ch;
+    uint8_t *source_planes[MAX_CH];
+
+    memcpy(source_planes, buf->extended_data,
+           nch_in * sizeof(source_planes[0]));
+
+    if (nch_out > nch_in) {
+        if (nch_out > FF_ARRAY_ELEMS(buf->data)) {
+            uint8_t **new_extended_data =
+                av_mallocz(nch_out * sizeof(*buf->extended_data));
+            if (!new_extended_data)
+                return;
+            if (buf->extended_data == buf->data) {
+                buf->extended_data = new_extended_data;
+            } else {
+                buf->extended_data = new_extended_data;
+                av_free(buf->extended_data);
+            }
+        } else if (buf->extended_data != buf->data) {
+            av_free(buf->extended_data);
+            buf->extended_data = buf->data;
+        }
+    }
+
+    for (ch = 0; ch < nch_out; ch++) {
+        buf->extended_data[s->map[ch].out_channel_idx] =
+            source_planes[s->map[ch].in_channel_idx];
+    }
+
+    if (buf->data != buf->extended_data)
+        memcpy(buf->data, buf->extended_data,
+           FFMIN(FF_ARRAY_ELEMS(buf->data), nch_out) * sizeof(buf->data[0]));
+
+    ff_filter_samples(outlink, buf);
+}
+
+static int channelmap_config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    ChannelMapContext *s = ctx->priv;
+    int i, err = 0;
+    const char *channel_name;
+    char layout_name[256];
+
+    if (s->mode == MAP_PAIR_STR_INT || s->mode == MAP_PAIR_STR_STR) {
+        for (i = 0; i < s->nch; i++) {
+            s->map[i].in_channel_idx = av_get_channel_layout_channel_index(
+                inlink->channel_layout, s->map[i].in_channel);
+            if (s->map[i].in_channel_idx < 0) {
+                channel_name = av_get_channel_name(s->map[i].in_channel);
+                av_get_channel_layout_string(layout_name, sizeof(layout_name),
+                                             0, inlink->channel_layout);
+                av_log(ctx, AV_LOG_ERROR,
+                       "input channel '%s' not available from input layout '%s'\n",
+                       channel_name, layout_name);
+                err = AVERROR(EINVAL);
+            }
+        }
+    }
+
+    return err;
+}
+
+AVFilter avfilter_af_channelmap = {
+    .name          = "channelmap",
+    .description   = NULL_IF_CONFIG_SMALL("Remap audio channels."),
+    .init          = channelmap_init,
+    .query_formats = channelmap_query_formats,
+    .priv_size     = sizeof(ChannelMapContext),
+
+    .inputs        = (AVFilterPad[]) {{ .name            = "default",
+                                        .type            = AVMEDIA_TYPE_AUDIO,
+                                        .filter_samples  = channelmap_filter_samples,
+                                        .config_props    = channelmap_config_input },
+                                      { .name = NULL }},
+    .outputs       = (AVFilterPad[]) {{ .name            = "default",
+                                        .type            = AVMEDIA_TYPE_AUDIO },
+                                      { .name = NULL }},
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 786c2dea7b..9c22b4fe9e 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -40,6 +40,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (ANULL,       anull,       af);
     REGISTER_FILTER (ASPLIT,      asplit,      af);
     REGISTER_FILTER (ASYNCTS,     asyncts,     af);
+    REGISTER_FILTER (CHANNELMAP,  channelmap,  af);
     REGISTER_FILTER (CHANNELSPLIT,channelsplit,af);
     REGISTER_FILTER (JOIN,        join,        af);
     REGISTER_FILTER (RESAMPLE,    resample,    af);