Inspired by MPlayer's af_channels filter and SoX's remix effect.
---
Changelog | 1 +
doc/filters.texi | 24 +++
libavfilter/Makefile | 1 +
libavfilter/af_channelmap.c | 406 +++++++++++++++++++++++++++++++++++++++++++
libavfilter/allfilters.c | 1 +
5 files changed, 433 insertions(+), 0 deletions(-)
create mode 100644 libavfilter/af_channelmap.c
diff --git a/Changelog b/Changelog
index b80ff88..580381d 100644
--- a/Changelog
+++ b/Changelog
@@ -25,6 +25,7 @@ version <next>:
be used with -of old.
- Indeo Audio decoder
- channelsplit audio filter
+- audio channel mapping filter
version 0.8:
diff --git a/doc/filters.texi b/doc/filters.texi
index f17dad8..00ab07e 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -232,6 +232,30 @@ front_center.wav -map '[LFE]' lfe.wav -map '[SL]'
side_left.wav -map '[SR]'
side_right.wav
@end example
+@section channelmap
+Remap input channels to new locations.
+
+This filter accepts the following named parameters:
+@table @option
+@item channel_layout
+Channel layout of the output stream.
+
+@item map
+A comma-seperated list of input to output mappings.
+@end table
+
+For example, assuming a 5.1+downmix input MOV file
+@example
+avconv -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
+@end example
+will create an output Wave file tagged as stereo from the downmix channels of
+the input.
+
+To fix a 5.1 wav improperly encoded in AAC's native channel order
+@example
+avconv -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1'
out.wav
+@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
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 955a97c..7d1ced0 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -30,6 +30,7 @@ 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_RESAMPLE_FILTER) += af_resample.o
diff --git a/libavfilter/af_channelmap.c b/libavfilter/af_channelmap.c
new file mode 100644
index 0000000..788affc
--- /dev/null
+++ b/libavfilter/af_channelmap.c
@@ -0,0 +1,406 @@
+/*
+ * 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;
+ int nch;
+ int output_layout;
+ struct ChannelMap map[MAX_CH];
+ 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 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);
+
+fail:
+ av_opt_free(s);
+ return ret;
+}
+
+static int 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 filter_samples(AVFilterLink *inlink, AVFilterBufferRef *buf)
+{
+ AVFilterContext *ctx = inlink->dst;
+ AVFilterLink *outlink = ctx->outputs[0];
+ const ChannelMapContext *s = ctx->priv;
+ const int nch_in = FFMIN(
+ av_get_channel_layout_nb_channels(inlink->channel_layout), MAX_CH);
+ 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;
+ }
+ }
+
+ switch (s->mode) {
+ case MAP_NONE:
+ case MAP_ONE_INT:
+ case MAP_PAIR_INT_INT:
+ for (ch = 0; ch < nch_out; ch++) {
+ buf->extended_data[s->map[ch].out_channel_idx] =
+ source_planes[s->map[ch].in_channel_idx];
+ }
+ break;
+ case MAP_PAIR_INT_STR:
+ for (ch = 0; ch < nch_out; ch++) {
+ int out_idx = av_get_channel_layout_channel_index(
+ s->output_layout, s->map[ch].out_channel);
+ buf->extended_data[out_idx] =
+ source_planes[s->map[ch].in_channel_idx];
+ }
+ break;
+ case MAP_ONE_STR:
+ case MAP_PAIR_STR_INT:
+ for (ch = 0; ch < nch_out; ch++) {
+ int in_idx = av_get_channel_layout_channel_index(
+ inlink->channel_layout, s->map[ch].in_channel);
+ buf->extended_data[s->map[ch].out_channel_idx] =
+ source_planes[in_idx];
+ }
+ break;
+ case MAP_PAIR_STR_STR:
+ for (ch = 0; ch < nch_out; ch++) {
+ int in_idx = av_get_channel_layout_channel_index(
+ inlink->channel_layout, s->map[ch].in_channel);
+ int out_idx = av_get_channel_layout_channel_index(
+ s->output_layout, s->map[ch].out_channel);
+ buf->extended_data[out_idx] = source_planes[in_idx];
+ }
+ break;
+ }
+ 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 config_output(AVFilterLink *outlink)
+{
+ AVFilterContext *ctx = outlink->src;
+ ChannelMapContext *s = ctx->priv;
+
+ outlink->channel_layout = s->output_layout;
+
+ return 0;
+}
+
+AVFilter avfilter_af_channelmap = {
+ .name = "channelmap",
+ .description = NULL_IF_CONFIG_SMALL("Remap audio channels."),
+ .init = init,
+ .query_formats = query_formats,
+ .priv_size = sizeof(ChannelMapContext),
+
+ .inputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .filter_samples = filter_samples },
+ { .name = NULL }},
+ .outputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .config_props = config_output },
+ { .name = NULL }},
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 118f09d..a2e7b27 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -39,6 +39,7 @@ 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 (RESAMPLE, resample, af);
--
1.7.7.3
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