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* Copyright (C) 2003-2011 The Music Player Daemon Project
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* http://www.musicpd.org
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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* This filter copies audio data between channels. Useful for
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* upmixing mono/stereo audio to surround speaker configurations.
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* Its configuration consists of a "filter" section with a single
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* "routes" entry, formatted as: \\
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* routes "0>1, 1>0, 2>2, 3>3, 3>4" \\
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* where each pair of numbers signifies a set of channels.
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* Each source>dest pair leads to the data from channel #source
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* being copied to channel #dest in the output.
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* routes "0>0, 1>1, 0>2, 1>3"\\
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* upmixes stereo audio to a 4-speaker system, copying the front-left
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* (0) to front left (0) and rear left (2), copying front-right (1) to
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* front-right (1) and rear-right (3).
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* If multiple sources are copied to the same destination channel, only
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* one of them takes effect.
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#include "audio_format.h"
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#include "audio_check.h"
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#include "filter_plugin.h"
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#include "filter_internal.h"
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#include "filter_registry.h"
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#include "pcm_buffer.h"
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* Inherit (and support cast to/from) filter
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* The minimum number of channels we need for output
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* to be able to perform all the copies the user has specified
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unsigned char min_output_channels;
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* The minimum number of input channels we need to
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* copy all the data the user has requested. If fewer
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* than this many are supplied by the input, undefined
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* copy operations are given zeroed sources in stead.
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unsigned char min_input_channels;
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* The set of copy operations to perform on each sample
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* The index is an output channel to use, the value is
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* a corresponding input channel from which to take the
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* data. A -1 means "no source"
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* The actual input format of our signal, once opened
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struct audio_format input_format;
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* The decided upon output format, once opened
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struct audio_format output_format;
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* The size, in bytes, of each multichannel frame in the
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size_t input_frame_size;
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* The size, in bytes, of each multichannel frame in the
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size_t output_frame_size;
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* The output buffer used last time around, can be reused if the size doesn't differ.
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struct pcm_buffer output_buffer;
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* Parse the "routes" section, a string on the form
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* where a... are non-unique, non-negative integers
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* and input channel a gets copied to output channel b, etc.
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* @param param the configuration block to read
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* @param filter a route_filter whose min_channels and sources[] to set
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* @return true on success, false on error
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route_filter_parse(const struct config_param *param,
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struct route_filter *filter,
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* With a more clever way of marking "don't copy to output N",
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* This could easily be merged into a single loop with some
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* dynamic g_realloc() instead of one count run and one g_malloc().
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int number_of_copies;
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// A cowardly default, just passthrough stereo
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config_get_block_string(param, "routes", "0>0, 1>1");
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filter->min_input_channels = 0;
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filter->min_output_channels = 0;
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tokens = g_strsplit(routes, ",", 255);
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number_of_copies = g_strv_length(tokens);
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// Start by figuring out a few basic things about the routing set
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for (int c=0; c<number_of_copies; ++c) {
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// String and int representations of the source/destination
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// Squeeze whitespace
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g_strstrip(tokens[c]);
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// Split the a>b string into source and destination
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sd = g_strsplit(tokens[c], ">", 2);
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if (g_strv_length(sd) != 2) {
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g_set_error(error_r, config_quark(), 1,
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"Invalid copy around %d in routes spec: %s",
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param->line, tokens[c]);
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source = strtol(sd[0], NULL, 10);
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dest = strtol(sd[1], NULL, 10);
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// Keep track of the highest channel numbers seen
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// as either in- or outputs
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if (source >= filter->min_input_channels)
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filter->min_input_channels = source + 1;
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if (dest >= filter->min_output_channels)
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filter->min_output_channels = dest + 1;
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if (!audio_valid_channel_count(filter->min_output_channels)) {
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g_set_error(error_r, audio_format_quark(), 0,
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"Invalid number of output channels requested: %d",
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filter->min_output_channels);
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// Allocate a map of "copy nothing to me"
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g_malloc(filter->min_output_channels * sizeof(signed char));
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for (int i=0; i<filter->min_output_channels; ++i)
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filter->sources[i] = -1;
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// Run through the spec again, and save the
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// actual mapping output <- input
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for (int c=0; c<number_of_copies; ++c) {
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// String and int representations of the source/destination
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// Split the a>b string into source and destination
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sd = g_strsplit(tokens[c], ">", 2);
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if (g_strv_length(sd) != 2) {
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g_set_error(error_r, config_quark(), 1,
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"Invalid copy around %d in routes spec: %s",
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param->line, tokens[c]);
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source = strtol(sd[0], NULL, 10);
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dest = strtol(sd[1], NULL, 10);
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filter->sources[dest] = source;
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static struct filter *
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route_filter_init(const struct config_param *param,
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G_GNUC_UNUSED GError **error_r)
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struct route_filter *filter = g_new(struct route_filter, 1);
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filter_init(&filter->base, &route_filter_plugin);
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// Allocate and set the filter->sources[] array
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route_filter_parse(param, filter, error_r);
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return &filter->base;
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route_filter_finish(struct filter *_filter)
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struct route_filter *filter = (struct route_filter *)_filter;
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g_free(filter->sources);
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static const struct audio_format *
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route_filter_open(struct filter *_filter, struct audio_format *audio_format,
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G_GNUC_UNUSED GError **error_r)
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struct route_filter *filter = (struct route_filter *)_filter;
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// Copy the input format for later reference
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filter->input_format = *audio_format;
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filter->input_frame_size =
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audio_format_frame_size(&filter->input_format);
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// Decide on an output format which has enough channels,
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// and is otherwise identical
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filter->output_format = *audio_format;
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filter->output_format.channels = filter->min_output_channels;
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// Precalculate this simple value, to speed up allocation later
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filter->output_frame_size =
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audio_format_frame_size(&filter->output_format);
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// This buffer grows as needed
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pcm_buffer_init(&filter->output_buffer);
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return &filter->output_format;
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route_filter_close(struct filter *_filter)
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struct route_filter *filter = (struct route_filter *)_filter;
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pcm_buffer_deinit(&filter->output_buffer);
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route_filter_filter(struct filter *_filter,
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const void *src, size_t src_size,
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size_t *dest_size_r, G_GNUC_UNUSED GError **error_r)
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struct route_filter *filter = (struct route_filter *)_filter;
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size_t number_of_frames = src_size / filter->input_frame_size;
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size_t bytes_per_frame_per_channel =
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audio_format_sample_size(&filter->input_format);
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// A moving pointer that always refers to channel 0 in the input, at the currently handled frame
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const uint8_t *base_source = src;
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// A moving pointer that always refers to the currently filled channel of the currently handled frame, in the output
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uint8_t *chan_destination;
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// Grow our reusable buffer, if needed, and set the moving pointer
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*dest_size_r = number_of_frames * filter->output_frame_size;
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chan_destination = pcm_buffer_get(&filter->output_buffer, *dest_size_r);
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// Perform our copy operations, with N input channels and M output channels
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for (unsigned int s=0; s<number_of_frames; ++s) {
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// Need to perform one copy per output channel
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for (unsigned int c=0; c<filter->min_output_channels; ++c) {
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if (filter->sources[c] == -1 ||
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(unsigned)filter->sources[c] >= filter->input_format.channels) {
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// No source for this destination output,
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// give it zeroes as input
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memset(chan_destination,
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bytes_per_frame_per_channel);
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// Get the data from channel sources[c]
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// and copy it to the output
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const uint8_t *data = base_source +
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(filter->sources[c] * bytes_per_frame_per_channel);
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memcpy(chan_destination,
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bytes_per_frame_per_channel);
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// Move on to the next output channel
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chan_destination += bytes_per_frame_per_channel;
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// Go on to the next N input samples
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base_source += filter->input_frame_size;
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// Here it is, ladies and gentlemen! Rerouted data!
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return (void *) filter->output_buffer.buffer;
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const struct filter_plugin route_filter_plugin = {
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.init = route_filter_init,
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.finish = route_filter_finish,
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.open = route_filter_open,
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.close = route_filter_close,
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.filter = route_filter_filter,
added
removed
src/filter/route_filter_plugin.c
