[PATCH 1/3] Add af_resample - sample fmt and channel layout conversion filter.
Stefano Sabatini
stefano.sabatini-lala
Fri Oct 1 14:58:22 CEST 2010
Patch by "S.N. Hemanth Meenakshisundaram" 5m33nak5 at uc5d.3du.
---
libavfilter/Makefile | 1 +
libavfilter/af_resample.c | 467 +++++++++++++++++++++++++++++++++++++++++++++
libavfilter/allfilters.c | 1 +
3 files changed, 469 insertions(+), 0 deletions(-)
create mode 100644 libavfilter/af_resample.c
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 74e55bb..e65995c 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -15,6 +15,7 @@ OBJS = allfilters.o \
parseutils.o \
OBJS-$(CONFIG_ANULL_FILTER) += af_anull.o
+OBJS-$(CONFIG_RESAMPLE_FILTER) += af_resample.o
OBJS-$(CONFIG_ANULLSRC_FILTER) += asrc_anullsrc.o
diff --git a/libavfilter/af_resample.c b/libavfilter/af_resample.c
new file mode 100644
index 0000000..2e7898e
--- /dev/null
+++ b/libavfilter/af_resample.c
@@ -0,0 +1,467 @@
+/*
+ * Copyright (C) 2010 S.N. Hemanth Meenakshisundaram <smeenaks at ucsd.edu>
+ * based on code in libavcodec/resample.c by Fabrice Bellard
+ * and libavcodec/audioconvert.c by Michael Neidermayer
+ *
+ * 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
+ * resample audio filter
+ */
+
+#include "avfilter.h"
+#include "libavcodec/audioconvert.h"
+
+typedef struct {
+ short reconfig_channel_layout; ///< set when channel layout of incoming buffer changes
+ short reconfig_sample_fmt; ///< set when sample format of incoming buffer changes
+
+ enum SampleFormat in_sample_fmt; ///< default incoming sample format expected
+ enum SampleFormat out_sample_fmt; ///< output sample format
+ int64_t in_channel_layout; ///< default incoming channel layout expected
+ int64_t out_channel_layout; ///< output channel layout
+
+ int in_nb_samples; ///< stores number of samples in previous incoming buffer
+ AVFilterBufferRef *s16_samples; ///< stores temporary audio data in s16 sample format for channel layout conversions
+ AVFilterBufferRef *s16_samples_ptr; ///< duplicate pointer to audio data in s16 sample format
+ AVFilterBufferRef *temp_samples; ///< stores temporary audio data in s16 sample format after channel layout conversions
+ AVFilterBufferRef *temp_samples_ptr; ///< duplicate pointer to audio data after channel layout conversions
+ AVFilterBufferRef *out_samples; ///< stores audio data after required sample format and channel layout conversions
+ AVFilterBufferRef *out_samples_ptr; ///< duplicate pointer to audio data after required conversions
+
+ AVAudioConvert *conv_handle_s16; ///< audio convert handle for conversion to s16 sample format
+ AVAudioConvert *conv_handle_out; ///< audio convert handle for conversion to output sample format
+
+ /**
+ * channel conversion routine, point to one of the routines below
+ */
+ void (*channel_conversion) (uint8_t *out[], uint8_t *in[], int , int);
+} ResampleContext;
+
+/**
+ * All of the routines below are for packed audio data. SDL accepts packed data
+ * only and current ffplay also assumes packed data only at all times.
+ */
+
+/* Optimized stereo to mono and mono to stereo routines - common case */
+static void stereo_to_mono(uint8_t *out[], uint8_t *in[], int nb_samples, int in_channels)
+{
+ short *input = (short *) in[0];
+ short *output = (short *) out[0];
+
+ while (nb_samples >= 4) {
+ output[0] = (input[0] + input[1]) >> 1;
+ output[1] = (input[2] + input[3]) >> 1;
+ output[2] = (input[4] + input[5]) >> 1;
+ output[3] = (input[6] + input[7]) >> 1;
+ output += 4;
+ input += 8;
+ nb_samples -= 4;
+ }
+ while (nb_samples > 0) {
+ output[0] = (input[0] + input[1]) >> 1;
+ output++;
+ input += 2;
+ nb_samples--;
+ }
+}
+
+static void mono_to_stereo(uint8_t *out[], uint8_t *in[], int nb_samples, int in_channels)
+{
+ int v;
+ short *input = (short *) in[0];
+ short *output = (short *) out[0];
+
+ while (nb_samples >= 4) {
+ v = input[0]; output[0] = v; output[1] = v;
+ v = input[1]; output[2] = v; output[3] = v;
+ v = input[2]; output[4] = v; output[5] = v;
+ v = input[3]; output[6] = v; output[7] = v;
+ output += 8;
+ input += 4;
+ nb_samples -= 4;
+ }
+ while (nb_samples > 0) {
+ v = input[0]; output[0] = v; output[1] = v;
+ output += 2;
+ input += 1;
+ nb_samples--;
+ }
+}
+
+/**
+ * This is for when we have more than 2 input channels, need to downmix to
+ * stereo and do not have a conversion formula available. We just use first
+ * two input channels - left and right. This is a placeholder until more
+ * conversion functions are written.
+ */
+static void stereo_downmix(uint8_t *out[], uint8_t *in[], int nb_samples, int in_channels)
+{
+ int i;
+ short *output = (short *) out[0];
+ short *input = (short *) out[0];
+
+ for (i = 0; i < nb_samples; i++) {
+ *output++ = *input++;
+ *output++ = *input++;
+ input += in_channels-2;
+ }
+}
+
+/**
+ * This is for when we have more than 2 input channels, need to downmix to mono
+ * and do not have a conversion formula available. We just use first two input
+ * channels - left and right. This is a placeholder until more conversion
+ * functions are written.
+ */
+static void mono_downmix(uint8_t *out[], uint8_t *in[], int nb_samples, int in_channels)
+{
+ int i;
+ short *input = (short *) in[0];
+ short *output = (short *) out[0];
+ short left, right;
+
+ for (i = 0; i < nb_samples; i++) {
+ left = *input++;
+ right = *input++;
+ *output++ = (left>>1)+(right>>1);
+ input += in_channels-2;
+ }
+}
+
+/* Stereo to 5.1 output */
+static void ac3_5p1_mux(uint8_t *out[], uint8_t *in[], int nb_samples, int in_channels)
+{
+ int i;
+ short *output = (short *) out[0];
+ short *input = (short *) in[0];
+ short left, right;
+
+ for (i = 0; i < nb_samples; i++) {
+ left = *input++; /* Grab next left sample */
+ right = *input++; /* Grab next right sample */
+ *output++ = left; /* left */
+ *output++ = right; /* right */
+ *output++ = (left>>1)+(right>>1); /* center */
+ *output++ = 0; /* low freq */
+ *output++ = 0; /* FIXME: left surround is either -3dB, -6dB or -9dB of stereo left */
+ *output++ = 0; /* FIXME: right surroud is either -3dB, -6dB or -9dB of stereo right */
+ }
+}
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+ ResampleContext *resample = ctx->priv;
+ char sample_fmt_str[16], ch_layout_str[16];
+
+ if (args)
+ sscanf(args, "%15[a-z0-9]:%15[a-z0-9]", sample_fmt_str, ch_layout_str);
+
+ resample->out_sample_fmt = avcodec_get_sample_fmt(sample_fmt_str);
+
+ if (*sample_fmt_str && (resample->out_sample_fmt >= SAMPLE_FMT_NB ||
+ resample->out_sample_fmt <= SAMPLE_FMT_NONE)) {
+ /**
+ * SAMPLE_FMT_NONE is a valid value for out_sample_fmt and indicates no
+ * change in sample format.
+ */
+ char *tail;
+ resample->out_sample_fmt = strtol(sample_fmt_str, &tail, 10);
+ if (*tail || resample->out_sample_fmt >= SAMPLE_FMT_NB ||
+ resample->out_sample_fmt < SAMPLE_FMT_NONE) {
+ av_log(ctx, AV_LOG_ERROR, "Invalid sample format %s\n", sample_fmt_str);
+ return AVERROR(EINVAL);
+ }
+ }
+
+ resample->out_channel_layout = *ch_layout_str ?
+ avcodec_get_channel_layout(ch_layout_str) : -1;
+
+ if (*ch_layout_str && resample->out_channel_layout < CH_LAYOUT_STEREO) {
+ /**
+ * -1 is a valid value for out_channel_layout and indicates no change
+ * in channel layout.
+ */
+ char *tail;
+ resample->out_channel_layout = strtol(ch_layout_str, &tail, 10);
+ if (*tail || (resample->out_channel_layout < CH_LAYOUT_STEREO &&
+ resample->out_channel_layout != -1)) {
+ av_log(ctx, AV_LOG_ERROR, "Invalid channel layout %s\n", ch_layout_str);
+ return AVERROR(EINVAL);
+ }
+ }
+
+ /* Set default values for expected incoming sample format and channel layout */
+ resample->in_channel_layout = CH_LAYOUT_STEREO;
+ resample->in_sample_fmt = SAMPLE_FMT_S16;
+ resample->in_nb_samples = 0;
+ /* We do not yet know the channel conversion function to be used */
+ resample->channel_conversion = NULL;
+
+ return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+ ResampleContext *resample = ctx->priv;
+ if (resample->s16_samples)
+ avfilter_unref_buffer(resample->s16_samples);
+ if (resample->temp_samples)
+ avfilter_unref_buffer(resample->temp_samples);
+ if (resample->out_samples)
+ avfilter_unref_buffer(resample->out_samples);
+ if (resample->conv_handle_s16)
+ av_audio_convert_free(resample->conv_handle_s16);
+ if (resample->conv_handle_out)
+ av_audio_convert_free(resample->conv_handle_out);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ AVFilterFormats *formats;
+
+ if (ctx->inputs[0]) {
+ formats = NULL;
+ formats = avfilter_all_formats(AVMEDIA_TYPE_AUDIO);
+ avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
+ }
+ if (ctx->outputs[0]) {
+ formats = NULL;
+ formats = avfilter_all_formats(AVMEDIA_TYPE_AUDIO);
+ avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
+ }
+
+ return 0;
+}
+
+static void convert_channel_layout(AVFilterLink *link)
+{
+ ResampleContext *resample = link->dst->priv;
+ AVFilterBufferRef *insamples = resample->s16_samples_ptr;
+ AVFilterBufferRef *outsamples = resample->temp_samples;
+ unsigned int num_ip_channels = avcodec_channel_layout_num_channels(resample->in_channel_layout);
+
+ if (insamples)
+ resample->in_channel_layout = insamples->audio->channel_layout;
+
+ /* Init stage or input channels changed, so reconfigure conversion function pointer */
+ if (resample->reconfig_channel_layout || !resample->channel_conversion) {
+
+ int64_t in_channel = resample->in_channel_layout;
+ int64_t out_channel = resample->out_channel_layout;
+
+ int num_channels = avcodec_channel_layout_num_channels(resample->out_channel_layout);
+ int out_sample_size = av_get_bits_per_sample_format(insamples->format) >> 3;
+
+ int size = num_channels*out_sample_size*insamples->audio->samples_nb;
+
+ if (outsamples)
+ avfilter_unref_buffer(outsamples);
+ outsamples = avfilter_get_audio_buffer(link, AV_PERM_WRITE|AV_PERM_REUSE2,
+ insamples->format, size,
+ out_channel, 0);
+ /*
+ * Pick appropriate channel conversion function based on input-output channel layouts.
+ * If no suitable conversion function is available, downmix to stereo and set buffer
+ * channel layout to stereo.
+ *
+ * FIXME: Add error handling if channel conversion is unsupported, more channel conversion
+ * routines and finally the ability to handle various stride lengths (sample formats).
+ */
+ if (in_channel == CH_LAYOUT_STEREO && out_channel == CH_LAYOUT_MONO)
+ resample->channel_conversion = stereo_to_mono;
+ else if (in_channel == CH_LAYOUT_MONO && out_channel == CH_LAYOUT_STEREO)
+ resample->channel_conversion = mono_to_stereo;
+ else if (in_channel == CH_LAYOUT_STEREO && out_channel == CH_LAYOUT_5POINT1)
+ resample->channel_conversion = ac3_5p1_mux;
+ else if (out_channel == CH_LAYOUT_MONO)
+ resample->channel_conversion = mono_downmix;
+ else {
+ resample->channel_conversion = stereo_downmix;
+ outsamples->audio->channel_layout = CH_LAYOUT_STEREO;
+ }
+
+ }
+
+ if (outsamples && insamples)
+ resample->channel_conversion(outsamples->data, insamples->data,
+ outsamples->audio->samples_nb,
+ num_ip_channels);
+ resample->temp_samples = outsamples;
+ resample->temp_samples_ptr = outsamples;
+}
+
+static void convert_sample_format_wrapper(AVFilterLink *link)
+{
+ ResampleContext *resample = link->dst->priv;
+ AVFilterBufferRef *insamples = resample->temp_samples_ptr;
+ AVFilterBufferRef *outsamples = resample->out_samples;
+ int out_channels, out_sample_size, planar, len;
+
+ /* Here, out_channels is same as input channels, we are only changing
+ * sample format. */
+ /* FIXME: Need to use hamming weight counting function instead once it is
+ * added to libavutil. */
+ out_channels = avcodec_channel_layout_num_channels(insamples->audio->channel_layout);
+ out_sample_size = av_get_bits_per_sample_format(resample->out_sample_fmt) >> 3;
+
+ planar = insamples->audio->planar;
+ len = insamples->audio->samples_nb;
+
+ if (resample->reconfig_sample_fmt || !outsamples || !outsamples->audio->size) {
+ int size = out_channels * out_sample_size * insamples->audio->samples_nb;
+
+ if (outsamples)
+ avfilter_unref_buffer(outsamples);
+ outsamples = avfilter_get_audio_buffer(link, AV_PERM_WRITE|AV_PERM_REUSE2,
+ resample->out_sample_fmt, size,
+ insamples->audio->channel_layout, 0);
+
+ if (resample->conv_handle_out)
+ av_audio_convert_free(resample->conv_handle_out);
+ resample->conv_handle_out = av_audio_convert_alloc(resample->out_sample_fmt,
+ out_channels, insamples->format,
+ out_channels, NULL, 0);
+ }
+
+ /* Timestamp and sample rate can change even while sample format/channel layout remain the same */
+ outsamples->pts = insamples->pts;
+ outsamples->audio->sample_rate = insamples->audio->sample_rate;
+
+ av_audio_convert(resample->conv_handle_out, (void* const*)outsamples->data,
+ outsamples->linesize, (const void* const*)insamples->data,
+ insamples->linesize, len);
+
+ resample->out_samples = outsamples;
+ resample->out_samples_ptr = outsamples;
+
+}
+
+static void convert_s16_format_wrapper(AVFilterLink *link, AVFilterBufferRef *insamples)
+{
+ ResampleContext *resample = link->dst->priv;
+ AVFilterBufferRef *outsamples = resample->s16_samples;
+ int out_channels, planar, len;
+
+ /* Here, out_channels is same as input channels, we are only changing sample format */
+ out_channels = avcodec_channel_layout_num_channels(insamples->audio->channel_layout);
+ planar = insamples->audio->planar;
+ len = insamples->audio->samples_nb;
+
+ if (resample->reconfig_sample_fmt || !outsamples || !outsamples->audio->size) {
+ int size = out_channels*2*insamples->audio->samples_nb;
+
+ if (outsamples)
+ avfilter_unref_buffer(outsamples);
+ outsamples = avfilter_get_audio_buffer(link, AV_PERM_WRITE|AV_PERM_REUSE2,
+ SAMPLE_FMT_S16, size,
+ insamples->audio->channel_layout, 0);
+
+ if (resample->conv_handle_s16)
+ av_audio_convert_free(resample->conv_handle_s16);
+ resample->conv_handle_s16 = av_audio_convert_alloc(SAMPLE_FMT_S16, out_channels,
+ insamples->format, out_channels,
+ NULL, 0);
+ }
+
+ /* Timestamp and sample rate can change even while sample format/channel layout remain the same */
+ outsamples->pts = insamples->pts;
+ outsamples->audio->sample_rate = insamples->audio->sample_rate;
+
+ av_audio_convert(resample->conv_handle_s16, (void* const*)outsamples->data,
+ outsamples->linesize, (const void* const*)insamples->data,
+ insamples->linesize, len);
+
+ resample->s16_samples = outsamples;
+ resample->s16_samples_ptr = outsamples;
+}
+
+static int config_props(AVFilterLink *link)
+{
+ AVFilterContext *ctx = link->dst;
+ ResampleContext *resample = ctx->priv;
+
+ if (resample->out_channel_layout == -1)
+ resample->out_channel_layout = link->channel_layout;
+
+ if (resample->out_sample_fmt == -1)
+ resample->out_sample_fmt = link->format;
+
+ return 0;
+}
+
+static void filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref)
+{
+ ResampleContext *resample = link->dst->priv;
+ AVFilterLink *outlink = link->dst->outputs[0];
+ short samples_nb_changed = 0;
+
+ /**
+ * If input data of this buffer differs from the earlier buffer/s, set flag
+ * to reconfigure the channel and sample format conversions.
+ */
+ samples_nb_changed = (samplesref->audio->samples_nb != resample->in_nb_samples);
+ resample->in_nb_samples = samplesref->audio->samples_nb;
+ resample->reconfig_sample_fmt = (samplesref->format != resample->in_sample_fmt) || samples_nb_changed;
+ resample->in_sample_fmt = samplesref->format;
+ resample->reconfig_channel_layout = (samplesref->audio->channel_layout != resample->in_channel_layout) || samples_nb_changed;
+ resample->in_channel_layout = samplesref->audio->channel_layout;
+
+ /* Convert to s16 sample format first, then to desired channel layout and finally to desired sample format */
+
+ if (samplesref->format == SAMPLE_FMT_S16)
+ resample->s16_samples_ptr = samplesref;
+ else
+ convert_s16_format_wrapper(link, samplesref);
+
+ if (samplesref->audio->channel_layout == resample->out_channel_layout)
+ resample->temp_samples_ptr = resample->s16_samples_ptr;
+ else
+ convert_channel_layout(link);
+
+ if (resample->out_sample_fmt == SAMPLE_FMT_S16)
+ resample->out_samples_ptr = resample->temp_samples_ptr;
+ else
+ convert_sample_format_wrapper(link);
+
+ avfilter_filter_samples(outlink, avfilter_ref_buffer(resample->out_samples_ptr, ~0));
+ avfilter_unref_buffer(samplesref);
+}
+
+AVFilter avfilter_af_resample = {
+ .name = "resample",
+ .description = NULL_IF_CONFIG_SMALL("Reformat the input audio to sample_fmt:channel_layout."),
+
+ .init = init,
+ .uninit = uninit,
+
+ .query_formats = query_formats,
+
+ .priv_size = sizeof(ResampleContext),
+
+ .inputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .filter_samples = filter_samples,
+ .config_props = config_props,
+ .min_perms = AV_PERM_READ, },
+ { .name = NULL}},
+ .outputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO, },
+ { .name = NULL}},
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index c5da648..de3b78a 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -35,6 +35,7 @@ void avfilter_register_all(void)
initialized = 1;
REGISTER_FILTER (ANULL, anull, af);
+ REGISTER_FILTER (RESAMPLE, resample, af);
REGISTER_FILTER (ANULLSRC, anullsrc, asrc);
--
1.7.1
--pWyiEgJYm5f9v55/--
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