lavfi: add asrc_abuffer - audio buffer source

Originally based on code by Stefano Sabatini and S. N. Hemanth.
Signed-off-by: Stefano Sabatini <stefano.sabatini-lala@poste.it>

configure

@@ -1501,6 +1501,7 @@ tcp_protocol_deps="network"
 udp_protocol_deps="network"
 
 # filters
+abuffer="strtok_r"
 aformat_filter_deps="strtok_r"
 blackframe_filter_deps="gpl"
 boxblur_filter_deps="gpl"

doc/filters.texi

@@ -194,6 +194,51 @@ Adler-32 checksum for each input frame plane, expressed in the form
 
 Below is a description of the currently available audio sources.
 
+@section abuffer
+
+Buffer audio frames, and make them available to the filter chain.
+
+This source is mainly intended for a programmatic use, in particular
+through the interface defined in @file{libavfilter/asrc_abuffer.h}.
+
+It accepts the following mandatory parameters:
+@var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
+
+@table @option
+
+@item sample_rate
+The sample rate of the incoming audio buffers.
+
+@item sample_fmt
+The sample format of the incoming audio buffers.
+Either a sample format name or its corresponging integer representation from
+the enum AVSampleFormat in @file{libavutil/samplefmt.h}
+
+@item channel_layout
+The channel layout of the incoming audio buffers.
+Either a channel layout name from channel_layout_map in
+@file{libavutil/audioconvert.c} or its corresponding integer representation
+from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
+
+@item packing
+Either "packed" or "planar", or their integer representation: 0 or 1
+respectively.
+
+@end table
+
+For example:
+@example
+abuffer=44100:s16:stereo:planar
+@end example
+
+will instruct the source to accept planar 16bit signed stereo at 44100Hz.
+Since the sample format with name "s16" corresponds to the number
+1 and the "stereo" channel layout corresponds to the value 3, this is
+equivalent to:
+@example
+abuffer=44100:1:3:1
+@end example
+
 @section anullsrc
 
 Null audio source, never return audio frames. It is mainly useful as a

libavfilter/Makefile

@@ -24,6 +24,7 @@ OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_ARESAMPLE_FILTER)              += af_aresample.o
 OBJS-$(CONFIG_ASHOWINFO_FILTER)              += af_ashowinfo.o
 
+OBJS-$(CONFIG_ABUFFER_FILTER)                += asrc_abuffer.o
 OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
 
 OBJS-$(CONFIG_ABUFFERSINK_FILTER)            += asink_abuffer.o

libavfilter/allfilters.c

@@ -39,6 +39,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (ARESAMPLE,   aresample,   af);
     REGISTER_FILTER (ASHOWINFO,   ashowinfo,   af);
 
+    REGISTER_FILTER (ABUFFER,     abuffer,     asrc);
     REGISTER_FILTER (ANULLSRC,    anullsrc,    asrc);
 
     REGISTER_FILTER (ABUFFERSINK, abuffersink, asink);

libavfilter/asrc_abuffer.h

+/*
+ * 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
+ */
+
+#ifndef AVFILTER_ASRC_ABUFFER_H
+#define AVFILTER_ASRC_ABUFFER_H
+
+#include "avfilter.h"
+
+/**
+ * @file
+ * memory buffer source for audio
+ */
+
+/**
+ * Queue an audio buffer to the audio buffer source.
+ *
+ * @param abuffersrc audio source buffer context
+ * @param data pointers to the samples planes
+ * @param linesize linesizes of each audio buffer plane
+ * @param nb_samples number of samples per channel
+ * @param sample_fmt sample format of the audio data
+ * @param ch_layout channel layout of the audio data
+ * @param planar flag to indicate if audio data is planar or packed
+ * @param pts presentation timestamp of the audio buffer
+ * @param flags unused
+ */
+int av_asrc_buffer_add_samples(AVFilterContext *abuffersrc,
+                               uint8_t *data[8], int linesize[8],
+                               int nb_samples, int sample_rate,
+                               int sample_fmt, int64_t ch_layout, int planar,
+                               int64_t pts, int av_unused flags);
+
+/**
+ * Queue an audio buffer to the audio buffer source.
+ *
+ * This is similar to av_asrc_buffer_add_samples(), but the samples
+ * are stored in a buffer with known size.
+ *
+ * @param abuffersrc audio source buffer context
+ * @param buf pointer to the samples data, packed is assumed
+ * @param size the size in bytes of the buffer, it must contain an
+ * integer number of samples
+ * @param sample_fmt sample format of the audio data
+ * @param ch_layout channel layout of the audio data
+ * @param pts presentation timestamp of the audio buffer
+ * @param flags unused
+ */
+int av_asrc_buffer_add_buffer(AVFilterContext *abuffersrc,
+                              uint8_t *buf, int buf_size,
+                              int sample_rate,
+                              int sample_fmt, int64_t ch_layout, int planar,
+                              int64_t pts, int av_unused flags);
+
+/**
+ * Queue an audio buffer to the audio buffer source.
+ *
+ * @param abuffersrc audio source buffer context
+ * @param samplesref buffer ref to queue
+ * @param flags unused
+ */
+int av_asrc_buffer_add_audio_buffer_ref(AVFilterContext *abuffersrc,
+                                        AVFilterBufferRef *samplesref,
+                                        int av_unused flags);
+
+#endif /* AVFILTER_ASRC_ABUFFER_H */

libavfilter/avfilter.h

@@ -29,7 +29,7 @@
 #include "libavutil/rational.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR 33
+#define LIBAVFILTER_VERSION_MINOR 34
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \