--- /dev/null
+/*
+ * MPEG-4 Audio common code
+ * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
+ *
+ * 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
+ */
+
+#include "bitstream.h"
+#include "mpeg4audio.h"
+
+const int ff_mpeg4audio_sample_rates[16] = {
+ 96000, 88200, 64000, 48000, 44100, 32000,
+ 24000, 22050, 16000, 12000, 11025, 8000, 7350
+};
+
+const uint8_t ff_mpeg4audio_channels[8] = {
+ 0, 1, 2, 3, 4, 5, 6, 8
+};
+
+static inline int get_object_type(GetBitContext *gb)
+{
+ int object_type = get_bits(gb, 5);
+ if (object_type == 31)
+ object_type = 32 + get_bits(gb, 6);
+ return object_type;
+}
+
+static inline int get_sample_rate(GetBitContext *gb, int *index)
+{
+ *index = get_bits(gb, 4);
+ return *index == 0x0f ? get_bits(gb, 24) :
+ ff_mpeg4audio_sample_rates[*index];
+}
+
+int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
+{
+ GetBitContext gb;
+ int specific_config_bitindex;
+
+ init_get_bits(&gb, buf, buf_size*8);
+ c->object_type = get_object_type(&gb);
+ c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
+ c->chan_config = get_bits(&gb, 4);
+ c->sbr = -1;
+ if (c->object_type == 5) {
+ c->ext_object_type = c->object_type;
+ c->sbr = 1;
+ c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
+ c->object_type = get_object_type(&gb);
+ } else
+ c->ext_object_type = 0;
+
+ specific_config_bitindex = get_bits_count(&gb);
+
+ if (c->ext_object_type != 5) {
+ int bits_left = buf_size*8 - specific_config_bitindex;
+ for (; bits_left > 15; bits_left--) {
+ if (show_bits(&gb, 11) == 0x2b7) { // sync extension
+ get_bits(&gb, 11);
+ c->ext_object_type = get_object_type(&gb);
+ if (c->ext_object_type == 5 && (c->sbr = get_bits1(&gb)) == 1)
+ c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
+ break;
+ } else
+ get_bits1(&gb); // skip 1 bit
+ }
+ }
+ return specific_config_bitindex;
+}
--- /dev/null
+/*
+ * MPEG-4 Audio common header
+ * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
+ *
+ * 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 FFMPEG_MPEG4AUDIO_H
+#define FFMPEG_MPEG4AUDIO_H
+
+#include <stdint.h>
+
+typedef struct {
+ int object_type;
+ int sampling_index;
+ int sample_rate;
+ int chan_config;
+ int sbr; //< -1 implicit, 1 presence
+ int ext_object_type;
+ int ext_sampling_index;
+ int ext_sample_rate;
+} MPEG4AudioConfig;
+
+extern const int ff_mpeg4audio_sample_rates[16];
+extern const uint8_t ff_mpeg4audio_channels[8];
+/**
+ * Parse MPEG-4 systems extradata to retrieve audio configuration.
+ * @param[in] c MPEG4AudioConfig structure to fill.
+ * @param[in] buf Extradata from container.
+ * @param[in] buf_size Extradata size.
+ * @return On error -1 is returned, on success AudioSpecificConfig bit index in extradata.
+ */
+int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size);
+
+#endif /* FFMPEG_MPEGAUDIO_H */