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authorDiego Biurrun <diego@biurrun.de>2017-04-26 18:57:54 +0200
committerDiego Biurrun <diego@biurrun.de>2017-05-02 18:50:34 +0200
commitb5f19f7478492307e4b4763aeac3180faf50e17f (patch)
tree0fb69992023b946295a3130e2066256e3caf88fe /libavcodec/adts_header.c
parent0ac1fec1c3dacedabbf3dd4122ef4bf8523e688c (diff)
downloadffmpeg-b5f19f7478492307e4b4763aeac3180faf50e17f.tar.gz
aac: Split function to parse ADTS header data into public and private part
This makes the currently semi-public avpriv_aac_parse_header() function private to libavcodec and adds a proper public API function to return the parts of the ADTS header required in libavformat.
Diffstat (limited to 'libavcodec/adts_header.c')
-rw-r--r--libavcodec/adts_header.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/libavcodec/adts_header.c b/libavcodec/adts_header.c
new file mode 100644
index 0000000000..3b845058ff
--- /dev/null
+++ b/libavcodec/adts_header.c
@@ -0,0 +1,71 @@
+/*
+ * Audio and Video frame extraction
+ * Copyright (c) 2003 Fabrice Bellard
+ * Copyright (c) 2003 Michael Niedermayer
+ * Copyright (c) 2009 Alex Converse
+ *
+ * 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
+ */
+
+#include "aac_ac3_parser.h"
+#include "adts_header.h"
+#include "adts_parser.h"
+#include "get_bits.h"
+#include "mpeg4audio.h"
+
+int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
+{
+ int size, rdb, ch, sr;
+ int aot, crc_abs;
+
+ if (get_bits(gbc, 12) != 0xfff)
+ return AAC_AC3_PARSE_ERROR_SYNC;
+
+ skip_bits1(gbc); /* id */
+ skip_bits(gbc, 2); /* layer */
+ crc_abs = get_bits1(gbc); /* protection_absent */
+ aot = get_bits(gbc, 2); /* profile_objecttype */
+ sr = get_bits(gbc, 4); /* sample_frequency_index */
+ if (!avpriv_mpeg4audio_sample_rates[sr])
+ return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
+ skip_bits1(gbc); /* private_bit */
+ ch = get_bits(gbc, 3); /* channel_configuration */
+
+ skip_bits1(gbc); /* original/copy */
+ skip_bits1(gbc); /* home */
+
+ /* adts_variable_header */
+ skip_bits1(gbc); /* copyright_identification_bit */
+ skip_bits1(gbc); /* copyright_identification_start */
+ size = get_bits(gbc, 13); /* aac_frame_length */
+ if (size < AV_AAC_ADTS_HEADER_SIZE)
+ return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
+
+ skip_bits(gbc, 11); /* adts_buffer_fullness */
+ rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */
+
+ hdr->object_type = aot + 1;
+ hdr->chan_config = ch;
+ hdr->crc_absent = crc_abs;
+ hdr->num_aac_frames = rdb + 1;
+ hdr->sampling_index = sr;
+ hdr->sample_rate = avpriv_mpeg4audio_sample_rates[sr];
+ hdr->samples = (rdb + 1) * 1024;
+ hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples;
+
+ return size;
+}