From ad5caf3ab74dcc2a8761c597ab8bee985026340f Mon Sep 17 00:00:00 2001
From: Alex Converse <alex.converse@gmail.com>
Date: Wed, 3 Jun 2009 18:50:46 +0000
Subject: AAC ADTS to AudioSpecificConfig bitstream filter

Originally committed as revision 19080 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/aac_adtstoasc_bsf.c | 114 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 libavcodec/aac_adtstoasc_bsf.c

(limited to 'libavcodec/aac_adtstoasc_bsf.c')

diff --git a/libavcodec/aac_adtstoasc_bsf.c b/libavcodec/aac_adtstoasc_bsf.c
new file mode 100644
index 0000000000..e6d51d0533
--- /dev/null
+++ b/libavcodec/aac_adtstoasc_bsf.c
@@ -0,0 +1,114 @@
+/*
+ * MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration bitstream filter
+ * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
+ *
+ * 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 "avcodec.h"
+#include "aac_parser.h"
+#include "put_bits.h"
+#include "get_bits.h"
+#include "mpeg4audio.h"
+#include "internal.h"
+
+typedef struct AACBSFContext {
+    int first_frame_done;
+} AACBSFContext;
+
+/**
+ * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
+ * ADTS header and removes the ADTS header.
+ */
+static int aac_adtstoasc_filter(AVBitStreamFilterContext *bsfc,
+                                AVCodecContext *avctx, const char *args,
+                                uint8_t  **poutbuf, int *poutbuf_size,
+                                const uint8_t *buf, int      buf_size,
+                                int keyframe)
+{
+    GetBitContext gb;
+    PutBitContext pb;
+    AACADTSHeaderInfo hdr;
+
+    AACBSFContext *ctx = bsfc->priv_data;
+
+    init_get_bits(&gb, buf, AAC_ADTS_HEADER_SIZE*8);
+
+    *poutbuf = (uint8_t*) buf;
+    *poutbuf_size = buf_size;
+
+    if (avctx->extradata)
+        if (show_bits(&gb, 12) != 0xfff)
+            return 0;
+
+    if (ff_aac_parse_header(&gb, &hdr) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
+        return -1;
+    }
+
+    if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
+        ff_log_missing_feature(avctx, "Multiple RDBs per frame with CRC is", 0);
+        return -1;
+    }
+
+    buf      += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
+    buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
+
+    if (!ctx->first_frame_done) {
+        int            pce_size = 0;
+        uint8_t        pce_data[MAX_PCE_SIZE];
+        if (!hdr.chan_config) {
+            init_get_bits(&gb, buf, buf_size);
+            if (get_bits(&gb, 3) != 5) {
+                ff_log_missing_feature(avctx, "PCE based channel configuration, where the PCE is not the first syntax element is", 0);
+                return -1;
+            }
+            init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
+            pce_size = ff_copy_pce_data(&pb, &gb)/8;
+            flush_put_bits(&pb);
+            buf_size -= get_bits_count(&gb)/8;
+            buf      += get_bits_count(&gb)/8;
+        }
+        avctx->extradata_size = 2 + pce_size;
+        avctx->extradata = av_malloc(avctx->extradata_size);
+
+        init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
+        put_bits(&pb, 5, hdr.object_type);
+        put_bits(&pb, 4, hdr.sampling_index);
+        put_bits(&pb, 4, hdr.chan_config);
+        put_bits(&pb, 1, 0); //frame length - 1024 samples
+        put_bits(&pb, 1, 0); //does not depend on core coder
+        put_bits(&pb, 1, 0); //is not extension
+        flush_put_bits(&pb);
+        if (pce_size) {
+            memcpy(avctx->extradata + 2, pce_data, pce_size);
+        }
+
+        ctx->first_frame_done = 1;
+    }
+
+    *poutbuf = (uint8_t*) buf;
+    *poutbuf_size = buf_size;
+
+    return 0;
+}
+
+AVBitStreamFilter aac_adtstoasc_bsf = {
+    "aac_adtstoasc",
+    sizeof(AACBSFContext),
+    aac_adtstoasc_filter,
+};
-- 
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