1 files changed, 156 insertions, 0 deletions
diff --git a/contrib/ffmpeg/libavcodec/ac3_parser.c b/contrib/ffmpeg/libavcodec/ac3_parser.c
new file mode 100644
index 000000000..9bda20380
--- /dev/null
+++ b/contrib/ffmpeg/libavcodec/ac3_parser.c
@@ -0,0 +1,156 @@
+/*
+ * AC3 parser
+ * Copyright (c) 2003 Fabrice Bellard.
+ * Copyright (c) 2003 Michael Niedermayer.
+ *
+ * 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 "parser.h"
+#include "ac3_parser.h"
+#include "aac_ac3_parser.h"
+#include "bitstream.h"
+
+
+#define AC3_HEADER_SIZE 7
+
+
+static const uint8_t eac3_blocks[4] = {
+    1, 2, 3, 6
+};
+
+
+int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
+{
+    GetBitContext gbc;
+    int frame_size_code;
+    int num_blocks;
+
+    memset(hdr, 0, sizeof(*hdr));
+
+    init_get_bits(&gbc, buf, 54);
+
+    hdr->sync_word = get_bits(&gbc, 16);
+    if(hdr->sync_word != 0x0B77)
+        return AC3_PARSE_ERROR_SYNC;
+
+    /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
+    hdr->bitstream_id = show_bits_long(&gbc, 29) & 0x1F;
+    if(hdr->bitstream_id > 16)
+        return AC3_PARSE_ERROR_BSID;
+
+    if(hdr->bitstream_id <= 10) {
+        /* Normal AC-3 */
+        hdr->crc1 = get_bits(&gbc, 16);
+        hdr->sr_code = get_bits(&gbc, 2);
+        if(hdr->sr_code == 3)
+            return AC3_PARSE_ERROR_SAMPLE_RATE;
+
+        frame_size_code = get_bits(&gbc, 6);
+        if(frame_size_code > 37)
+            return AC3_PARSE_ERROR_FRAME_SIZE;
+
+        skip_bits(&gbc, 5); // skip bsid, already got it
+
+        skip_bits(&gbc, 3); // skip bitstream mode
+        hdr->channel_mode = get_bits(&gbc, 3);
+        if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) {
+            skip_bits(&gbc, 2); // skip center mix level
+        }
+        if(hdr->channel_mode & 4) {
+            skip_bits(&gbc, 2); // skip surround mix level
+        }
+        if(hdr->channel_mode == AC3_CHMODE_STEREO) {
+            skip_bits(&gbc, 2); // skip dolby surround mode
+        }
+        hdr->lfe_on = get_bits1(&gbc);
+
+        hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
+        hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
+        hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
+        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
+        hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
+    } else {
+        /* Enhanced AC-3 */
+        hdr->crc1 = 0;
+        skip_bits(&gbc, 2); // skip stream type
+        skip_bits(&gbc, 3); // skip substream id
+
+        hdr->frame_size = (get_bits(&gbc, 11) + 1) << 1;
+        if(hdr->frame_size < AC3_HEADER_SIZE)
+            return AC3_PARSE_ERROR_FRAME_SIZE;
+
+        hdr->sr_code = get_bits(&gbc, 2);
+        if (hdr->sr_code == 3) {
+            int sr_code2 = get_bits(&gbc, 2);
+            if(sr_code2 == 3)
+                return AC3_PARSE_ERROR_SAMPLE_RATE;
+            hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
+            hdr->sr_shift = 1;
+            num_blocks = 6;
+        } else {
+            num_blocks = eac3_blocks[get_bits(&gbc, 2)];
+            hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
+            hdr->sr_shift = 0;
+        }
+
+        hdr->channel_mode = get_bits(&gbc, 3);
+        hdr->lfe_on = get_bits1(&gbc);
+
+        hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
+                        (num_blocks * 256.0));
+        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
+    }
+
+    return 0;
+}
+
+static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
+                    int *bit_rate, int *samples)
+{
+    int err;
+    AC3HeaderInfo hdr;
+
+    err = ff_ac3_parse_header(buf, &hdr);
+
+    if(err < 0)
+        return 0;
+
+    *sample_rate = hdr.sample_rate;
+    *bit_rate = hdr.bit_rate;
+    *channels = hdr.channels;
+    *samples = AC3_FRAME_SIZE;
+    return hdr.frame_size;
+}
+
+static int ac3_parse_init(AVCodecParserContext *s1)
+{
+    AACAC3ParseContext *s = s1->priv_data;
+    s->inbuf_ptr = s->inbuf;
+    s->header_size = AC3_HEADER_SIZE;
+    s->sync = ac3_sync;
+    return 0;
+}
+
+
+AVCodecParser ac3_parser = {
+    { CODEC_ID_AC3 },
+    sizeof(AACAC3ParseContext),
+    ac3_parse_init,
+    ff_aac_ac3_parse,
+    NULL,
+};