ffmpeg source update for sep 09

source/patched-ffmpeg-mt/libavformat/ac3dec.c

+/*
+ * RAW AC-3 and E-AC-3 demuxer
+ * Copyright (c) 2007 Justin Ruggles <justin.ruggles@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 "libavutil/crc.h"
+#include "libavcodec/ac3_parser.h"
+#include "avformat.h"
+#include "rawdec.h"
+
+static int ac3_eac3_probe(AVProbeData *p, enum CodecID expected_codec_id)
+{
+    int max_frames, first_frames = 0, frames;
+    uint8_t *buf, *buf2, *end;
+    AC3HeaderInfo hdr;
+    GetBitContext gbc;
+    enum CodecID codec_id = CODEC_ID_AC3;
+
+    max_frames = 0;
+    buf = p->buf;
+    end = buf + p->buf_size;
+
+    for(; buf < end; buf++) {
+        buf2 = buf;
+
+        for(frames = 0; buf2 < end; frames++) {
+            init_get_bits(&gbc, buf2, 54);
+            if(ff_ac3_parse_header(&gbc, &hdr) < 0)
+                break;
+            if(buf2 + hdr.frame_size > end ||
+               av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, hdr.frame_size - 2))
+                break;
+            if (hdr.bitstream_id > 10)
+                codec_id = CODEC_ID_EAC3;
+            buf2 += hdr.frame_size;
+        }
+        max_frames = FFMAX(max_frames, frames);
+        if(buf == p->buf)
+            first_frames = frames;
+    }
+    if(codec_id != expected_codec_id) return 0;
+    // keep this in sync with mp3 probe, both need to avoid
+    // issues with MPEG-files!
+    if   (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
+    else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
+    else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
+    else if(max_frames>=1) return 1;
+    else                   return 0;
+}
+
+#if CONFIG_AC3_DEMUXER
+static int ac3_probe(AVProbeData *p)
+{
+    return ac3_eac3_probe(p, CODEC_ID_AC3);
+}
+
+AVInputFormat ac3_demuxer = {
+    "ac3",
+    NULL_IF_CONFIG_SMALL("raw AC-3"),
+    0,
+    ac3_probe,
+    ff_raw_audio_read_header,
+    ff_raw_read_partial_packet,
+    .flags= AVFMT_GENERIC_INDEX,
+    .extensions = "ac3",
+    .value = CODEC_ID_AC3,
+};
+#endif
+
+#if CONFIG_EAC3_DEMUXER
+static int eac3_probe(AVProbeData *p)
+{
+    return ac3_eac3_probe(p, CODEC_ID_EAC3);
+}
+
+AVInputFormat eac3_demuxer = {
+    "eac3",
+    NULL_IF_CONFIG_SMALL("raw E-AC-3"),
+    0,
+    eac3_probe,
+    ff_raw_audio_read_header,
+    ff_raw_read_partial_packet,
+    .flags= AVFMT_GENERIC_INDEX,
+    .extensions = "eac3",
+    .value = CODEC_ID_EAC3,
+};
+#endif