move aac and ac3 parsers in their own files

Originally committed as revision 8941 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 162 insertions, 0 deletions

diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c
new file mode 100644
index 0000000000..0563b8b2b1
--- /dev/null
+++ b/libavcodec/ac3_parser.c
@@ -0,0 +1,162 @@
+/*
+ * 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;
+
+    memset(hdr, 0, sizeof(*hdr));
+
+    init_get_bits(&gbc, buf, 54);
+
+    hdr->sync_word = get_bits(&gbc, 16);
+    if(hdr->sync_word != 0x0B77)
+        return -1;
+
+    /* read ahead to bsid to make sure this is AC-3, not E-AC-3 */
+    hdr->bsid = show_bits_long(&gbc, 29) & 0x1F;
+    if(hdr->bsid > 10)
+        return -2;
+
+    hdr->crc1 = get_bits(&gbc, 16);
+    hdr->fscod = get_bits(&gbc, 2);
+    if(hdr->fscod == 3)
+        return -3;
+
+    hdr->frmsizecod = get_bits(&gbc, 6);
+    if(hdr->frmsizecod > 37)
+        return -4;
+
+    skip_bits(&gbc, 5); // skip bsid, already got it
+
+    hdr->bsmod = get_bits(&gbc, 3);
+    hdr->acmod = get_bits(&gbc, 3);
+    if((hdr->acmod & 1) && hdr->acmod != 1) {
+        hdr->cmixlev = get_bits(&gbc, 2);
+    }
+    if(hdr->acmod & 4) {
+        hdr->surmixlev = get_bits(&gbc, 2);
+    }
+    if(hdr->acmod == 2) {
+        hdr->dsurmod = get_bits(&gbc, 2);
+    }
+    hdr->lfeon = get_bits1(&gbc);
+
+    hdr->halfratecod = FFMAX(hdr->bsid, 8) - 8;
+    hdr->sample_rate = ff_ac3_freqs[hdr->fscod] >> hdr->halfratecod;
+    hdr->bit_rate = (ff_ac3_bitratetab[hdr->frmsizecod>>1] * 1000) >> hdr->halfratecod;
+    hdr->channels = ff_ac3_channels[hdr->acmod] + hdr->lfeon;
+    hdr->frame_size = ff_ac3_frame_sizes[hdr->frmsizecod][hdr->fscod] * 2;
+
+    return 0;
+}
+
+static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
+                    int *bit_rate, int *samples)
+{
+    int err;
+    unsigned int fscod, acmod, bsid, lfeon;
+    unsigned int strmtyp, substreamid, frmsiz, fscod2, numblkscod;
+    GetBitContext bits;
+    AC3HeaderInfo hdr;
+
+    err = ff_ac3_parse_header(buf, &hdr);
+
+    if(err < 0 && err != -2)
+        return 0;
+
+    bsid = hdr.bsid;
+    if(bsid <= 10) {             /* Normal AC-3 */
+        *sample_rate = hdr.sample_rate;
+        *bit_rate = hdr.bit_rate;
+        *channels = hdr.channels;
+        *samples = AC3_FRAME_SIZE;
+        return hdr.frame_size;
+    } else if (bsid > 10 && bsid <= 16) { /* Enhanced AC-3 */
+        init_get_bits(&bits, &buf[2], (AC3_HEADER_SIZE-2) * 8);
+        strmtyp = get_bits(&bits, 2);
+        substreamid = get_bits(&bits, 3);
+
+        if (strmtyp != 0 || substreamid != 0)
+            return 0;   /* Currently don't support additional streams */
+
+        frmsiz = get_bits(&bits, 11) + 1;
+        fscod = get_bits(&bits, 2);
+        if (fscod == 3) {
+            fscod2 = get_bits(&bits, 2);
+            numblkscod = 3;
+
+            if(fscod2 == 3)
+                return 0;
+
+            *sample_rate = ff_ac3_freqs[fscod2] / 2;
+        } else {
+            numblkscod = get_bits(&bits, 2);
+
+            *sample_rate = ff_ac3_freqs[fscod];
+        }
+
+        acmod = get_bits(&bits, 3);
+        lfeon = get_bits1(&bits);
+
+        *samples = eac3_blocks[numblkscod] * 256;
+        *bit_rate = frmsiz * (*sample_rate) * 16 / (*samples);
+        *channels = ff_ac3_channels[acmod] + lfeon;
+
+        return frmsiz * 2;
+    }
+
+    /* Unsupported bitstream version */
+    return 0;
+}
+
+static int ac3_parse_init(AVCodecParserContext *s1)
+{
+    AC3ParseContext *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(AC3ParseContext),
+    ac3_parse_init,
+    ac3_parse,
+    NULL,
+};