avcodec/dolby_e: split decoder and parser more thoroughly

Neither module should depend on the other.

Move shared functions to its own file for this purpose, and ensure
source files are compiled only when the required modules are enabled.

Signed-off-by: James Almer <jamrial@gmail.com>

1 files changed, 180 insertions, 0 deletions

diff --git a/libavcodec/dolby_e_parse.c b/libavcodec/dolby_e_parse.c
new file mode 100644
index 0000000000..df2ba4a017
--- /dev/null
+++ b/libavcodec/dolby_e_parse.c
@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2017 foo86
+ *
+ * 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 "get_bits.h"
+#include "put_bits.h"
+#include "dolby_e.h"
+
+static const uint8_t nb_programs_tab[MAX_PROG_CONF + 1] = {
+    2, 3, 2, 3, 4, 5, 4, 5, 6, 7, 8, 1, 2, 3, 3, 4, 5, 6, 1, 2, 3, 4, 1, 1
+};
+
+static const uint8_t nb_channels_tab[MAX_PROG_CONF + 1] = {
+    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 6, 6, 6, 6, 6, 6, 6, 4, 4, 4, 4, 8, 8
+};
+
+static int skip_input(DBEContext *s, int nb_words)
+{
+    if (nb_words > s->input_size) {
+        return AVERROR_INVALIDDATA;
+    }
+
+    s->input      += nb_words * s->word_bytes;
+    s->input_size -= nb_words;
+    return 0;
+}
+
+static int parse_key(DBEContext *s)
+{
+    if (s->key_present) {
+        const uint8_t *key = s->input;
+        int      ret = skip_input(s, 1);
+        if (ret < 0)
+            return ret;
+        return AV_RB24(key) >> 24 - s->word_bits;
+    }
+    return 0;
+}
+
+static int convert_input(DBEContext *s, int nb_words, int key)
+{
+    const uint8_t *src = s->input;
+    uint8_t *dst = s->buffer;
+    PutBitContext pb;
+    int i;
+
+    av_assert0(nb_words <= 1024u);
+
+    if (nb_words > s->input_size) {
+        return AVERROR_INVALIDDATA;
+    }
+
+    switch (s->word_bits) {
+    case 16:
+        for (i = 0; i < nb_words; i++, src += 2, dst += 2)
+            AV_WB16(dst, AV_RB16(src) ^ key);
+        break;
+    case 20:
+        init_put_bits(&pb, s->buffer, sizeof(s->buffer));
+        for (i = 0; i < nb_words; i++, src += 3)
+            put_bits(&pb, 20, AV_RB24(src) >> 4 ^ key);
+        flush_put_bits(&pb);
+        break;
+    case 24:
+        for (i = 0; i < nb_words; i++, src += 3, dst += 3)
+            AV_WB24(dst, AV_RB24(src) ^ key);
+        break;
+    default:
+        av_assert0(0);
+    }
+
+    return init_get_bits(&s->gb, s->buffer, nb_words * s->word_bits);
+}
+
+int ff_dolby_e_parse_init(DBEContext *s, const uint8_t *buf, int buf_size)
+{
+    int hdr;
+
+    if (buf_size < 3)
+        return AVERROR_INVALIDDATA;
+
+    hdr = AV_RB24(buf);
+    if ((hdr & 0xfffffe) == 0x7888e) {
+        s->word_bits = 24;
+    } else if ((hdr & 0xffffe0) == 0x788e0) {
+        s->word_bits = 20;
+    } else if ((hdr & 0xfffe00) == 0x78e00) {
+        s->word_bits = 16;
+    } else {
+        if (s->avctx)
+            av_log(s->avctx, AV_LOG_ERROR, "Invalid frame header\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    s->word_bytes  = s->word_bits + 7 >> 3;
+    s->input       = buf + s->word_bytes;
+    s->input_size  = buf_size / s->word_bytes - 1;
+    s->key_present = hdr >> 24 - s->word_bits & 1;
+
+    return 0;
+}
+
+int ff_dolby_e_parse_header(DBEContext *s, DolbyEHeaderInfo *hdr)
+{
+    int i, ret, key, mtd_size;
+
+    if ((key = parse_key(s)) < 0)
+        return key;
+    if ((ret = convert_input(s, 1, key)) < 0)
+        return ret;
+
+    skip_bits(&s->gb, 4);
+    mtd_size = get_bits(&s->gb, 10);
+    if (!mtd_size) {
+        if (s->avctx)
+            av_log(s->avctx, AV_LOG_ERROR, "Invalid metadata size\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if ((ret = convert_input(s, mtd_size, key)) < 0)
+        return ret;
+
+    skip_bits(&s->gb, 14);
+    hdr->prog_conf = get_bits(&s->gb, 6);
+    if (hdr->prog_conf > MAX_PROG_CONF) {
+        if (s->avctx)
+            av_log(s->avctx, AV_LOG_ERROR, "Invalid program configuration\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    hdr->nb_channels = nb_channels_tab[hdr->prog_conf];
+    hdr->nb_programs = nb_programs_tab[hdr->prog_conf];
+
+    hdr->fr_code      = get_bits(&s->gb, 4);
+    hdr->fr_code_orig = get_bits(&s->gb, 4);
+    if (!sample_rate_tab[hdr->fr_code] ||
+        !sample_rate_tab[hdr->fr_code_orig]) {
+        if (s->avctx)
+            av_log(s->avctx, AV_LOG_ERROR, "Invalid frame rate code\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    skip_bits_long(&s->gb, 88);
+    for (i = 0; i < hdr->nb_channels; i++)
+        hdr->ch_size[i] = get_bits(&s->gb, 10);
+    hdr->mtd_ext_size = get_bits(&s->gb, 8);
+    hdr->meter_size   = get_bits(&s->gb, 8);
+
+    skip_bits_long(&s->gb, 10 * hdr->nb_programs);
+    for (i = 0; i < hdr->nb_channels; i++) {
+        hdr->rev_id[i]     = get_bits(&s->gb,  4);
+        skip_bits1(&s->gb);
+        hdr->begin_gain[i] = get_bits(&s->gb, 10);
+        hdr->end_gain[i]   = get_bits(&s->gb, 10);
+    }
+
+    if (get_bits_left(&s->gb) < 0) {
+        if (s->avctx)
+            av_log(s->avctx, AV_LOG_ERROR, "Read past end of metadata\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    return skip_input(s, mtd_size + 1);
+}