avcodec: add cri parser

1 files changed, 105 insertions, 0 deletions

diff --git a/libavcodec/cri_parser.c b/libavcodec/cri_parser.c
new file mode 100644
index 0000000000..9790747a9e
--- /dev/null
+++ b/libavcodec/cri_parser.c
@@ -0,0 +1,105 @@
+/*
+ * CRI parser
+ * Copyright (c) 2021 Paul B Mahol
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * CRI parser
+ */
+
+#include "libavutil/bswap.h"
+#include "libavutil/common.h"
+
+#include "parser.h"
+
+typedef struct CRIParser {
+    ParseContext pc;
+    int count;
+    int chunk;
+    int read_bytes;
+    int skip_bytes;
+} CRIParser;
+
+#define KEY (((uint64_t)'\1' << 56) | ((uint64_t)'\0' << 48) | \
+             ((uint64_t)'\0' << 40) | ((uint64_t)'\0' << 32) | \
+             ((uint64_t)'\4' << 24) | ((uint64_t)'\0' << 16) | \
+             ((uint64_t)'\0' <<  8) | ((uint64_t)'\0' <<  0))
+
+static int cri_parse(AVCodecParserContext *s, AVCodecContext *avctx,
+                     const uint8_t **poutbuf, int *poutbuf_size,
+                     const uint8_t *buf, int buf_size)
+{
+    CRIParser *bpc = s->priv_data;
+    uint64_t state = bpc->pc.state64;
+    int next = END_NOT_FOUND, i = 0;
+
+    s->pict_type = AV_PICTURE_TYPE_I;
+    s->key_frame = 1;
+    s->duration  = 1;
+
+    *poutbuf_size = 0;
+    *poutbuf = NULL;
+
+    for (; i < buf_size; i++) {
+        state = (state << 8) | buf[i];
+        bpc->read_bytes++;
+
+        if (bpc->skip_bytes > 0) {
+            bpc->skip_bytes--;
+            if (bpc->skip_bytes == 0)
+                bpc->read_bytes = 0;
+        } else {
+            if (state != KEY)
+                continue;
+        }
+
+        if (bpc->skip_bytes == 0 && bpc->read_bytes >= 8) {
+            bpc->skip_bytes = av_bswap32(state & 0xFFFFFFFF);
+            bpc->chunk = state >> 32;
+            bpc->read_bytes = 0;
+            bpc->count++;
+        }
+
+        if (bpc->chunk == 0x01000000 && bpc->skip_bytes == 4 &&
+            bpc->read_bytes == 0 && bpc->count > 1) {
+            next = i - 7;
+            break;
+        }
+    }
+
+    bpc->pc.state64 = state;
+    if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0) {
+        *poutbuf = NULL;
+        *poutbuf_size = 0;
+        return buf_size;
+    }
+
+    *poutbuf      = buf;
+    *poutbuf_size = buf_size;
+
+    return next;
+}
+
+AVCodecParser ff_cri_parser = {
+    .codec_ids      = { AV_CODEC_ID_CRI },
+    .priv_data_size = sizeof(CRIParser),
+    .parser_parse   = cri_parse,
+    .parser_close   = ff_parse_close,
+};