[FFmpeg-devel] [PATCH] avcodec: add photocd parser

[Paul B Mahol]

Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
 libavcodec/Makefile         |  1 +
 libavcodec/parsers.c        |  1 +
 libavcodec/photocd_parser.c | 87 +++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+)
 create mode 100644 libavcodec/photocd_parser.c

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 2ddf021f04..b06b028ae4 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1114,6 +1114,7 @@ OBJS-$(CONFIG_MPEGVIDEO_PARSER)        += mpegvideo_parser.o    \
                                           mpeg12.o mpeg12data.o
 OBJS-$(CONFIG_OPUS_PARSER)             += opus_parser.o opus.o opustab.o \
                                           opus_rc.o vorbis_data.o
+OBJS-$(CONFIG_PHOTOCD_PARSER)          += photocd_parser.o
 OBJS-$(CONFIG_PNG_PARSER)              += png_parser.o
 OBJS-$(CONFIG_PNM_PARSER)              += pnm_parser.o pnm.o
 OBJS-$(CONFIG_RV30_PARSER)             += rv34_parser.o
diff --git a/libavcodec/parsers.c b/libavcodec/parsers.c
index 93af25ac14..d3353a6b39 100644
--- a/libavcodec/parsers.c
+++ b/libavcodec/parsers.c
@@ -59,6 +59,7 @@ extern AVCodecParser ff_mpeg4video_parser;
 extern AVCodecParser ff_mpegaudio_parser;
 extern AVCodecParser ff_mpegvideo_parser;
 extern AVCodecParser ff_opus_parser;
+extern AVCodecParser ff_photocd_parser;
 extern AVCodecParser ff_png_parser;
 extern AVCodecParser ff_pnm_parser;
 extern AVCodecParser ff_rv30_parser;
diff --git a/libavcodec/photocd_parser.c b/libavcodec/photocd_parser.c
new file mode 100644
index 0000000000..844327f799
--- /dev/null
+++ b/libavcodec/photocd_parser.c
@@ -0,0 +1,87 @@
+/*
+ * PhotoCD 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
+ * PhotoCD parser
+ */
+
+#include "libavutil/common.h"
+
+#include "parser.h"
+
+typedef struct PhotoCDParser {
+    ParseContext pc;
+    int count;
+} PhotoCDParser;
+
+#define KEY (((uint64_t)'P' << 56) | ((uint64_t)'C' << 48) | \
+             ((uint64_t)'D' << 40) | ((uint64_t)'_' << 32) | \
+             ((uint64_t)'I' << 24) | ((uint64_t)'P' << 16) | \
+             ((uint64_t)'I' <<  8) | ((uint64_t)'\0'<<  0))
+
+static int photocd_parse(AVCodecParserContext *s, AVCodecContext *avctx,
+                     const uint8_t **poutbuf, int *poutbuf_size,
+                     const uint8_t *buf, int buf_size)
+{
+    PhotoCDParser *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];
+
+        if (state == KEY)
+            bpc->count++;
+
+        if (state == KEY && bpc->count >= 2) {
+            next = i - (7+2048);
+            bpc->count = 0;
+            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_photocd_parser = {
+    .codec_ids      = { AV_CODEC_ID_PHOTOCD },
+    .priv_data_size = sizeof(PhotoCDParser),
+    .parser_parse   = photocd_parse,
+    .parser_close   = ff_parse_close,
+};
-- 
2.17.1