Interplay MVE: Implement frame format 0x10

This implements the 0x10 frame format for Interplay MVE movies. The
format is a variation on the 0x06 format with some changes. In addition
to the decoding map there's also a skip map. This skip map is used to
determine what 8x8 blocks can change in a particular frame.

This format expects to be able to copy an 8x8 block from before the last
time it was changed. This can be an arbitrary time in the past. In order
to implement this this decoder allocates two additional AVFrames where
actual decoding happens. At the end of a frame decoding changed blocks
are copied to a finished frame based on the skip map.

The skip map's encoding is a little convulted, I'll refer to the code
for details.

Values in the decoding map are the same as in format 0x06.

Signed-off-by: Hein-Pieter van Braam <hp@tmm.cx>

1 files changed, 52 insertions, 16 deletions

diff --git a/libavformat/ipmovie.c b/libavformat/ipmovie.c
index 7f2454b..7f5a8c6 100644
--- a/libavformat/ipmovie.c
+++ b/libavformat/ipmovie.c
@@ -66,9 +66,9 @@
 #define OPCODE_CREATE_GRADIENT         0x0B
 #define OPCODE_SET_PALETTE             0x0C
 #define OPCODE_SET_PALETTE_COMPRESSED  0x0D
-#define OPCODE_UNKNOWN_0E              0x0E
+#define OPCODE_SET_SKIP_MAP            0x0E
 #define OPCODE_SET_DECODING_MAP        0x0F
-#define OPCODE_UNKNOWN_10              0x10
+#define OPCODE_VIDEO_DATA_10           0x10
 #define OPCODE_VIDEO_DATA_11           0x11
 #define OPCODE_UNKNOWN_12              0x12
 #define OPCODE_UNKNOWN_13              0x13
@@ -107,6 +107,8 @@ typedef struct IPMVEContext {
     int audio_chunk_size;
     int64_t video_chunk_offset;
     int video_chunk_size;
+    int64_t skip_map_chunk_offset;
+    int skip_map_chunk_size;
     int64_t decode_map_chunk_offset;
     int decode_map_chunk_size;
 
@@ -156,9 +158,9 @@ static int load_ipmovie_packet(IPMVEContext *s, AVIOContext *pb,
 
     } else if (s->frame_format) {
 
-        /* send the frame format, decode map, the video data, and the send_buffer flag together */
+        /* send the frame format, decode map, the video data, skip map, and the send_buffer flag together */
 
-        if (av_new_packet(pkt, 6 + s->decode_map_chunk_size + s->video_chunk_size))
+        if (av_new_packet(pkt, 8 + s->decode_map_chunk_size + s->video_chunk_size + s->skip_map_chunk_size))
             return CHUNK_NOMEM;
 
         if (s->has_palette) {
@@ -181,6 +183,7 @@ static int load_ipmovie_packet(IPMVEContext *s, AVIOContext *pb,
         AV_WL8(pkt->data + 1, s->send_buffer);
         AV_WL16(pkt->data + 2, s->video_chunk_size);
         AV_WL16(pkt->data + 4, s->decode_map_chunk_size);
+        AV_WL16(pkt->data + 6, s->skip_map_chunk_size);
 
         s->frame_format = 0;
         s->send_buffer = 0;
@@ -189,24 +192,39 @@ static int load_ipmovie_packet(IPMVEContext *s, AVIOContext *pb,
         avio_seek(pb, s->video_chunk_offset, SEEK_SET);
         s->video_chunk_offset = 0;
 
-        if (avio_read(pb, pkt->data + 6, s->video_chunk_size) !=
+        if (avio_read(pb, pkt->data + 8, s->video_chunk_size) !=
             s->video_chunk_size) {
             av_packet_unref(pkt);
             return CHUNK_EOF;
         }
 
-        pkt->pos = s->decode_map_chunk_offset;
-        avio_seek(pb, s->decode_map_chunk_offset, SEEK_SET);
-        s->decode_map_chunk_offset = 0;
+        if (s->decode_map_chunk_size) {
+            pkt->pos = s->decode_map_chunk_offset;
+            avio_seek(pb, s->decode_map_chunk_offset, SEEK_SET);
+            s->decode_map_chunk_offset = 0;
 
-        if (avio_read(pb, pkt->data + 6 + s->video_chunk_size,
-            s->decode_map_chunk_size) != s->decode_map_chunk_size) {
-            av_packet_unref(pkt);
-            return CHUNK_EOF;
+            if (avio_read(pb, pkt->data + 8 + s->video_chunk_size,
+                s->decode_map_chunk_size) != s->decode_map_chunk_size) {
+                av_packet_unref(pkt);
+                return CHUNK_EOF;
+            }
+        }
+
+        if (s->skip_map_chunk_size) {
+            pkt->pos = s->skip_map_chunk_offset;
+            avio_seek(pb, s->skip_map_chunk_offset, SEEK_SET);
+            s->skip_map_chunk_offset = 0;
+
+            if (avio_read(pb, pkt->data + 8 + s->video_chunk_size + s->decode_map_chunk_size,
+                s->skip_map_chunk_size) != s->skip_map_chunk_size) {
+                av_packet_unref(pkt);
+                return CHUNK_EOF;
+            }
         }
 
         s->video_chunk_size = 0;
         s->decode_map_chunk_size = 0;
+        s->skip_map_chunk_size = 0;
 
         pkt->stream_index = s->video_stream_index;
         pkt->pts = s->video_pts;
@@ -444,8 +462,6 @@ static int process_ipmovie_chunk(IPMVEContext *s, AVIOContext *pb,
                     s->video_width, s->video_height);
             break;
 
-        case OPCODE_UNKNOWN_0E:
-        case OPCODE_UNKNOWN_10:
         case OPCODE_UNKNOWN_12:
         case OPCODE_UNKNOWN_13:
         case OPCODE_UNKNOWN_14:
@@ -527,6 +543,15 @@ static int process_ipmovie_chunk(IPMVEContext *s, AVIOContext *pb,
             avio_skip(pb, opcode_size);
             break;
 
+        case OPCODE_SET_SKIP_MAP:
+            av_log(s->avf, AV_LOG_TRACE, "set skip map\n");
+
+            /* log position and move on for now */
+            s->skip_map_chunk_offset = avio_tell(pb);
+            s->skip_map_chunk_size = opcode_size;
+            avio_skip(pb, opcode_size);
+            break;
+
         case OPCODE_SET_DECODING_MAP:
             av_log(s->avf, AV_LOG_TRACE, "set decoding map\n");
 
@@ -546,6 +571,16 @@ static int process_ipmovie_chunk(IPMVEContext *s, AVIOContext *pb,
             avio_skip(pb, opcode_size);
             break;
 
+        case OPCODE_VIDEO_DATA_10:
+            av_log(s->avf, AV_LOG_TRACE, "set video data format 0x10\n");
+            s->frame_format = 0x10;
+
+            /* log position and move on for now */
+            s->video_chunk_offset = avio_tell(pb);
+            s->video_chunk_size = opcode_size;
+            avio_skip(pb, opcode_size);
+            break;
+
         case OPCODE_VIDEO_DATA_11:
             av_log(s->avf, AV_LOG_TRACE, "set video data format 0x11\n");
             s->frame_format = 0x11;
@@ -614,8 +649,9 @@ static int ipmovie_read_header(AVFormatContext *s)
     /* initialize private context members */
     ipmovie->video_pts = ipmovie->audio_frame_count = 0;
     ipmovie->audio_chunk_offset = ipmovie->video_chunk_offset =
-    ipmovie->decode_map_chunk_offset = 0;
-    ipmovie->decode_map_chunk_size = ipmovie->video_chunk_size = 0;
+    ipmovie->decode_map_chunk_offset = ipmovie->skip_map_chunk_offset = 0;
+    ipmovie->decode_map_chunk_size = ipmovie->video_chunk_size =
+    ipmovie->skip_map_chunk_size = 0;
     ipmovie->send_buffer = ipmovie->frame_format = 0;
 
     /* on the first read, this will position the stream at the first chunk */