[FFmpeg-devel] [PATCH 04/12] avcodec/sanm: misc fixes

[Manuel Lauss]

- clear the front buffer with color 0 when processing data.
  Fixes a lot of Rebel Assault 1 videos and Rebel Assault 2 space
  scenes (e.g. 08PLAY.SAN which consists only of codec1/2/21 objects
  which only ever touch parts of the buffer).
- for ANIMv1 (Rebel Assault 1): set palette index 0 to all zeroes.
  This fixes a lot of stray colors in e.g L1HANGAR.ANM, L2INTRO.ANM,
  space scenes.
- Esp in RA1, there are a lot of FRME objects which don't contain
  any video data (prebuffering some audio only). Account for that.

Signed-off-by: Manuel Lauss <manuel.lauss at gmail.com>
---
 libavcodec/sanm.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
index 9f656e6ba8..fbb6e7231a 100644
--- a/libavcodec/sanm.c
+++ b/libavcodec/sanm.c
@@ -515,6 +515,8 @@ static av_cold int decode_init(AVCodecContext *avctx)
         ctx->subversion = AV_RL16(avctx->extradata);
         for (i = 0; i < PALETTE_SIZE; i++)
             ctx->pal[i] = 0xFFU << 24 | AV_RL32(avctx->extradata + 2 + i * 4);
+        if (ctx->subversion < 2)
+            ctx->pal[0] = 0xFFU << 24;
     }
 
     return 0;
@@ -1349,6 +1351,8 @@ static int process_xpal(SANMVideoContext *ctx, int size)
         if (size >= PALETTE_DELTA * 2 + 4 + PALETTE_SIZE * 3) {
             for (i = 0; i < PALETTE_SIZE; i++)
                 ctx->pal[i] = 0xFFU << 24 | bytestream2_get_be24u(&ctx->gb);
+            if (ctx->subversion < 2)
+                ctx->pal[0] = 0xFFU << 24;
         }
     }
     return 0;
@@ -1762,7 +1766,11 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
     bytestream2_init(&ctx->gb, pkt->data, pkt->size);
 
     if (!ctx->version) {
-        int to_store = 0;
+        int to_store = 0, have_pic = 0;
+
+        /* clear the front buffer */
+        if (ctx->frm0_size)
+            memset(ctx->frm0, 0, ctx->frm0_size);
 
         while (bytestream2_get_bytes_left(&ctx->gb) >= 8) {
             uint32_t sig, size;
@@ -1785,12 +1793,15 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
                 }
                 for (i = 0; i < PALETTE_SIZE; i++)
                     ctx->pal[i] = 0xFFU << 24 | bytestream2_get_be24u(&ctx->gb);
+                if (ctx->subversion < 2)
+                    ctx->pal[0] = 0xFFU << 24;
                 break;
             case MKBETAG('F', 'O', 'B', 'J'):
                 if (size < 16)
                     return AVERROR_INVALIDDATA;
                 if (ret = process_frame_obj(ctx))
                     return ret;
+                have_pic = 1;
                 break;
             case MKBETAG('X', 'P', 'A', 'L'):
                 if (ret = process_xpal(ctx, size))
@@ -1801,6 +1812,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
                 break;
             case MKBETAG('F', 'T', 'C', 'H'):
                 memcpy(ctx->frm0, ctx->stored_frame, ctx->buf_size);
+                have_pic = 1;
                 break;
             default:
                 bytestream2_skip(&ctx->gb, size);
@@ -1815,9 +1827,13 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
         }
         if (to_store)
             memcpy(ctx->stored_frame, ctx->frm0, ctx->buf_size);
-        if ((ret = copy_output(ctx, NULL)))
-            return ret;
-        memcpy(ctx->frame->data[1], ctx->pal, 1024);
+
+        if (have_pic && ctx->have_dimensions) {
+            if ((ret = copy_output(ctx, NULL)))
+                return ret;
+            memcpy(ctx->frame->data[1], ctx->pal, 1024);
+            *got_frame_ptr = 1;
+        }
     } else {
         SANMFrameHeader header;
 
@@ -1848,12 +1864,13 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
 
         if ((ret = copy_output(ctx, &header)))
             return ret;
+
+        *got_frame_ptr = 1;
+
     }
     if (ctx->rotate_code)
         rotate_bufs(ctx, ctx->rotate_code);
 
-    *got_frame_ptr = 1;
-
     return pkt->size;
 }
 
-- 
2.48.1