[FFmpeg-devel] [PATCH 2/2] avcodec/sanm: codec31/32 (SEGA-CD) support
Manuel Lauss
manuel.lauss at gmail.com
Fri May 30 14:19:03 EEST 2025
codec31/32 are like codec1/3 (RLE coding) but with 2 4-bit pixels per byte.
---
libavcodec/sanm.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
index 46cad3c703..975f33992f 100644
--- a/libavcodec/sanm.c
+++ b/libavcodec/sanm.c
@@ -928,6 +928,62 @@ static int old_codec1(SANMVideoContext *ctx, GetByteContext *gb, int top,
return 0;
}
+static int old_codec31(SANMVideoContext *ctx, GetByteContext *gb, int top,
+ int left, int width, int height, int p1, int opaque)
+{
+ int i, j, len, flag, code, val, end, pxoff;
+ const int maxpxo = ctx->height * ctx->pitch;
+ uint8_t *dst = (uint8_t *)ctx->fbuf;
+
+ for (i = 0; i < height; i++) {
+ if (bytestream2_get_bytes_left(gb) < 2)
+ return AVERROR_INVALIDDATA;
+
+ len = bytestream2_get_le16u(gb);
+ end = bytestream2_tell(gb) + len;
+
+ pxoff = left + ((top + i) * ctx->pitch);
+ while (bytestream2_tell(gb) < end) {
+ if (bytestream2_get_bytes_left(gb) < 2)
+ return AVERROR_INVALIDDATA;
+
+ code = bytestream2_get_byteu(gb);
+ flag = code & 1;
+ code = (code >> 1) + 1;
+ if (flag) {
+ val = bytestream2_get_byteu(gb);
+ for (j = 0; j < code; j++) {
+ if ((0 != (val & 0xf)) || opaque) {
+ if (pxoff >= 0 && pxoff < maxpxo)
+ *(dst + pxoff) = p1 + (val & 0xf);
+ }
+ pxoff++;
+ if ((0 != (val >> 4)) || opaque) {
+ if (pxoff >= 0 && pxoff < maxpxo)
+ *(dst + pxoff) = p1 + (val >> 4);
+ }
+ pxoff++;
+ }
+ } else {
+ if (bytestream2_get_bytes_left(gb) < code)
+ return AVERROR_INVALIDDATA;
+ for (j = 0; j < code; j++) {
+ val = bytestream2_get_byteu(gb);
+ if ((pxoff >= 0) && (pxoff < maxpxo) && ((0 != (val & 0xf)) || opaque))
+ *(dst + pxoff) = p1 + (val & 0xf);
+ pxoff++;
+ if ((pxoff >= 0) && (pxoff < maxpxo) && ((0 != (val >> 4)) || opaque))
+ *(dst + pxoff) = p1 + (val >> 4);
+ pxoff++;
+ }
+ }
+ }
+ }
+ ctx->rotate_code = 0;
+
+ return 0;
+}
+
static int old_codec2(SANMVideoContext *ctx, GetByteContext *gb, int top,
int left, int width, int height)
{
@@ -1708,6 +1764,9 @@ static int process_frame_obj(SANMVideoContext *ctx, GetByteContext *gb)
return old_codec21(ctx, gb, top, left, w, h);
case 23:
return old_codec23(ctx, gb, top, left, w, h, param, parm2);
+ case 31:
+ case 32:
+ return old_codec31(ctx, gb, top, left, w, h, param, (codec == 32));
case 37:
ret = old_codec37(ctx, w, h); break;
case 45:
--
2.49.0
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