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avcodec/sanm: minor comment and size detection changes

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Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
This commit is contained in:
Manuel Lauss
2025-10-09 10:25:10 +02:00
parent c46c1cb0db
commit aa91ae25b8
1 changed files with 15 additions and 18 deletions
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33
libavcodec/sanm.c
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@@ -1952,7 +1952,7 @@ static int process_frame_obj(SANMVideoContext *ctx, GetByteContext *gb,
uint16_t w, h, parm2;
uint8_t codec, param;
int16_t left, top;
int fsc, sote;
int fsc;
codec = bytestream2_get_byteu(gb);
param = bytestream2_get_byteu(gb);
@@ -1973,9 +1973,11 @@ static int process_frame_obj(SANMVideoContext *ctx, GetByteContext *gb,
/* codecs with their own buffers */
fsc = (codec == 37 || codec == 47 || codec == 48);
/* special case for "Shadows of the Empire" videos */
sote = ((w == 640) && (h == 272) && (codec == 47));
if (sote)
/* special case for "Shadows of the Empire" videos: they have top=60
* at all frames to vertically center the video in the 640x480 game
* window, but we don't need that.
*/
if ((w == 640) && (h == 272) && (top == 60) && (codec == 47))
left = top = 0;
if (!ctx->have_dimensions) {
@@ -1996,16 +1998,11 @@ static int process_frame_obj(SANMVideoContext *ctx, GetByteContext *gb,
/* detect common sizes */
xres = w + left;
yres = h + top;
if (sote) {
/* SotE: has top=60 at all times to center video
* inside the 640x480 game window
*/
xres = w;
yres = h;
ctx->have_dimensions = 1;
} else if (((xres == 424) && (yres == 260)) || /* RA2 */
((xres == 320) && (yres == 200)) || /* ft/dig/... */
((xres == 640) && (yres == 480))) { /* ol/comi/mots... */
if (((xres == 424) && (yres == 260)) || /* RA2 */
((xres == 320) && (yres == 200)) || /* FT/Dig */
((xres == 640) && (yres == 272)) || /* SotE */
((xres == 640) && (yres == 350)) || /* MotS */
((xres == 640) && (yres == 480))) {
ctx->have_dimensions = 1;
}
@@ -2394,8 +2391,8 @@ static int bl16_block(SANMVideoContext *ctx, int cx, int cy, int blk_size)
my = c47_mv[opcode][1];
/* The original implementation of this codec precomputes a table
* of int16_t all motion vectors for given image width.
* For larger widths, starting with 762 pixels, the calculation of
* of int16_t of all motion vectors a for given image width.
* For widths starting at 762 pixels, the calculation of
* mv table indices 1+ and 255- overflow the int16_t, inverting the
* sign of the offset. This is actively exploited in e.g. the
* "jonesopn_8.snm" video of "Indiana Jones and the Infernal Machine".
@@ -2810,8 +2807,8 @@ static int decode_anim(AVCodecContext *avctx, int *got_frame_ptr)
*/
bytestream2_seek(&ctx->gb, pos + size, SEEK_SET);
if ((pos + size) & 1) {
if (0 != bytestream2_get_byteu(&ctx->gb))
bytestream2_seek(&ctx->gb, pos + size, SEEK_SET);
if (bytestream2_peek_byte(&ctx->gb) == 0)
bytestream2_skip(&ctx->gb, 1);
}
}