diff options
| -rw-r--r-- | src/libmpeg2/header.c | 14 | ||||
| -rw-r--r-- | src/libmpeg2/mpeg2_internal.h | 4 |
2 files changed, 13 insertions, 5 deletions
diff --git a/src/libmpeg2/header.c b/src/libmpeg2/header.c index 7f1ef1fc8..c0df02c7f 100644 --- a/src/libmpeg2/header.c +++ b/src/libmpeg2/header.c @@ -101,6 +101,14 @@ static uint32_t get_bits(uint8_t *buffer, uint32_t count, uint32_t *bit_position return result; } +static int32_t get_bits_signed(uint8_t *buffer, uint32_t count, uint32_t *bit_position) { + uint32_t value = get_bits(buffer, count, bit_position); + uint32_t sign_mask = (uint32_t)(-1 << (count - 1)); + if (value & sign_mask) + value |= sign_mask; /* sign-extend value */ + return (int32_t)value; +} + void mpeg2_header_state_init (picture_t * picture) { picture->scan = mpeg2_scan_norm; @@ -291,13 +299,13 @@ static int picture_display_extension (picture_t * picture, uint8_t * buffer) { bit_position = 0; padding = get_bits(buffer, 4, &bit_position); - picture->frame_centre_horizontal_offset = get_bits(buffer, 16, &bit_position); + picture->frame_centre_horizontal_offset = get_bits_signed(buffer, 16, &bit_position); padding = get_bits(buffer, 1, &bit_position); - picture->frame_centre_vertical_offset = get_bits(buffer, 16, &bit_position); + picture->frame_centre_vertical_offset = get_bits_signed(buffer, 16, &bit_position); padding = get_bits(buffer, 1, &bit_position); #ifdef LOG_PAN_SCAN - printf("Pan & Scan centre (x,y) = (%u, %u)\n", + printf("Pan & Scan centre (x,y) = (%d, %d)\n", picture->frame_centre_horizontal_offset, picture->frame_centre_vertical_offset); #endif diff --git a/src/libmpeg2/mpeg2_internal.h b/src/libmpeg2/mpeg2_internal.h index c2ffbf909..345e73080 100644 --- a/src/libmpeg2/mpeg2_internal.h +++ b/src/libmpeg2/mpeg2_internal.h @@ -177,8 +177,8 @@ typedef struct picture_s { int progressive_sequence; int repeat_first_field; int progressive_frame; - uint32_t frame_centre_horizontal_offset; - uint32_t frame_centre_vertical_offset; + int32_t frame_centre_horizontal_offset; + int32_t frame_centre_vertical_offset; uint32_t video_format; uint32_t colour_description; uint32_t colour_primatives; |