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fix(mp4): Use fixed-width integer types in bswap functions #1923

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Merged
cfsmp3 merged 1 commit into from
Dec 29, 2025
Merged

fix(mp4): Use fixed-width integer types in bswap functions #1923

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16 changes: 9 additions & 7 deletions src/lib_ccx/mp4.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,15 +31,17 @@
#define GF_ISOM_SUBTYPE_MPEG4 GF_4CC('M', 'P', 'E', 'G')
#endif

static short bswap16(short v)
static int16_t bswap16(int16_t v)
{
return ((v >> 8) & 0x00FF) | ((v << 8) & 0xFF00);
}

static long bswap32(long v)
static int32_t bswap32(int32_t v)
{
// For 0x12345678 returns 78563412
long swapped = ((v & 0xFF) << 24) | ((v & 0xFF00) << 8) | ((v & 0xFF0000) >> 8) | ((v & 0xFF000000) >> 24);
// Use int32_t instead of long for consistent behavior across platforms
// (long is 4 bytes on Windows x64 but 8 bytes on Linux x64)
int32_t swapped = ((v & 0xFF) << 24) | ((v & 0xFF00) << 8) | ((v & 0xFF0000) >> 8) | ((v & 0xFF000000) >> 24);
return swapped;
}
static struct
Expand Down Expand Up @@ -82,10 +84,10 @@ static int process_avc_sample(struct lib_ccx_ctx *ctx, u32 timescale, GF_AVCConf
nal_length = s->data[i];
break;
case 2:
nal_length = bswap16(*(short *)&s->data[i]);
nal_length = bswap16(*(int16_t *)&s->data[i]);
break;
case 4:
nal_length = bswap32(*(long *)&s->data[i]);
nal_length = bswap32(*(int32_t *)&s->data[i]);
break;
}
const u32 previous_index = i;
Expand Down Expand Up @@ -151,10 +153,10 @@ static int process_hevc_sample(struct lib_ccx_ctx *ctx, u32 timescale, GF_HEVCCo
nal_length = s->data[i];
break;
case 2:
nal_length = bswap16(*(short *)&s->data[i]);
nal_length = bswap16(*(int16_t *)&s->data[i]);
break;
case 4:
nal_length = bswap32(*(long *)&s->data[i]);
nal_length = bswap32(*(int32_t *)&s->data[i]);
break;
default:
mprint("Unexpected nal_unit_size %u in HEVC config\n", c->nal_unit_size);
Expand Down
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