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authorPřemysl Eric Janouch <p@janouch.name>2023-06-05 20:54:04 +0200
committerPřemysl Eric Janouch <p@janouch.name>2023-06-05 21:04:24 +0200
commit399c4bdf6980b463bc37f15dbeccbf64d2310f5c (patch)
tree0725666fb244822038fcf65f429b99c1f2659d1a /tools
parenta9b34ca3f27ed0b3c10effd3fb884936d9b02485 (diff)
downloadfiv-399c4bdf6980b463bc37f15dbeccbf64d2310f5c.tar.gz
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info: decode WebP dimensions
Diffstat (limited to 'tools')
-rw-r--r--tools/info.c51
1 files changed, 50 insertions, 1 deletions
diff --git a/tools/info.c b/tools/info.c
index 03da252..440939f 100644
--- a/tools/info.c
+++ b/tools/info.c
@@ -110,6 +110,49 @@ detect_webp(const uint8_t *p, size_t len)
}
static jv
+parse_webp_vp8(jv o, const uint8_t *p, size_t len)
+{
+ if (len < 10 || (p[0] & 1) != 0 /* key frame */ ||
+ p[3] != 0x9d || p[4] != 0x01 || p[5] != 0x2a) {
+ return add_warning(o, "invalid VP8 chunk");
+ }
+
+ o = jv_set(o, jv_string("width"), jv_number(u16le(p + 6) & 0x3fff));
+ o = jv_set(o, jv_string("height"), jv_number(u16le(p + 8) & 0x3fff));
+ return o;
+}
+
+static jv
+parse_webp_vp8l(jv o, const uint8_t *p, size_t len)
+{
+ if (len < 5 || p[0] != 0x2f)
+ return add_warning(o, "invalid VP8L chunk");
+
+ // Reading LSB-first from a little endian value means reading in order.
+ uint32_t header = u32le(p + 1);
+ o = jv_set(o, jv_string("width"), jv_number((header & 0x3fff) + 1));
+ header >>= 14;
+ o = jv_set(o, jv_string("height"), jv_number((header & 0x3fff) + 1));
+ header >>= 14;
+ o = jv_set(o, jv_string("alpha_is_used"), jv_bool(header & 1));
+ return o;
+}
+
+static jv
+parse_webp_vp8x(jv o, const uint8_t *p, size_t len)
+{
+ if (len < 10)
+ return add_warning(o, "invalid VP8X chunk");
+
+ // Most of the fields in this chunk are duplicate or inferrable.
+ // Probably not worth decoding or verifying.
+ // TODO(p): For animations, we need to use the width and height from here.
+ uint8_t flags = p[0];
+ o = jv_set(o, jv_string("animation"), jv_bool((flags >> 1) & 1));
+ return o;
+}
+
+static jv
parse_webp(jv o, const uint8_t *p, size_t len)
{
if (!detect_webp(p, len))
@@ -144,7 +187,13 @@ parse_webp(jv o, const uint8_t *p, size_t len)
chunks = jv_array_append(chunks, jv_string(fourcc));
p += 8;
- // TODO(p): Decode VP8 and VP8L chunk metadata.
+ // TODO(p): Decode more chunks.
+ if (!strcmp(fourcc, "VP8 "))
+ o = parse_webp_vp8(o, p, chunk_size);
+ if (!strcmp(fourcc, "VP8L"))
+ o = parse_webp_vp8l(o, p, chunk_size);
+ if (!strcmp(fourcc, "VP8X"))
+ o = parse_webp_vp8x(o, p, chunk_size);
if (!strcmp(fourcc, "EXIF"))
o = parse_exif(o, p, chunk_size);
if (!strcmp(fourcc, "ICCP"))