This gives some gains, but would probably be nicer if it leveraged the
type system by defining a specific type for 12-byte keys so there can
be no accidental mixup
/Tomas
From 367a59ac08624326841bfbecbb5cffb664567d27 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomas=20H=C3=A4rdin?= <g...@haerdin.se>
Date: Sat, 14 Sep 2024 11:48:45 +0200
Subject: [PATCH 2/5] lavf/mxfdec: Add and use IS_KLV_KEY_FAST() in some places
---
libavformat/mxfdec.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 99bf352e00..5fe6918353 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -376,6 +376,8 @@ static const uint8_t mxf_mastering_display_uls[4][16] = {
};
#define IS_KLV_KEY(x, y) (!memcmp(x, y, sizeof(y)))
+// IS_KLV_KEY_FAST can be used when we know the first four bytes are mxf_klv_key
+#define IS_KLV_KEY_FAST(x, y) (!memcmp(&x[4], &y[4], sizeof(y) - 4))
static void mxf_free_metadataset(MXFMetadataSet **ctx, enum MXFMetadataSetType type)
{
@@ -3740,7 +3742,7 @@ static int mxf_read_header(AVFormatContext *s)
size_t x;
ret = klv_read_packet(mxf, &klv, s->pb);
- if (ret < 0 || IS_KLV_KEY(klv.key, ff_mxf_random_index_pack_key)) {
+ if (ret < 0 || IS_KLV_KEY_FAST(klv.key, ff_mxf_random_index_pack_key)) {
if (ret >= 0 && avio_size(s->pb) > klv.next_klv)
av_log(s, AV_LOG_WARNING, "data after the RandomIndexPack, assuming end of file\n");
/* EOF - seek to previous partition or stop */
@@ -3753,11 +3755,11 @@ static int mxf_read_header(AVFormatContext *s)
PRINT_KEY(s, "read header", klv.key);
av_log(s, AV_LOG_TRACE, "size %"PRIu64" offset %#"PRIx64"\n", klv.length, klv.offset);
if (mxf_match_uid(klv.key, mxf_encrypted_triplet_key, sizeof(mxf_encrypted_triplet_key)) ||
- IS_KLV_KEY(klv.key, mxf_essence_element_key) ||
- IS_KLV_KEY(klv.key, mxf_canopus_essence_element_key) ||
- IS_KLV_KEY(klv.key, mxf_avid_essence_element_key) ||
- IS_KLV_KEY(klv.key, mxf_system_item_key_cp) ||
- IS_KLV_KEY(klv.key, mxf_system_item_key_gc)) {
+ IS_KLV_KEY_FAST(klv.key, mxf_essence_element_key) ||
+ IS_KLV_KEY_FAST(klv.key, mxf_canopus_essence_element_key) ||
+ IS_KLV_KEY_FAST(klv.key, mxf_avid_essence_element_key) ||
+ IS_KLV_KEY_FAST(klv.key, mxf_system_item_key_cp) ||
+ IS_KLV_KEY_FAST(klv.key, mxf_system_item_key_gc)) {
if (!mxf->current_partition) {
av_log(mxf->fc, AV_LOG_ERROR, "found essence prior to first PartitionPack\n");
@@ -3785,7 +3787,7 @@ static int mxf_read_header(AVFormatContext *s)
for (x = 0; x < FF_ARRAY_ELEMS(mxf_metadata_read_table); x++) {
const MXFMetadataReadTableEntry *metadata = &mxf_metadata_read_table[x];
- if (IS_KLV_KEY(klv.key, metadata->key)) {
+ if (IS_KLV_KEY_FAST(klv.key, metadata->key)) {
if (metadata->read) {
if ((ret = mxf_parse_klv(mxf, klv, metadata->read, metadata->ctx_size, metadata->type)) < 0)
return ret;
@@ -4015,9 +4017,9 @@ static int mxf_read_packet(AVFormatContext *s, AVPacket *pkt)
klv = mxf->current_klv_data;
max_data_size = klv.next_klv - pos;
}
- if (IS_KLV_KEY(klv.key, mxf_essence_element_key) ||
- IS_KLV_KEY(klv.key, mxf_canopus_essence_element_key) ||
- IS_KLV_KEY(klv.key, mxf_avid_essence_element_key)) {
+ if (IS_KLV_KEY_FAST(klv.key, mxf_essence_element_key) ||
+ IS_KLV_KEY_FAST(klv.key, mxf_canopus_essence_element_key) ||
+ IS_KLV_KEY_FAST(klv.key, mxf_avid_essence_element_key)) {
int body_sid = find_body_sid_by_absolute_offset(mxf, klv.offset);
int index = mxf_get_stream_index(s, &klv, body_sid);
int64_t next_ofs;
--
2.39.2
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