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Code Issues Releases Activity

lavf/mxfdec: Speed up klv_read_packet()

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Tomas Härdin 2024-09-14 11:48:09 +02:00
parent 262e6f8430
commit e3fa469a55
1 changed files with 18 additions and 1 deletions
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19
libavformat/mxfdec.c
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@ -458,10 +458,26 @@ static int mxf_read_sync(AVIOContext *pb, const uint8_t *key, unsigned size)
return i == size; return i == size;
} }
// special case of mxf_read_sync for mxf_klv_key
static int mxf_read_sync_klv(AVIOContext *pb)
{
uint32_t key = avio_rb32(pb);
// key will never match mxf_klv_key on EOF
if (key == AV_RB32(mxf_klv_key))
return 1;
while (!avio_feof(pb)) {
key = (key << 8) | avio_r8(pb);
if (key == AV_RB32(mxf_klv_key))
return 1;
}
return 0;
}
static int klv_read_packet(MXFContext *mxf, KLVPacket *klv, AVIOContext *pb) static int klv_read_packet(MXFContext *mxf, KLVPacket *klv, AVIOContext *pb)
{ {
int64_t length, pos; int64_t length, pos;
if (!mxf_read_sync(pb, mxf_klv_key, 4)) if (!mxf_read_sync_klv(pb))
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
klv->offset = avio_tell(pb) - 4; klv->offset = avio_tell(pb) - 4;
if (klv->offset < mxf->run_in) if (klv->offset < mxf->run_in)
@ -3982,6 +3998,7 @@ static int mxf_read_packet(AVFormatContext *s, AVPacket *pkt)
ret = klv_read_packet(mxf, &klv, s->pb); ret = klv_read_packet(mxf, &klv, s->pb);
if (ret < 0) if (ret < 0)
break; break;
// klv.key[0..3] == mxf_klv_key from here forward
max_data_size = klv.length; max_data_size = klv.length;
pos = klv.next_klv - klv.length; pos = klv.next_klv - klv.length;
PRINT_KEY(s, "read packet", klv.key); PRINT_KEY(s, "read packet", klv.key);