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Metadata: Parse ASFs (=WMVs)

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The simplest video-formats to parse so far.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
This commit is contained in:
Berthold Stoeger 2018-07-12 23:51:42 +02:00
parent 4de0b7dd3d
commit 772935b596
1 changed files with 85 additions and 0 deletions
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85
core/metadata.cpp
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@ -403,6 +403,89 @@ static bool parseAVI(QFile &f, metadata *metadata)
return found_riff;
}
static bool parseASF(QFile &f, metadata *metadata)
{
f.seek(0);
// Parse the header of the header object:
// id (16 bytes)
// size (8 bytes)
// number of header objects (4 bytes)
// reserved (2 bytes)
// ------------------------------------------
// total (30 bytes)
char header[30];
if (f.read(header, 30) != 30)
return false;
// Check if this is indeed an ASF header.
if (memcmp(&header[0], "\x30\x26\xb2\x75\x8e\x66\xcf\x11\xa6\xd9\x00\xaa\x00\x62\xce\x6c", 16) != 0)
return false;
uint64_t header_len = getLE<uint64_t>(&header[16]);
uint32_t num = getLE<uint32_t>(&header[24]);
// Sanity check
if (header_len <= 30 || num > 10000)
return false;
header_len -= 30;
// Read through all the header objects
for (uint32_t i = 0; i < num && header_len > 24; ++i) {
// Each objects starts with the same header:
// id (16 bytes)
// size (8 bytes)
char data[24];
if (f.read(data, 24) != 24)
return false;
uint64_t object_len = getLE<uint64_t>(&data[16]);
// Sanity check
if (object_len < 24 || object_len > header_len)
return false;
header_len -= object_len;
object_len -= 24;
if (!memcmp(data, "\xa1\xdc\xab\x8c\x47\xa9\xcf\x11\x8e\xe4\x0\xc0\xc\x20\x53\x65", 16) != 0) {
// This is a file properties object. The interesting data are:
// quadword (64 bit) at byte 24: creation date in 100-nanoseconds since Jan. 1, 1601.
// quadword (64 bit) at byte 40: duration in 100-nanoseconds.
// quadword (64 bit) at byte 56: offset in msec (to be subtracted from duration)
// But first a sanity check:
if (object_len < 80 || object_len > 4096)
break;
std::vector<char> v(object_len);
if (f.read(v.data(), object_len) != (int)object_len)
break;
uint64_t creation_date = getLE<uint64_t>(&v[24]);
// OK - first convert to seconds
creation_date /= 10000000;
// Check if this is during the UNIX epoch and convert into epoch
if (creation_date <= 11644473600)
metadata->timestamp = 0; // Can't determine creation date, sorry!
else
metadata->timestamp = creation_date - 11644473600;
uint64_t duration = getLE<uint64_t>(&v[40]);
uint64_t offset = getLE<uint64_t>(&v[56]);
metadata->duration.seconds = lrint(duration / 10000000.0 - offset / 1000.0);
// We found everything that we wanted -> return success
return true;
} else {
// Skip over unknown object
if (!f.seek(f.pos() + object_len)) // TODO: switch to QFile::skip()
break;
}
}
// We didn't find a file properties object. According to the ASF specification, this is
// *not* a valid ASF-file. Return failure accordingly.
return false;
}
extern "C" mediatype_t get_metadata(const char *filename_in, metadata *data)
{
data->timestamp = 0;
@ -422,6 +505,8 @@ extern "C" mediatype_t get_metadata(const char *filename_in, metadata *data)
res = MEDIATYPE_VIDEO;
else if(parseAVI(f, data))
res = MEDIATYPE_VIDEO;
else if(parseASF(f, data))
res = MEDIATYPE_VIDEO;
// If we couldn't get a creation date from the file (for example AVI files don't
// have a standard way of storing this datum), use the file creation date of the file.