Disable all checksum verification in flac/metaflac
"Manuel Bertsch" <[email protected]> Thu, 29 Jun 2023 22:28:39 +0200
| Newsgroups | gmane.comp.audio.compression.flac.devel |
|---|---|
| Message-ID | <[email protected]> |
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Hello all,
=20
I=92m trying to use flac and metaflac as tooling to analyze the =
generated FLAC
files of a new encoder implementation. However, while my own third-party
decoder can handle the output just fine, flac, metaflac, and other tools
discard the output since the frame checksum (footer CRC-16) is invalid. =
This
is expected, since I have no checksum generation implemented apart from =
the
frame header checksum (all other checksums are written as 0), but it
prevents me from making development process without being able to check =
my
outputs against the reference implementation. I looked around and I =
couldn=92t
find a way to turn off either tool=92s checksum verification. So I=92d =
like to
know how one could turn off checksum verification in the tools, and if
that=92s not currently possible, I=92d like to see that as a feature in =
a future
version of flac. (In that case I would also try to disable the checks in
code permanently, though my solution is most likely not going to be
upstreamable in any capacity.)
=20
FYI, the third-party decoder is highly compliant according to the spec =
test
suite, producing identical audio playback on almost all of the files, =
but it
also doesn=92t verify or error on any checksums. ffplay and ffmpeg both =
accept
the file and can play and transcode it correctly, although they ignore =
the
sample count in the streaminfo header and will read all frames they can
find. The latter leads me to believe that checksums are the actual =
issue,
even though flac reports the generic =93Bad Header=94 and =93Lost =
Sync=94.
=20
Greetings and thanks in advance,
=20
Kleines Filmr=F6llchen
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link=3D"#0563C1" vlink=3D"#954F72"><div class=3DWordSection1><p =
class=3DMsoNormal>Hello all,<o:p></o:p></p><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal><span =
lang=3DEN-US>I’m trying to use flac and metaflac as tooling to =
analyze the generated FLAC files of a new encoder implementation. =
However, while my own third-party decoder can handle the output just =
fine, flac, metaflac, and other tools discard the output since the frame =
checksum (footer CRC-16) is invalid. This is expected, since I have no =
checksum generation implemented apart from the frame header checksum =
(all other checksums are written as 0), but it prevents me from making =
development process without being able to check my outputs against the =
reference implementation. I looked around and I couldn’t find a =
way to turn off either tool’s checksum verification. So I’d =
like to know how one could turn off checksum verification in the tools, =
and if that’s not currently possible, I’d like to see that =
as a feature in a future version of flac. (In that case I would also try =
to disable the checks in code permanently, though my solution is most =
likely not going to be upstreamable in any =
capacity.)<o:p></o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-US><o:p> </o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-US>FYI, the third-party decoder is highly compliant according =
to the spec test suite, producing identical audio playback on almost all =
of the files, but it also doesn’t verify or error on any =
checksums. ffplay and ffmpeg both accept the file and can play and =
transcode it correctly, although they ignore the sample count in the =
streaminfo header and will read all frames they can find. The latter =
leads me to believe that checksums are the actual issue, even though =
flac reports the generic “Bad Header” and “Lost =
Sync”.<o:p></o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-US><o:p> </o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-US>Greetings and thanks in advance,<o:p></o:p></span></p><p =
class=3DMsoNormal><span lang=3DEN-US><o:p> </o:p></span></p><p =
class=3DMsoNormal><span lang=3DEN-US>Kleines =
Filmr=F6llchen<o:p></o:p></span></p></div></body></html>
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